Determinants of malaria in irrigated and non-irrigated villages of Mwea: a comparative assessment

Abstract

Today, approximately 40% o f the world’s population, mostly those living in the poorest countries, are at risk of malaria, which causes more than 300 million acute illnesses and at least one million deaths annually. Ninety per cent o f deaths due to malaria occur m subSaharan Africa, mostly among young children. The importance o f malaria cannot be over emphasized. A project, (Agro-ecosystem Management for Community-Based Integrated Malaria Control in East African Irrigation Schemes) is currendy underway in Mwca Division, Kirinyaga District, Kenya, under the auspices o f the International Development Research Centre (IDRC) Canada and the International Centre o f Insect Physiology and Ecology (ICIPE) in conjunction with the International Water Management Institute (IWMI). The overall aim o f this ICIPE-IW M I Project is to improve the health and well being of communities in irrigation schemes through the development o f sustainable strategies for reduction o f malaria and other health risks based on improved agro-ecosystem management. In Kenya, a considerable part of the area under irrigation is for rice production. The choice o f Mwca is appropriate since it provides an ideal setting in which human health can be factored into agro-ecosystem research, thereby meeting the objectives o f the ICIPE-IWMI Project. This cross-sectional descriptive study was part o f the larger ICIPE-IWMI Project. Its main objective was to compare malaria prevalence and to assess the potential environmental and socio-economic determinants of the disease in irrigated (Ciagi-ini and Mbui Njcni) and non irrigated (Kagio and Murinduko) villages of Mwea. Quantitative data was obtained from one cycle o f malaria prevalence surveys, undertaken in two villages within the irrigated area that were matched with two control villages in the non-irrigated area beyond the flight range of mosquitoes. This collective Malaria Prevalence Survey was carried out on 213 children MJCW aged 9 years and under, in December 2001 and February 2002. The response rate was 74.5%. Qualitative data was obtained through participatory methodologies earned out within the four villages and involved selected stakeholders and other target groups from Mwea. In addition, a Community Diagnosis was earned out in 420 households within the four villages. Malaria was ranked as the major health problem in all the four study villages (except at the Stakeholders’ Consultative Workshop where it was ranked second). Within the lmgated villages, malaria, alcoholism, and lack o f clean water were the predominant problems. Within the non-irrigated villages, the predominant problems were poor nutrition, HIV/AIDS, lack o f sewerage systems, poverty, and ignorance. Poverty was not perceived as a problem at all within the irrigated villages but was a problem in Munnduko village in the non-irrigated area. Kagio, also in the non-irrigated area, was perceived to be relatively wealthy. Community Diagnosis generated inclusive quantitative household data on health, incomes, and the environment. A comparison o f results from quantitative and qualitative data showed a high degree o f consistency. However, an inconsistency occurred in \lbui Njeru village where the qualitative data ranked malaria as the major health problem whereas the quantitative data from the Malaria Prevalence Survey, which was conducted during the wet season, showed no positive cases o f malaria. The Malaria Prevalence Survey results showed that the overall prevalence for the four villages was 23.5 per 100. Within the irrigated villages, the prevalence was 6.7 per 100, while in the non-irrigated villages it was 36 per 100, indicating that malaria prevalence was higher within the non-imgated villages than within the irrigated villages. Relatively more males (68%) than females (32%) were positive for malaria parasites despite the roughly equal distribution o f the sexes. Malaria prevalence was significandy related to the age and occupation of the household head, with those household heads that were that were in the MK2004 XVI 41-50 year age group and those that were unemployed/retired having the highest proportion of children with a positive blood slide. In addition, there was a significant relationship between malaria prevalence and type of house. The majority (78%) of children with a positive blood slide lived in temporary structures. There was no significant relationship between use o f bed nets and a positive blood slide. However, there were significant differences in reported use o f bed nets between irrigated and non-irrigated villages. More respondents in the irrigated villages reported that all household members used bed nets as compared to the non-irrigated villages. More respondents in the non-irrigated villages reported that they did not use bed nets at all. There was a significant relationship between the use o f anti-malarial drugs in the preceding three days and a positive blood slide. Most of the children who had used an anti-malanal dmg had a negative blood slide. The average number o f Anopheles arabiensis mosquitoes in a house was significantly related to irrigation and to a positive blood slide. There was also a significant difference in the average number of Anopheles arabiensis mosquitoes in a house between irrigated and non-irrigated villages. Houses that had a lower average number o f Anopheles arabiensis mosquitoes had a higher proportion of positive blood slides. This cross-sectional survey only revealed the malaria situation at one point in time. Therefore, study that is more extensive is required in order to provide a wider picture o f malaria in Mwea throughout the year. More research is necessary to explain the unusual difference in malaria prevalence between irrigated and non-irrigated villages. More work is also needed to investigate other findings such as the difference in prevalence between the sexes, and between villages with a predominance o f cattle and those with a predominance of other types o f livestock. V0C2XM The symptoms o f malaria are similar to those o f other illnesses, notably typhoid, and this may partly explain the apparent inconsistency between qualitative and quantitative data on malaria prevalence observed in Mbui Njeru village. Ecological development may have important effects on the epidemiology o f vector borne diseases such as malaria. This may be particularly significant where disease transmission is unstable for example, in highland areas. Intersectional partnership is necessary, such as was the case in this study, in order to reduce the disease burden in Mwea. Understanding community perceptions o f aetiology, symptom identification, and treatment o f malaria is an important step towards control of the disease. More detailed and ongoing research is vital if lasting solutions are to be found. Research projects should of necessity be participatory at all stages, such as was the case with the ICIPE-IW M1 Project, and even more importantly, continuous, because o f the need for monitoring, evaluation, and sharing o f new information among concerned parties. The residents o f Mwea require empowerment in terms o f acquisition o f relevant health education and sound economic and business principles in order to improve their socio economic status and therefore be able to adopt malaria-prevention measures.