Population based disease surveillance in Kenya The epidemiology of selected infectious diseases

The greatest burden of infectious diseases is in low- and middle-income countries, yet obtaining precise disease burden estimates is challenging. Among other uses, data are needed to inform prioritization and targeting of resources for prevention and treatment purposes. The studies in my thesis were based on longitudinal population based disease surveillance platforms set up in two sites – almost 400 kms apart - in Kenya; Kibera in Nairobi, and Lwak in Asembo in rural western Kenya. Each site had approximately 25,000 people enrolled in the surveillance project. Project field workers visited participants every two weeks in their homes and collected data about symptoms of illness and associated care seeking for those found ill. At each site were referral clinics staffed with project medical teams where free care was available to study participants presenting with any potentially infectious condition. Demographic and clinical data as well as biological specimens were collected during the sick-visits as appropriate.
The thesis describes health utilization patterns for various syndromes, characterizes the epidemiology of disease and lastly provides examples of interventions on disease. In some chapters rural-urban comparisons in disease burden are provided.
The data revealed changes in health care seeking after implementation of free care by the project, and after a large-scale home-based HIV counselling and testing activity. Secondly, in characterising the epidemiology of RSV, young children bore the greatest burden of disease in both rural and urban Kenya. And lastly we demonstrated the indirect protection of adults from pneumococcal pneumonia disease after the introduction of a 10-valent pneumococcal conjugate vaccine into the infant immunization program in Kenya.
In conclusion, continuous disease surveillance in well-defined populations is important in determining burden and seasonality of disease, the etiologies of such diseases, and in evaluating impact of interventions.