This is a collection of articles archived for the excellence of their content.
Domestic water tanks, construction sites
The Times of India, Sep 03 2016
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
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.
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.
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.
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.
The repellent economy in 2018
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.
REGION- / CITY- WISE
City Most Vulnerable To Mosquitoes In Sept
The public health department of East Delhi Municipal Corporation has carried out an analysis of vector-borne diseases and mosquito-breeding data from 2016-2020 to determine the peak vulnerability periods.
The report has thrown up several interesting aspects about the incidence of dengue, malaria and chikungunya cases in the trans-Yamuna areas while putting the spotlight on the alarming levels of vacancies in key supervisory posts in the department.
The five-year data on detection of mosquito breeding shows that the weekly count peaked between the 32nd and the 38th weeks of the year, with September witnessing the highest number of cases. Relatively larger number of cases were seen last year in the 1-14 years age group and among men.
Large-scale vacancies in various public health posts were also highlighted, with 50 of the 65 posts of malaria inspectors, all six posts of senior inspectors and both positions of anti-malaria officers lying vacant.
As many as 63% of 153 posts of assistant malaria inspectors and 78% of senior field workers lie vacant. Overall, 430 of the 1,423 posts in the malaria division area are yet to be filled. The data shows that a bulk of supervisory staff is absent with most of the posts being filled at field and domestic breeding checkers’ level. Similar large-scale vacancies in the public health department at the supervisory levels are seen in south and north Delhi municipal corporations.
The vector-borne disease data for 2020 shows that weekly mosquito-breeding peaked around September with 5,419 positive cases. The maximum number of malaria cases were seen in 1-14 years category. As far as dengue was concerned, the maximum number of cases were again seen in the 1-14 years category, followed by the 25-34 category. Comparatively a, larger number of dengue-malaria cases were registered among males, the report shows.
A senior public health official said the trends would apply to the entire city and help make better policy decisions.
An SDMC public health department analysis shows that peri-domestic containers --such as money plant, vase, flower pots, bird pots, tin, tyre and fountain water -- account for a chunk of mosquito-breeding sites (38%).
Madurai is home to about 40 species of mosquitoes which have adapted to all climatic conditions, and worse, they suck about 100 litres a day from city residents. The stinging claims were made at a national conference on “Emerging Trends in Entomology” held at the American College.
Former head of the department of zoology at the college, Dr R Selvaraj Pandian, pointed out that urbanisation had resulted in mosquitoes, which were earlier confined to the cooler rural climes, migrating to the cities. Dr Pandian has worked on mosquitoes for over 30 years and guided nine PhD scholars. He said that the mosquitoes seen in Madurai belonged to five genera — aedes, armigeres, anopheles, culex and mansonia.
Some species were found in larger numbers in some parts of the city. For instance, five species of aedes were seen in South Gate and central parts of the city. Mosquitoes have shown greater adaptability and the expansion of the city had resulted in the species seen in the villages entering the urban parts. While it is conceived that aedes breeds only in clean water stored in containers, he said that he had observed the insects breeding in clean water stagnating on uneven roads in Nagamalai Pudukottai.
Transport had resulted in mosquitoes spreading from place to place. As they could go without food for 10 days at a stretch, they could be transported by humans on cars, buses and trains. Once they came to a place, they started breeding and expanding their population. Mansonia was a mosquito which usually bred in aquatic plants and were rural-oriented. With the introduction of newage gardening and plants being grown in artificial ponds in parks and big buildings, they had started breeding in the city. The life cycle of a mosquito from egg to adult might vary from seven to 15 days. An adult could live from six months to a year, when conditions were conducive, he said. Blood meals from biting humans were required for mosquitoes to develop their eggs. They could consume about one-and-a-half times their body weight of blood. But blood was consumed only to reproduce, otherwise they fed on plant juice. They were also known to feed on sugar juices.
Dr Pandian said that at many places like Melavasal, Kuruvikkaran Salai and Narimedu, people slept in the open and were bitten more. According to him, they had recorded about 1,000 mosquitoes biting a person a day about a decade ago at these places. In some other parts, a person experienced about 100 bites per day. M Rajesh, assistant professor of Zoology, American College, said, ``Mosquito breeding is enhanced in drains when plastics clog them and prevent water flow. The menace can be controlled with a cleaner environment.” However, district malaria officer Dr John Victor contested the claims on the bites. ``To say that mosquitoes in Madurai consumed 100 litres of blood a day is hypothetical” . Many mosquito-borne diseases have come down in Madurai and what is required is public participation to control the menace. ``Lot of awareness is created but people do not act on what is disseminated to them through awareness programmes,’’ he said.