Profile: The Kilifi Health and Demographic Surveillance System (KHDSS)

Abstract

The Kilifi Health and Demographic Surveillance System (KHDSS), located on the Indian Ocean coast of Kenya, was established in 2000 as a record of births, pregnancies, migration events and deaths and is maintained by 4-monthly household visits. The study area was selected to capture the majority of patients admitted to Kilifi District Hospital. The KHDSS has 260 000 residents and the hospital admits 4400 paediatric patients and 3400 adult patients per year. At the hospital, morbidity events are linked in real time by a computer search of the population register. Linked surveillance was extended to KHDSS vaccine clinics in 2008. KHDSS data have been used to define the incidence of hospital presentation with childhood infectious diseases (e.g. rotavirus diarrhoea, pneumococcal disease), to test the association between genetic risk factors (e.g. thalassaemia and sickle cell disease) and infectious diseases, to define the community prevalence of chronic diseases (e.g. epilepsy), to evaluate access to health care and to calculate the operational effectiveness of major public health interventions (e.g. conjugate Haemophilus influenzae type b vaccine). Rapport with residents is maintained through an active programme of community engagement. A system of collaborative engagement exists for sharing data on survival, morbidity, socio-economic status and vaccine coverage.

Figure 1

Situation of Kilifi District in Kenya and map of Kilifi District showing the rate of paediatric admissions to Kilifi District Hospital by administrative sublocation and the boundary of the KHDSS. Data are taken from reported sublocations of children aged <5 years admitted to hospital during 1998–2000. The district and sublocation boundaries are those relevant to 2001. In 2009, the Government of Kenya subdivided the district into three new districts but the KHDSS boundaries have remained constant

Figure 2

The population pyramid of the KHDSS in 2001 and in 2011. Data are taken from the initial census (date of median observation: 27 April 2001) and from the 23rd enumeration round (date of median observation: 18 March 2011)

Figure 3

Population pyramids of the 15 administrative locations within the KHDSS. Data are taken from the 23rd enumeration round (date of median observation: 18 March 2011). Predominantly rural environments (the majority) show a marked attenuation of adult residents especially evident among males. Urban (Kilifi Township) and peri-urban areas (Mtwapa, Tezo) show a more gradual attenuation of the population with age, and a more even sex ratio

Figure 4

A census interview underway in a homestead within the KHDSS area

Figure 5

Mothers with their children queue for immunization services in a health facility within the KHDSS area during the World Pneumonia Day celebrations (12 November 2011)