Bangladesh exploring new bio-control strategies to fight off dengue

Bangladesh is now exploring new bio-control strategies to fight off dengue in the long run as the mosquito-borne disease has come to a head.

Director General for health services Professor Abul Kalam Azad told bdnews24.om that they have asked the World Health Organisation (WHO) to send information related to “Oxitec friendly mosquito” method and “Wolbachia” as soon as possible.

“Global experience shows it’s difficult to control Aedes mosquitos with the conventional methods since it mostly breeds inside homes,” he said.

“We have asked the WHO to advise us whether those two techniques are available, effective, and applicable in Bangladesh’s context, its impact on human health and affordability,” he said.

As on Monday, the government has recorded 5, 637 cases of dengue in July only, the highest number for a month since 2000 when the mosquito-borne viral disease first stuck Bangladesh.

According to the WHO, the global incidence of dengue has grown dramatically in recent decades. About half of the world's population is now at risk.

In Malaysia, there were 62,421 dengue cases between Jan 1 and June 29 this year with 93 deaths compared to 32,435 cases with 53 deaths in the same period last year.

WHAT IS WOLBACHIA?

Malaysia, which is also grappling to fight off dengue, has introduced “Wolbachia” method this month following a successful pilot project in 2017.

It is the second country after Australia to use the strategy in which Wolbachia bacteria are injected into Aedes mosquitos.

Wolbachia are natural bacteria present in up to 60 percent of insect species, including some mosquitoes. However, it is not usually found in Aedes aegypti mosquito, which is responsible for transmitting human viruses such as dengue, chikungunya and Zika.

When introduced into the Aedes aegypti mosquito, Wolbachia can help reduce the transmission of these viruses to people, the World Mosquito Program’s research has shown.

When a female mosquito mates with a male, with at least one of them bearing Wolbachia, they will produce Wolbachia-infected mosquitos.

Mosquitos with Wolbachia have a reduced ability to transmit viruses to people, decreasing the risk of fatal diseases such as dengue.

The Nature journal in an article on July 17 said two islands in the Chinese city of Guangzhou have reduced the Aedes albopictus, or Asian tiger mosquito, by up to 94 percent using the method.

WHAT IS OXITEC METHOD?

Oxitec is a British biotechnology company which develops genetically modified insects to assist in insect control.

They have “friendly” Aedes mosquitoes that can reduce the vector that spreads dengue, Zika and other diseases, the director general for health services said.

According to the company, their “friendly” mosquito strains are designed to significantly reduce the population of a targeted mosquito species in the wild without impact on human or environmental health.

Upon release into the environment, Oxitec’s 2nd generation male-selecting strains mate with females, and only male offspring with a self-limiting gene survive to adulthood.

The female offspring from such mating will die before reaching adulthood. Only female mosquitoes bite.

The surviving non-biting males subsequently seek out and mate with more wild females and pass along the self-limiting trait for up to 10 generations before being extinct, according to Oxitec.