Wolbachia, 'ultimate weapon' against dengue?

It is no exaggeration to say that mosquitoes are one of the deadliest creatures on our planet.

Creatures associated with deadly diseases

The yellow fever in the Spanish-American War (1898), spread by Aedes aegypti mosquitoes , was the leading cause of death for US soldiers, instead of being hit by enemy bullets.

Malaria causes approximately 627,000 deaths in 2012 alone (statistics provided by Scientific American.) Now, Aedes aegypti mosquitoes are the culprit that spread rapidly dengue dengue worldwide.

According to the World Health Organization, about half of the world's population is at risk. Aedes aegypti mosquitoes, identified by white on legs and white spots in the body, can reproduce in any stagnant puddle, making it extremely difficult to control them.

This mosquito lives in areas of tropical and subtropical climate around the world - in Africa, America, Eastern Mediterranean, Southeast Asia and Western Pacific.

Aedes aegypti mosquitoes are the culprits that spread fast dengue dengue.(Source: NBC).

However, dengue fever does not appear naturally on these organisms - they take the virus from people who carry the disease and infect it to healthy people. To date, about 390 million people have a fever and 3.9 billion people are at risk every year.

Vietnam Preventive Medicine Department said that recently, dengue outbreaks have occurred continuously in 5 out of 6 regions that are members of WHO, except for the European region. The period of the first report was recorded from 1955-1959, with an average of only 908 cases per year during this period.

However, from 1960-1969, the average number of cases was 15 times higher than the previous period. These cases continue to increase in the next periods and by 2010 the number of cases of dengue in the world has reached more than 2 million cases.

In Southeast Asia, up to 7 out of 10 countries in the region have severe dengue fever and are the leading cause of child hospitalizations and deaths. In Vietnam, dengue fever appeared from 1959 to now.

The disease circulates in most provinces and cities and is at high risk in rainy months. The disease is mainly recorded in the southern provinces and cities and has cyclical and outbreak characteristics every 4-5 years.

Infecting mosquitoes to fight disease

Dengue fever causes huge economic losses, estimated at 8.9 billion USD per year. The cost of treating a disease can be three times more expensive than a family's income. Therefore, anti-dengue fever should be considered a great goal of every society.

Because there are no drugs or treatments for dengue fever, the main anti-disease strategy is still attacking Aedes aegypti. However, insecticides such as temephos have lost a lot of effectiveness, because mosquitoes develop resistance to drugs. Mosquito nets and nets also seem to have little effect, as Aedes aegypti mosquitoes often go out to feed during the day.

Raising mosquitoes in the laboratory for research against dengue.(Source: Smug).

In that context, fighting disease by infecting mosquitoes is a seriously considered roundabout.

Currently, one of the most promising tools to kill dengue fever is Wolbachia . Wolbachia is an intracellular bacterium, living in insect cells and transmitted from one generation to the next through insect eggs.

Wolbachia has four independent effects on mosquitoes such as reducing mosquito populations in the dry season; Wolbachia infected mosquitoes are often difficult to infect dengue fever; make mosquitoes' suction hose weaken and reduce the life of mosquitoes. These effects reduce the possibility of dengue virus infection and some other mosquito viruses, including Zika virus. However, these are just the results of laboratory research.

Wolbachia is found naturally in more than 60% of insects living around humans, including those that normally bite humans. However, it does not exist in Aedes aegypti, the main vector transmits dengue fever.

In 2010, Michigan State University (MSU) scientists reported injecting Wolbachia embryos into Aedes aegypti mosquitoes. Wolbachia lives in Aedes aegypti mosquitoes for nearly six years so they can be transmitted from mother mosquitoes to baby mosquitoes.

According to scientists, when a male mosquito infected with Wolbachia mates with a normal female mosquito, the bacteria will cause the female mosquito to reproduce abnormally and its embryos die prematurely.

Wolbachia does not affect the development of mosquito embryos when female mosquitoes are infected with the same bacteria as male mosquitoes. Therefore, this bacteria can spread very quickly to the mosquito population, preventing viruses that cause dengue fever to reside and reproduce in mosquitoes.

In addition, Wolbachia cannot spread from mosquitoes to humans. From here, scientists came to the conclusion that Wolbachia can be an effective tool for controlling dengue virus.

Vietnam is leading in testing Wolbachia infected mosquitoes

In an effort to promote research on Wolbachia, the Dengue Dengue (Elimitate Dengue) elimination program was born. This is a non-profit international cooperation program, under the leadership of researchers at Monash University, Australia.

There is currently no specific drug and dengue dengue vaccine.(Source: NBC)

The program is run by Professor Scott O'Neill, to bring together scientists from all over the world, with many skills and experiences in the areas of: Wolbachia genetics, biology and ecology about mosquitoes, epidemics and dengue dengue control, health education and awareness.

The program now has the cooperation of scientists from Vietnam, Australia, Indonesia, Brazil, Colombia, China, England, Singapore and the US. The project in Vietnam is called "Towards eliminating dengue fever".

The project has been approved by the Ministry of Health since 2006, at Tri Nguyen Island, Nha Trang City. In April 2013, the project began deploying applications to release Wolbachia infected mosquitoes on the field of Tri Nguyen Island.

Vietnam is the second country in the world, after Australia, to test Wolbachia carrying Aedes aegypti in the field.

Mosquito release ended in November 2014 and currently the project is conducting activities to monitor mosquito populations on Tri Nguyen Island. In parallel with the continued monitoring of Wolbachia populations of Tri Nguyen Island, the project is currently conducting basic studies on epidemiology, vectors of disease transmission and understanding of economic and cultural factors. and society related to dengue dengue in Nha Trang city to collect basic database, contributing to developing a research protocol to apply the method of using Wolbachia in dengue fever prevention in the city .