3 min readNew DelhiMay 10, 2016 04:28 AM IST
First published on: May 10, 2016 at 04:28 AM IST
The fog is a mixture of diesel and a cocktail of insecticides. (Source: Express Photo by Tashi Tobgyal)AN AUSTRALIAN vector control expert said India needs to step up its dengue vector control activities and take it beyond fumigation to be able to control the spread of the virus.
Speaking to The Indian Express before a public lecture at AIIMS Monday, Prof. Scott Ritchie from the James Cook University in Australia said fumigation does not work well, especially for the Aedes Aegypti mosquito which has a tendency to go indoors.
“Aedes Aegypti is like the cockroach of mosquitoes. It loves to go indoors. As fogging is mostly done outdoors, it misses out on these mosquitoes. Fogging only creates a toxic cloud temporarily which disperses and does not leave any residual effect. So it does not affect all mosquitoes,” said Prof Ritchie.
He added that this was the reason why fogging was more effective on other mosquito vectors such as the Japanese Encephalitis (JE) vector, which do not stay indoors. According to Ritchie, controlling the Aedes Aegypti mosquito has assumed special significance with the spread of the Zika virus.
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Ritchie said the paradigm of vector control is shifting all across the world — “from spray and slam to rear and release”.
“Trials in Australia, Brazil, Indonesia, Vietnam and Columbia are underway for ‘rear and release’ methods. Male mosquitoes are sterilised and released, so it works as a mosquito birth control method,” he said.
In another method, he said a bacteria was injected into the dengue vector mosquito. “This vaccinates mosquitoes, thereby preventing their ability to transmit the virus. These treated vectors mate with other mosquitoes and pass on the protection. In a way, we are altering the entire vector population,” he added.
Ritchie said while trials for these methods will take time to be completed and be proved effective in India, other measures that could be implemented sooner should be considered.
Ritchie said Indoor Residual Spraying (IRS) methods, a common method to control malaria, is now being modified for dengue vector control. “After local trials, IRS methods can be implemented in India. If areas within the city where dengue numbers are higher are mapped, IRS can be started without delay. A massive sanitation campaign is also needed to clean up localities,” said the professor.
He added that chemicals used for fogging need to be frequently changed to check if mosquitoes are becoming resistant to it.
According to Ritchie, the nature of the dengue virus also makes vector control efforts difficult. “The dominant serotype of the virus changes every few years after a population develops immunity to a particular type. So, vector control methods need to be dynamic,” he said.
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The fog is a mixture of diesel and a cocktail of insecticides. (Source: Express Photo by Tashi Tobgyal)
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