Article

Reemergence of recombinant vaccine-derived poliovirus outbreak in Madagascar.

Unité de Virologie, Institut Pasteur de Madagascar, Madagascar.
The Journal of Infectious Diseases (impact factor: 6.41). 05/2008; 197(10):1427-35. DOI:10.1086/587694 pp.1427-35
Source: PubMed

ABSTRACT 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.
We conducted epidemiological and virological investigations for each polio case patient and for their contacts.
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 (<50%).
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 3 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.

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Keywords

4 lineages
 
4 recombinant lineages
 
5 cases
 
acute flaccid paralysis
 
children 2-3 years old
 
different vaccine strain serotypes
 
Genetic relatedness
 
genetic relationship
 
healthy contacts
 
low vaccination coverage
 
outbreak reoccurred
 
polio case patient
 
previous outbreak
 
rapid cocirculation
 
recombinant vaccine-derived polioviruses
 
related HEV-C strains
 
showed complex mosaic genomic structures originating
 
type-2 VDPV
 
vaccine strains
 
VDPV 3 years