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Journalism of Courage
Mumbai registered its first dengue death this year with 32-year-old Mulund resident on July 20. Health officials are seeing a surge in the viral infection, transmitted by Aedes Aegypti mosquito. The mosquito-borne infection has successively risen in the last few years in Mumbai. How has weather played a role? What is BMC’s advisory for people?
Dengue is a mosquito-borne viral infection that peaks from Monsoons every year. In Mumbai, the cases have risen from 919 in 2015 to 1003 in 2018. In the same period, the suspected dengue cases significantly rose from 12,447 to 14,110.
This year already 71 dengue cases have been confirmed by the BMC till July 14.
Unlike malaria mosquito (Anopheles) that breeds in water accumulating in open areas, Aedes aegypti mosquito breeds in freshwater in the peri-domestic atmosphere, meaning petri dishes, under refrigerator plates, water containers, on sagged tarpaulin sheets, in households. The mosquito’s reach to human beings becomes closer.
During heavy rainfall, water continuously accumulates and gets washed away, thus sweeping away any mosquito larvae. In Mumbai, however, the last fortnight has seen a dry spell, forcing rainwater to remain stagnant. This kind of weather is best suited for mosquitoes to breed and multiply. “The mosquito’s life cycle is 7-8 days, to grow from larvae to adult stage. With the dry spell, the water is not washed away and remains stagnant allowing the larvae to develop into an adult mosquito,” said Dr Padmaja Keskar, executive health officer in Brihanmumbai Municipal Corporation (BMC).
Dr Mahendra Jagtap, from Maharashtra epidemiology cell, explains a combination of climatic conditions which includes rains, followed by dry spell, and water accumulation encourage mosquitoes to breed. “67 per cent dengue cases come from urban areas, which means household breeding is higher,” Jagtap said.
Dengue is prevalent in Maharashtra, Gujarat, Rajasthan towards west, Delhi, Harayana, Punjab in north, West Bengal towards east and most of southern India. Till May 26, 2019, 5,504 dengue cases have been recorded by the National Vector Borne Disease Control Programme (NVBDCP).
In 2018, provisional records show 172 people died due to dengue and 1.01 lakh people were infected. Punjab (14,980), Maharashtra (11,011) and Gujarat (7,579) accounted for maximum cases.
“The reason for these states to have higher cases is not only weather but also infrastructure to confirm dengue diagnosis. Maharashtra has 42 laboratories that help in more case detection,” Jagtap said.
This year, 23,000 samples have already been screened for dengue virus.
Apart from regular health camp and door-to-door survey to screen patients in the neighbourhood where dengue death has been recorded, the BMC insecticide department also visits households, residential and commercial complexes, even government buildings to look for mosquito breeding sites and destroy them.
In the last two weeks, a dry spell has made Mumbai conducive for mosquito breeding. The insecticide department inspected at least 24 flats in the building where Mulund resident died due to dengue and found Aedes Aegypti breeding in four places. Similar exercise of inspection, detection and larvae destruction has been taking place across Mumbai.
But on Wednesday, heavy rains lashed the city. The breeding sites destroyed again hold opportunity for mosquitos to lay eggs. “The water will accumulate again following this rain. Our work starts from scratch,” says Dr Rajan Naringrekar, insecticide department head.
The BMC has been aggressively conducting sensitisation workshops in residential societies. The general advice is to wear full sleeves and consult a doctor at earliest if symptoms of fever, chills, body ache, emerge. In addition, civic officials claim it is physically impossible to keep inspecting private premises regularly. Sometimes residential societies refuse entry to BMC team for inspection.
The NVBDCP states Aedes breeds generally in desert coolers, drums, jars, pots, buckets, flower vases, plant saucers, tanks, cisterns, bottles, tins, tyres, roof gutters, refrigerator drip pans, cement blocks, cemetery urns, bamboo stumps, coconut shells, tree holes and many more places where rainwater collects or is stored. The residents, in such a situation, have to ensure they drain accumulated water from these articles every week to cut short the mosquito’s life cycle. Slum-dwellers must clean the tarpaulin sheets lining their ceiling.
