Around a year after the repeated detection of polioviruses in the US state of New York, the outbreak appears to have been largely contained. After isolated pathogens were detected in the state’s wastewater at the beginning of the year, none have been found for a long time, the health authorities said. The disaster that Governor Kathy Hochul declared last year expired in December. The World Health Organization (WHO) has declared October 24th (Tuesday) as World Polio Day – with the aim of eradicating polio worldwide.
The current development in the USA does not mean an international all-clear. The goal set by the WHO and its partners 35 years ago to eradicate the disease, also known as poliomyelitis, has not yet been achieved, according to the current Epidemiological Bulletin of the Robert Koch Institute. In 2022, there was an increase in recorded wild poliovirus (WPV) infections in parts of Pakistan and Afghanistan. However, infections with so-called vaccine-derived polioviruses (cVDPV) have posed an even greater problem in recent years.
According to the bulletin, 880 such cases have been recorded worldwide for 2022 and 305 for 2023. They occur primarily in areas where a high proportion of the population is unvaccinated. “The weakened viruses in the oral vaccination can circulate undetected for a long time, change in the process and ultimately cause acute flaccid paralysis again,” says the RKI. Due to the very low number of cases associated with symptoms, around 200 additional, unrecognized infections are expected for each confirmed illness.
Vaccination routine interrupted
Routine vaccinations such as those against polio were interrupted in many countries during the pandemic years. African countries are particularly affected by cVDPV infections due to low vaccination rates, the RKI said. There was also evidence last year in Israel and Great Britain, among others. The oral vaccination is still used in Africa, Asia and Israel, for example, while the USA, Great Britain and Germany have long been working with inactivated vaccines that do not contain any viable viruses.
In the USA, the infectious disease was actually already considered extinct after there had been no cases for around a decade. But then in the summer of 2022, a young man north of the metropolis of New York became infected with the virus and his legs are now partially paralyzed. For a while afterwards, polio pathogens were repeatedly detected in the wastewater of several communities in the state and also in the metropolis.
The disease, which is often spread via contaminated hands as a so-called smear infection or via contaminated water, can cause paralysis and lead to death; small children in particular can suffer permanent paralysis. There is currently no cure.
Before vaccinations were introduced, there were thousands of sick people and hundreds of deaths every year in Germany alone. The global vaccination campaigns initiated in 1988 have so far saved around 20 million people from paralysis and one and a half million from death, according to the WHO. However, vaccination rates are now far too low in many places. In Germany, babies from two months of age are vaccinated; the national average vaccination rate is around 90 percent.
