400 mosquito species in India: all carriers of diseases

Are we fighting a losing battle against mosquitoes? The jury is still out even as experts say that erratic weather patterns due to climate change have added an uncertain, surprise dimension to the battle against mosquitoes, making outbreak of vector borne diseases more unpredictable.

“An increase in temperature produces more mosquito-friendly habitats, resulting in larger number of mosquitoes,” Dr Lalit Kant, a Senior Advisor in Infectious Diseases at the New Delhi-based Public Health Foundation of India (PHFI), explained to National Herald.

Dr Kant said, more mosquitoes may not necessarily “translate into more number of diseases. But if the infection is there in community, the mosquitoes are able to transmit it.”

And our cities do have a history

Indian cities have been struggling with the outbreak of vector-borne diseases in recent years. In 2015, at least 486 deaths were reported due to dengue in Delhi alone, according to the official data of the Delhi government. 2016 was not any better, or may be even worse.

According to the South Delhi Municipal Corporation (SDMC), 4,431 cases of dengue and 9,749 of chikungunya were reported from the Capital region in 2016. It is said to be one of the worst outbreaks in recent memory.

Unpredictable weather only seems to have added to Delhi’s woes.

The SDMC, which is responsible for maintaining the data for all of Delhi’s civic bodies, informed last week that at least 79 cases of chikungunya and 24 of dengue had been reported from Delhi in the first three months of 2017. Both these diseases are primarily transmitted by the female Aedes mosquito, but usually afflict the community during the monsoon and late summer months.

Dr Atul Gogia, a consulting physician at Sir Ganga Ram Hospital, blamed the surge in cases during off-season (January-March) on “unseasonal” rains that struck Delhi and the surrounding regions last month.

“Mosquitoes breed well in hot and humid conditions. Delhi didn’t experience a bitterly cold winter this time around as it usually does. Then, there were off-season rains. All this contributed to high-number of cases we saw in the first three months,” Dr Gogia told National Herald.

The physician also noted that mosquitoes won’t survive in extreme heat conditions either, referring to weather forecast of a scorching summer season this year.

A bit about India’s mosquitoes

There are more than 404 species and subspecies of mosquitoes in India, Dr Kant informed. “The common ones belong to Anopheles, Culex, Aedes and Mansonides.”

Dr Kant informed that all the 400 mosquito species found in the country are carriers of diseases. The most common vector-borne diseases that afflict Indians, including dengue and chikungunya, are transmitted by female Aedes mosquito.

What measures can people take to prevent mosquito-borne diseases?

1. The best thing people could do is keep mosquitoes from breeding in their vicinity, said Dr Atul Gogia from Sir Ganga Ram Hospital. “Mosquitoes lay their eggs in water. Mosquito breeding places can be reduced by emptying, covering, or treating any items/objects that hold water,” said Dr Kant from the PHFI .
2. Dr Kant also reckoned that mosquitoes should be prevented from entering people’s homes by ensuring that window and door screens are in good repair and are tightly attached.
3. “Consider wearing long-sleeve shirts, long trousers, and socks if you spend time outdoors during peak mosquito biting times,” Dr Kant suggested. According to a report released by the All India Institute of Medical Sciences (AIIMS) in 2007, people should shun wearing half-sleeve shirts and T-Shirts, and shorts during July to September which is usually the high season for dengue and malaria.
4. “If outdoors during peak mosquito biting times, apply insect repellents,” according to Dr Kant. According to the AIIMS report, the use of mosquito repellent sprays, creams, coils and mats are also effective means to combat mosquitoes at home.
5. It is also advisable not to turn away council workers enlisted to visit neighbourhood homes to fumigate the interiors. It was reported earlier this week that the South Delhi Municipal Corporation would soon launch an app to monitor the activity of domestic breeding checkers (DBCs) to better enforce the rules surrounding the prevention of mosquito-borne diseases. A senior SDMC official was quoted as saying in The Hindustan Times, “There are cases when DBCs are not allowed to enter households but the corporation is later blamed for the spread of diseases. In such cases, the DBCs will have the advantage to mark it in the application and we will have specific date when our workers are not allowed to enter.
6. Keeping the surroundings and the neighbourhood clean could also go a long way in preventing the spread of vector-borne diseases, according to the AIIMS report. A report, Delhi Citizens’ Handbook 2016, published in September 2016, however, highlighted that none of Delhi’s three municipal bodies had utilised the funds allocated to them under Swachh Bharat Mission. While the North corporation didn’t spend anything out of ₹46.28 crore in financial year 2015-16, the SDMC used up only 0.25% of ₹31.63 crore sanctioned by the Centre.
7. Get in touch with your local municipality in case you note an increase in the number of mosquitoes in the neighbourhood.