Cholera epidemic in Yemen
Authors: Fekri Dureab, Khalid Shibib, Yazoumé Yé, Albrecht Jahn, Olaf Müller
Journal: The Lancet Global Health (2018)

Anton Camacho and colleagues1Camacho A Bouhenia M Alyusfi R et al.Cholera epidemic in Yemen, 2016–18: an analysis of surveillance data.Lancet Glob Health. 2018; 6: e680-e690Summary Full Text Full Text PDF PubMed Scopus (97) Google Scholar have reported data from the first two waves of the ongoing cholera epidemic in Yemen. They demonstrated that the small first wave in 2016 was followed by a much larger wave in 2017. Moreover, they showed a positive association between weekly rainfall and cholera incidence during the second wave, and published their concern that there might be another large wave associated with the 2018 rainy season. However, we are not convinced by the hypothesis that rainfall is the major risk factor for this large cholera outbreak. Firstly, the initial wave occurred in winter 2016, and the second in summer 2017, with obviously very different weather conditions. Secondly, rainfall is generally low but very variable in Yemen, ranging from only 50 mm in the coastal and desert areas to 800 mm in the Western Highlands; and in many parts of the country there are no clearly defined rainy seasons and often no rain at all.2Farquharson FAK Plinston DT Sutcliffe JV Rainfall and runoff in Yemen.Hydrolog Sci J. 1996; 41: 797-811Crossref Scopus (19) Google Scholar, 3Mohamed H Elayah M Schuplen L Yemen between the impact of climate change and the ongoing Saudi-Yemen war: a real tragedy. Radbound University, Nov, 2017www.ru.nl/publish/pages/871321/a_real_tragedy.pdfDate accessed: May 11, 2018Google Scholar Thirdly, the accurateness of rainfall estimates by the Climate Hazards Group Infrared Precipitation with Stations data is questionable, in particular in rural areas where over 70% of Yemenis live.4Climate Hazards GroupClimate Hazards Group InfraRed Precipitation with Station data.http://chg.geog.ucsb.edu/data/chirps/Date: March 6, 2018Date accessed: May 15, 2018Google Scholar Finally, and as shown by the authors themselves, there was no clear association between cholera attack rates and rainfall pattern in governorates; while attack rates were high in coastal governorates with very little rainfall, they were low in more distant governorates located in the desert.1Camacho A Bouhenia M Alyusfi R et al.Cholera epidemic in Yemen, 2016–18: an analysis of surveillance data.Lancet Glob Health. 2018; 6: e680-e690Summary Full Text Full Text PDF PubMed Scopus (97) Google Scholar What exactly drives this cholera epidemic in Yemen is unclear. There have been several cholera outbreaks in recent years, with the current one being the largest nationally and globally.5Dureab F Shibib K Jahn A et al.Yemen: cholera outbreak and the ongoing armed conflict.J Infect Dev. 2018; 12: 397-403Crossref Scopus (23) Google Scholar Cholera incidence can be high during rainy periods because of contamination of water supplies, but can also be high during dry periods because of people being more dependent on unsafe water sources—the latter scenario probably being more likely under the prevailing conditions of drought and conflict in the country. As we had shown before,5Dureab F Shibib K Jahn A et al.Yemen: cholera outbreak and the ongoing armed conflict.J Infect Dev. 2018; 12: 397-403Crossref Scopus (23) Google Scholar the epidemic is associated with the ongoing war and civil war, which has led to massive population movements, an intensified shortage of water resources and related hygiene problems, and disruption of services including health services. Destruction of water reservoirs has even been used as a weapon during the conflict.3Mohamed H Elayah M Schuplen L Yemen between the impact of climate change and the ongoing Saudi-Yemen war: a real tragedy. Radbound University, Nov, 2017www.ru.nl/publish/pages/871321/a_real_tragedy.pdfDate accessed: May 11, 2018Google Scholar It is now estimated that almost two-thirds of the Yemenis population have no access to clean water supply and sanitation.3Mohamed H Elayah M Schuplen L Yemen between the impact of climate change and the ongoing Saudi-Yemen war: a real tragedy. Radbound University, Nov, 2017www.ru.nl/publish/pages/871321/a_real_tragedy.pdfDate accessed: May 11, 2018Google Scholar Yemen urgently needs more efforts to establish comprehensive interventions to guarantee access to safe water and sanitation, probably supported by mass vaccination campaigns to avoid potential further large waves of the epidemic. We declare no competing interests. Cholera epidemic in Yemen, 2016–18: an analysis of surveillance dataOur analysis suggests that the small first cholera epidemic wave seeded cholera across Yemen during the dry season. When the rains returned in April, 2017, they triggered widespread cholera transmission that led to the large second wave. These results suggest that cholera could resurge during the ongoing 2018 rainy season if transmission remains active. Therefore, health authorities and partners should immediately enhance current control efforts to mitigate the risk of a new cholera epidemic wave in Yemen. Full-Text PDF Open AccessCholera epidemic in Yemen – Author's replyDureab and colleagues1 concur with our call for urgent measures to enhance cholera preparedness and response in Yemen to stop the outbreak that has persisted for more than 2 years. However, they challenge our finding that the large second epidemic wave was associated with the start of the rainy season from April to May, 2017. They suggest that rainfall is unlikely to be a major risk factor for cholera transmission in Yemen because cholera and rainfall are spatially and temporally variable within the country, and because our analyses used modelled and not measured estimates of precipitation. Full-Text PDF Open AccessYemen needs a concrete plan—nowMore than 3 years into the current conflict, the situation in Yemen has reached catastrophic proportions. These have been exacerbated by the collapse of the national economy and by intense fighting around Hodeidah, the country's principal port on the Red Sea where most commodities, including food and medicines, enter the largely import-based Yemeni market. The planned peace negotiations are dependent on the goodwill of two warring parties whose disregard for international law has already led to large civilian casualties and the destruction of essential infrastructure such as health facilities, water systems, roads, and markets. Full-Text PDF Open Access