Mekonnen Yohannes

Incidence of malaria among children living near dams in northern Ethiopia: community based incidence survey

Abstract Objective: To assess the impact of construction of microdams on the incidence of malaria in nearby communities in terms of possibly increasing peak incidence and prolonging transmission. Design: Four quarterly cycles of malaria incidence surveys, each taking 30 days, undertaken in eight at risk communities close to dams paired with eight control villages at similar altitudes but beyond flight range of mosquitoes. Setting: Tigray region in northern Ethiopia at altitudes of 1800 to 2225 m. Subjects: About 7000 children under 10 years living in villages within 3 km of microdams and in control villages 8-10 km distant. Main outcome measures: Incidence of malaria in both communities. Results: Overall incidence of malaria for the villages close to dams was 14.0 episodes/1000 child months at risk compared with 1.9 in the control villages—a sevenfold ratio. Incidence was significantly higher in both communities at altitudes below 1900 m. Conclusions: There is a need for attention to be given to health issues in the implementation of ecological and environmental development programmes, specifically for appropriate malaria control measures to counteract the increased risks near these dams. Key messages Environmental development may have important effects on the epidemiology of vector borne diseases such as malaria This may be particularly important where disease transmission is unstable—for example, in highland areas Children in villages near recently constructed microdams in northern Ethiopia had a significantly increased risk of malaria It seems that this irrigation development programme is leading to increased malaria transmission across a range of altitudes and seasons Intersectoral collaboration is necessary in development projects that may affect communities both positively and negatively

Household risk factors for malaria among children in the Ethiopian highlands

Malaria transmission varies from village to village and even from family to family in the same village. The current study was conducted in northern Ethiopia to identify risk factors responsible for such variations in a hypoendemic highland malaria setting: 2114 children aged < 10 years living in 6 villages situated close to small dams at altitudes from 1775 to 2175 m were monitored. Monthly malaria incidence was determined 4 times over a 1-year period during 1997. Incidence results were then analysed by 14 individual and household factors using Poisson multivariate regression. Among 14 factors analysed, use of irrigated land (rate ratio[RR] = 2.68, 95% CI 1.64-4.38), earth roof (RR = 2.15, 95% CI 1.31-3.52), animals sleeping in the house (RR = 1.92, 95% CI 1.29-2.85), windows (RR = 1.84, 95% CI 1.30-2.63), open eaves (RR = 1.85, 95% CI 1.19-2.88), no separate kitchen (RR = 1.57, 95% CI 1.10-2.23), and 1 sleeping room (RR = 1.52, 95% CI 1.05-2.20), were significantly associated with malaria. The proportion of infection among children exposed to one or no risk factor was 2.1%, increasing with the number of risk factors and reaching 29.4% with 5 or more. Further studies are needed to confirm the importance of particular risk factors, possibly leading to simple health education and control measures that could become part of routine control programmes, implemented with inter-sectoral collaboration.

Can source reduction of mosquito larval habitat reduce malaria transmission in Tigray, Ethiopia?

The development of irrigation schemes by dam construction has led to an increased risk of malaria in Tigray, Ethiopia. We carried out a pilot study near a microdam to assess whether environmental management could reduce malaria transmission by Anopheles arabiensis, the main vector in Ethiopia. The study took place in Deba village, close to a dam; Maisheru village, situated 3–4 km away from the dam, acted as a control. Baseline entomological and clinical data were collected in both villages during the first 12 months. Source reduction, involving filling, draining and shading of potential mosquito‐breeding habitats was carried out by the community of Deba in the second year and routine surveillance continued in both villages during the second year. Anopheles arabiensis was highly anthropophilic (Human Blood Index = 0.73), biting early in the night before people went to bed. The major breeding habitats associated with the dam were areas of seepage at the dam base (28%), leaking irrigation canals (16%), pools that formed along the bed of streams from the dam (13%), and man‐made pools (12%). In the pre‐intervention year, 5.9–7.2 times more adult vectors were found in the dam village compared with the control village. There was a 3.1% higher prevalence of an enlarged spleen in children under 10 years in the dam village than in the control village during the pre‐intervention period, but no statistically significant difference was found in the incidence of falciparum malaria between the two villages during the same period. Source reduction was associated with a 49% (95% CI = 46.6–50.0) relative reduction in An. arabiensis adults in the dam village compared with the pre‐intervention period. There were very few cases of malaria during the intervention period in both villages making it impossible to judge whether malaria incidence had been reduced. These preliminary findings suggest that in areas of low intensity transmission community‐led larval control may be a cheap and effective method of controlling malaria. Further, large‐scale studies are needed to confirm these findings.

Options for water storage and rainwater harvesting to improve health and resilience against climate change in Africa

West and East Africa experience high variability of rainfall that is expected to increase with climate change. This results in fluctuations in water availability for food production and other socioeconomic activities. Water harvesting and storage can mitigate the adverse effects of rainfall variability. But past studies have shown that when investments in water storage are not guided by environmental health considerations, the increased availability of open water surface may increase the transmission of water-related diseases. This is demonstrated for schistosomiasis associated with small reservoirs in Burkina Faso, and for malaria in Ethiopia around large dams, small dams, and water harvesting ponds. The concern is that the rush to develop water harvesting and storage for climate change adaptation may increase the risk for already vulnerable people, in some cases more than canceling out the benefits of greater water availability. Taking health issues into account in a participatory approach to planning, design, and management of rainwater harvesting and water storage, as well as considering the full range of water storage options would enable better opportunities for enhancing resilience against climate change in vulnerable populations in sub-Saharan Africa.

Emerging chronic non-communicable diseases in rural communities of Northern Ethiopia: evidence using population-based verbal autopsy method in Kilite Awlaelo surveillance site

INTRODUCTION In countries where most deaths are outside health institutions and medical certification of death is absent, verbal autopsy (VA) method is used to estimate population level causes of death. METHODS VA data were collected by trained lay interviewers for 409 deaths in the surveillance site. Two physicians independently assigned cause of death using the International Classification of Diseases manual. RESULTS In general, infectious and parasitic diseases accounted for 35.9% of death, external causes 15.9%, diseases of the circulatory system 13.4% and perinatal causes 12.5% of total deaths. Mortalities attributed to maternal causes and malnutrition were low, 0.2 and 1.5%, respectively. Causes of death varied by age category. About 22.1, 12.6 and 8.4% of all deaths of under 5-year-old children were due to bacterial sepsis of the newborn, acute lower respiratory infections such as neonatal pneumonia and prematurity including respiratory distress, respectively. For 5-15-year-old children, accidental drowning and submersion, accounting for 34.4% of all deaths in this age category, and accidental fall, accounting for 18.8%, were leading causes of death. Among 15-49-year-old adults, HIV/AIDS (16.3%) and tuberculosis (12.8%) were commonest causes of death, whereas tuberculosis and cerebrovascular diseases were major killers of those aged 50 years and above. CONCLUSION In the rural district, mortality due to chronic non-communicable diseases was very high. The observed magnitude of death from chronic non-communicable disease is unlikely to be unique to this district. Thus, formulation of chronic disease prevention and control strategies is recommended.

Schistosome transmission, water-resource development and altitude in northern Ethiopia

Abstract Schistosomiasis continues to be a major public-health problem, not least in association with water-resource developments. The impact of microdam construction in the northern Ethiopian highlands, in relation to possible increased risks of Schistosoma mansoni infection, has now been assessed. The results of incidence studies, carried out on 473 individuals sampled across eight microdam sites at altitudes of 1800-2225m above sea level, indicated an overall annual incidence of 0.20 infections/person at risk. A multivariate Poisson regression model showed altitude and sex to be significant risk factors for infection, whereas proximity to a microdam was not significant, except possibly at very high altitudes. It was concluded that altitude was the major factor in this environment and that therefore, at least in terms of public-health planning, microdams should be sited as high as local geography permits.

Micro Water Harvesting for Climate Change Mitigation: Trade-Offs between Health and Poverty Reduction in Northern Ethiopia

Water harvesting is an important tool for mitigating the adverse effects of climate change. This report investigates the trade-offs between health and poverty reduction by considering the impacts of water harvesting on health in Tigray region, northern Ethiopia. In particular, we assess the prevalence of malaria in association with ponds and wells. The determinants of malaria incidence are explored with multivariate analysis. We investigate people’s willingness to pay (WTP) for improved malaria control using a contingent valuation method (CVM). We applied a double-bounded dichotomous choice CV surveys to elicit households’ WTP for improved health services to control malaria. With interval regression, the WTP was explained as a function of household characteristics, health and health service conditions, and village level factors. The malaria prevalence rate is very high, more than 30 percent in low land communities, although rates are higher after the rainy season. This suggests that ponds and wells are important factors in determining the prevalence of malaria. Better housing conditions, toilet type, and availability of bed nets are all factors which reduce the incidenceof malaria. Pond and well ownership affects the WTP for improved malaria control in a negative and positive way respectively, indicating differences in their economic attractiveness. WTP decreases with altitude and thus malaria incidence. Education and household asset holding generally increases WTP for improved health services. The results suggest that valuation results on household’s WTP in poor economies may be underestimated because of cash constraint. Consequently, alternative payment vehicles in eliciting households’ WTP have to be considered. Similarly, the estimated mean WTP for the external health cost of wells and ponds may be underestimated. In our case, ponds and wells are not fully exploited, as our results suggest that they do not contribute to household income or welfare. Thus the presence of ponds and wells pose high external costs to the economy.