Find out how to get rid of the dengue virus

Scientists in Australia and Indonesia injected Wolbachia bacteria into the body of striped mosquitoes to interfere with the ability to transmit dengue virus, destroy the pathogen.

According to the World Health Organization (WHO), viral diseases have increased rapidly in recent decades. In 2019, the number hit a record.

Through the World Mosquito Control Program (WMP), scientists from Monash University, Australia and Indonesia have conducted a test of new technology to help eliminate dengue virus in Southeast Asia and around the world. They injected Aedes aegypti (the striped mosquito) mosquito - the main species that transmits dengue to humans, a bacterium called Wolbachia. This bacterium interferes with the ability of insects to transmit viruses, including dengue, without stopping mosquito populations or affecting the ecosystem.

This process lasted for three years, the results were announced in August and reported by the media on October 13. The number of cases of dengue fever in the city of Yogyakarta, where the experiment took place, has been significantly reduced compared to areas where conventional methods such as spraying, luminescence, and pond removal are reported, scientists say stagnant water, ...

To conduct the study, the scientists released mosquitoes carrying Wolbachia bacteria into 12 areas of Yogyakarta city within 7 months. These mosquitoes infect local mosquito populations. They then tracked the number of dengue cases across the city. Symptomatic patients will provide detailed information about where and where to travel, and receive diagnostic testing.

 

Mosquito samples were injected with Wolbachia bacteria at WMP's laboratory in Indonesia. Photo: SCMP

Two years later, the scientists found that dengue prevalence had decreased 77% in the Wolbachia mosquito-releasing areas. The detailed results of the experiment will be presented in more detail at an international scientific conference in November.

WMP says Wolbachia is found in the cells of 60% of insects on the planet, including moths and some other mosquitoes. But they do not naturally exist in striped mosquitoes.

The prevalence of dengue fever has increased dramatically over the past decade, from 1.2 million in 2010 to 4.2 million in 2019, according to WHO. About half of the world's population is at risk of developing the disease in the future, the organization says.

There are two main reasons for this. First of all, striped mosquitoes tend to live near urban areas. As the city's population grows, the mosquitoes have a chance to feed and breed. Second, climate change has extended the range of mosquito activity further north. This means that dengue begins to return to areas where the pathogen has disappeared.

Other factors include poor urban planning, inadequate public services and infrastructure like tap water. Travel and trade are developing more and more, creating favorable conditions for striped mosquitoes to breed in areas that were previously free of diseases.

"The rise in greenhouse gas concentrations globally is increasing surface temperatures as well as the rate of replication, viral viability, mosquito breeding and biting rates. This is leading to the seasons. The epidemic is prolonged, allowing dengue fever to spread to higher regions, "said associate professor Rachel Lowe, member of the Royal Society of Dorothy Hodgkin based at London School of Hygiene and Tropical Medicine.

Specialists working at WMP's laboratory. Photo: SCMP

It is difficult to give an exact figure of the total number of annual dengue cases globally, as the majority of cases are asymptomatic, therefore are not reported or misclassified. Out of 390 million cases of dengue fever each year, according to WHO, only an estimated 96 million cases are manifest.

Symptoms of dengue include nausea, vomiting, rash, and body aches. Although less common, some severe patients can experience severe bleeding, organ failure or die if they are not treated promptly.

The trial by WMP was the largest to date. The team is proud of the results, saying that the 77% reduction in dengue cases was "significant and significant". Releasing mosquitoes in the community requires a great deal of trust from the people, especially after many years of mobilizing awareness.

"The community where we work is used to living with dengue fever. Many people have been infected or have loved ones with dengue fever. We found that once they understood the Wolbachia method and what we tried to do. They will support them enthusiastically and vigorously, "said Cameron Simmons, WMP director of Oceania.

In Vietnam, since 2013 mosquitoes carrying Wolbachia bacteria have also been released in Tri Nguyen Island, Nha Trang, for a research project on dengue elimination. In June this year, mosquitoes carrying Wolbachia bacteria continue to be released in 15 wards in Nha Trang. The project is currently in the research process.