Today, Vietnam continues to report a rising numbers of dengue fever infections. More than 60 000 people in Vietnam (50 000 last year) have been affected by Dengue fever since the beginning of the year. Vietnam is one of the countries most affected by the illness due to its favorable environment for mosquitos.
Dengue occurs year round in Vietnam with peak transmission in the warmer rainy season from April through October in the north and June through December in the south, and is caused by a viral infection coming from four type of virus: DENV1, DENV2, DENV3, DENV4, transmitted by the bite of infected female mosquitoes the Aedes aegypti and the Aedes albopictus that feed both outdoors and indoor during the day time. This year towns most concerns are Da Nang, Binh Duong, Ho Chi Minh City, Ba Ria – Vung Tau, Binh Phuoc, Soc Trang, Phu Yen, Quang Nam, Dong Nai, Ha Noi.
The control of mosquitoes by the use of chemical pesticides remains until now the favorite weapon, but many people have reported seeing the re-population of mosquitoes in their neighborhood just a few days after pesticides were sprayed. Many observations show that mosquitos might have developed a resistance to certain pesticides. The intensive and repeated use of the same insecticides (especially pyrethroids and organophosphates) for too many years has led to a selection and a diffusion of different type of resistances not only in Vietnam but on a worldwide scale. The management of these resistances becomes worldly problematic because today very few new insecticides are developed and come mainly from the agricultural market. The mosquitoes’ ability to withstand these products makes them ineffective and poses today worldwide a serious threat to humans. Mosquitos adapt very quickly and react to the control methods place in front of them. Until now some mechanisms of resistance remain still unknown to scientists, including the genetic factors allowing them to synthesize detoxification enzymes to degrade insecticides… Is it illusory today to think that one molecule, one drug, one insecticide, can solve the problem or should we envisage to diversify the ways to fight them?