Non-polio enteroviruses serotypes circulating in Nigeria.

Enteroviruses is one of the most common group of human pathogens, causing a wide range of acute symptoms involving the cardiac and skeletal muscles, central nervous system, pancreas,skin and mucous membranes. In spite of the success recorded in polio eradication globally, infections with other enteroviruses remain frequent and sometimes very serious, requiring hospitalization. In this study we determined the various circulating serotypes of non-polio enteroviruses (NPEVs) with a view to providing information on the activity of these viruses among the Nigerian children, who usually are the most affected. Stool samples were obtained from hospitalized children at two major secondary community hospitals in Ibadan and acute flaccid paralysis (AFP) cases from 26 states ofNigeria. A presumptive identification of NPEVs was based on growth in RD cells. Isolates were identified by neutralization assay using sera obtained from the Institute for Public Health and the Environment, the Netherlands. The problems associated with this assay prompted the use of genotypic method developed at the Centers for Disease Control, Atlanta, USA for the final identification of isolates. Neutralization assay identified the 138 isolates into echoviruses (43.5%), coxsackie B viruses (29.7%) and untypeable isolates (26.8%). Finally genotyping identified echoviruses (E3, E6, E7, E11, E12, E13, E14, E19, E20, E21, E24, E29, E30, E33), coxsackieviruses (CVA3, CVA4, CVA6, CVA17, CVB3, CVB5, CVB6) and enteroviruses (EV69, EV71). The causal association of isolates with different diseases was also established. Majority of the isolates belonged to the human enterovirus gropup B (HEV-B) specie, followed by 4 and 1 in the HEV-A and HEV-C species respectively. This study forms the basis of molecular epidemiology of NPEVs being established for the first time in Nigeria. The implication of the presence of neurotropic serotypes (E3, E6, E7, E11, E14, E20, E24, E29, E30, EV71, CVB3 and CVB5) is that AFP may still be prevalent following polio eradication.