KENYA- Health officials in Kenya have detected the poliovirus in a sewage sample collected from Nairobi, raising concerns about the continued viral spread.
This is the second vaccine-derived poliovirus reported in the country this year.
The sample, collected on May 15, 2024, tested positive for the circulating vaccine-derived poliovirus type 2 (cVDPV2) at the Kenya Medical Research Institute laboratories.
No associated cases of paralysis have been detected so far, and the risk to the general public in Nairobi is considered low.
The virus found in the sewage is likely to have been excreted by a person vaccinated with the oral polio vaccine (OPV), which contains a live but weakened virus.
The OPV is more effective than the injectable vaccine used in most rich countries, as it stimulates long-lasting immune responses in the intestines where polio replicates.
However, the weakened viruses can be excreted live and become active again, especially in communities with poor sanitation.
In sporadic cases, people infected with the excreted virus can develop paralysis if not vaccinated.
This is the second case of vaccine-derived poliovirus reported in Kenya this year, after a stool sample collected on February 21 also tested positive for polio.
Kenya is among the many countries that monitor sewage to predict potential polio outbreaks.
This highly infectious disease primarily affects children under five years of age and can cause permanent paralysis.
Eradicating polio requires 100% vaccine coverage, but the WHO estimates the vaccination rate in Kenya is around 91%, with some areas near Somalia having rates as low as 77%.
After eight cases of vaccine-derived poliovirus were confirmed in Kenya last year, the Ministry of Health conducted three rounds of vaccination, reaching millions of children.
However, the current cases may pose a challenge due to a shortage of polio vaccines in the country.
The International Rescue Committee Kenya country director is warning of a crisis in the Hagadera refugee camp at Dadaab, where only 60 doses of Oral Polio Vaccine remain.
The Ministry of Health has not indicated any immediate action regarding the two reported cases this year.
The situation underscores the need for continued vigilance and sustained efforts to maintain high vaccination coverage and improve sanitation to prevent the spread of polio in Kenya.
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