In a statement on August 25, the WHO announced the eradication of the wild strain responsible for poliomyelitis in Africa. The main focus of contamination in the early 2000s, Nigeria has not had a case for four years.
- The WHO has announced the eradication of the virus responsible for poliomyelitis, with the last case dating back to 2014.
- However, the virus continues to circulate in Afghanistan and Pakistan.
- If the wild strains have been eradicated by the different vaccination campaigns, vaccine strains that have mutated can still spread through populations at risk.
It’s official: the African continent has now eradicated the wild poliovirus responsible for poliomyelitis. The announcement has been made by press release Tuesday, August 25 by the World Health Organization (WHO), which welcomed the news. “Now that this historic milestone has been reached, 5 of the 6 WHO regions — representing more than 90% of the world’s population — are now free of wild poliovirus and the global eradication of poliomyelitis is ever closer”, writes the health agency attached to the UN. “Thanks to the efforts of governments, health workers and communities, more than 1.8 million children have been saved.”
A highly contagious infectious disease
Due to wild poliovirus (PVS), poliomyelitis is an acute infectious disease that invades the nervous system of the spinal cord and can totally paralyze an individual in just a few hours. Mostly affecting children under 5, polio causes irreversible paralysis in one out of 200 cases, and for 5 to 10% of paralyzed patients, the disease is fatal. The first symptoms generally observed are vomiting, fever, headache, pain in the limbs or stiffness in the neck.
The transmission of the disease is mainly by the faecal-oral route, that is to say that a person becomes infected when he puts in contact with his mouth things that have been soiled by faeces (finger, object, food). Once the person is infected, the virus multiplies in the intestine.
As there is currently no treatment for poliomyelitis, the only way to act against the virus is vaccination, developed in the 1950s, when the virus was then widespread throughout the world.
If the developed countries quickly carried out vaccination campaigns which allowed a rapid eradication of the virus, Africa and Asia remained important infectious foci until the 2000s.
Global vaccination campaigns
Thus, in 1988, the WHO counted 350,000 cases worldwide. In 1996, Africa still had more than 70,000 cases of poliomyelitis, despite large-scale vaccination campaigns launched across the continent from 1988.
It is thanks to the latter that the poliovirus ended up being extinguished. In total, 19 billion dollars have been injected over 30 years to fight poliomyelitis. “We went from 35,000 cases notified in 125 endemic countries in 1988, to 8,500 cases in 60 countries in 1994 and 784 cases in 7 countries in 2003.details at Figaro Professor Pierre Saliou, former President of the Overseas Academy of Sciences and Associate Professor of Val-de-Grâce.
In addition to the two existing vaccines, which are sometimes difficult to accept by local populations, the WHO has relied on tracing the virus in wastewater. A paying strategy, especially in Nigeria which was still, until 2014, one of the endemic centers of poliomyelitis. “This reversal made it possible to limit the circulation of the virus even before the appearance of new cases. Only one in a hundred infected people show symptoms of paralysis. Nothing prevents the epidemic from progressing quietly, if we are content with observing the sick”, says Maël Bessaud, researcher in the Viral Populations and Pathogenesis Unit at the Institut Pasteur. Result: the last case of poliomyelitis on Niger soil was recorded in 2014.
The global fight against poliovirus is far from over, however. According to the WHO, 29 cases of poliomyelitis have been identified in Afghanistan since the beginning of the year and 58 in Pakistan. Likewise, while wild strains have disappeared in Africa, mutated vaccine strains can still spread around the world,”in certain contexts”warns the WHO.
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