Women May Be More Susceptible to Mosquito-borne Infections Than Men

Research published on November 7th in the Proceedings of the National Academy of Sciences (PNAS), suggests that outbreaks of mosquito-borne infections—specifically, Chikungunya—start in and around the home, with women more likely to become infected than men.

The findings, although focused on a different virus, have significant implications for the ongoing fight against Zika in South America, the Caribbean, and Southeast Asia. Officials in affected countries, including the United States, have long emphasized the importance of mosquito control, on both a macro and micro level. The Centers for Disease Control and Prevention, for example, credited large-scale pesticide spraying in Miami with ending one outbreak of Zika virus in the area.

For the PNAS study, an international team of researchers from Johns Hopkins Bloomberg School of Public Health, the Institut Pasteur in Paris, and the International Centre for Diarrhoeal Disease Research in Bangladesh analyzed a Chikungunya outbreak in Palpara, Bangladesh that occurred in 2012. They visited every household in the village and interviewed 1,933 village residents from 460 households. In all, 364 of the villagers interviewed reported symptoms consistent with the mosquito-borne virus—which, like Zika, has been linked with the Aedes species—between May 29 and December 1, 2012.

Notably, the researchers found that more than one fourth of the human cases of Chikungunya reported in the village were spread within the same household, and that half of infections occurred in households less than 200 meters apart. In Bangladesh, due to societal norms, women spend more time at home than men, and because of this, the authors of the PNAS study found that women were 1.5 times more likely to become infected with the virus than men.

The authors wrote, “We found that in this outbreak, viral spread was largely driven by transmissions at distances not much farther away than neighboring households. Human mobility in rural Bangladesh is very limited with individuals spending >50% of the time in and around the home. Females in particular spend the vast majority of their day around their homes. These human mobility patterns were consistent with our estimates of the spread of chikungunya and could explain the higher risk of infection observed in females. Release—recapture experiments have demonstrated that the Aedes mosquito, responsible for chikungunya and dengue transmission, does not travel very far and often stays within the same residence for days. For viral infections to spread over small distances as observed here may require human movement."

​Brian P. Dunleavy is a medical writer and editor based in New York. His work has appeared in numerous healthcare-related publications. He is the former editor of Infectious Disease Special Edition.