Cholera outbreak in senegal in 2005: was climatea factor?

Abstract

Cholera is an acute diarrheal illness caused byVibrio choleraeand occurs as widespread epidemics in Africa. In 2005, therewere 31,719 cholera cases, with 458 deaths in the Republic of Senegal. We retrospectively investigated the climate origin ofthe devastating floods in mid-August 2005, in the Dakar Region of Senegal and the subsequent outbreak of cholera alongwith the pattern of cholera outbreaks in three other regions of that country. We compared rainfall patterns between 2002and 2005 and the relationship between the sea surface temperature (SST) gradient in the tropical Atlantic Ocean andprecipitation over Senegal for 2005. Results showed a specific pattern of rainfall throughout the Dakar region duringAugust, 2005, and the associated rainfall anomaly coincided with an exacerbation of the cholera epidemic. Comparison ofrainfall and epidemiological patterns revealed that the temporal dynamics of precipitation, which was abrupt and heavy,was presumably the determining factor. Analysis of the SST gradient showed that the Atlantic Ocean SST variability in 2005differed from that of 2002 to 2004, a result of a prominent Atlantic meridional mode. The influence of this intenseprecipitation on cholera transmission over a densely populated and crowded region was detectable for both Dakar andThie`s, Senegal. Thus, high resolution rainfall forecasts at subseasonal time scales should provide a way forward for an earlywarning system in Africa for cholera and, thereby, trigger epidemic preparedness. Clearly, attention must be paid to bothnatural and human induced environmental factors to devise appropriate action to prevent cholera and other waterbornedisease epidemics in the region