Revision as of 08:09, 10 March 2019

Breeding grounds

Domestic water tanks, construction sites

The Times of India, Sep 03 2016

Sushmi Dey 

86% killer mosquitoes breed in domestic water tanks: Study

 As the country battles a chikungunya and dengue crisis, a government assessment has found that 86% of the breeding of Aedes mosquitoes happens in household water storage containers including overhead tanks, plastic drums, desert coolers, flower pots and iron containers, often found at construction sites.

A review report by the health ministry shows vectorborne diseases can be prevented through good sanitation and effective awareness and communication campaigns.

Official data shows total 12,255 cases of chikungunya and 27,879 of dengue were recorded till August 31 this year, with 60 people having succumbed to dengue till now. Cases are expected to rise sharply over the next two months.

Monitoring by the government has revealed that 41% of breeding of mosquitoes takes place in plastic drums and containers used mainly for water storage in households and shops.Besides, desert coolers account for 12% and iron containers mainly used in construction sites account for 17% of breeding.

In his latest review meeting with the health secretary, cabinet secretary P K Sinha said the Centre as well as different state governments and municipal authorities must take action to prevent and manage the growing dengue and chikungunya menace and said that these actions should be further intensified by running public awareness programmes, making medicines and doctors available, providing helpline facilities to the people and use of mobile clinics.

Sinha has also asked local municipal bodies to increase fogging. Through intensified awareness campaigns, the health ministry has also emphasized on the need for residents to maintain cleanliness.

Health secretary C K Mishra said, from next week the government will also start door to door campaigning. “Hospitals are prepared to tackle the burden. We are doing regular inspections and there are enough medicines and testing kits.We are also going to intensify campaigning for cleanliness,“ Mishra said.

Report: Cutting Food Source Leads to Dramatic Drop in Number of Mosquitoes

Washington

Insecticides, mosquito nets, and disrupting breeding grounds all reduce mosquito populations and slow the spread of malaria. Now, researchers want to take away the insect's food to fight the disease that kills a child every two minutes.

Mosquitoes mostly feed on plant sugars that can be hard to find during the dry season in Africa, where 90 percent of malaria cases develop. Researchers thought one potential source of food might be from the flowers on a small type of mesquite tree. The tree, imported from Mexico 40 years ago to provide firewood and shore up irrigation dykes, quickly became invasive and grew out of control.

To test their idea, researchers monitored mosquito populations in six villages in the Bandiagra District of Mali. After a week, they removed the flowers from the mesquite trees in half of the villages.

Anopheles gambiae mosquito, which spreads the malaria parasite

The report, published in Malaria Journal, found that with less food around, the mosquitoes didn't live as long and populations dropped 69 percent. This didn't just mean fewer mosquitoes, it meant fewer old mosquitoes. That's important because it takes 12 days for the malaria virus to get to the salivary glands of a mosquito where it could infect a human. So if mosquitoes die even a couple of days earlier, that could greatly reduce the number of mosquitoes that pose a threat.

"This suggests that removal of the flowers could be a new way to shift inherently high malaria transmission areas to low transmission areas," said Gunter Muller, lead author of the study from Hebrew University Hadassah Medical School.

Devil tree

But getting rid of mesquite is easier said than done. It's not as if people haven't tried to control the tree before. It encroaches on crop lands, makes areas inaccessible, and can use up what little water there is. It has been known to grow up though the floors of huts. Even getting to the flowers is a challenge, due to the 10-centimeter-long thorns that grow along the branches.

Getting to the flowers is a challenge, due to the 10 centimeter long thorns that grow along the branches.

Many refer to it as the devil tree, but Medusa tree may be just as apt a name, since it can grow back from just its roots after it is cut down. Biologist Dawn Wesson from the Tulane University School of Public Health and Tropical Medicine said this was one of the first attempts she has seen to control mosquito populations by restricting their food source.

Wesson, who was not involved in the research, highlighted that not only were populations depressed, but that the degree of impact varied greatly depending on the species of mosquito. In this case all of the species can carry malaria, but Wesson hopes that in other contexts this could be used to help a benign species of mosquito displace a dangerous species of mosquito. That impact could extend beyond the end of any food control measures.

Approach could backfire

But Wesson also cautioned that removing mesquite might backfire. Without flowers to feed on, these mosquitoes might turn to blood meals. This could lead to more frequent bitings and increased transmission of malaria. "It's probably unlikely," she told VOA. "They did show a nice decrease ... in the older female mosquitoes. But remember their study only took place over a period of about eight days."

The next step, she suggests, should be to measure the impact of removing mesquite, not just on mosquito populations, but also on the incidence of malaria.

Repellents

The repellent economy in 2018

Shobita Dhar, The machhar economy is growing, April 22, 2018: The Times of India

The efficacy of two types of repellents
From: Shobita Dhar, The machhar economy is growing, April 22, 2018: The Times of India

From bats and blankets to ACs and lamps, repellants have become quite innovative

A year ago, Mumbai businessman Prateek Damani was searching the net for effective antimosquito options for his joint family that included five kids. He chanced upon a blanket and curious about whether it would live up to its promise of keeping the blood-suckers away, he ordered one. “Now, I even carry one along when I travel for work,” says Damani, who has bought three to four blankets.

The blankets are coated with a diluted form of DEET — or N,N-diethyl-meta-toluamide — a widely used repellent. “The blanket repels mosquitoes but does not kill them or knock them unconscious,” says Anil Kumar, an executive at Posse Enterprises, a Mumbai-based company that manufactures blankets and curtains that repel mosquitoes.

With the mosquito menace growing every year, all kinds of innovative products such as ACs, lamps, patches and bands have hit the market. They co-exist with traditional insecticides dominated by Godrej, Reckitt Benckiser and Jyothy Labs. A 2016 Euromonitor report found that India’s insect repellent market clocked Rs 4,400 crore in retail sales each year.

Bhavna Kulshrestha, a homemaker, has installed an anti-mosquito air conditioner by LG in her daughter’s bedroom. “I was reluctant to use chemical repellents for my five-year-old daughter. The AC is quite effective, though there are nights when I have to use a vapouriser as well,” says Kulshrestha, who lives in Bengaluru.

According to LG Electronics’ business head for ACs in India, the brand has sold close to 3 lakh units of its ‘mosquito-away’ model since its launch in 2014. “It uses ultrasonic waves to repel mosquitoes. We have also launched TV and mobile phone models with this feature in India,” says Kulbhushan Bhardwaj, business head, LG electronics, India.

Mahesh Toshniwal’s startup, Aviral Resources, has developed an outdoor mosquito killing system. “Mosquitoes are attracted to the CO2 that humans exhale so, this machine emits controlled amounts of the gas over a period of time, fooling these bugs into sitting on it. They are then consumed by the machine,” says Toshniwal who has sold 2,000 units since 2011 mostly to hotels and municipal corporations. Each unit costs Rs 75,000 plus taxes. Even Gujarat Narmada Valley Fertilisers & Chemicals, a PSU, has announced plans to introduce mattresses coated with neem oil to keep bugs away.

Electric lamps attract mosquitoes with a combination of bright light and CO2. A high-speed fan draws them into the unit where they get trapped and die.

While these products are new and promising, they can’t match the appeal of Chinesemade electric bats. Sold at traffic intersections and local shops, the bat, costing around Rs 170 – Rs 300, has become a household staple. The charged bat zaps the insect, killing it immediately with a soul-satisfying frying sound. It’s fast, cheap and effective, and does wonders for your forehand.

However, there have been concerns over the use of lead in its components. Internationally permissible concentration of lead in electronic goods is less than 1,000 ppm (parts per million) but the China-made bats have been found to contain between 3,000 and 80,000 ppm. Once discarded, the lead from these bats finds its way into soil and water.