Detection of viral respiratory and gastrointestinal pathogens among healthy adults and children of an informal settlement (Kibera) in Nairobi, Kenya

Abstract

Background: Asymptomatic individuals (AIs) serve as reservoirs of pathogens associated with disease transmission. The objective of this study was to identify the presence and diversity of selected viral respiratory and gastrointestinal (GI) pathogens in AIs among residents of an informal settlement in Nairobi, Kenya. Methods & Materials: In 2006, KEMRI/CDC established a population-based infectious disease surveillance site within Kibera in Nairobi, Kenya. AIs (healthy controls) were enrolled as part of the system among persons who presented to the study’s referral facility (Tabitha Medical Clinic). Persons presenting without current or previous 2 weeks history of fever, respiratory or diarrheal symptoms were eligible for enrollment as healthy controls. Following consent, participants provided stool and nasopharyngeal/oropharyngeal (NP/OP) specimens. Stool samples were tested by culture for bacterial pathogens and rotavirus by enzyme-linked immunoassay. Respiratory viruses were detected in NP/OP swabs by real time PCR. Results:Between01st November 2008 and31st December 2011, 384 stool samples and 779 NP/OP swabs were obtained from AIs. Pathogenswere found in23 (6.0%) of the384 stool samples. Shigella, 10 (43.5%), was the predominant bacterial pathogen isolated; S. dysenteriae (10%), S. flexneri (70%), and 2 unsubtypable Shigella species. Other bacterial species identified included Campylobacter coli (4.3%) and C. jejuni (17.3%). Rotavirus was the only viral pathogen targeted for isolation; however, it was only detected in <2% of the participants (n=384; 1.8%). Of the 779 NP/OP swabs, adenovirus (11%), respiratory syncytial virus (RSV) (2.8%), human metapnuemovirus (hMPV) (2.7%), influenza virus type A and B (2.3 and 0.5%, respectively), parainfluenza (PIV) type 1, 2 and 3 (0.9, 1.0 and 1.9%, respectively) were detected. Adenovirus, hMPV, RSV, and influenza B were found more frequently in ages 5-17 years (28.1%, 33.3%, 45.5%, and 75% respectively). Adenovirus (78.9%) and all cases of RSV and PIV 1-3 in 18-34 years were identified more among females.Within the same age group Influenza A (85.7%) and hMPV (60%) were more common among males. Conclusion: AIs did show evidence of infection and could serve as reservoirs for thesepathogens throughclose contact in thisurban settlement especially among immunocompromised individuals.