Four African countries report polio cases

oral polio

Louie Rosencrans/CDC

Four African countries—the Democratic Republic of the Congo (DRC), Guinea, Nigeria, and Somalia—reported new polio cases this week, according to the latest report from the Global Polio Eradication Initiative (GPEI).

The DRC reported the most, with six new cases of circulating vaccine-derived polio virus type 1, raising the year’s total to 60 cases. Last year the country recorded 146 cases.

In Guinea, four vaccine-derived polio type 2 (cVDPV2 ) cases were recorded, and in Nigeria five cases were reported. GPEI said there have been 24 cVDPV2 cases reported this year and 48 cases in 2022. In Somalia one case was reported.

In a related study in Morbidity and Mortality Weekly Report, researchers note the emergence of vaccine-derived polio from a novel type 2 oral poliovirus vaccine (nOPV2).

Though the novel oral vaccine was shown in clinical trials to be less likely than the original Sabine-type vaccine to revert to paralytic variants, 61 paralytic cases and 39 environmental surveillance samples were detected in six countries—Burundi, Central African Republic (CAR), the DRC, Nigeria, Tanzania, and Zambia—between 2021 and 2023.

Approximately 700 million doses of nOPV2 have been administered worldwide in response to outbreaks of cVDPV2 polio.

"A preliminary estimate suggests that cVDPV2 emergences occur after mOPV2 use at a rate of one emergence per 10 million mOPV2 doses administered; for nOPV2, this rate is approximately 10 times lower, at one emergence per 100 million doses," the authors concluded.

Ukrainian outbreak declared over

Yesterday the World Health Organization (WHO) released a statement on the end of Ukraine's polio outbreak, which started in 2021, a victory in that country despite the ongoing Russian invasion. Ukraine recited a WHO certificate of polio eradication on September 8.

Stopping the spread of poliovirus in the midst of a devastating war is a major achievement.

"Stopping the spread of poliovirus in the midst of a devastating war is a major achievement and a clear demonstration of the highest level of political commitment of the Government of Ukraine to the welfare of its population," Hans Henri P. Kluge, MD, the WHO Regional Director for Europe, said in a press release.

Two children were sickened and paralyzed in the fall of 2021 after the virus was likely imported from Pakistan. An accelerated catch-up immunization campaign was launched just weeks before Russia invaded the country.

No cases have been detected since December of 2021.

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