EXPLAINER: What is polio?

MANILA, Philippines – The Philippines is at high risk for poliovirus transmission, the Department of Health (DOH) announced on Saturday, August 17. 

The DOH said that a 2019 test of Manila’s sewage showed two samples that tested positive for poliovirus. Though the DOH has so far not recorded any infection, it has urged parents to make sure children are protected, since the virus was already found in one community.

This is alarming news: the Philippines has been polio-free since 2000, according to the DOH and the World Health Organization (WHO), with the last case of wild poliovirus in the country recorded in 1993. 

Only 3 countries are not polio-free: Pakistan, Afghanistan, and Nigeria, or what the Global Polio Eradication Initiative (GPEI) classifies as endemic countries. This means the transmission of polio has never stopped in these areas. 

The GPEI also watches out for 12 outbreak countries spread out in Africa, the Eastern Mediterranean, the Western Pacific, and Southeast Asia. In these countries, there are cases of wild poliovirus reinfection due to wild or vaccine-derived poliovirus (VDPV). 

What does it mean if the country is at high risk for poliovirus transmission? And what can we do to ensure that the disease does not return?

What is polio? 

Poliomyelitis or polio is a highly contagious disease caused by poliovirus invading the nervous system. It starts with feces – poliovirus in feces enters the body through the mouth and spreads through contact with an infected person’s feces. In rare cases, the virus is transmitted through sneezing or coughing.  

The poliovirus can live in an infected person’s feces for many weeks and can contaminate food and water in unsanitary conditions. 

Symptoms are flu-like: fever, fatigue, headache, vomiting, stiff neck, and sudden onset of floppy arms or legs. 

In more serious cases, the brain and spinal cord may be affected. People with poliovirus infection can experience paresthesia or feeling pins and needles in the legs, and meningitis or an infection of the covering of the spinal cord or the brain. 

Severe infection can also lead to permanent paralysis or even death. Paralysis can lead to death because the virus may affect muscles that help us breathe.

Children under 5 years of age are most vulnerable to the disease.

There is also such a thing as VDPV, which may spread when a community is under-immunized and living with poor sanitary conditions. 

Because the polio vaccine contains a weakened vaccine-virus to activate immune response, it will be excreted through an immunized person’s feces. But if the community is under-immunized and unsanitary, the “excreted vaccine-virus can continue to circulate for an extended period of time,” WHO said.

Why is the Philippines at risk?

The Philippines had been certified as polio-free since 2000, but low vaccination coverage, poor early surveillance of polio symptoms, and substandard sanitation practices, put the country at risk of losing the status, based on the 2018 risk analysis of the National Certification Committee for Polio. 

The vaccination schedule for preventing polio, as recommended by the WHO, involves 3 doses of oral polio vaccine (OPV) and one dose of inactivated polio vaccine (IPV). It is the OPV that contains live, weakened virus that may cause VDPV. 

“In 2018, the vaccine coverage for the third dose of OPV was 66%. This figure is below the 95% target required to ensure that the whole population is protected against polio,” the DOH disclosed on Saturday, August 31. 

Health Undersecretary Eric Domingo told ANC’s Headstart on Wednesday, August 21, that low immunization could also be due to the public scare caused by the Dengvaxia controversy, which saw parents refusing to get children immunized. (READ: A year after Dengvaxia: Immunization drops, measles outbreaks soar) 

But polio has no cure, and vaccination is the best way to prevent the disease. The DOH said it would conduct 3 rounds of synchronized polio vaccination for all children under 5 years old, regardless of their previous vaccination status. 

The health department already concluded its first round in the city of Manila, where the VDPV sample was found. The vaccination campaign is set to expand to all cities in the National Capital Region (NCR) by October, and later on to priority regions – which the DOH has yet to identify – by November 2019. 

“The problem is we haven’t achieved the 95% rate of immunization, just like when the measles outbreak happened. This happens for many reasons, not just due to vaccine hesitancy, but also due to limited coverage due to manpower and funding shortages,” said Josh San Pedro of the Coalition for People's Right to Health (CPRH). 

“The DOH and those in public health must regain the trust of the population in order for our efforts to truly be meaningful in preventing preventable diseases from returning. Doing this must entail proper stocking of essential vaccines, proper access to health centers, and adequate manpower for the population,” San Pedro added. 

Because transmission of the disease happens through contact with feces, good hygiene practices – both individual and community-based – are also very important in eradicating the disease.

The health department urges local governments to intensify their Zero Open Defecation program and calls for proper sanitation practices. 

“If we do not take appropriate actions now, polio will return,” Health Secretary Francisco Duque III said. “We need to urgently act to stop its spread in our communities.” – Rappler.com