Mosquito-Borne Diseases: Women at risk, more than men

Women in Bangladesh are more prone to diseases like chikungunya, dengue and zika than men, suggests a new study conducted by the Johns Hopkins Bloomberg School of Public Health, the Institut Pasteur in Paris and icddr,b.

Mosquitoes that transmit such diseases remain in and around the household where, on average, Bangladeshi women spend 66 percent of their day time. On the other side, men, on average, spend 45 percent of their day time at home, the report adds.

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To facilitate the study, researchers investigated a 2012 chikungunya outbreak in Palpara, a village under Gopalpur upazila in Tangail, according to a statement by the icddr,b issued yesterday.

Symptoms of chikungunya include rash or joint pain, fever, headache and backache. Chikungunya is transmitted by Aedes mosquito, which also spreads other diseases like dengue and zika.

Zika poses greater risks for pregnant women as the virus can cause severe birth defects, including microcephaly marked by small head and underdeveloped brains.

The World Health Organization says zika will keep spreading in Asia as Aedes mosquito is widely found in the region, which also sees high volume of travel.

The new findings, published on November 7 in the Proceedings of the National Academy of Sciences, offer key insights into how health officials can combat other diseases, including zika, that spread in the same way.

The findings are important for Bangladesh where 5,000 dengue cases have so far been reported this year, the highest since 2003.

The researchers interviewed 1,933 individuals from each of 460 households of the village. As many as 364 people or 18 percent reported having symptoms consistent with chikungunya between May 29 and December 1, 2012.

The research found that more than a quarter of human infections spread within the same household and that half of infections occurred in households less than 200 metres away.

“We had good reasons to suspect that women in Bangladesh spend a lot more time at home than men,” Emily Gurley, co-senior author and director of the emerging pathogens programme at icddr,b, says.

“However, this study allowed us to quantify exactly how big this difference is and demonstrate how this could be responsible for increased risk of infection by some mosquito-borne pathogens.

Outbreaks of viruses such as dengue and zika that spread by the same mosquito as chikungunya are likely to disproportionately affect women in such communities, too,” she observes.

Overall, the researchers found that women in Palpara were 1.5 times more likely to develop chikungunya than men. The researchers also found that coils designed to repel mosquitoes did not work to prevent transmission of the disease.