Polio comeback in a number of countries: Should India be worried?

Abantika Ghosh
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Polio immunisation programme in Agartala in 2018. (Express File Photo: Abhishek Saha)

In the last one year or so, polio has made a comeback in countries such as the Philippines, Malaysia, Ghana, Myanmar, China, Cameroon, Indonesia and Iran, mostly as vaccine-derived polio infection. All these countries had wiped the virus out at various times during the last couple of decades; some, such as Iran and Malaysia, had done so even earlier.

Which are the countries that have seen polio outbreaks in recent months?

On December 8, 2019, the Ministry of Health in Malaysia announced the country’s first case of polio since 1992. The World Health Organization (WHO) announced that tests have confirmed that the virus is genetically linked to poliovirus circulating in the Philippines.

On September 19 last year, the Philippines had declared an outbreak of polio. Two cases have been reported to date, both caused by vaccine-derived poliovirus type 2. The first case was confirmed on September 14 following testing by the National Polio Laboratory at the Research Institute for Tropical Medicine, the Japan National Institute of Infectious Diseases (NIID) and the United States Centers for Disease Control and Prevention (CDC).

Last month, the CDC published a list of Asian countries where polio outbreaks have been reported. These are Afghanistan, Burma (Myanmar), China, Indonesia, Malaysia, Pakistan, Papua New Guinea and the Philippines. Except for Afghanistan and Pakistan, all these countries are new entrants into the list.

The CDC recommends that “all travelers to these countries be vaccinated fully against polio. Before traveling to these countries, adults who completed their routine polio vaccine series as children should receive a single, lifetime adult booster dose of polio vaccine”. WHO recommends that these countries require residents and long-term (4 weeks or more) visitors show proof of polio vaccination before leaving the country.

What is polio and why is it so feared?

According to CDC, “Polio is a crippling and potentially deadly disease that affects the nervous system... Because the virus lives in the faeces (poop) of an infected person, people infected with the disease can spread it to others when they do not wash their hands well after defecating (pooping). People can also be infected if they drink water or eat food contaminated with infected feces. Most people with polio do not feel sick. Some people have only minor symptoms, such as fever, tiredness, nausea, headache, nasal congestion, sore throat, cough, stiffness in the neck and back, and pain in the arms and legs. In rare cases, polio infection causes permanent loss of muscle function (paralysis). Polio can be fatal if the muscles used for breathing are paralyzed or if there is an infection of the brain.”

The virus multiplies in the intestine, from where it can invade the nervous system and can cause paralysis. Once that happens, the patient is crippled for life because there is no treatment for the affliction. That is why polio is so dreaded. Polio infection, however, is easily preventable by a vaccine.

There are three variants of the polio virus, numbered 1 to 3. For a country to be declared polio-free, wild transmission of all three kinds has to be stopped. For eradication, cases of both wild and vaccine-derived polio infection to be reduced to zero.

Where does India stand?

In January 2014, India was declared polio-free after three years on zero cases, an achievement that is widely believed to have been spurred by the successful pulse polio campaign in which all children were administered polio drops. In fact, lessons from the programme were later incorporated in Mission Indradhanush to bump up India’s immunisation campaign, and with great success.

In 2018, there was a brief scare when some vials of the polio vaccine were found contaminated with the polio 2 virus that had been eradicated from the country in 1999. However, WHO quickly issued a statement saying that all vaccines used in the government programme in India were safe.

The last case due to wild poliovirus in the country was detected on January 13, 2011.

What do multiple outbreaks in the vicinity mean for India?

It calls for heightened vigilance, in short. Officials in the Ministry of Health are clear that there is no reason for undue panic because, thanks to shared borders with a polio-endemic country (Pakistan), India’s preparedness for preventing a polio influx is already very high. “There is no reason for any knee-jerk response because our polio surveillance mechanism is always on high alert and at airports we already look out for polio entry from seven-eight countries at all times. We are very well prepared to defend our polio-free status,” said a senior Health Ministry official.

Some years ago, India introduced the injectable polio vaccine in the Universal Immunisation Programme. This was to reduce chances of vaccine-derived polio infection, which continues to happen in the country. If both wild and vaccine-derived polio infection are reduced to zero, it would mean there is no trace left of the virus anywhere in the world, except in controlled situations in laboratories for future contingencies.