It is official: the African continent has now eradicated the wild poliomyelitis virus that causes polio. The World Health Organization (WHO) issued a statement on Tuesday 25 August welcoming the announcement. “Now that this milestone has been reached, 5 of the 6 WHO regions – representing over 90% of the world’s population – are now free of the wild poliovirus and the global eradication of polio is getting closer and closer, wrote the United Nations Health Agency. “Thanks to the efforts of governments, health workers and communities, more than 1.8 million children have been saved.” said the WHO.
A highly contagious infectious disease
Due to the wild poliovirus (WPV), polio is an acute infectious disease that penetrates the nervous system of the spinal cord and can completely paralyze an individual in a few hours. In children under 5 years of age, polio causes irreversible paralysis in one in 200 cases and in 5-10% of crippled patients the disease is fatal. The first symptoms usually seen are vomiting, fever, headache, pain in the limbs, or stiffness in the neck.
The disease is mainly transmitted through the fecal-oral route, i.e., a person becomes infected if they bring things contaminated with fecal material (finger, object, food) into contact with their mouth. When a person is infected, the virus multiplies in the intestine.
As there is no cure for polio, the only way to fight the virus is vaccination, which was developed in the 50’s, when the virus spread all over the world.
While developed countries carried out rapid vaccination campaigns that led to the rapid eradication of the virus, Africa and Asia remained major focus until the 2000s.
Global vaccination campaigns
In 1988, for example, the WHO had 350,000 cases worldwide. In 1996 there were still more than 70,000 cases of polio in Africa, despite large-scale vaccination campaigns launched across the continent from 1988.
However, it was thanks to these campaigns that the polio virus was finally extinguished. A total of $19 billion has been injected over 30 years to fight polio.
In addition to the two existing vaccines, sometimes difficult to accept by the local population, the WHO has chosen to detect the virus in the wastewaters. This strategy has borne fruit, especially in Nigeria, which has been one of the polio endemic focal points until 2014. “This reversal has helped limit the circulation of the virus, even before new cases emerge. Only one person in every 100 infected shows signs of paralysis. Nothing will stop the epidemic if we only observe the sick,” says Maël Bessaud, a researcher at the Viral Populations and Pathogenesis Unit of the Pasteur Institute. As a result, the last case of polio on Nigerian soil was registered in 2014.
However, the global fight against poliovirus is far from over. According to the WHO, 29 cases of polio have been reported in Afghanistan and 58 in Pakistan since the beginning of the year. Although wild polio in Africa have disappeared, mutant vaccine strains can still spread globally, “in some settings,” warns the WHO.