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RAINFALL, TEMPERATURE AND CHOLERA INCIDENCE

Wednesday, 1st of June 2011

‘A 1°C increase in temperature at 4 months lag resulted in a 2-fold increase of cholera cases, and an increase of 200 mm of rainfall at 2 months lag resulted in a 1.6-fold increase of cholera cases.’

Abstract below; full text online to subscribers of Am J Trop Med Hyg

 

Climate Variability and the Outbreaks of Cholera in Zanzibar, East Africa: A Time Series Analysis

Rita Reyburn*, Deok Ryun Kim, Michael Emch, Ahmed Khatib, Lorenz von Seidlein and  Mohammad Ali

+ Author Affiliations

1. 1.    International Vaccine Institute, Seoul, Korea; University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Ministry of Health and Social Welfare, Zanzibar, Tanzania

+ Author Notes

• Authors' addresses: Rita Reyburn, International Vaccine Institute (IVI), CHOZAN project, Zanzibar, Tanzania, E-mail: rita_reyburn@hotmail.com. Deok Ryun Kim, Lorenz von Seidlein, and Mohammad Ali, International Vaccine Institute, SNU Research Park, Seoul, Korea, E-mails: drkim@ivi.int, lseidlein@ivi.int, and mali@ivi.int. Michael Emch, Department of Geography, University of North Carolina, Saunders Hall, Chapel Hill, NC, E-mail: emch@email.unc.edu. Ahmed Khatib, Ministry of Health and Social Welfare, Zanzibar, Tanzania, E-mail: ahmedbenga@yahoo.com.

1. ↵*Address correspondence to Rita Reyburn, IVI, CHOZAN Project, PO Box 3524, Zanzibar, Tanzania. E-mail: rita_reyburn@hotmail.com

Abstract.

Global cholera incidence is increasing, particularly in sub-Saharan Africa. We examined the impact of climate and ocean environmental variability on cholera outbreaks, and developed a forecasting model for outbreaks in Zanzibar. Routine cholera surveillance reports between 1997 and 2006 were correlated with remotely and locally sensed environmental data. A seasonal autoregressive integrated moving average (SARIMA) model determined the impact of climate and environmental variability on cholera. The SARIMA model shows temporal clustering of cholera. A 1°C increase in temperature at 4 months lag resulted in a 2-fold increase of cholera cases, and an increase of 200 mm of rainfall at 2 months lag resulted in a 1.6-fold increase of cholera cases. Temperature and rainfall interaction yielded a significantly positive association (P < 0.04) with cholera at a 1-month lag. These results may be applied to forecast cholera outbreaks, and guide public health resources in controlling cholera in Zanzibar.

Footnotes

• Financial support: Support for this study was provided by the Bill & Melinda Gates Foundation through the Cholera Vaccine Initiative (CHOVI) Program, administered by the International Vaccine Institute (IVI), and the Swedish International Development Cooperation Agency (SIDA).