Rainfall anomalies and typhoid fever in Blantyre, Malawi. (10th May 2022)

• Record Type: Journal Article
• Authors: Gauld, Jillian S.; Bilima, Sithembile; Diggle, Peter J.; Feasey, Nicholas A.; Read, Jonathan M.
• Is Part Of: Epidemiology and infection. Volume 150(2022)
• Publication Date: 2022-05-10
• Subjects: Typhoid fever -- rainfall -- weather -- statistical analysis; Communicable diseases -- Periodicals; Epidemiology -- Periodicals; 614.4
• DOI: 10.1017/S0950268822000759
• Languages: English
• ISSNs: 0950-2688

Abstract

Abstract: Typhoid fever is a major cause of illness and mortality in low- and middle-income settings. We investigated the association of typhoid fever and rainfall in Blantyre, Malawi, where multi-drug-resistant typhoid has been transmitting since 2011. Peak rainfall preceded the peak in typhoid fever by approximately 15 weeks [95% confidence interval (CI) 13.3, 17.7], indicating no direct biological link. A quasi-Poisson generalised linear modelling framework was used to explore the relationship between rainfall and typhoid incidence at biologically plausible lags of 1–4 weeks. We found a protective effect of rainfall anomalies on typhoid fever, at a two-week lag ( P = 0.006), where a 10 mm lower-than-expected rainfall anomaly was associated with up to a 16% reduction in cases (95% CI 7.6, 26.5). Extreme flooding events may cleanse the environment of S. Typhi, while unusually low rainfall may reduce exposure from sewage overflow. These results add to evidence that rainfall anomalies may play a role in the transmission of enteric pathogens, and can help direct future water and sanitation intervention strategies for the control of typhoid fever.