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Using genomes to understand transmission of RSV in the community

For a mother, nothing worries like waking up in the middle of the night with an infant with a fever and difficulty in breathing. But these are common occurrences for infants and young children especially in a household with school going children. KEMRI Wellcome Trust research Programme in Kilifi has been at the fore in understanding the spread of the leading virus in severe infant respiratory disease in households ultimately aiming at eliminating this problem.

Dr Charles Agoti and colleagues who just had their paper published on Virus Evolution (https://academic.oup.com/ve/article/doi/10.1093/ve/vex006/3066353/Transmission-patterns-and-evolution-of-respiratory) journal talks to me about his work in trying to understand how transmission of Respiratory Syncytial Virus (RSV) occurs in Kilifi community. The overall aim of the ongoing work was to understand who in the household introduces the infection and who actually infects the infant. The reported analysis utilizes the virus genetic code data to understand how the virus is spread in the community and to also find out whether there would be multiple virus strains transmitted in the same household.

The team intensively studied 9 households within the Kilifi Health Demographic surveillance area. This is because it has been previously seen that households happen to be the most ideal environment for respiratory virus transmission due to the level of contact that happens between members.

This is the first study in the world to use full genomic data to show RSV infection spread and also assist in assigning the source of infection in the particular community. They were able to show that the virus that is introduced in a household is the same virus that is spread to other family members with very little change in the virus genetic code. The study findings were also able to support an earlier held theory that it is the young school-going children who are the primary introducers of the virus into the family. This data was also instrumental in showing the connections in infections between households in a community.

So what does it mean? Charles notes that in order to stop spread of most respiratory infections it is critical to understand how they get introduced and spread to the most vulnerable individuals in a household like the infants. “If you can stop introduction by applying control measures at the source then you are better placed in having a reduced number of cases and ultimately controlling the problem”.  He adds, “ It is also important to be sure about where most spread occurs, e.g. is it households, schools, markets, workplaces etc.”  The use of genomic data helps understand the relationship of any two clinical infectious disease cases and will help identify who infects whom with the ultimate aim of distinguishing the entry point, understanding spread and controlling it like intended in the Agoti and colleagues study.