Caseless Polio Outbreak in Israel Extinguished; what about Brazil?

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. 

World Cup polio risks in 2010 were far worse than in 2014, based on number of cases and countries. In 2010, 20 countries combined for over one thousand cases versus (so far) 2014's slightly more than one hundred cases in nine countries. Accordingly, the CDC emphasized flu risks more than polio for the World Cup. Hand washing, however, is also mentioned.

Why is WHO crying wolf on polio?

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 21st 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. 

Polio in Nigeria: at the cusp of the cusp

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

Outbreak Emphasis (Again) Obscures Polio Progress

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.

If this continues, polio in Nigeria won't

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. 

Eradication Effort Cornering Polio in Pakistan

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.

Somali Outbreak Obscuring Progress Against Polio

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.

Polio almost crushed in Africa—except Nigeria

In anticipation of future performance: Rotary recognized Nigerian president Jonathan Goodluck in April for his vision of a polio free Nigeria. (Photo: Nigeria PolioPlus Committee)

Polio cases across Africa are near zero, with the exception of Nigeria where they are surging, jeopardizing a continent that is close to polio-free after decades of effort. Nigeria and international agencies are taking measures to halt the recrudescence and prevent spread outside the country, but the amount of disease and mobility of populations gives the virus a fighting chance to kindle outbreaks elsewhere on the continent.

With India having rid itself of polio, Nigeria now is the main front in the effort to eradicate the virus. Nigeria is the only African country which has never interrupted transmission of the disease, making it a supplier of poliovirus to its neighbors and the rest of the continent. Nigeria made huge strides, bringing cases down to 21 cases in 2010.  But then public health lost out to politics. Elections in early 2011 turned attention away from polio and cases bounced back to 65 for the year. Already in 2012 there are 35, even though it is the low season for cases. The only other country in Africa to report cases this year is Chad with three.

Vaccination rounds have been scheduled in countries neighboring Nigeria, but polio’s renewed momentum could carry it to any number of places in Africa where population immunity is low. “That’s the big question,” says the Gates Foundation’s Apoorva Mallya concerning the possibility of export. “We are trying a lot of new strategies, but it is definitely a tough challenge,” he said. Outbreaks could go undetected in remote areas, becoming larger and even seeding secondary outbreaks, undoing at least part of the work in getting rid of polio.  At the same time, the Global Polio Eradication Initiative has become adept at swiftly extinguishing outbreaks. And the initiative has returned to the some of the same countries several times already to stamp out recurrences of polio.

The World Health Assembly voted last week to make polio a global health emergency, raising the profile of the issue and perhaps attracting additional funding for a project continuously declaring funding shortfalls. The emergency declaration could also mean travel restrictions for countries that fail to bring polio under control, Nigeria being the obvious candidate. Leaving the country might come to require proof of vaccination.

Polio also continues to roam freely in parts of Pakistan and Afghanistan. That locus is considered a lesser threat for exporting the disease, although polio did cross from Pakistan into China before being quickly smothered.

Nigeria, hard pressed today, is perhaps at best several years away from putting an end to polio. President Jonathan Goodluck has set 2015 as his target, and global health authorities believe Nigerian leadership is sincere in its efforts. As in India, the tactics or “micro plans” for vaccination are changing to emphasize mobile and remote populations which have been consistently missed, perhaps since eradication efforts began decades ago. India shows eradication can be done and, in many ways how, but also the enormity of the effort required.

India triumphs over polio

A two-woman vaccination team in Firozabad, Uttar Pradesh, (Photo: UNICEF)

From my article on Ars Technica:

In the year since January 13, 2011, India has had zero cases of polio. Previously, India led the world, accumulating over 5,000 cases since 2000. Polio's last victim in India was 18 month-old Rukhsar, a girl in West Bengal who began showing signs of paralysis on this day in 2011. Now, epic immunization efforts have brought global eradication of the disease a giant step closer. Outside India, however, backsliding Pakistan and Nigeria and splotches of polio across Africa have blocked the final stamping out of the disease worldwide...