Though malaria has been eliminated in several countries, the mosquito-borne disease still remains a major public health concern in many parts of the world, including sub-Saharan Africa. Mozambique, for example, has the fourth highest prevalence of malaria in sub-Saharan Africa and is particularly vulnerable due to a range of factors, including inadequate healthcare infrastructure, limited access to prevention measures, and climatic conditions conducive to mosquito breeding. A new study from the University of Minnesota School of Public Health (SPH) adds another factor to the mix: residential structure damage from severe weather.

Like other vector-borne diseases, malaria transmission is highly dependent on weather and climate-related factors — mosquitoes, after all, reproduce in higher numbers in wetter, warmer weather. Countries like Mozambique are seeing first-hand the impact of global climate change on local weather conditions. Over the past 35 years, Mozambique has experienced more than 75 declared natural disasters related to floods, droughts, and  cyclones. And, from 2005 to 2023, Mozambique had 16 named tropical cyclones and storms that severely impacted the population.

In 2019, Cyclone Idai — one of the worst tropical cyclones ever recorded in the Southern Hemisphere — caused catastrophic damage to people, buildings, and other infrastructure across Mozambique. The destruction of housing is of particular concern, as poor housing conditions can increase interactions with mosquitoes and thus malaria risk in the immediate and long-term, as well as hampering the efficiency of disease-control efforts.

The primary objective of the SPH study was to investigate and quantify the malaria risk associated with household damage caused by Cyclone Idai. To gather data for the study, SPH researchers conducted a survey in a village called Sussundenga, a rural agrarian village located in western Mozambique. The study, published in Nature, found that nearly one year after the storm:

• Sixty-four percent of study participants lived in households that sustained damage during Cyclone Idai.
• The overall malaria prevalence (measured by rapid diagnostic test) was 31%.
• The odds of malaria infection was nearly threefold higher among participants who lived in damaged households.
• Malaria prevalence increased with increasing levels of household damage. Malaria prevalence was higher in households with significant damage (35.8%) or complete destruction (44.2%) compared to households with no damage (22.1%).

“Previous studies have used simulations and prediction models to explore the impact climate change is having on malaria risk,” says Kelly Searle, SPH assistant professor and lead author. “By using real-world observations, this study is among the first to conclusively demonstrate the associations between climate change, severe weather, and increased prevalence of malaria. We found that participants who experienced household damage incurred during Cyclone Idai increased the odds of malaria infection by nearly threefold compared to those who did not experience household damage in an area of already high malaria incidence. This is a substantial concern, considering our data collection was conducted nearly one year after Cyclone Idai occurred.”

The study also calls attention to the need for more effective long-term disaster response efforts, citing the fact that only one household interviewed by researchers reported receiving any assistance from response organizations in the aftermath of Cyclone Idai.