Molecular Detection of Astrovirus in Diarrhoeic Stools of Children in North East Nigeria

Background: Human astroviruses are a leading cause of severe viral gastroenteritis and are responsible for at least 95% of nonbacterial gastroenteritis outbreaks throughout the world.

Methods: Six hundred (600) diarrhoeic stools of children under 5 years were collected between May 2013 – April 2014 and screened for astrovirus using a 3rd generation Ridascreen ELISA kit (R-Biopharm AG, Germany). Demographic data were collected via a questionnaire. Analysis of the data was done using online Easy-Chi-square (p<0.05) statistical package. The ELISA positive astrovirus samples were further analysed by reverse transcription polymerase chain reaction (RT-PCR) and amplicons generated were sequenced. Phylogenetic tree of sequences was constructed using the Neighbour-Joining Model with 1000 replicate bootstrap value in MEGA 6.0.

Results: Astrovirus prevalence of 5.0% (30/600) was obtained. The prevalence of astrovirus in Taraba, Bauchi and Borno states was 5.5% (11/200), 4.5% (9/200) and 5.0% (10/200), respectively. Of the 30 astrovirus positive samples, 63.3% (19/30) were male and 36.7% (11/30) female. Female children were more likely to be infected with astrovirus (OR= 1.38; 95% CI) compared to male children. The highest astrovirus prevalence (8%: 9/112) and lowest (1.9%: 1/54) prevalence were in children 1-2 years and 0-6 months respectively. Most children were infected before 2 years. Of the 30 astrovirus, ELISA positive samples analysed by RT-PCR, 5 (16.5%) amplicons of ORF genes with 400bp were seen and subsequently sequenced.

Conclusion: Sequence analysis showed that all the strains were HAstV-5 indicating the strain prevalent in the study area. The results of the present study suggest that astrovirus contribute significantly to the disease burden of childhood diarrhoea in parts of North Eastern Nigeria.