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Asymptomatic RSV cases prevalent, undetected in Kenya
Asymptomatic respiratory syncytial virus infections may be more prevalent among Kenyan households than previously believed, suggesting a need for respiratory virus detection regardless of clinical presentation, according to recently published data.
In a prospective cohort study, researchers evaluated 47 households, including 493 family members, in coastal Kenya who were registered with the Kilifi Health and Demographic Surveillance System. The participants were sampled weekly for 4 weeks and then tested twice a week, regardless of illness status, from December 2009 through June 2010.
Field assistants recorded all respiratory symptoms such as cough, runny nose or blocked nose, or breathing difficulties at each assessment. In addition, the researchers collected nasopharyngeal swabs and used real-time PCR to assay them for RSV groups A and B, human rhinoviruses, human coronaviruses (hCOV-OC43, NL63 and 229E) and adenoviruses.
Among the 16,928 tested samples, the investigators found 205 RSV infections among 37.1% of patients living in 40 households. Forty-two percent of these cases were symptomless.
Independent predictors of increased asymptomatic RSV risk included being older, shorter infection duration, larger household size, lower peak viral load, a lack of coexisting RSV infections among others in the household, group B RSV infection and no previous human rhinovirus infection. The risk for RSV transmission within households was contingent on symptom status and the extent of virus shed (duration and viral load).
According to the researchers, detection of asymptomatic cases is necessary to develop a complete picture of the RSV epidemiology within a community.
“Our results show that a significant proportion of RSV infections are asymptomatic,” the researchers wrote,” thus the amount of the virus circulating in the community would be underestimated if the contribution of asymptomatic infections is overlooked.” – by Jen Byrne
Disclosure: The researchers report no relevant financial disclosures.