Women More Likely to Get Chikungunya When Compared to Men

Highlights

• Women were 1.5 times more likely to develop chikungunya than men. Coils designed to repel mosquitoes did not work to prevent transmission of chikungunya infection
• Mosquitoes are very lazy, they bite someone in a household and get infected with a virus and then bite someone else in the same home or very nearby.
• The extra time women spend in and around their home means they are at increased risk of getting infected by the mosquito

Chikungunya is a viral infection that is transmitted by mosquitoes. A study by researchers from Johns Hopkins Bloomberg School of Public Health, Institut Pasteur along with the International Centre for Diarrhoeal Disease Research has found that the disease is caused by the infection that is harbored in and around homes. Chikungunya is transmitted by the mosquito Aedes aegyptii and the study focused on a rural village in Bangladesh to understand the spread of the disease. The insights that were obtained from the study are published in the Journal Proceedings of the National Academy of Sciences and are useful to guide research aimed at understanding yellow fever and dengue, spread by the same mosquito.

Dr Henrik Salje, who is the lead of the study and a post-doctoral fellow in the Department of Epidemiology at the Bloomberg School apart from being a visiting scientist at Institut Pasteur. "Typically when there is an outbreak, we study who is sick and try to understand why. In this case, we not only studied those who became infected with chikungunya, but also those who avoided illness. This allowed us to determine what factors may impact who comes down with a disease and who does not - and to help us determine the best way to intervene."

Chikungunya Outbreak in Palpara

Palpara is a small village which is about 60 miles from the Bangladesh capital of Dhaka where there was an outbreak of chikungunya in the year 2012. The team of researchers visited all households to understand the spread of disease

• Study conducted during the period between May 29^th and Dec 2012
• 460 households were visited by the team of researchers.
• 1,933 individuals were spoken to
• 364 people had symptoms of chikungunya-18%

Mosquitoes Look for Close Targets

The mosquitoes that transmit chikungunya seemed lazy and hardly travelled far for their next human prey. They travelled for no longer than 200 metres, leading to infective pockets where everyone within that region was infected with the virus. This means that closely spaced colonies were at a higher risk of being infected.

1.5 Times Higher Risk of Women Being Infected

The researchers determined the percentage of time that a man and a woman spent in their homes. Since mosquitoes chose targets close by, longer periods of stay at home meant greater risk of being infected.

• Women were home 65% of the time
• Men were home 45% of the time

Since the time spent by women at home was far greater than men, they had a higher risk of being infected. They were found to have 1.5 times more risk of being infected than men.

What Makes Mosquito-Borne Illnesses Spread?

The study unearthed useful information about the spread of mosquito-borne illnesses. The researchers found that

• Mosquito coils did not prevent transmission
• Understanding the clusters where infection is rampant will aid in avoiding those regions
• Poor access to medical care in Bangladesh
• Doctors in rural Bangladesh are unaware of an epidemic till it is over
• No vaccine available

Dr Salje added "We don't yet have a very good toolbox for fighting these disease. But once we do, this research tells us how we could trigger a response and tailor our interventions - particularly in rural communities - to those at the greatest risk, and those people are the ones who spend the most time in and around their homes.

The study highlights the mode of spread of the disease and precautions that could be taken which include

• Use sprays and mosquito repellants, other than coils, which we found to be ineffective.
• It highlights the need to determine a cost effective method of mosquito repellant that poor rural families could use.
• Improve awareness about preventing mosquito breeding grounds near homes.
• Increase awareness about women and child health risk

The mosquito, Aedis aegyptii that transmits chikungunya also transmits yellow fever and dengue, therefore defining preventive measures will prevent the spread of diseases.

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Chikungunya

Chikungunya is a mosquito-borne illness with symptoms that could be misdiagnosed with dengue. It is characterized by fever and severe joint pain. The duration and severity of the joint pain varies from individual to individual.

It normally lasts for 3 to 7 days but the joint pain may persist for months. Some people complain of rash associated with the condition. Recently there have been reports of chikungunya affecting the eyes. Chikungunya is more prominent among newborns and people over the age of 65 years.

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This disease is found in Africa, Asia and in the Indian subcontinent. However, its spread to Europe and America has also been recorded. There was a relatively small outbreak of the disease in a small city in Italy in 2007.

References:

1. Symptoms, Diagnosis, & Treatment of Chikungunya - (https://www.cdc.gov/chikungunya/symptoms/)

Source-Medindia