Q3) a. Identify and explain two potential strengths and two potential weaknesses of the selection of controls. (8 marks)

b. A number of exposures were of interest in this study. What were the broad categories of exposures in this study?

c. Identify and explain one strength and one limitation of the methods for exposure assessment. Article:

Published by Oxford University Press on behalf of the International Epidemiological Association International Journal of Epidemiology 2008:37:344-352 The Author 2008; all rights reserved. Advance Access publication 9 January 2008 doi: 10.1093/ije/dym275 INFECTIOUS DISEASE Risk factors of visceral leishmaniasis in East Africa: a case-control study in Pokot territory of Kenya and Uganda Jan H Kolaczinski,12* Richard Reithinger,23 Dagemlidet T Worku,* Andrew Ocheng,' John Kasimiro,' Narcis Kabatereine' and Simon Brooker? Accepted 11 December 2007 Background In East Africa, visceral leishmaniasis (VL) is endemic in parts of Sudan, Ethiopia, Somalia, Kenya and Uganda. It is caused by Leishmania donovani and transmitted by the sandfly vector Phlebotomus martini. In the Pokot focus, reaching from western Kenya into eastern Uganda, formulation of a prevention strategy has been hindered by the lack of knowledge on VL risk factors as well as by lack of support from health sector donors. The present study was conducted to establish the necessary evidence-base and to stimulate interest in supporting the control of this neglected tropical disease in Uganda and Kenya. Methods A case-control study was carried out from June to December 2006. Cases were recruited at Amudat hospital, Nakapiripirit district, Uganda, after clinical and parasitological confirmation of sympto- matic VL infection. Controls were individuals that tested negative using a rK39 antigen-based dipstick, which were recruited at random from the same communities as the cases. Data were analysed using conditional logistic regression. Results Ninty-three cases and 226 controls were recruited into the study. Multivariate analysis identified low socio-economic status and treating livestock with insecticide as risk factors for VL. Sleeping near animals, owning a mosquito net and knowing about VL symptoms were associated with a reduced risk of VL. Conclusions VL affects the poorest of the poor of the Pokot tribe. Distribution of insecticide-treated mosquito nets combined with dissemination of culturally appropriate behaviour-change education is likely to be an effective prevention strategy. Keywords Visceral leishmaniasis, risk factors, Uganda, Kenya, case-control study, prevention Malaria Consortium Africa, Plot 2A, Sturrock Road, * Medecins Sans Frontieres, Geneva, Switzerland. PO Box 8045, Kampala, Uganda. Vector Control Division, Ministry of Health, PO Box 1661, Department of Infectious and Tropical Disease, London School Kampala, Uganda. of Hygiene and Tropical Medicine, Keppel Street, London * Corresponding author. Public Health Specialist, Malaria WCIE 7HT, UK. Consortium, African Regional Office, Kampala, Uganda. Clinical Trials Area, Westat, Rockville MD 20850, USA. E-mail: j.kolaczinski@malariaconsortium.org 344RISK FACTORS OF VISCERAL LEISHMANIASIS IN EAST AFRICA 345 Introduction Case definition and recruitment Visceral leishmaniasis (VL) is a chronic, systemic Cases were individuals that reported to the out- disease characterized by fever, (hepato) splenomegaly, patients department of Amudat hospital with lymphadenopathy, pancytopenia, weight loss, weak- suspected clinical VL, i.e. a history of prolonged ness and, if left untreated, death. The disease is fever (2 weeks or more) associated with clinical usually caused by Leishmania donovani or L. infantum, splenomegaly or wasting, that was subsequently protozoan parasites transmitted to human and animal confirmed using a rK39 antigen-based dipstick hosts by the bite of phlebotomist sandflies. (IT-Leish, DiaMed AG, Switzerland). In Uganda, this East Africa is one of the world's main endemic areas dipstick has high sensitivity and specificity. "Because for VL, which over the last 20 years has seen a VL treatment is provided free of charge by MSF and dramatic increase in the number of VL cases, due to awareness of VL among the local population is a complexity of factors. Several studies have convinc apparently high," many individuals with symptoms ingly shown that malnutrition, HIV and genetic of VL present voluntarily at the outpatients depart- susceptibility are individual risk factors for VL.34 ment. For logistical reasons, only cases living in However, data on socio-economic, behavioural and communities within 80 km from Amudat town were entomological risk factors for VL are comparatively included in the analysis. Confirmed cases were scarce, and in East Africa, no study, to our knowl- admitted to the VL ward and treated with daily edge, has investigated risk factors for VL. This severely intramuscular injections of meglumine antimoniate hampers efforts to prevent and control the disease in (Glucantime", Sanofi-Aventis, Paris, France) at the region. To fill this knowledge gap, we carried 20 mg/kg per day for 30 days according to standard out a case-control study to identify individual and MSF treatment protocol.2 household level risk factors for VL in an endemic Controls were individuals who had been selected focus in eastern Ugandaorth-western Kenya. at random from the same communities as the cases. Two controls were matched according to village and frequency-matched according to age group ( 98%. activities at Kacheliba health centre, Kenya. A recent Haemoglobin concentration (Hb) was estimated to an KAP study in the study area indicated that 95% of accuracy of 1 g/l using a portable haemoglobinometer individuals had heard of VL, known locally as (Hemocue Ltd, Sheffield, UK). Weight was measured 'termes', meaning enlarged spleen." Most individuals to the nearest 0.1 kg using an electronic balance regarded VL as a potentially fatal disease, were aware (Soehnle, Leifheit AG, Nassau, Germany) and height of its main clinical signs and knew that drug was measured to the nearest 0.1 cm using a portable treatment is available and effective. VL in Pokot stadiometer (Leicester Height Measure, Child Growth territory is caused by L. donovani and infection is Foundation, London, UK). transmitted by the sandfly Phlebotomus martini, one Ethical clearance for the study was obtained from of the main vectors of VL in East Africa. $ 10 the Uganda National Council of Science and from the346 INTERNATIONAL JOURNAL OF EPIDEMIOLOGY ethics committee of the London School of Hygiene and Tropical Medicine. UK. Individuals were informed of the studfs purpose and methodology and were made aware that participation was voluntary and that they were able to withdraw from the study at any time. For study subjects. consent was obtained from all adult subjects and from parents or guardians of children by use of a written consent form; ascent was obtained from children. Household surveys A pro-tested standardized household questionnaire was administered to each case or their guardian at Amudat hospital. Cases were accompanied home by a surveyor to verify the accuracy of the information provided in the questionnaire. All controls were interviewed at home. For young children included in the study it was common that a parent or guardian responded to the majority of questions. The ques- tionnaire recorded details on socioeconomic charac- teristics. including ownership of selected household assets. animal ownership and household construction. Information was also collected on knowledge of V1. and the behaviour of subjects. in this context. we defined 'sleeping near animals' as being within 5-15m from livestock kept outdoors within the confines of the manyatta. The list of household assets and indicators were selected based on pub- lished literature and discussions with key local informants. Data analysis Anthropometric lndices were calculated using Anthro 1.02 software (CDC. Atlanta. GA. USA). which uses the U.S. National Centre for Health Statistics (NCHS) reference values. '4 Three anthropometric indices height-for-agc (HA2). weight-for-age (WAZJ and weight-for-height (WHZlwere expressed as differ- ences from the median in standard deviation units or z-scores. individuals were classified as stunted. underweight and wasted if HA2. WAZ and WHZ were >2 SD below the NCHS median, respectively. Anaemia was defined as a haemoglobin level