On August 10, the United Kingdom launched an emergency vaccination campaign against polio for all children under the age of 10 living in London. The reappearance of the virus across the Channel, in Israel and the United States, where a man has been partially paralyzed since July, raises fears of an epidemic.
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It is a disease that seemed from another age to the West. On July 21, the United States reported its first case of polio for almost ten years. The 20 -year -old affected man lies in Rockland County, 48 kilometers from New York. He went to the hospital following a leg paralysis. Quickly diagnosed as being infected with poliovirus, the agent responsible for the disease, he still suffers from partial paralysis. He was not vaccinated.
The rich countries had almost forgotten this very contagious affection, due to a virus which attacks the nervous system and can cause a permanent engine handicap. Its usual mode of transmission is the oro-flexible route, from water or soiled food. Before the start of massive vaccination campaigns, in the middle and the late 1950s in the West, this disease sowed dread. Especially in parents of children under the age of 5, targets of predilection of the virus. In France, between 1943 and 1988, the polio caused 32,793 paralysis and killed 3,315 people.
Since 1988, the number of polio cases collapsed by 99 %. A spectacular fall, due to the deployment of the global initiative for the eradication of polio, launched under the leadership of national governments, the World Health Organization, Rotary International, Centers for Control and Prevention American diseases and UNICEF. She then received the massive support from the Bill and Melinda Gates and GAVI Foundation, the Alliance of the Vaccine. Result: while in 1988, the number of cases was estimated at 350,000, with an endemic virus in more than 125 countries, only six cases of paralysis due to wild polioviruses were notified in 2021. Only two countries, the Afghanistan and Pakistan, continue to know outbreaks of polio linked to the wild virus.
The young American, however, was not contaminated in one of these countries. Its paralysis results from a disturbing fact, already observed elsewhere. The virus that struck it derived from an oral vaccine used in many developing countries. A vaccine containing a poliovirus made harmless but still alive, which then transferred, because it has multiplied in many unvaccinated people.
“A danger in New York”
The scenario is as follows. One person receives one of these oral vaccines. She then excreted the poliovirus in her stool for several weeks. “If, around her, there are only people vaccinated orally, this virus will not find anyone to infect, says Maël Bessaud, expert of polioviruses at the Pasteur Institute. But if she meets many unvaccinated individuals, Or if it goes to a region where only the inactivated vaccine is used, this virus will be able to circulate. “If it spreads for several months from a person not vaccinated to another, he can accumulate many modifications in his genome. It is then that he can become virulent again and cause paralysis.
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