Amdadul Haque
The current monsoon may increase the risk of dengue infection transmitted by Aedes mosquitoes which usually breed this season amid coronavirus scare. At the onset of the Bangla month Baishak, it started raining all over the country, including in greater Dhaka. The monsoon season, with occasional torrential rain, benefits the Aedes mosquitoes to lay millions of eggs in left over containers, like flower pots, tyres, plastic and tin containers, broken jars and coconut shells. The fresh water in urban environment helps the eggs, which can carry dengue virus, to mature and possibly bite people to infect the virus.
Entomologists say that the larvae of Aedes mosquito eggs hatch as soon as it rains. The larvae or the eggs will complete a 10-day life cycle. In this case, the larvae need undisturbed fresh clean water to mature. Experts say that if the outbreak of Aedes mosquito increases amid coronavirus, public health concerns can tun complicated. Therefore, effective steps have to be taken from the beginning of the rainy season.
Although both the city corporations (north and south) claim they have been actively working to control Aedes mosquitoes outbreak since the beginning of the year, in reality except for a very few incidents anti-mosquito drive is virtually absent. Md Abdul Latif, Professor of Entomology of Sher-e-Bangla Agricultural University, said that Aedes mosquito grows only when it rains. If the rain water touches it, the larvae will come out from the pre-eggs of the mosquito. The larvae will transform into Aedes mosquitoes after completing a 10-day life cycle.
Preventive Medicine Specialist Lelin Chowdhury said that there are still Aedes-carrying dengue mosquitoes all over the country. There are mosquito eggs somewhere also. Larvae will be fouind wherever water accumulates due to rain. According to the US Centers for Disease Control and Prevention (CDC), there are four stages in the life cycle of the Aedes mosquito - laying eggs, larvae, pupa and adult mosquitoes. The larvae hatch after a few days or a few months after laying eggs. It takes a minimum of 5 days to transform from larva to pupa. Then it takes a minimum of two to three days for an adult mosquito to take shape.
The CDC says a female mosquito can lay at least 100 eggs. Eggs have the ability to survive in any environment and can survive for more than eight months, even in the harsh winter. According to the Directorate of Health Services, Aedes mosquitoes can breed if the temperature is between 25 and 30 degrees Celsius and the humidity is above 70 percent of the atmosphere.
“This spell of rain will increase the density of Aedes mosquito if the authorities concerned as well as people from all walks of life do not continue their efforts to control the Aedes mosquito,” said Prof Kabirul Bashar, an entomologist of Jahangirnagar University. He said that the drive against the mosquitoes would have to go on at least this month to maintain the declining trend of dengue patients.
“This rain will help increase the breeding sources of the mosquitoes and the authorities concerned and the people will have to destroy the sources,” he said. Professor Dr Md Abdul Latif said, “Arrangements have to be made to remove the rainwater from the place where it accumulates. Need to increase cleanliness as it is the right time for Aedes mosquitoes to breed. If it is not controlled now, it will take a deadly turn later on. He said common left over containers are sources where rainwater can accumulate and facilitate the mosquitoes to lay egss.
Chief Health Officer of Dhaka North City Corporation Brigadier General Mominur Rahman said, "We have been working since the beginning of the year considering the possibility. Special activities have been conducted in the hotspots identified by the Directorate of Health Services.”
Dhaka South City Corporation Chief Health Officer Brigadier General Md Sharif Ahmed said, "We are continuing our activities to prevent the spread of Aedes mosquitoes. We are regularly spraying medicines to all areas through mosquito eradication programmes. Areas that are prone to waterlogging are being cleaned as well.”
According to Bangladesh Meteorological Department, Dhaka experienced a big amount of rain in last few days. Mohammad Shaheenul Islam, a met office officer, said that it might rain across the country, especially in Dhaka, till the end of this month. Dhaka may experience heavy rain also.
Entomologist Manzur Chowdhury, former president of Geological Society of Bangladesh, said, “We have to give emphasis on larviciding (spraying medicines on eggs) as well as cleaning activities round the year to control the mosquitoes.” “Only cleaning is not enough to control the mosquitoes. Cleaning and using insecticides are both very important to control it,” he said, adding that the latest pesticides will have to be available so that people can purchase those easily and use those in their houses.
Dhaka North City Corporation Mayor Atiqul Islam said apart from the annual budget, they were planning to keep a separate budget for controlling the Aedes mosquito under a project.
