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Reemergence of Recombinant Vaccine‐Derived Poliovirus Outbreak in Madagascar

2008; Oxford University Press; Volume: 197; Issue: 10 Linguagem: Inglês

10.1086/587694

1537-6613

Mala Rakoto‐Andrianarivelo, Nicksy Gumede, Sophie Jégouic, Jean Balanant, Seta Andriamamonjy, Sendraharimanana Rabemanantsoa, Maureen Birmingham, Bakolalao Randriamanalina, Léon Nkolomoni, Marietjie Venter, Barry D. Schoub, Françis Delpeyroux, Jean‐Marc Reynes,

Animal Virus Infections Studies

Background.After the 2001-2002 poliomyelitis outbreak due to recombinant vaccine-derived polioviruses (VDPVs) in the Toliara province of Madagascar, another outbreak reoccurred in the same province in 2005.Methods.We conducted epidemiological and virological investigations for each polio case patient and for their contacts.Results.From May to August 2005, a total of 5 cases of acute flaccid paralysis were reported among unvaccinated or partially vaccinated children 2-3 years old.Type-3 or type-2 VDPV was isolated from case patients and from healthy contacts.These strains were classified into 4 recombinant lineages that showed complex mosaic genomic structures originating from different vaccine strain serotypes and probably from human enterovirus C (HEV-C) species.Genetic relatedness could be observed among these 4 lineages.Vaccination coverage of the population was very low (Ͻ50%).Conclusions.The broad distribution of VDPVs in the province and their close genetic relationship indicate intense and rapid cocirculation and coevolution of the vaccine strains and of their related HEV-C strains.The occurrence of an outbreak due to VDPV ϳ3 years after a previous outbreak indicates that a short period with low vaccination coverage is enough to create favorable conditions for the emergence of VDPV in this setting.