Aedes aegypti are known to be the main vector for dengue fever and other mosquito-borne diseases, but researchers are still unclear about the effects of weather anomalies on mosquito populations caused by climate change.
Now, a new study reported in the PLOS Neglected Tropical Diseases journal by Cameron Nosrat from Stanford University in the United States along with collaborators indicates that early interventions can prevent the spread of diseases even as adverse climate events are likely to boost the number of A. aegypti populations.
Rainfall and temperature have considerable effects on the abundance of A. aegypti population, and climate change will probably intensify the frequency of adverse climate events, like droughts, floods, cold waves and heatwaves.
To find out how weather anomalies have a specific impact on the dynamics of vector-borne disease transmission, the investigators carried out a retrospective cohort study to establish the effect of severe rainfall and temperature on the abundance of mosquito population and the threat of dengue infections in Kenya.
With the help of satellite-derived climate data, the study authors categorized severe climate events of rainfall and temperatures as in the lower or upper 10% of historical averages.
They subsequently tracked the abundance of A. aegypti population with the help of trapping techniques and new cases of dengue fever through blood samples obtained from a cohort of 7,653 children.
Flood seasons played a more considerable role in the abundance of A. aegypti egg and adult population.
But a greater abundance of A. aegypti populations and adverse climate events did not correspond with an increased number of verified cases of dengue fever.
Human behaviors can alter the link between disease transmission and mosquito abundance, and also influence the risk of infection. Preventative measures in the study locations may have contributed to reduced transmission of dengue infections.
A significant restriction of the study was the dearth of long-term Kenya climate data; but according to the authors, their new study effectively analyzes the impact of weather anomalies on different life stages of A. aegypti abundance.
Dengue is the fastest-growing mosquito-borne disease in the world, and as climate change accelerates, many vulnerable populations will continue to be disproportionately impacted by this virus. Having shown floods to result in significantly increased dengue vector abundance, we hope to encourage actionable interventions to limit infection risk in light of these extreme climate events.
Nosrat, C., et al. (2021) Impact of recent climate extremes on mosquito-borne disease transmission in Kenya. PLOS Neglected Tropical Diseases. doi.org/10.1371/journal.pntd.0009182.