'Vaccination for mosquitoes': Strange application in the prevention of dengue fever

Dengue fever spreads through mosquitoes, but the strange thing is that Vietnamese scientists are trying to breed this type of mosquito and release it into the environment.

Prevent dengue fever by vaccinating mosquitoes

The danger from dengue

Dengue haemorrhagic fever (DHF) is currently a huge public health problem globally and is evaluated by the World Health Organization (WHO) as one of the most important vector-transmitted diseases. Dengue disease discovered in the 50s of the last century, has continuously spread to countries around the world, currently circulating in over 100 countries belonging mainly in areas with tropical climate and Asia. tropical like Southeast Asia and the Western Pacific.

Recently, dengue epidemics have occurred continuously in 5 of the 6 regions that are members of the World Health Organization (WHO), except for the European region. The period of the first report from 1955-1959, on average in this period, only about 908 cases per year, however the period from 1960-1969 had an average of 15 times higher cases than the period. previous paragraph. The number of these cases continues to increase in the next periods, by 2010, the number of cases of dengue in the world has reached 2,204,516 cases.

In Southeast Asia, up to 7 out of 10 countries in the region with severe dengue, are the leading cause of hospitalizations and deaths in children; The prevalence of dengue in the region has increased significantly over the last 17 years and from 1980 onwards, the number of dengue cases has increased nearly 5 times compared to 30 years ago.

In 2015, according to WHO's announcement, DHG has increased in many countries around the world, especially in the Asia Pacific region: Malaysia has recorded 85,448 cases, up 21.5% over the same period last year. 2014 and increased by 300% compared to the same period in 2013; Philippines increased by 10.2%; Cambodia increased by 170%; Thailand increased by 100% compared to the same period in 2014; India recorded the highest number of cases in the last 5 years.

In Vietnam, dengue fever appeared from 1959 up to now, the disease circulates in almost all provinces and cities, has a high risk in the rainy season, the disease is recorded mainly in provinces and cities. Southern region and cyclical nature, outbreaks every 4-5 years. In the past, several hundred thousand cases / year, especially in 1987, recorded more than 300,000 cases with more than 1,000 deaths.

In recent years, the number of cases has decreased to about 50-100,000 cases. In 2015, the number of cases was lower than the same period in the period of 2010-2014 but higher than in 2014 (2014 was the year with the lowest number of cases in the past 11 years).

The team is working on feeding blood to mosquitoes.

Raising mosquitoes to kill mosquitoes

Dengue dengue fever is transmitted by Aedes mosquitoes and now this disease prevention is still difficult because there is no vaccine for prevention and no specific treatment. The main and effective preventive measure is based on controlling the vector of disease transmission.

In order to contribute more effectively to the prevention of mosquito transmission, the Ministry of Health always attaches great importance to scientific research. One of the studies being tested in Tri Nguyen Island, Vietnam is to use Wolbachia to infect mosquitoes, make mosquitoes die early and limit Dengue virus infection and develop on infected mosquitoes.

Wolbachia is an intracellular bacterium, living in insect cells and transmitted from one generation to the next through insect eggs. Wolbachia is found naturally in more than 60% of insects that live around humans, including those that normally bite humans, but it does not exist in the Aedes aegypti, the main vector of transmission. Dengue.

In Vietnam, the research team started research on Wolbachia since 2006 with the support of international experts. The project has successfully transplanted and successfully cultured local Aedes aegypti mosquitoes carrying Wolbachia in the laboratory of NIHE.

Based on the scientific and practical results obtained during the research period from 2006-2013, the operation of Wolbachia infected Aedes aegypti was approved by the Ministry of Health in April 2014 on the field of Tri Nguyen Island, NhaTrang, with a population of over 3,000 people.

In May 2014, Wolbachia infected Aedes aegypti mosquitoes were released at each household on the island. After 27 weeks of releasing Aedes aegypti, Wolbachia infected Aedes aegypti is 87%. Results of monitoring of natural populations of Aedes aegypti mosquitoes in May 2015 show that infection is over 95%.

Thus, the research results at Tri Nguyen Island have demonstrated the possibility of penetrating into the wild population of Wolbachia Aedes aegypti. Thus, the initial study has shown that Wolbachia infected mosquitoes have established and replaced almost all natural Aedes aegypti populations.

In addition, according to the surveillance results of dengue cases from mid-2014 to present, in Tri Nguyen island, no concentrated dengue outbreaks or local dengue cases were recorded. It is for this reason that scientists say that using Wolbachia for mosquitoes is no different from 'vaccinating mosquitoes' . From restricting Dengue virus infection and development on mosquitoes, the shortened life of mosquitoes has an effective impact on the prevention of dengue. This successful study will actively contribute to the prevention of dengue fever.