Why do some villages, families or individuals have a higher risk of malaria than others? What environmental factors increase susceptibility? How can structural improvements to housing protect families from infection? Researchers from the Tigray Health Bureau, Ethiopia and the UK University of Nottingham investigated malaria risk factors in the Ethiopian highlands.
The study involved six villages in the Tigray region. Researchers identify household and individual risk factors for malaria and make recommendations for structural alterations to prevent infection. Improvements using low-cost local materials could have a major impact, they conclude.
In villages with established malaria transmission in Ethiopia, the risk can still vary from house to house. The researchers studied six villages near microdams. They found that malaria incidence is increased by having an earth roof, windows, open eaves, a single sleeping room, no separate kitchen, animals sleeping in the house and irrigated land. By contrast, malaria is unaffected by sex, age, number of animals owned, source of water during the dry or wet season and radio ownership.
Discussing these results, the researchers suggest that:
- When animals are kept in the same house as humans, they do not act as a 'decoy', but attract more mosquitoes to the house, where they preferentially bite humans.
- Smoke from cooking may repel mosquitoes in the early hours of the evening. However, the repellent effect will wear off during the rest of the evening as the smoke dissipates.
- The traditional wood and earth roof may provide a favourable resting place for mosquitoes.
- Overcrowding may increase the risk of malaria due to higher levels of carbon dioxide and odours attractive to mosquitoes. In addition, mosquitoes can infect more than one person on the same night in a crowded house.
- Irrigated land provides breeding sites for mosquitoes and increases malaria risk for families living nearby.
Structural improvements to houses could have a considerable impact on malaria risk, they conclude. However, policy-makers implementing such programmes should:
- focus on one-off strategies that use locally available and low-cost materials, such as closing open eaves with mud and constructing a kitchen separate from the bedroom
- address cultural barriers to change, such as the preference for keeping livestock in the family compound
- recognise that income is likely to dictate whether families can afford more sleeping rooms to avoid overcrowding
- intensify grass-roots level health education to convince communities of the value of structural improvements to reduce malaria risk factors
- involve the community in the planning and selection of suitable strategies
- integrate structural improvements with the ongoing community-based malaria control programme in the region
- collaborate with the agricultural and education sectors as well as community groups.
Source(s):
'Household risk factors for malaria among children in the Ethiopian
highlands' by T. Ghebreyesus et al., Transactions of the Royal Society of
Tropical Medicine and Hygiene 94 (2000)
Funded by:
SIDA/SAREC, Sweden; WHO TDR
id21 Research Highlight: 15 June 2001
Further Information:
Tedros Ghebreyesus
Tigray Health Bureau
PO Box 89
Mekelle
Ethiopia
Tel:
+251 4 401539
Fax:
+251 4 403329
Contact the contributor: tedrosag@hotmail.com
Tigray Health Bureau
Peter Byass
School of Community Health Sciences
University of Nottingham
Nottingham
NG13 8FD
UK
Tel:
+44 (0)115 970 9306
Fax:
+44 (0)115 970 9316
Contact the contributor: peter.byass@nottingham.ac.uk
University of Nottingham
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