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Wild poliovirus found in sewage in Brazil
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Health officials in Brazil isolated wild poliovirus type 1 from sewage samples collected in March from the Viracopos International Airport in the state of São Paulo, according to WHO.
However, samples collected later from the same site either tested negative for wild poliovirus or tested positive for Sabin strains or non-polio enteroviruses. There is no evidence of transmission of wild poliovirus in the country, and no paralytic cases of polio have been reported. The positive sample came from an imported case of polio, according to WHO.
The WHO region of the Americas has been free of polo transmission since 1991, and there have been no autochthonous cases reported in Brazil since 1989. The last national immunization campaign against polio in Brazil was conducted in June 2013, achieving more than 95% coverage in the state of São Paulo. The next campaign is planned for November, targeting children aged 6 months to 5 years with oral polio vaccine.
Genetic sequencing of the virus collected from the airport sewage suggests that it is closely related to a strain of wild poliovirus isolated in a case from Equatorial Guinea. WHO said the risk of additional exportations of the virus from that country is high.
In response to news of the positive sample, Brazil health authorities have heightened surveillance of wild poliovirus transmission and paralytic polio.