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, deaths and cause of 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 284 000 residents and covers 891 km2 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.
Unit of Analysis
CMD2013.v1: For piblic distribution
Emigration and Immigration [N01.224.625.350]
Birth Rate [N01.224.935.849.500]
Kilifi District is situated 60km to the north of Mombasa on the Kenyan coast. It has an area of approximately 2,500 square kilometres and a population of 650,000. A flat coastal strip extends approximately 10km inland to low hills rising to an altitude of 250 metres
An area of 891 km2 was selected as the smallest number of administrative sublocations that collectively included the stated sublocation of residence of at least 80% of paediatric inpatients in the preceding 3 years (1998-2000). KDH is located in Kilifi town, 3° south of the equator and KHDSS extends up and down the coastal strip for 35 km from Kilifi. KDH is the only inpatient facility offering paediatric services in the KHDSS area. The local economy is based on subsistence farming of maize, cassava, cashew nuts and coconuts as well as goats and dairy cows. Two large agricultural estates, two research institutes and several tourist hotels contribute to local employment.
Unit of Analysis
All individuals in the HDSS area
Producers and sponsors
Authoring entity/Primary investigators
KEMRI Wellcome Trust Research Programme (KWTRP)
KEMRI Wellcome Trust Research Programme (KWTRP)
KEMRI Wellcome Trust Research Programme (KWTRP)
Population of Kilifi HDSS
No sampling, complete population surveyed
Deviations from the Sample Design
On an average, the response rate is 99.9% over the years in every round.
Dates of Data Collection (YYYY/MM/DD)
2017 Release Coverage
Frequency of Data Collection
Three rounds in a year
Mode of data collection
Proxy Respondent [proxy]
1. Spot checks
Spot checks refer to random verification of certain details or information about the study. For example, a field supervisor can flip through a fieldworker’s records after the fieldworker has visited a homestead to ascertain that all records are complete. Another area for a spot check is a field supervisor visiting a home previously visited by a fieldworker to confirm that the interview was conducted as indicated. The supervisor can verify few details for example, date of birth of certain individuals at the homestead and details of a migration event. These are then compared with the records earlier presented by a fieldworker.
2. Repeat interviews
This can be done at the end of the round by picking a 5% sample then re-interviewing. After the re-interviews, the collected data are compared with that captured by the fieldworkers to check if they were accurate. Another approach is to conduct a repeat interview a day after the initial interview but still take note of the respondent
3. Field Data verification
4. Field follow ups for refusals
Type of Research Instrument
1. Enumeration of persons
The Enumeration of People Data Entry Form has all names of residents within an homestead (Hm). This form bears the Enumeration Zone ( EZ) and Hm numbers, Hm name and name of homesteadhead. Also, it has details of each individual such as name, sex, ethinicity, pregnancy status, Kenya national identification number, Mother's national identification card number as well as the BU where an individual sleeps. A Fw uses this form to up-date the residence status of people.
2. Enumeration of buildings
This form has a list of all homesteads and existing buildings in each homestead (Hm). The form indicates: Hm name, Hm number and building units(BUs) in alphabet numbers. The geographical co-ordinates and materials used to make each building are also included. The census FWs update this form to show if the building unit still exists or if the BU has been demolished.
3. Listing of all registered Homesteads
The Listing of All Registered Homesteads form has all active Hms in a sub-enumeration zone (sub- EZ) according to the previous census round. It is used to confirm number and specific HMs in a sub-EZ with the records of Building Structure (BS) Data Entry Form
4. In migrants
This form is used to record new people who have moved into an existing or a new homestead, or people who have been present but missed in the previous census rounds and intend to stay for the next three or more months.
This form is used to record all new born babies by resident mothers. In this form, all personal details of the baby are recorded and linked to those of the mother if she is a resident.
All resident women within the reproductive age bracket i.e., between 15 and 49 years, are usually flagged in the Enumeration Data Entry form to be asked about their pregnancy status.
7. Change person details
Change Personal Details Data Entry form is designed to record changes of personal details.The Change Personal Details Data Entry form provides fields and codes used to effect such changes or corrections. Accuracy of the new value must be supported by evidence, preferrably documented evidence for example, a national identification card for date of birth.
8 .Change buildings details
The change buildings details data entry form is designed to record changes relating to building materials, category and coordinates of a building unit as well as change of homestead names. Potential areas for changes and corrections include the Hm name, roof, wall, storey, longitudes, latitudes and elevation. Specific codes are used to describe the type of a building characteristic to be changed.
KHDSS enumerators use EZ maps with a list of Hms that bears coresponding Hm numbers. Vital landmarks, roads and other features are displayed on a map to assist locate and identify Hms. These maps are up-dated every census round by the mapping team and enumerators. Global Positioning System (GPS) and Geographic Information System (GIS) technologies are used to develop and maintain a mapping database. ETrex garmin GPS receivers are used to collect spatial data and ArcGIS 10 is used to manipulate, edit, store and generate maps.
Kilifi Health and Demographic Surveillance System
A manual editor on daily basis checks completed tools for completeness and consistency. Those that have issues are returned to the responsible fieldworkers for correction and/or follow ups. Manual editor’s reports are instrumental in evaluating fieldworkers after every two weeks.
Complementary nature of KEMRI studies
Kemri-Wellcome Trust Programme has a number of research studies being conducted in the same KHDSS census area. Some of these studies are nested within the KHDSS and have proved useful in improving data quality. For example, issues have been raised concerning some details such as date of birth and sex, which prompted verifications in the field and corrections.
The following processing checks are done during the ETL process.
1. If the first event is legal. Like the first event must beenumeration, birth or inmigration.
2. If the last event is legal. Like the last event must be end of observtion, death or outmigration.
3. If the transition events are legal.
The list of legal transitions:
Birth followed by death
Birth followed by exit
Birth followed by end of observation
Birth followed by outmigration
Death followed by none
Entry followed by death
Entry followed by exit
Entry followed by end of observation
Entry followed by outmigration
Enumeration followed by death
Enumeration followed by exit
Enumeration followed by outmigration
Exit followed by entry
Inmigration followed by Death
Inmigration followed by exit
Inmigration followed by end of observation
Inmigration followed by outmigration
End of observation followed by none
Outmigration followed by none
Outmigration followed by enumeration
Outmigration followed by inmigration
The list of illegal transitions:
Birth followed by none
Birth followed by birth
Birth followed by entry
Birth followed by enumeration
Birth followed by inmigration
Death followed by birth
Death followed by death
Death followed by entry
Death followed by enumeration
Death followed by exit
Death followed by inmigration
Death followed by outmigration
Death followed by end of observation
Entry followed by none
Entry followed by birth
Entry followed by entry
Entry followed by enumeration
Entry followed by inmigration
Enumeration followed by none
Enumeration followed by birth
Enumeration followed by entry
Enumeration followed by enumeration
Enumeration followed by inmigration
Exit followed by birth
Exit followed by death
Exit followed by exit
Exit followed by end of observation
Exit followed by outmigration
Inmigration followed by none
Inmigration followed by birth
Inmigration followed by entry
Inmigration followed by enumeration
Inmigration followed by inmigration
End of observation followed by birth
End of observation followed by death
End of observation followed by entry
End of observation followed by enumeration
End of observation followed by exit
End of observation followed by inmigration
End of observation followed by end of observation
End of observation followed by outmigration
Outmigration followed by birth
Outmigration followed by death
Outmigration followed by exit
Outmigration followed by end of observation
Outmigration followed by outmigration
List of edited events:
Exit followed by none
Exit followed by enumeration
Exit followed by inmigration
Outmigration followed by entry
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Any use of this dataset must cite the digital object identifier (doi) associated with this dataset. Using the following form:
"Kilifi HDSS INDEPTH Core Dataset 2002-2013 (Release 2016). Provided by the INDEPTH Network Data Repository. www.indepth-network.org<http://www.indepth-network.org>. doi:10.7796/INDEPTH.KE011.CMD2013.v1"
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