Wild poliovirus began circulating in Israel in early 2013 but, more than a year later, appears to have been halted with no cases of polio reported. Cotemporaneously, however, a sewage sample in Brazil from March tested positive for polio, a strain related to an outbreak in Equatorial Guinea. No further samples in Brazil have tested positive nor have any cases been reported. Risks are likely lower at the World Cup than the annual pilgrimage to Mecca where stringent vaccination requirements have squelched transmission since a large outbreak in 2005.

The caseless transmission seen in Israel is possible in any population immunized only with inactivated polio vaccine (IPV). IPV protects against the potentially debilitating effects of poliovirus but does not prevent infection. Infected vaccinees can remain healthy but still transmit the virus.

The virus in Israel is related to strains originating in Pakistan. Perhaps coming by way of Egypt, the virus found its way into southern Israel, in Be'er Sheva, and spread northward. Those affected were "[m]ainly Arab Israelis but we believe there was some circulation among Jewish populations," according to Itamar Grotto, Director, Public Health Services at the Israeli Ministry of Health. 

In the developing world, polio mostly circulates where a lack of sanitation systems and clean water lead to ingestion of feces-contaminated water harboring the virus. The virus can survive four to six weeks in sewage. However, in Israel, instead of unclean water, "person-to-person transmission [was] through 'dirty' hands," according to Apoorva Mollya, program manager at the Bill & Melinda Gates Foundation. 

Bruce Aylward, assistant director general at the World Health Organization (WHO), explained: "Polio is one of those viruses where you only need an incredibly small infectious dose to get infected. If the virus is circulating in an area, there’s a high probability that you could get exposed."

Research on an outbreak in 1992-93 in a partially-immunized primary school in the Netherlands found evidence of infection in one third of the students. In New York City in the 1950s, a school outbreak quickly spread to an apartment building then to two more schools. 

According to Donda Hansen at the Centers for Disease Control (CDC), person-to-person spread of poliovirus within households can be as rapid and efficient as the adenoviruses that cause colds.

Israel experienced no cases of polio because of very high population coverage with IPV, roughly 95%, and perhaps a bit of luck that the virus either did not reach or didn't cause disease among those without polio antibodies. To stamp out circulation, Israel employed oral polio vaccine (OPV). OPV not only protects against disease but produces a local, mucosal immune response that limits replication of the poliovirus in the intestine, breaking the oral-fecal chain of transmission. After two waves of vaccination aimed at children under ten, first in Israel and then the West Bank and Gaza Strip, sewage samples positive for polio stopped.

WHO waits half a year before judging a type-1 outbreak like Israel's to be extinguished. "[F]ingers crossed that they make it over the 6-month mark," said WHO spokesperson Sona Bari. But in the eyes of Itamar Grotto, "It really seems that the 'event' is over." 

Israel has added the oral vaccine back to its routine immunization schedule, although it is not without risks. OPV uses a live version of the virus which very rarely mutates and causes polio. There were no vaccine-derived cases in Israel even though millions of children were immunized, perhaps because they were already protected by IPV. The science is not conclusive, but according to the Gates Foundation's Mallya, "Generally, it is thought that IPV would protect/prevent against cVDPV (vaccine-derived poliorvirus)."

Brazil uses both. And with over 90% population coverage and polio-specific immunization campaigns every year, the population of Brazil is thought to be well-protected. Owing to the health emergency recently declared by WHO, travelers from polio-infected nations should be vaccinated at least four weeks before traveling. The annual pilgrimage to Mecca has similar requirements although no chances are being taken: "Irrespective of previous immunization history, all visitors under 15 years arriving in Saudi Arabia will also receive 1 dose of OPV at border points," according to Saudi health regulations. In 2005, Nigerian polio strains were suspected of leading to an outbreak of over 300 cases in Indonesia with pilgrims transporting the virus far across the globe, resulting in heightened vaccination requirements in 2006. 

[Note: See the latest developments here.]

A new paper suggests drug-resistant malaria might be present in Angola, perhaps brought there by an annual flow of some 40,000 Vietnamese migrant workers. Pockets of drug-resistant malaria, first found in Cambodia, now spot much of Southeast Asia, including Thailand, Vietnam, Myanmar and Laos. The expanding front comes despite containment efforts, begun in late 2008, aimed at preventing spread to Africa which already has the world’s highest malaria mortality.

A 58-year old Vietnamese construction worker returned from Angola after three years to his malaria-free village in Nam Dinh Province. Four days later, malaria symptoms appeared which went undiagnosed and eventually resulted in hospitalization. But artesunate, the frontline, fast-acting anti-malarial given to the patient, scarcely dented the number of teeming parasites. Even in severe malaria cases like this, patients usually begin to get better in just one day because artemisinin-based drugs act so quickly. (The patient also received the slower acting clindamycin to eliminate any parasites surviving the artemisinin onslaught, a combination approach meant to prevent drug resistance.)

Switching to a different combination of dihydroartemisinin and piperaquine also failed to knock down parasite levels. Only when subjected to quinine and doxycycline did malaria subside, allowing the once-endangered patient to return home about one month after admission.

The strength of resistance to the frontline artemisinin-based drugs seems considerably greater than that seen in Southeast Asia. As a rule of thumb, researchers suspect resistance if artemisinin doesn’t fully eliminate parasites after three days in cases of “uncomplicated” malaria. The Vietnamese patient’s severe malaria makes comparisons problematic. Still, Nick White, of Mahidol Oxford Tropical Medicine Research Unit, has "never seen such resistance, even in Cambodia." White, other researchers and the World Health Organization (WHO) are withholding final judgment as to whether this single case means artemisinin-resistant Plasmodium falciparum malaria is now present in Angola. According to White, “No, this doesn’t mean there is resistance in Africa—there may be but you need more than this.”

White raises the possibility that parasites actually killed by artemisinin might have remained in the patient’s blood, giving an appearance of resistance. Pascal Ringwald, WHO lead for the drug-resistant malaria containment effort, further explained: “the hyperparasitemia (10%) associated with insufficient drug blood levels could explain the extremely slow clearance after artesunate treatment...” Christopher Plowe, Howard Hughes Medical Institute investigator and professor at the University of Maryland, notes that “many factors other than intrinsic parasite resistance affect the treatment outcome, including immunity, fluid dynamics, pharmacokinetics and so forth.” But Plowe concludes: “This did look more like bona fide high-level resistance.” Continued Plowe:

“This is deeply worrying. It is just one case but the evidence of resistance is pretty good. It seems plausible that artemisinin-resistant parasites were carried to Angola from Vietnam and then locally transmitted among these migrant workers.”

How has it been missed, particularly if resistance is so strong? “Bit odd no one has noticed this before if this is a focus of the most artemisinin resistant parasites in the world,” observed White. Reports from Angola to WHO in 2013 found no evidence of resistance. There was “No sign of delayed clearance and 100% dihydroartemsinin-piperaquine efficacy,” according to Ringwald, who added that “Data were validated by CDC Atlanta.” However, Ringwald acknowledged that “the studies were not performed in the same province,” Luanda Sul, suspected as the origin of the drug-resistant malaria. The WorldWide Antimalarial Resistance Network (WWARN) has no data on Angola. WWARN is working on a study of three-day parasite clearance rates in Africa based on data from 15,000 patients, but fewer than one hundred are from Angola and come from a 2003 study in Kuito, well outside Luanda Sul province.*

A missing piece of the puzzle is whether malaria parasites in this case exhibit mutations in the K13 gene, a biomarker associated with artemisinin resistance in Southeast Asia. The status of such a test is far from clear. According to Ringwald, “It is not a WHO study and it not under our control,” who notes that the case occurred over a year ago. Conceivably, there are no samples to test. The corresponding author of the study did not reply to an email inquiry.

Ringwald downplays the importance of the case and asserts that “Artemisinin resistance is already reported in Africa.” But while mutations in K13 have been reported, clinical resistance in Africa has not. Also, the mutations reported there so far might merely be polymorphisms that are not part of a genetic network that confers resistance to artemisinin.

While Ringwald expressed skepticism about the Vietnamese case, “Nevertheless, we are investigating with CDC Atlanta in Angola if K13+ is also present like many other countries.” Further, in order “to reassure everybody we will specifically conduct [a study of parasite clearance rates] with dihydroartemisinin-piperaquine in the same province,” Luanda Sul .

--------------------------

Related: Drug resistant malaria takes new ground, raising fears of global spread

*This post has been updated. WWARN's study of three-day clearance in 15,000 people previously was said to have no data from Angola. The study includes 93 patients from Kuito, Angola in 2003.

The World Health Organization (WHO) recently declared polio to be a public health emergency, prompting fears and headlines about possible spread even to the United States. But the eradication goal actually sits closer than ever. The “emergency” comes not from health risk but schedule risk to the 2018 eradication deadline. Because polio is the number one priority of Bill Gates, WHO now invokes the specter of polio outbreaks, a ploy to galvanize the public reminiscent of weapons of mass destruction.

Polio is 99% wiped out, crushed over decades from hundreds of thousands of cases to fewer than 2,000 a year so far in the 21^st century. Risk of spread has only gone down together with the fall in cases and countries with transmission. Today, in two of the three remaining polio endemic countries, Nigeria and Afghanistan, cases hover tantalizingly close to zero, unprecedented historic lows. Pakistan, the third endemic country, has wrecked eradication progress for years. But the ongoing shooting of vaccinators by extremists in Pakistan, for example, did not prompt the polio “emergency.” Instead, WHO cited an outbreak of 36 cases in Syria and the subsequent export of a single case to Iraq. But the Syrian outbreak has been snuffed and amounts to nearly a non-event in the annals of polio conflagrations. The year before, Somalia saw a much larger, 194-case detonation, large enough to reach Kenya and Ethiopia and paralyze two dozen more. Today, WHO reports the other cause for alarm is cross border polio transmission from Cameroon to Equatorial Guinea. However, the six cases so far, while tragic, are inconsequential compared to Africa as recently as 2011 when four countries leapt from zero cases to 41. The same year, China saw an unprecedented 21 cases. No emergency.

Polio does not even merit consideration for emergency status. Swine flu occasioned WHO’s last emergency declaration in 2009, prompted by a rapid accumulation of 1,003 cases in 20 countries on four continents. Flu can spread swiftly, directly from human to human, unlike polio which usually comes from contact with feces-contaminated water. Wealthy nations are already highly vaccinated against polio whereas swine flu vaccination necessarily followed the discovery of the new virus, H1N1. In the United States, the Centers for Disease Control (CDC) estimated there were 57 million H1N1 infections resulting in 11,000 deaths. Polio rarely kills.

However, eradication efforts cost $1 billion a year, a sizeable piece of the $30 billion spent on global health annually. Eradication dollars could be spent on increasing coverage of routine vaccinations, building hospitals and health systems, or providing clean water. But Bill Gates champions polio eradication. It is “the single thing I work on the most,” according to Gates. And it’s his show: Gates, not WHO, orchestrated funding of the $5.5 billion effort to eradicate polio by 2018. “We’ve raised three-quarters of that money,” Gates reported in 2013. But the Gates-approved plan calls for ending transmission by 2014, already impossible. Eradication has never been closer, but the schedule is at risk. Thus the theater of polio public health emergency.

As the Gates Foundation blog notes, “The sounding of an emergency often is seen as a sign of distress, and news of this announcement certainly communicated that.” Indeed, the announcement fueled headlines like “Polio, Spreading Abroad, Threatens US.” However, “what this alarm really signals,” continued the foundation’s blog, is doing “what it takes to end this disease as quickly as possible,” which includes stoking false fear. The CDC isn’t stockpiling oral polio vaccine to extinguish outbreaks. Instead, the CDC said of the polio declaration: “we do not believe this reflects an increased risk to the US.” But with deadlines looming, a WHO spokesperson stated: “we need to pull out all the stops, which is what the emergency should help us to do.”

The International Health Regulations on emergencies emphasize “public health risk,” not schedule risk. Whether technically legitimate or not, the polio “emergency” hides its real motivation and makes people afraid when actual polio risks are close to the lowest level in all of human history.

Eradicating polio, while a noble intention, distorts rational global health priority-setting. Eradication gives the wealthy world a trophy to brandish before its own citizens and taxpayers while ignoring and overriding the priorities of the developing world. The polio emergency wraps this distortion in deception. Bill Gates believes eradication will serves as a symbol and portent of further triumphs. But he has substituted symbol manipulation for the pursuit of optimal global health policy in open society. 

Immunization coverage for polio continues to climb in Nigeria. The most recent campaigns in April reached more children than ever and continue a solid upward trend over the last two years. The key threshold of 80% coverage has been reached. That level, sustained over time, usually crushes polio inexorably.

India, in 2011, stood in similar circumstances just prior to the high season--and knocked polio out, enduringly. Nigeria has a chance as the high season approaches, beginning around July. However, elimination poses different challenges in every country. In Nigeria, not only widely-publicized security issues obstruct. But upcoming elections might also impinge on sustaining coverage gains. With luck, Nigeria might stop polio transmission this year. But the World Health Organization's Sona Bari cautions that India at this point, "was in a far stronger position in terms of surveillance quality, immunity levels and political commitment." Most likely, Nigeria is at the cusp of the cusp

Polio in Syria and the spread of a single case to Iraq "signal an absolute failure of the global eradication effort," according to an expert quoted by the New York Times. A Guardian headline described the new obstacles as the "most challenging in history." Even global health bloggers concluded eradication is "further off than it had been just a year ago." Actually, eradication is closer than ever. 

Outbreaks, while tragic and not to be taken lightly, are a spectacular side show. There are already five in 2014, equaling the total for all of 2013. But 19 outbreaks hammered the eradication project in 2009, clearly short of any breaking point. Polio coverage emphasizing outbreaks has completely missed that two of the three remaining endemic countries, Nigeria and Afghanistan, have seen only a single indigenous case of the disease this year. 

Nigeria has been steadily raising vaccination coverage in key high risk areas, accounting for the drop in cases. If coverage continues to climb, transmission might be interrupted and polio eliminated from the country. High season, which generally begins in July and extends through September, will be a major test. Any number of factors might derail progress. Still, today polio teeters closer than ever to extinction in Nigeria. 

In Afghanistan, all polio cases this year have been in eastern in provinces near Pakistan, and sequencing shows similarity to strains from from across the border. 

Pakistan performs much worse than the other two endemic nations, but despite even the targeting and killing of polio vaccinators, Pakistan's case level is not extraordinarily high by historical standards.

Choking off endemic sources stops outbreaks from occurring to begin with. Outbreaks plummeted after India knocked out polio at the end of 2010. The Global Polio Eradication Initiative has stamped out every single polio outbreak there has ever been; today there are five more that must also be dispatched. In Syria, the 41 cases so far and emergence of a single related case in Iraq is concerning. But a 2013 outbreak hit Somalia with 194 cases and spread a further two dozen cases to Kenya and Ethiopia. Nonetheless, that fire is now out and probably will remain far larger and thus more difficult than reckoning with the smaller (to this point) recrudescence in Syria. 

War in Syria undoubtedly complicates vaccination efforts there. But in Somalia, kidnappings and killings forced Médecins Sans Frontières to leave the country in the middle of the polio outbreak after more than two decades in the country.

Polio eradication, in retrospect, is not a good idea. "Vertical," single-disease campaigns are inferior to building health systems, and polio has never been as deadly as say, diarrhea. Eradication is extremely costly.

Regardless, however, polio eradication is succeeding. Local news reporting on fires and gunshots distorts the reality of less crime and fewer fires. Similarly, despite media coverage, eradication of polio has never been so near.

This is why polio cases in Nigeria are now hovering near zero. According to the Global Polio Eradication Initiative (3.12.2014):

...almost 90% of Local Government Areas (LGAs) in the 11 high-risk states achieved coverage of at least 80% during last week’s conducted IPDs. This compares to less than 65% of LGAs in these same states achieving the same level of coverage just 12 months ago.

If 80% coverage continues and expands geographically, endemic circulation of polio in Nigeria will likely end. 

As 2013 becomes history, efforts to combat polio have pushed the disease closer to a permanent place in the past. In the last tally of the year, only Pakistan reported new cases. Excepting eleven cases originating from Pakistan, Afghanistan experienced no polio in 2013. And Nigeria, which led the world in cases last year, has reported none since early October, a string of zeroes unprecedented in this century. [Update: Nigeria has subsequently reported a single case that dates to December 15.] Nigeria might also have recorded the world’s last case of type 3 polio more than a year ago, in November 2012; no type 3 cases have been reported anywhere since. Type 2 was eradicated in 1999, leaving only type 1 of the wild polio virus.

The spectacular outbreaks in Syria and Somalia, afflicting hundreds with polio-induced paralysis, originated from Pakistan and Nigeria respectively. A handful of cases in Cameroon also trace back to Nigeria. Until India snuffed out polio, about one year ago, the disease leapt to places as far away as Angola. But when the reservoirs are extinguished, the outbreaks cease. 

Although Nigeria has yet to run the mid-year gauntlet where cases have peaked over the last several years (see graph below), the multibillion dollar eradication program might now have polio cornered in Pakistan.

A spectacular polio outbreak—over 100 cases in Somalia—is obscuring progress in eradicating the disease. It’s not the first time. 2010 saw an even larger outbreak, 460 cases in Tajikistan.  Yet the next year, cases went to zero in India which once led the world in polio.

Today the good news is that the type three strain of polio might be gone forever, joining type two in oblivion and leaving only type one to reckon with.  There have been no type three cases detected in the world since last November.  However, because type three polio is less paralytic than type one, it is harder to detect. But surveillance is bulked up in places where type three has appeared previously. And, encouragingly, sewage samples have been negative suggesting an absence of asymptomatic circulation. Type two polio was driven to extinction in 1999, the last case appearing in India. The disappearance of type three would represent “another proof-of-principle, like the eradication of [type two],” according to WHO spokesperson Sona Bari. The virus is under pressure. “If [type three] can be interrupted, it gives us more evidence that [type one] eradication is not far behind.” Bari emphasizes, however, that “we are still holding our breath” to see if type three is really gone.

The Somali outbreak has little impact on the main eradication fronts: Nigeria, Pakistan and Afghanistan. Afghanistan has pushed cases down to just four this year, historic lows reached not with the help of chance as in the past but improvement in the quality of immunization campaigns, according to Apoorva Mallya, program officer at the Bill & Melinda Gates Foundation. The number of children never receiving vaccine is down. Because more children are being vaccinated, population immunity is up.

The gains in Afghanistan come against a backdrop of insecurity not unlike that in Somalia. Somalia suffered an outbreak of over 100 cases in 2005 but was polio free again by the end of 2007. The country has since served as the exemplar for smashing the virus despite instability. 

The eradication program doesn’t take the Somali outbreak lightly, but it is “nothing to detract from the 2018 timeline,” said Mallya of the plan to complete eradication. “Outbreaks are going to happen,” he said. The current eradication plan anticipates and budgets for them. Global capacity for rapidly subduing outbreaks has never been better. Indeed, the Somali outbreak could have received a different storyline, one of rapid and courageous response to a crisis.

Nigeria and Pakistan loom as far larger problems than outbreaks. It is not clear that case trajectories point enduringly down in those two countries. So far this year, cases number in the dozens, not the single digits that might augur eradication. And although Afghanistan represents a bright spot, it is inextricably tied to progress across borders with Pakistan where deadly attacks have been orchestrated against vaccinators.  

The remaining obstacles are daunting but of a kind that have been overcome before. Even with outbreaks, eradication can and likely will be done.

For decades, following failed efforts in the mid-20th century to eradicate malaria, global policy aimed to control the disease. However, in a single moment late in 2007, Melinda Gates switched the world back onto eradication. Today that aim is more distant than five years ago because of drug resistance, a paucity of new drugs, the failure of bed nets, and slim prospects for an effective vaccine. These developments raise questions about eradication and how the world sets global health policies.

Speaking at the first World Malaria Forum, convened by the Gates Foundation in 2007, Melinda Gates said the moment represented a “historic opportunity not just to treat malaria or to control it—but to chart a long-term course to eradicate it.” Director general of the World Health Organization (WHO), Margaret Chan, converted on the spot and, from the audience, stood to voice her approbation. Thus was a policy decided that affected hundreds of millions people. The small audience of blue-ribbon researchers and policy makers sat stunned. Eradication had been embarrassing or even catastrophic decades before. In just minutes and without peer review, eradication was back.

The last disease officially targeted for eradication was polio. In May 1988, the World Health Assembly, governing body of WHO, unanimously endorsed a polio eradication resolution.  Regarding whether there would be a vote on malaria eradication, a Gates Foundation spokesperson said: “Not as far as I know.” However eradication remains the de facto goal of malaria policy.

Towards the end of 2007, the head of malaria at WHO, Arata Kochi, spoke out against these incursions on WHO turf. He circulated a memo describing a "cartel" of leading malaria researchers assembled and funded by the Gates Foundation. Kochi noted “intense and aggressive opposition” from Gates-backed scientists and the foundation. His memo recommended that WHO “stand up to such pressures and ensure that the review of evidence is rigorously independent of vested interests.” Kochi was replaced after his memo leaked to the New York Times.

Behavioral economics

Over the last dozen years, WHO has been slowly going broke. By the time of the 2007 Gates Malaria Forum, the purchasing power of WHO’s budget had fallen by almost 25 percent compared with 2000.

Going down: WHO’s weighted purchasing power. (Source: WHO)

Adding to these difficulties, half the WHO budget formerly came directly from member nation contributions. Increasingly, however, WHO has been forced to scurry, hat in hand, competing for grants with many non-government organizations and other entities. By 2006, such “voluntary” contributions tied to specific activities reached three quarters of WHO’s budget, and they have stayed there. By 2010, the Gates Foundation was the second largest voluntary contributor to WHO, providing $220m, more than the United Kingdom. According to Chris Murray, professor of global health at the University of Washington, “the behavior of organizations is profoundly affected by where they get their money from.” Most funding for global health comes from nation states, yet the foundation wields a disproportionate influence. According to Murray, “the influence of the Gates Foundation far exceeds the fraction of development of assistance for health that channels through their resources.” The reason, he continued, “is the way they have been funding and who they have been funding around the world.”

Gates’ man in Geneva

The United States is by far the largest funder of WHO, contributing 23 percent of WHO’s discretionary budget, nearly twice that of the next largest contributor, Japan. As the leading WHO funder, the US begins with more influence than any other nation.

Wielding that influence is Nils Daulaire. In late 2010, President Obama nominated Daulaire to be the US representative to the WHO executive board. Prior to his nomination, Daulaire served for more than a decade as president and CEO of the Global Health Council. In 2000, Daulaire’s non-profit became responsible for selecting the winner of the $1m Gates Award for Global Health. Since 2000 the Global Health Council received more than $36m from the Gates Foundation, about 40 percent of the Council’s revenue, according to Daulaire.

Daulaire said he "does not see the Gates Foundation or private entities as having a rightful role in establishing WHO’s priorities.” He dismisses suggestions that the Gates Foundation has an outsized role although he said: “There are member states who believe the Gates Foundation has more influence than it ought.” Daulaire said it is “entirely wrong” that the United States is increasing the foundation’s role.

Nils Daulaire at the 2011 World Health Assembly (Source: US Mission Geneva)

Following Daulaire’s nomination, reform of WHO rose to the top of its agenda. WHO “hit a financial wall” in 2011,” according to Daulaire. He said the United States was not a prime mover on reform which he described as driven by economic considerations. But in a statement before the 2011 World Health Assembly, Daulaire said the "financing discussion has sparked an important discussion on the role of WHO at the center of global health and how to ensure the organization is best placed to respond to the challenges of the 21st century." Making these determinations would be a private consulting firm paid by the Gates Foundation.

WHO's executive board passed a proposal that addressed “the overall design of the program of reform,” one which would reengineer WHO head offices and the entire organization. The comprehensive review and changes would extend to “all expected results, indicators, targets and baselines.” Money for this rewrite of WHO’s institutional DNA had “been secured from the Bill & Melinda Gates Foundation,” according to the resolution. Daulaire said he had no involvement arranging the Gates funding. WHO staff are “given the license to hunt” for funds, he said. The Gates Foundation declined comment concerning its involvement in WHO reform.

The reform resolution also called for creation of a new entity, the World Health Forum. Its charter was to “define the rules of engagement in global health,” particularly among its many players. The Forum might potentially have revised the central role of WHO and the World Health Assembly, perhaps institutionalizing a role for privately-funded organizations, including corporations. Planning for the first World Health Forum, originally scheduled for the end of 2012, was to be funded by the Gates Foundation. But the proposal “received little support,” Margaret Chan told the executive board in November 2011, and the idea was shelved.

Nonetheless, the World Health Assembly (WHA) has adopted key policies initiated by the Gates Foundation, setting the global health agenda in the near and long term. The WHA adopted the foundation’s “Decade of vaccines” vision, first articulated by Bill Gates. Vaccines are hardly new to global health. But the idea of placing at them at the center of global health for the next ten years originated from the Gates Foundation. A foundation press release referred to “the January 2010 call by Bill and Melinda Gates for the next ten years to be the Decade of Vaccines. “ In 2011, Gates addressed the WHA, pressing for his vaccines vision. "Our priorities are your priorities," he said. He pointed to a shared interest in child and maternal mortality before talking "about how you can provide the leadership to make this the Decade of Vaccines." In 2012, the WHA gave Gates' vision its stamp of approval.

Shorter term, the Gates Foundation’s highest priority is polio eradication. Following a vote at the 2012 WHA, polio eradication is now the sole health emergency worldwide. The US delegation co-sponsored both the decade of vaccines and polio resolutions. “We were an early mover on polio,” said Daulaire of the polio resolution.  But Daulaire claimed that on polio, WHO led and the foundation followed. In email he wrote: “The Gates Foundation's wishes and priorities were not a consideration in the WHO debate, but it's nice that they are on board.” Chronologically, however, the Gates Foundation ratcheted polio to its top priority in 2010, with WHO following two years later.

With WHO’s disempowerment has come a drift toward irrelevance. “WHO would like to be a partner and work with you,” Margaret Chan importuned at a Gates-funded gathering of global health influentials in 2010. But confidence in WHO’s capacities has dwindled. In a particularly embarrassing revelation, academics Chris Murray and Alan Lopez reported in 2004 that WHO couldn’t count: “The sum of deaths claimed by different WHO programs exceeded the total number of deaths in the world.” Each disease department exaggerated deaths in a bid to maximize funding. Also, because WHO is comprised of member states, political considerations also influenced estimates, according to Murray and Lopez. They concluded: “the only viable solution will be to create a new, independent, health monitoring organization.”

Independent of who(m)?

In 2007, the Gates Foundation awarded Murray a 10-year, $105 million grant for a new Institute for Health Metrics and Evaluation (IHME), affiliated with the University of Washington. Murray’s group took a wrecking ball to WHO’s already crumbling credibility. Using new methods, IHME published different estimates than WHO for child, maternal and, most recently, malaria mortality. 

IHME has become an alternative, perhaps preferred alternative, for global health metrics, displacing WHO and other UN-related entities. The Lancet endorsed IHME’s methods and results by cosponsoring a conference with IHME on maternal and child mortality in 2010. At the conference, Lancet editor Richard Horton said global health metrics had “broken out of traditional citadels,” bringing a “democratization of health.”

IHME's Murray had lectured his students that “the behavior of organizations is profoundly affected by where they get their money from.” And IHME’s research and publicity on malaria, specifically bednets, may reflect Gates Foundation influence. IHME claimed bednets prevented deaths from malaria in a press release although their research did not support such a claim. (See the previous story in this series: Bednets are failing.)

From overstatement, IHME passed to non-statement on bednets. Earlier this year, a headline-making IHME paper in the Lancet on malaria mortality was silent on whether bednets saved the lives of African children even though hundreds of millions of nets have been distributed in one of the world's largest health interventions.

The paper did say, however, that bednets did not reduce deaths of adults in Africa. Only in email did IHME's Stephen Lim write  “ITNs [bednets] were a statistically significant predictor of African child mortality,” meaning bednets did save children under five in Africa from dying of malaria. If true, however, it is unclear why the peer-reviewed paper omitted such an important finding. IHME declined to answer questions in email regarding the statistical basis for the claim. Lead author of the paper, Chris Murray, did not reply to an email asking for confirmation of Lim's statement.

A Lancet editorial accompanying the IHME study said that "One aspect of the findings that is unlikely to raise objections is the implication that interventions scaled up since 2004 have been phenomenally successful in reducing the number of malaria deaths." The successful interventions included, said the editorial, the distribution of anti-malarial drugs and 230 million bednets. But the only finding on bednets in the IHME paper was a negative one, that nets did not save adults.

Lancet, heal thyself

In 2010, the Lancet ran a series on malaria elimination. An accompanying comment, co-written by Horton, concluded that the goal of elimination was “worthy, challenging, and just possible.” Although none of the Lancet articles carried notice that the series was externally funded, support came at least in part from the Malaria Elimination Group (MEG) which is funded by the Gates Foundation.

The series labeled MEG as a "collaborating partner." Other Lancet series, health and climate change, for example, identify collaborators and funders separately. Other series (e.g. health in Brazil) have neither collaborators nor funders.

Asked about funding of the malaria series, Lancet spokesperson Tony Kirby initially said in email that “ 'supported' means led, devised, and written by members of MEG.” The usual financial connation of "supported" did not apply.

However, in subsequent correspondence, Kirby acknowledged a funding role for MEG: “All external funds are raised by the partners we work with to do the academic work and analysis that forms the basis of the Series, to have a peer review meeting, and for a launch.” Asked whether the external funds for the malaria series ought to have been disclosed to readers, Kirby did not reply.

The Lancet puts malaria elimination under the microscope and examines the technical, operational, and financial challenges that confront malaria-eliminating countries.

However, a group with malaria elimination as its goal largely authored and provided funding for the series published in the Lancet which provided no disclosure of the external funding.

"There is a definite lack of transparency," wrote Ana Marusic in email of the non-disclosure by the Lancet. Marusic co-authored a New England Journal of Medicine paper updating the conflict of interest policy for the International Committee of Medical Journal Editors (ICMJE). The Lancet, according to its website, is a signatory to ICMJE's guidelines. "Financial relationships," read the ICMJE requirements, "are the most easily identifiable conflicts of interest and the most likely to undermine the credibility of the journal, the authors, and of science itself."

Alongside the malaria series, the Lancet published a laudatory profile of the head of MEG entitled, “Richard Feachem—scaling the heights of global health leadership.” MEG is coordinated by the Malaria Elimination Initiative, part of the Global Health Group at the University of Califormia, San Francisco. Feachem declined say to what portion of his funding for malaria comes from the Gates Foundation. His group won Gates grants for malaria of $9 million in 2010 and $5 million in 2007.

More ambigously yet still potentially worrisome, in late 2011, the Lancet received a paper reporting the spread of drug resistant malaria to western Thailand. Recognizing the importance of the findings, the Lancet fast-tracked the submission for publication within four weeks. However, the paper was then taken off the fast track. It languished for months. According to one of the paper’s authors, who did not wish to be identified, only the publication of a related paper in Science caused the Lancet to publish it, nearly six months after submission. The authors wondered if their paper had been intentionally suppressed because it seemed like bad news for malaria elimination efforts. “We never comment on internal procedures relating to our papers,” wrote Lancet spokesperson Tony Kirby in email.

Oversight: Congress and malaria

Gates Foundation: well-represented at congressional hearing on malaria (Source: CSPAN)

The United States is one of the largest funders of anti-malaria efforts through the $5 billion President's Malaria Initiative. In December of 2011, the House Committee on Foreign Affairs held a hearing on global efforts to eliminate malaria. The goal of elimination was set by the Gates Foundation—and the committee mostly heard from the Gates Foundation concerning progress. Only one member of the six-person panel came from an organization not funded by the foundation: Richard Bate of the American Enterprise Institute.

By contrast, panelist Regina Rabinovich served as the Gates Foundation's director of infectious diseases. The other panelists came from PATH, Malaria No More, the Medicines for Malaria Venture and the US Global Leadership Coalition, each recipient of $10 million or more from the Gates Foundation.

PATH runs the Gates-backed Malaria Vaccine Initiative which has shepherded the RTS,S vaccine into final clinical trials. PATH won the very first Gates Foundation grant in global health, $250,000 for family planning and birth control in 1995. In 2011, PATH received 14 grants totaling $81 million, according to the Gates Foundation website. (See the third story in this series: The long struggle: vaccines against malaria.)

Malaria No More has won more than $10 million in Gates funding to support advocacy efforts. In 2009, Malaria No More partnered with Ashton Kutcher who raced CNN to one million Twitter followers to raise awareness for bednets.

The Medicines for Malaria Venture has received significant Gates Foundation funding in its pursuit of new anti-malarial drugs, most recently a $134 million grant. (See the second story in this series: After artemisinin: searching for the next front-line malaria drug.) 

The US Global Leadership Coalition (USGLC) lobbies Congress on foreign aid, "advocating for increases in the International Affairs Budget," according to its website. USGLC has received more than $11 million in Gates funding for advocacy since 2007.

The 2011 panelists raised concerns and caveats about progress against malaria, but the hearing represented an "opportunity to testify on the great strides we have made and are making toward eliminating malaria," as Malaria No More's David Bowen testified. Bowen echoed the comment of an earlier panelist and emphasized that malaria was "an underpublicized and underappreciated success story..."

Some testimony overstated progress. The Gates Foundation’s Regina Rabinovich testified: “When I visited The Gambia ten years ago, there were three children to a bed for a disease that has almost disappeared from The Gambia ten years later.” However, malaria “is far from disappearing,” according to Umberto Dalessandro, who works on control and elimination for the Medical Research Council in The Gambia. Malaria has been greatly diminished but most of the country remains at medium-high levels of transmission, according to the Malaria Atlas Project. The Gambia is not pursuing elimination.

Malaria in The Gambia: Darker means more malaria. Areas in white are neighboring countries (Source: Malaria Atlas Project)

Richard Bate of the American Enterprise Institute was the only panelist without financial ties to the Gates Foundation. Bate also testified about malaria in 2004. The composition of the panel then was very different. Besides Bate, the other two panelist came from government organizations, representatives from USAID and the World Health Organization. By 2011, Congress heard mostly the voice of the Gates Foundation. WHO has been supplanted. And USAID, which directs most of the US foreign aid budget, today is helmed by Rajiv Shah who spent seven years at the Gates Foundation.

Bill & Melinda Gates: peerless, reviewless

When Melinda Gates switched the world to malaria eradication in 2007, it wasn’t on the basis of peer-reviewed science but because she was able to see “all the way to the horizon,” as she put it at the 2011 Gates Malaria Forum. By contrast, she does not advocate tuberculosis eradication because of scientific unknowns.

But the scientific examination of what would be needed for to eradicate malaria came three years after commitment to that goal, and science has put the horizon much further out than Melinda Gates’ own estimate. Pedro Alonso, who oversaw the Gates-funded MalERA initiative delineating the science needed for eradication, described it as a “massive research agenda.” Even the half-way point lies an unknown distance ahead. Brian Greenwood, of the London School of Hygiene and Tropical Medicine, said: “What needs to be done scientifically is more challenging than what has been done.”

Meanwhile, to sustain the eradication vision, Bill Gates leaned on non-peer-reviewed science. At the 2011 Gates Malaria Forum, he described models as “quite exciting” and presented one developed by Intellectual Ventures, run by Nathan Myhrvold the former chief technology officer at Microsoft. Myrhvold's training is in theoretical physics and mathematical economics. His two peer-reviewed papers are on dinosaurs. Based on Myhrvold’s malaria model, Gates said that adding a 50 percent effective vaccine—like the Gates-backed RTS,S—to existing interventions of insecticides, bednets, and antimalarial drugs, could locally eliminate malaria.

Bill Gates at the 2011 Gates Foundation World Malaria Forum 

Remarkably, elimination advocates are uncertain which country represents the greatest victory so far over malaria. Asked what country overcame the most intense malaria transmission so far, MEG’s Richard Feachem said that was “a very good question.” He did not know the answer. No one does. The best guesses are Taiwan or Singapore, which got rid of malaria decades ago, in 1965 and 1982 respectively. Both are islands (greatly aiding elimination) and comparatively wealthy. Malaria is at least ten times more powerful in its African strongholds. However, Feachem believed that the world had paid insufficient attention to the recent accomplishments of Morocco and Turkmenistan in eliminating malaria.

Modern day Cassandra

Nearly every aspect of malaria from research to policy and advocacy is influenced and sometimes controlled by the Gates Foundation. “Everyone is a client,” Chris Murray, lectured his global health students in 2008. (Murray did not mention that IHME is as well. In 2011, Murray received a salary of $460,000 according to state records, making him the highest paid tenured professor at the University of Washington.) Vocal opponents like the former head of malaria at WHO, Arata Kochi, are removed. Many rank-and-file scientists keep quiet. “I’m not sure if I would tell a journalist I don’t believe eradication is possible,” said one anonymous Gates-funded researcher.

A number of Kochi’s 2007 allegations seem supported by current evidence. He claimed the foundation “takes its vested interest to seeing the data it helped generate taken to policy.” The foundation has funded testing and development of the RTS,S vaccine. That vaccine seems not only part of Bill Gates’ modeling exercise: the foundation’s continued support suggests it may push for licensing and deployment of the vaccine. Acting as judge, jury and advocate, warned Kochi years ago, “could have implicitly dangerous consequences on the policy-making process in world health.” He described the foundation’s decision-making as “a closed internal process, and as far as can be seen, accountable to none other than itself.” For this series, the Gates Foundation declined comment on the spread of drug resistant malaria, the failure of bednets, concerns about the effects of RTS,S on transmission and the foundation’s involvement in the remaking of WHO.

Bill and Melinda Gates are following in the footsteps of the Rockefeller Foundation, which arguably invented global health roughly a century ago. However, with the advent of the World Health Organization in 1948, the Rockefeller Foundation ceded its de facto leadership to that new institution of civil society. Today, global health appears to be passing back into private hands.

The Gateses are noble people embarked on an admirable and exceedingly difficult mission. Their foundation is a force for good. The best way to save lives, however, is not to dominate science or democratic institutions. A surfeit of zeal can actually harm the battle against malaria: “The history of special antimalarial campaigns,” reads a 1927 League of Nations report, “is chiefly a record of exaggerated expectations followed sooner or later by disappointment and abandonment of the work,” a cycle that has already been repeated.

A new one seems to have begun. In 2012, American Idol finalist Katharine McPhee told USA Today "I feel like (ending) malaria – like hunger here in the United States – is easily attainable." McPhee's statement is simply false. Although Bill and Melinda Gates are much more circumspect, their support underlies the misleading USA Today story: the article arose from McPhee's trip to Africa with Malaria No More—fueled by a $7.3 million grant from the Gates Foundation.

Undefeated (© IRD / M. Dukhan)

Bednets seemed the perfect malaria intervention: cheap, needing no doctors or needles but saving the lives of perhaps five children for every thousand covered. But unfurling hundreds of millions of mosquito-killing nets across Africa has provoked a wave of insecticide resistance. Resistant mosquitos pass through and bite instead of dying. Also, children eventually come out from under bednets when they are older which might be worse than having had no protection to begin with in areas with intense malaria transmission. Remarkably, the most recent and comprehensive research on malaria mortality shows weak or no evidence that bednets save the lives of children in Africa.

In 2000, health officials set a goal to protect 60 percent of the population at greatest risk of dying from malaria, children under five and pregnant women.  Compelling studies had shown that bednets dramatically reduced malaria and saved lives. In 2005, the World Health Assembly voted to hoist the target to 80 percent. Distribution of nets leapt to 47 million in 2006, up from 17 million the year before. In 2007, Melinda Gates called for the total global eradication of malaria. In 2008, the world spun up and delivered more than 60 million nets. Nets became a cause célèbre, with Ashton Kutcher leading the charge on Twitter in 2009. In 2010, more than 140 million nets were shipped to sub-Saharan Africa, where more than 750 million people are at risk for malaria.

Scale-up drives resistance

But living organisms try to stay that way. And the immense selective pressure of mosquitocidal nets drove a proportionate resistance pushback. More nets, deployed for more time, select for a more resistant mosquito population. For example, in a large trial in Asembo, Kenya, as bed net coverage ascended, a key mutation conferring insecticide resistance expanded through the mosquito population. When bednet coverage reached 100 percent, the resistance mutation also neared 100 percent frequency.

Treated nets all use pyrethroids, a class of insecticides originally derived from chrysanthemums. Pyrethroids are enormously toxic to mosquitos but comparatively safe for humans. Pyrethroids act on nerve cells by binding to a receptor site on a sodium channel, inhibiting its deactivation. In susceptible mosquitos, pyrethroids trigger rapid paralysis or “knockdown,” then death.

Not all die, however. Mosquitos have evolved a number of defenses. Some are metabolic — insects rapidly detoxifying or sequestering poisons. In addition, researchers looking at mosquito feet with an electron microscope have even detected “cuticular thickening” which slows or blocks insecticide absorption when mosquitos touch down on nets. Mosquitos might be evolving their behavior as well to avoid bednets. A recent study of two villages in Benin found that mosquitos shifted their peak feeding time from the middle of the night, when nets protect people sleeping under them, toward dawn when villagers are waking up and exposed. 

The frequency of resistance genes within a population ebbs and flows, and pyrethroids can still do serious damage even where resistance is present. Although the large number of nets drives selection for resistance, the insecticide onslaught also kills huge numbers of mosquitos, reducing transmission. Against susceptible mosquitos, bednets radically reduce bloodfeeding, by 90 percent or more. By contrast, bloodfeeding of knockdown-resistant mosquitos is essentially unaffected by the pyrethroids on bednets. And, by itself, the physical barrier presented by nets provides only very partial protection.

The search for alternatives

Venerable pyrethroids are now roughly half a century old. There are efforts to find new insecticides, but none are in sight. The Innovative Vector Control Consortium (IVCC), set up and funded by the Bill and Melinda Gates Foundation, has been working on the problem since 2005.  IVCC’s current portfolio shows no new chemicals entering into a development or registration for use phase. If there are any promising candidates further upstream, IVCC chief operating officer Tom McLean won’t talk about them. He fielded a question on status by saying: “At this early stage of the development process it is not appropriate to publish specific chemical structures of what is in the pipeline because it is essential to preserve the commercially competitive nature of these products.”

The Gates Foundation directly funded out-of-the-box projects like “click chemistry” in which two non-toxic chemicals bind together lethally inside mosquitos. But that clever idea did not pan out.

According to Helen Pate Jamet, senior scientist for bednet maker Vestergaard Frandsen, “ideally we need at least 2-3 new insecticides from completely different insecticide classes in order to have a real impact on resistance and have the ability to rotate/mix different classes.”

Meanwhile, Vestergaard Frandsen is testing nets impregnated with chlorfenapyr which comes from a new class of insecticides called pyrroles. Unfortunately, they aren’t as good as pyrethroids. Chlorfenapyr is less toxic to mosquitos and more harmful to humans than pyrethroids. Chlorfenapyr is a "prodrug" that has to be broken down before starting the chain of events that, in time, kills the mosquito. Consequently, chlorfenapyr-treated nets provide little to no personal protection from malaria. Mosquitos still bite, only dying later. “Any inhibition of blood feeding associated with the insecticide treatment was not statistically significant,” according to one study of chlorfenapyr–laced bednets. To work, much of the community must also sleep under a net, thereby reducing the mosquito population. The direct life-saving benefit of pyrethroid bednets is lost.

Geographic extent and implications

Pyrethroid resistance has been found all over the African continent. Mosquitos have developed resistance to other insecticides, but according to WHO's most recent report, "Resistance to pyrethroids seems to be the most widespread." And it's worsening. Previously there were pockets of resistance; now there are pockets of susceptibility. 

Yet remarkably there is debate about whether insecticide resistance impacts malaria control. “[T]here is broad consensus that the degree of resistance that has developed and its likely trajectory are a cause for serious concern,” according to Scott Filler, senior advisor at the Global Fund for Aids, TB and Malaria. The trajectory, Filler says is toward “widespread control failure,” but “the pace of this process and the degree of reduction in malaria control effectiveness remains unknown.” The Global Fund purchases the majority of the world’s bednets, some 56 million in 2010.

Janet Hemingway, director of the Liverpool School of Tropical Medicine concurs that there is “undoubtedly a rapid increase” in pyrethroid resistance in Africa and that “at some point we will get failure.”

However, according to Christian Lengeler, it is “probably right” that “we have already now some detrimental effect...” because of pyrethroid resistance. Lengeler is director of the health interventions unit at the Swiss Tropical and Public Health Institute. Together with WHO, Lengeler advocated for bednets in the mid-1990s. He also authored the influential meta-analysis of bednet trials in 2004 showing 5.5 lives could be saved for each 1,000 children covered by nets.

Uncertainty principle

Getting a grip on the actual effects of bednets is difficult. The Global Fund’s Filler gave a mixed message on whether a decline in effectiveness can be measured. “No – no such [study] design exists,” said Filler. But he then added: “This can be accomplished in carefully designed trials but these are complex, expensive and need a high level of epidemiological expertise to conduct….”

A study of bednets in the village of Dielmo in Senegal published last year showed nets rapidly reduced malaria when first introduced, consistent with many previous studies. However, within two years, 48 percent of mosquitos had a mutation for pyrethroid knockdown resistance, up from 8 percent at the beginning of the study. Cases of malaria rebounded to just below pre-bednet levels.

Controversy ensued. “This paper is bad,” Lengeler said of the Dielmo study. The study, Lengeler continued, “has no credit whatsoever in the malaria community.” A commentary accompanying the Dielmo study applauded the rigor of the research but cautioned against extrapolating its conclusions to the rest of Africa.

However, the authors of the commentary themselves produced a study just a few months earlier which appeared to show bednet failure. In Luangwa, Zambia, bednet use rose dramatically in two years from about half the population to 86 percent. However, malaria infections went up. Although the paper seemed to demonstrate some kind of failure, one of the authors, Thomas Eisele, wrote in email: "That is not accurate.” Eisele, of the Tulane University School of Public Health and Tropical Medicine, did not reply to subsequent requests to elaborate. He pointed instead to research from the Institute for Health Metrics & Evaluation (IHME) showing more favorable results.

Claims on nets overstretching evidence

The IHME study found that bednets were associated with a statistically significant reduction of mortality from any cause of 23%. However, the study did not examine the effect of insecticide treated nets (ITNs) on death from malaria. As the study authors pointed out, "we were only able to examine the relationship between ITNs and all-cause mortality as the surveys we used do not include information on cause-specific mortality." 

However, a press release from IHME about the study used less cautious language, claiming: "researchers found clear evidence that bed nets reduce the number of child deaths from malaria." That statement did not appear in the peer-reviewed paper and is not supported by evidence in the paper.

IHME recently published a more comprehensive, exhaustive malaria mortality study. It made global headlines, reporting a higher death toll for malaria than previous estimates. Part of the difference came from a much larger estimate of deaths among adults. However, the study found that bednets did not reduce adult deaths from malaria in Africa: "coverage of insecticide-treated bednets," read the report, "was not a statistically significant predictor of African adult malaria mortality." But on the even larger question of whether bednets save children in Africa, the study is silent.

Asked that question in email, however, one of the paper’s authors, IHME’s Stephen Lim, replied that “ITNs [bednets] were a statistically significant predictor of African child mortality.” In other words, bednets worked to save the lives of the largest and most vulnerable group, children in Africa.

But the basis for this unpublished claim isn’t clear. The IHME study incorporates data from many smaller studies of particular geographic areas and then extrapolates as needed to country and continent levels using sophisticated, computationally-intensive modeling techniques. IHME actually generated many hundreds of models which were then averaged together into an ensemble to most closely approximate reality. However, Lim said IHME did not calculate an average hazard ratio for the effects of bednets. (A  hazard ratio is a number that indicates whether an intervention increases or decreases risk, in this case the risk of dying from malaria.) “Analytically,' said Lim in email, "we can calculate an ‘average’ hazard ratio but it is not something we have currently in place and would involve a considerable amount of work.” 

Not having a hazard ratio raises the question of how the statistical significance of bednets was assessed. IHME spokesperson William Heisel wrote in email that 131 models found bednet coverage to be a significant predictor of malaria mortality for children under five in Africa. However, at one point in the analysis, there are a total of 214 models for children under five in Africa. IHME did not reply to an email asking if this meant 131 models were and 83 models were not significant for bednets. 

A greater number of models does not necessarily mean the variable being tested is statistically significant because models are weighted differently. IHME had earlier cautioned against simply counting the models in their list: “This list by itself," wrote Lim, "is not easily interpretable as different individual models are given more weight in generating the ensemble model.”

Asked whether IHME had based their assessment of statistical significance on a count of models, Heisel replied that IHME would not answer any more questions in email, .

Possible mistake?

Although difficult to countenance, distributing bednets in high transmission areas—like much of sub-Saharan Africa—might have been a mistake.

Intensity of malaria transmission worldwide. Darkest color indicates very high (>40 percent) infection prevalence and high transmission.  Gething, et al., “A new world malaria map: Plasmodium falciparum endemicity in 2010” DOI: 10.1186/1475-2875-10-378

Where malaria is intense, being bitten is a kind of deadly hazing ritual with survival conferring a degree of immunity. In very young, non-immune children, malaria infection leads to fever—and possibly death. The fatality rate of malaria infections is, perhaps contrary to expectations, very low. Only an estimated 0.3 percent of infections globally cause death. But infections are so numerous that hundreds of thousands of children die each year. Children who survive, however, generally can better control infections later in life and even show no symptoms while carrying perhaps millions of parasites.

Research in the late 1990s concluded that “a critical determinant of life-time disease risk is the ability to develop clinical immunity early in life…” Malaria, including cerebral malaria and severe malaria, declined as children got older. Risk for severe malaria was highest where transmission was less intense, likely because people don’t acquire immunity without exposure to considerable infective biting.

Such natural tolerance is a mystery. There is no definitive set of biomarkers for it. And it’s no free pass: immunity may wane without some amount of continued infective biting, making severe disease a possibility.

One of the authors of the study, Robert Snow, now head of the public health group at the Kenya Medical Research Institute/Wellcome Trust Program, said recently, “I remain convinced that a certain degree of parasite exposure is required to develop functional immune responses to reduce risks of death and severe disease from malaria.”

Nets were originally targeted at children under five because most deaths from malaria occurred in that age range. But where malaria is intense, infection is unavoidable, with bednets deferring it to a later age. The age range least likely to sleep under a net is age 5 to 19. The most protected become the least protected—with potentially more adverse health consequences. Studies have found a shift in disease burden to older age groups following introduction of bednets. Trape and colleagues found this in Dielmo, Senegal. Other researchers, in an earlier 2009 paper, showed that nets reduced malaria risk in younger but not older children, a finding “consistent with older children having used [bednets] when they were younger, and therefore having acquired less immunity.” Thus to the extent bednets have saved lives in high transmission settings, they may also have created a population with reduced natural immunity, possibly setting the stage for a rebound of malaria.

“The issue of rebound and building up a time-bomb of susceptibles is interesting and you will find people willing to argue either side,” said Simon Hay, of Oxford University where he heads the Malaria Atlas Project.

The Global Fund’s Scott Filler said rebound concerns were “one major progenitor to move from targeted distribution of [bednets] to children under five to the goal of achieving universal coverage…” WHO switched to recommending universal coverage in 2007. (As the graph above shows, however, bednets distributed actually declined in 2011.)

Gerry Killeen of the Ifakara Health Institute in Tanzania believes rebound “is highly implausible unless the interventions themselves fail (resistance) or are withdrawn.”  His parenthetical mention of resistance, however, could mean trouble. Azra Ghani, of Imperial College London, and colleagues concluded that “If the effectiveness of the intervention gradually wanes, the impact on immunity is likely to be minimal and the incidence of clinical disease will return to pre-intervention settings,” perhaps ten years later.

Diaphanous nets and ghosts of the past

Bednets were hoped to be a precise, stealthy intervention beneath the notice of mosquitos. But protecting even a portion of the population appears to have engaged their evolutionary attention.  The switch to universal coverage also shifted the strategy: the purpose of the nets has become to kill mosquitos. “In order for their full potential to be realized,” reads the WHO position statement, bednets “should be deployed as a vector control intervention.”

However, if the goal was to knock transmission into an unrecoverable tailspin, it hasn’t worked. Transmission in high intensity areas dropped, but the force of infection still “needs a bit more help get it over a hump of stability that will impact on disease burden in the longer term,” said Robert Snow. The question is how because, continued Snow, the “expectation that [bednets] alone were to be the panacea in high transmission areas was misplaced.”

Resistance to DDT caused the technical failure of the mid-20^th century effort to eradicate malaria. Nonetheless, over time, bednet policy has taken on a worrying semblance to this unsuccessful strategy. The previous effort didn’t even attempt to take on the heartland of malaria in sub-Saharan Africa, with some researchers arguing success was impossible using DDT. Also, planners of the oft-maligned effort actually knew resistance would be a problem where DDT was used and consequently they set a blitzkrieg timeline for achieving victory in a few years before resistance rose up. In comparison, the bednet strategy seems ad hoc and improvisational.

The coverage targets, initally 60 percent and then 80 percent, “were moved because we weren't going to meet them on time,” said David Smith of the University of Florida. “Instead of admitting nothing was happening, the intervention coverage target was increased and the date moved back—seeming to have some thought behind it, but mostly just saving face.”

Pyrethroid resistance was not part of the agenda at the Gates World Malaria Forum last October nor was it mentioned in congressional hearings on malaria last December. That omission may come from a concern, expressed by Killeen, “that doom-and-gloom stories will kill public enthusiasm for things that have saved many lives,” which he estimates to be half a million in Tanzania over the last five years. Scaling up such interventions “took a long time to get in place.” He concludes, “I am the father of two under fives and I live in a part of rural Tanzania where over 80 percent of people use [bednets] so this is a very real issue for me.”

Malaria is horrific, nature unsentimental. Sustainably reducing or ridding the disease from the world is unquestionably desirable. “But as we are now seeing,” say other researchers, controlling mosquitos with chemical killing agents comes at a price, “and the price is resistance.”