Published by Oxford University Press on behalf of the International Epidemiological Association International Journal of Epidemiology 2013;42:1678–1685 ß The Author 2013; all rights reserved. doi:10.1093/ije/dyt180 HEALTH AND DEMOGRAPHIC SURVEILLANCE SYSTEM PROFILE Profile: The Mbita Health and Demographic Surveillance System Sheru Wanyua,1* Morris Ndemwa,1 Kensuke Goto,1,2 Junichi Tanaka,1,2 James K’Opiyo,1 Silas Okumu,1 Paul Diela,1 Satoshi Kaneko,1,2 Mohamed Karama,1,4 Yoshio Ichinose1,3 and Masaaki Shimada1,3 1Nagasaki University Institute of Tropical Medicine-Kenya Medical Research Institute Project, Nairobi, Kenya, 2Department of Eco-Epidemiology, Nagasaki University, Nagasaki, Japan, 3Centre for Infectious Disease Research in Asia and Africa, Nagasaki University Institute of Tropical Medicine, Nairobi, Kenya and 4Centre for Public Health Research, Kenya Medical Research Institute, Nairobi, Kenya *Corresponding author. NUITM-KEMRI Project, PO Box 19993, 00202, Nairobi, Kenya. E-mail: [email protected] Downloaded from Accepted 31 July 2013 The Mbita Health and Demographic Surveillance System (Mbita HDSS), located on the shores of Lake Victoria in Kenya, was estab- http://ije.oxfordjournals.org/ lished in 2006. The main objective of the HDSS is to provide a platform for population-based research on relationships between diseases and socio-economic and environmental factors, and for the evaluation of disease control interventions. The Mbita HDSS had a population of approximately 54 014 inhabit- ants from 11 576 households in June 2013. Regular data are collected using personal digital assistants (PDAs) every 3 months, which in- by guest on September 10, 2015 cludes births, pregnancies, migration events and deaths. Coordinates are taken using geographical positioning system (GPS) units to map all dwelling units during data collection. Cause of death is inferred from verbal autopsy questionnaires. In addition, other health-related data such as vaccination status, socio-economic status, water sources, acute illness and bed net distribution are collected. The HDSS has also provided a platform for conducting various other research activities such as entomology studies, research on neglected tropical diseases, and environmental health projects which have bene- fited the organization as well as the HDSS community residents. Data collected are shared with the community members, health officials, local administration and other relevant organizations. Opportunities for collaboration and data sharing with the wider research community are available and those interested should contact shimadam@ nagasaki-u.ac.jp or [email protected]. Why was the HDSS set up? institutions, and to strive for excellence in the follow- ing areas: The mission of the Institute of Tropical Medicine at Nagasaki University (also known as Nekken (i) spear-heading research in tropical medicine and in abridged Japanese or NUITM in Kenya) is to international health; overcome tropical diseases, particularly infectious (ii) global contribution through disease control and diseases, and the various health problems health promotion in the tropics by applying the associated with them, in cooperation with related fruits of the research; 1678 THE MBITA HEALTH AND DEMOGRAPHIC SURVEILLANCE SYSTEM 1679 (iii) cultivation of the researchers and specialists in Table 1 Summary of additional health data collected the above fields.1 YEAR In order to attain this mission, a research project TOPIC 2008 2009 2010 2011 2012 was launched in 2005 in collaboration with the Kenya 3333 Medical Research Institute (KEMRI). The HDSS was Vaccination started as a major part of this collaborative project. Nutritional status of 333 The Mbita HDSS site is located in an area which has children one of the highest HIV prevalence rates and the some of Toilet and latrine 3333 the poorest health indicators in Kenya. Malaria is the coverage leading cause of morbidity and mortality among chil- Handwashing practices 3 dren in the region. Its specific objectives are as follows: Acute illness and health 3333 (i) to establish baseline data on the demographic, seeking behaviour socio-economic, environmental and health Disability 3 characteristics of the communities in Mbita dis- Education level 33 trict in Kenya; 33 (ii) to document all births, deaths, in-migrations, out- Employment 3 migrations, socio-economic status, pregnancy out- Dental hygiene Downloaded from comes and causes of death at given intervals; Bed net use 33333 (iii) to investigate and evaluate interrelationships be- Water sources, storage 33 tween health and socio-economic interventions and treatment and their impact on morbidity and mortality; 3333 (iv) to provide a platform for scientific studies in School attendance the prevention, management and control of http://ije.oxfordjournals.org/ parasitic, viral, bacterial, degenerative and life- style-related diseases; The population lives on subsistence farming, small- (v) to provide a platform for education and training scale businesses, fishing and keeping domestic ani- and multidisciplinary research for health pro- mals. Two wet seasons usually occur annually from fessionals, graduate students and researchers. March to June and October to November, but the periods vary to some extent each year.4 The administrative locations covered in this system What does it cover now? are Rusinga West, Rusinga East, Gembe West and by guest on September 10, 2015 The project integrates different scientific and oper- Gembe East as well as two islands, namely Takawiri ational research projects which are aimed at solving and Kibuogi, as shown in Figure 1. Rusinga West, problems not only in the HDSS site but also in areas Rusinga East and Gembe West formed the original where similar challenges prevail, especially with regard HDSS area from 2006, and Gembe East was added to the goals specified in the UN Millennium project.2 to the surveillance area in June 2008. The whole Intensive baseline data were collected during the HDSS area, currently consisting of Rusinga West, first survey and thereafter most data collections Rusinga East, Gembe West and Gembe East, was have been done to update vital events (births, subdivided into 21 field interviewer areas. deaths, migrations and pregnancies). Additionally, The residential unit is the compound which consists structured questionnaires are administered from of one or more households together. Traditional time to time to get a better understanding of the houses are mud and grass thatch huts. Modern con- health situation in the area. Examples of the type of structions, made of concrete and corrugated iron, tend health data collected are summarized in Table 1. to replace traditional houses. The households obtain The HDSS also serves as a platform for other re- their water from various sources such as the Lake search projects which have been listed elsewhere.3 Victoria, Ministry of Water taps, rivers, boreholes and open dams as well as rain water. There are 30 health facilities within the study zone, providing Where is the HDSS area? basic services to the study population. These include the main sub-district hospital, health centres, dispen- The Mbita HDSS is located on the shores of Lake saries and clinics. Victoria in Homa Bay County, one of 47 Counties in Kenya. It is a mostly rural area found between lati- tudes 08 21’ and 08 32’ south and longitudes 348 04’ Who is covered by the HDSS and and 348 24’ east. It is about 400 km west of Nairobi, how often have they been the capital city of Kenya and it covers 163.28 km2. The field station in Mbita is located in the International followed up? Centre for Insect Physiology and Ecology (ICIPE) Between 1 August 2006 and 15 December 2006, the research compound. baseline survey was conducted during which all 1680 INTERNATIONAL JOURNAL OF EPIDEMIOLOGY Ethiopia Lake Victoria Rusinga Kenya Rusinga East West Mbita HDSS Nairobi Gembe West Lake Victoria Gembe Indian East Ocean 0 500km 0 10km Figure 1 Map of Mbita HDSS Downloaded from Static population of Mbita HDSS Gembe-Rusinga (June 2013) http://ije.oxfordjournals.org/ 85+ 80-84 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 by guest on September 10, 2015 35-39 30-34 25-29 20-24 15-19 10-14 5- 9 0- 4 5000 4500 4000 3500 3000 2500 2000 1500 1000 500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 Males Females Source: Mbita Health and Demographic Surveillance System Figure 2 The static population pyramid of the Mbita HDSS as of June 2013 inhabitants were registered using the PDAs assigned December 2012, the HDSS had a population of to all field interviewers. Up to 31 May 2008, 40 472 54 395 from 11 576 households, as shown in residents in Rusinga East, Rusinga West and Gembe Figure 2. Other demographic characteristics are pre- West locations in Mbita district had been followed up. sented elsewhere.3 After expansion of the surveillance area by addition of Follow-up surveys have been conducted in the pilot the Gembe East location from 1 June 2008, the popu- area since January 2007. Through these surveys we lation increased to 55 806 residents. receive updated information on the baseline survey Re-registration of residents was done between (new members and houses), migration of residents, October and December 2008 with the incorporation pregnancies and deaths. Data are currently updated of GPS units for mapping all structures within the at 3-month intervals. The data collection rounds and HDSS site. The number registered was 54 782 from changes within the HDSS since 2006 have been sum- 12 897 households, a participation level of 96%. In marized in a flowchart in Figure 3. During every THE MBITA HEALTH AND DEMOGRAPHIC SURVEILLANCE SYSTEM 1681 follow-up survey, different types of questions are What has been measured and how added to the routine update surveys summarized in Table 1. After successive rounds, collected data are have the HDSS databases been checked and used for updating the database.