Polio outbreak threatens global eradication

Just on the heels of the recent Ebola scare in the Democratic Republic of the Congo, a polio outbreak in the same country now threatens global attempts to eradicate the crippling and potentially deadly disease.

The recent incidence of polio, which has paralyzed 29 children so far, is spreading. In June, officials confirmed a case of polio on the other side of Congo from the initial outbreak. Two weeks later, another case appeared in the northeast corner, close to the Ugandan border. Michel Zaffran, head of the World Health Organization’s Global Polio Eradication Initiative (GPEI) described the situation as the most worrisome polio outbreak in recent times, Science Magazine reported.

Global efforts to immunize children have reduced polio cases by 99.9 percent. But the prevention that saves can also sicken. Oral polio vaccines contain weakened forms of the live virus, which has now mutated and become capable of sickening people and spreading.

In 2016, health experts determined that vaccines currently cause more cases of polio than “wild viruses” (those naturally occurring in the environment). In April of that year, the GPEI removed the type 2 virus, one of three polio strains, from vaccines. Immunization efforts have successfully eradicated the wild type 2 virus. But since the GPEI removed type 2 from the vaccine, immunity has waned, and vaccine-induced type 2 polio continues to spread from viruses introduced before they were taken out of oral vaccines. The stage is set for an explosive outbreak, according to Zaffran.

The GPEI now has a stockpile of new oral vaccines that target only the type 2 virus. Zaffran is hopeful that judicious use of those vaccines can stop the current outbreak without causing another one. But Congo poses a special challenge because of its remote villages, deteriorating infrastructure, and inadequate health system. —J.B.



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