Malaria in the Rift Valley in Ethiopia

Gari T, Kenea O, Loha E, Deressa W, Hailu A, Balkew M, Gebre-Michael T, Robberstad B, Overgaard HJ, Lindtjørn B: Malaria incidence and entomological findings in an area targeted for a cluster-randomized controlled trial to prevent malaria in Ethiopia: results from a pilot study. Malaria Journal 2016, 15.

Background  This study was part of the work to prepare for a cluster-randomized controlled trial to evaluate the effect of combining indoor residual spraying and long-lasting insecticidal nets on malaria incidence. A pilot study was done to estimate the variations of malaria incidence among villages, combined with entomological collections and an assessment of susceptibility to insecticides in malaria vectors.

Methods  A cohort of 5309 residents from four kebeles (the lowest government administrative unit) in 996 households was followed from August to December 2013 in south-central Ethiopia. Blood samples were collected by a finger prick for a microscopic examination of malaria infections. A multilevel mixed effect model was applied to measure the predictors of malaria episode. Adult mosquitoes were collected using light traps set indoors close to a sleeping person, pyrethrum spray sheet catches and artificial outdoor pit shelters. Enzyme-linked immunosorbent assays were used to detect the sources of mosquito blood meals, while mosquito longevity was estimated based on parity. The World Health Organization’s tube bioassay test was used to assess the insecticide susceptibility status of malaria vectors to pyrethroids and carbamates.

Results  The average incidence of malaria episode was 4.6 per 10,000 person weeks of observation. The age group from 5 to 14 years (IRR = 2.7; 95 % CI 1.1–6.6) and kebeles near a lake or river (IRR = 14.2, 95 % CI 3.1–64) were significantly associated with malaria episode. Only 271 (27.3 %) of the households owned insecticide-treated nets. Of 232 adult Anophelesmosquitoes collected, Anopheles arabiensis (71.1 %) was the predominant species. The average longevity of An. arabiensiswas 14 days (range: 7–25 human blood index days). The overall human blood index (0.69) for An. arabiensis was higher than the bovine blood index (0.38). Statistically significant differences in Anopheline mosquitoes abundance were observed between the kebeles (P = 0.001). Anopheles arabiensis was susceptible to propoxur, but resistant to pyrethroids. However, An. pharoensis was susceptible to all pyrethroids and carbamates tested.

Conclusions  This study showed a high variation in malaria incidence and Anopheles between kebeles. The observed susceptibility of the malaria vectors to propoxur warrants using this insecticide for indoor residual spraying, and the results from this study will be used as a baseline for the trial.

Does location matter? A study of malnutrition amongst Ethiopian children

Each month, a paper is selected by one of the Editors of the five Nutrition Society Publications (British Journal of Nutrition, Public Health Nutrition, Nutrition Research Reviews, Proceedings of the Nutrition Society and Journal of Nutritional Science). This month, Seifu Hagos Gebreyesus’ paper on ‘Local spatial clustering of stunting and wasting among children under the age of 5 years: implications for intervention strategies’ was selected.

Seifu wrote on The Nutrition Socienty Blog:

As malnutrition is a major public health problem in Ethiopia, we aimed to find out how the acute and chronic forms of undernutrition occur in the districts and kebeles (a kebele is the smallest administrative unit in Ethiopia). Such knowledge could be helpful in improving our understanding of the distribution of undernutrition on a local scale, as well as designing targeted nutrition intervention programmes.

For this purpose, we surveyed children aged less than five years, who were found in 1744 households. We measured children’s height, weight, and the geographic locations (latitudes and longitudes) of households. Using data from 2371 children aged less than five years of age, we evaluated how malnutrition is distributed within a district and kebeles.

Although many believe that undernutrition is equally distributed within an area, we found that children living in locations within a district are more susceptible to undernutrition than children in other locations but living in the same district. For example, children living in these locations were 1.5 times more likely to be stunted and 1.7 times more likely to be severely stunted than children living in other locations within the district. Similarly, in some kebeles, children living in some small areas experience more acute malnutrition (wasting and severe wasting).

Our finding has important implications to nutritional intervention strategies. Stunting and wasting are not equally distributed in an area, suggesting that planning of nutrition interventions may need to consider the variations in the vulnerability.

To help accelerate the reduction of malnutrition, it could be important to consider targeting locations where more susceptible children live. The approach would help reach children who are most likely to benefit from intervention programmes.

We recommend that this research needs to be repeated in other areas of Ethiopia and other developing countries. We also would like to recommend further study possibly using an implementation research approach to evaluate the feasibility, advantages and effectiveness of targeting nutritional interventions.