Does climate influence the distribution and severity of trachoma?
Evidence indicates that climate change will contribute to the global burden of disease through a variety of different mechanisms, including the direct effect of global warming and more extreme weather conditions; through change in fauna and flora and the impact this might have on the ecosystem, agriculture and hence food security and the economy; increases in extreme weather events are likely to increase diarrhoeal disease, vector-borne diseases and malnutrition; and there are also likely to be consequences of population migration away from threatened environments into those less affected. All of these may impact on eye health, particularly those that affect more vulnerable populations who are at the margins of subsistence. These populations are vulnerable to an increase in vitamin A deficiency, a major cause of blindness in children, and trachoma, in which active infection is associated with dry, dirty environments as the infection is transmitted in part by eye seeking flies. The distribution of onchocerciasis may also be affected, as global warming is likely to affect the breeding sites of the vector i.e. Simulium damnosum. Limited research has been undertaken to address the impact of climate on diseases such as trachoma, on the flies implicated in trachoma transmission. Without an understanding of how climate currently influences the distribution and severity of disease it is not possible to predict the possible impact of climate change.
The aim of this study is to review, synthesize and document existing literature on the connections between climate and trachoma, as well as the flies implicated in the transmission of trachoma. The first review has been published, suggesting that high temperatures and low rainfall are associated with an increased risk of active trachoma. However, only a few studies met the criteria for inclusion in this review, suggesting that more research is needed. The second review focuses on the effect of climate variables such as heat rainfall and humidity on the abundance and lifestyle of the Musca sorbens fly.
- Anita Ramesh, Sari Kovats, Dominic Haslam, Elena Schmidt and Clare E Gilbert. The impact of climatic risk factors on the prevalence, distribution, and severity of acute and chronic trachoma. PLoS Negl Trop Dis. 2013 Nov 7;7(11):e2513. Article
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Image credit: A Somali woman and child at a treatment center in Dollow, on the Somalia-Ethiopia border. Jennifer O’Gorman. Creative Commons License Attribution 2.0 Generic