Identification of diarrhoea causing viral agents and molecular characterisation of group of rotaviruses in children below five years from Mukuru slums, Nairobi county
Gikonyo, Ndung'u Joshua
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Enteric viruses have been recognized as the most important etiologic agents of gastroenteritis, the root cause of diarrhoea and a major worldwide menace responsible for childhood morbidity and mortality. In Kenya, there is no evidence of studies carried out on outpatient populations to assess the relative importance of enteric diarrhoea-causing viruses such as noroviruses, astroviruses, rotaviruses and enteric adenoviruses. The aim of this study was to investigate the prevalence of these enteric viruses as agents of diarrhoea in children less than five years of age, in and around Mukuru slums in Nairobi County, and to genotype group A rotaviruses. Stool samples were collected at two medical laboratories; one in Reuben medical center and the other one in St. Mary's health center, between January 2010 and March 2011 from 340 children less than five years of age seeking treatment for diarrhoea. The samples were screened for rotavirus (RVs), enteric adenovirus (EAdVs), astrovirus (AstVs) and noroviruses (NVs) Genotype I and II using Reverse transcriptase polymerase chain reaction. Shedding of RV was detected in 24%, EAdV in 2.7%, NV in 1.7%, and AsV in 1.5% of the samples analyzed. Rotaviruses and adenoviruses were found to be in circulation throughout the period of study, while astroviruses and noroviruses were absent in different months of the study. However, an increased shedding of all the viruses under study was noted in the wet and cold months of July and August. The average age of children infected with these viruses was less than 2 years. The incidence and diversity of the main human rotavirus genotypes (G 1, G2, G3, G4 and G9 and P[S], P[ 4], P[ 6], and P) were determined by using established and adapted reverse transcriptase PCR-based genotyping methods. The P type (VP4 associated) was successfully determined in 35 (S7.5%) of the 40 page positive samples, while the G type (VP7 associated) was successfully determined in 37 (92.5%). Only five samples could not be assigned a G or P type. Three P types existed in Mukuru slums, P[S] (60%), P (22.9%), P (11.4) and their relative incidence varied over the 15 months of this study. No P or P[ 10] types were detected. Type G 1 was the most predominant of the G types (40.5 %), and the incidences of G3 and G9 were 21.6 and 32.4% respectively. Mixed types G3/G9 were detected at 5.4%, while G2, G4 and GS-type viruses were not detected. These findings indicate that rotaviruses, noroviruses, enteric adenoviruses and astroviruses are important causes of acute gastroenteritis in Mukuru slums Nairobi Kenya, and rotaviruses are the leading cause of viral gastrointestinal infections followed by adenoviruses. An indication that the prevalence of certain genotypes may change over a rotavirus season is significant and mirrors observations from studies in other tropical climates. Thus monitoring of the genotypic changes among circulating viruses should be encouraged over the coming years.