The Impact of Tropical Cyclones on Infectious Disease Incidence and Public Health Infrastructure in Madagascar

Abstract

Background: Tropical cyclones, which are intense low-pressure storm systems that form over tropical and subtropical waters, are a significant life-threatening hazard for populations living around the southwest Indian Ocean basin. Cyclone activity in this basin poses a particularly grave threat to Madagascar, one of the poorest countries in the world, with almost 80% of its population living on less than $1.90 a day. Anthropogenic climate change is projected to increase the intensity and frequency of tropical cyclones making landfall on Madagascar, which means that the nation must develop and implement more robust climate resilience strategies across public and private sectors if it hopes to withstand climate shocks in the future. Public health infrastructure and infectious disease burden are two areas in the health sector that stand to be most adversely impacted in the event of more devastating tropical cyclones.

Methods: To address the gap in knowledge of how tropical cyclones affect Madagascar’s health sector, we conducted two studies: (1) a field study in Antananarivo, Madagascar’s capital, on the specific impacts of cyclones on public and private health centers and the current resilience strategies in place to address the unique challenges posed by cyclone events, and (2) an epidemiological analysis on the association between tropical cyclones and infectious disease incidence (of malaria, diarrheal disease, acute respiratory infection pneumonia, and cough and cold) in Madagascar. Interviews were conducted with public health officials and clinicians at different health centers, and descriptive analyses were used to characterize common trends. Data from the epidemiological analysis was obtained from public databases (climatic, cyclone, and population date) and from the Malagasy Ministry of Health (incidence data). A case cross-over design was used to conduct appropriate statistical analyses (Wilcoxon signed-rank tests, paired t-tests, and risk ratio analyses) to evaluate differences between pre- and post-cyclone incidence.

Results: Findings from the health center field study in Antananarivo indicate that health centers are negatively impacted by tropical cyclones due a range of reasons including unmanageable patient volumes, shortages of medicines and supplies, physical damages to facilities, and troubles with resource allocation. We also observed a high degree of variability in how well implemented and effective the current cyclone preparation and response strategies are. The epidemiological infectious disease analysis revealed that compared to pre-cyclone reference periods, there are statistically significant differences in the risk and incidence for malaria during a 0 month lag period (p = 3.618e-08; RR: 1.196, 95% CI: 1.102-1.297), malaria during a 1 month lag period (p = 0.001526; RR: 1.210, 95% CI: 1.103-1.328), diarrheal disease during a 0 month lag period(p = 7.497e-10; RR: 0.915, 95% CI: 0.864-0.969), diarrheal disease during a 1 month lag period(p = 6.632e-15; RR: 0.833, 95% CI: 0.786-0.884), and cough and cold during a 0 month lag period(p =0.0008582; RR: 1.113, 95% CI: 1.042-1.188).

Conclusions: These results show that Madagascar’s health sector in its current state may not be adequately prepared to face increasingly destructive tropical cyclones in the future. Following cyclones, infectious disease incidence for malaria and cough and cold increases, and incidence for diarrheal disease decreases. Madagascar’s health sector will need to adapt by prioritizing policies that instill resilience across the country’s public health infrastructure and reduce the additional disease burden that may arise during the aftermath of storms.