A health worker sprays insecticides in the southern province of Phú Yên. — VNA/VNS Photo

In a recent interview with Việt Nam News reporters Vân Nguyễn & Minh Phương, Lê Trung Kiên, head Of Experimental Chemistry of the National Institute of Malariology, Parasitology and Entomology spoke about the country's strategy in preventing and controlling dengue fever, which has infected more than 247,200 people and killed 100 so far this year. 

The number of dengue infections and deaths in Việt Nam this year has spiked. Why is the situation worse this year? 

Basically, dengue fever has seasons. Another reason is that with the COVID-19 pandemic occurring in 2020-2022, the attention of local people and the health sector for dengue decreases as human resources and workload are given mostly to monitoring and handling COVID-19.

There are also difficulties with the budget. Localities like Hà Nội and HCM City can’t buy insecticides, which limits the ability to proactively prevent the spread of the disease.

Another factor is due to this year’s climate. There has been higher rainfall. Dengue is associated with two factors, humidity and water. With higher rainfall, the density of larvae and mosquitoes increases, leading to a rising number of outbreaks and infections.

How do you evaluate the preventive strategy of Việt Nam?

Mosquito-borne diseases are among the ones that cause the world’s highest mortality rate. Currently, there is no treatment medicine for dengue yet, therefore, preventive measures against disease-carrying mosquitoes are among the priority strategy recommended by the WHO and the health ministry.

WHO and Việt Nam’s Ministry of Health have issued guidance and recommendations as well as built a programme for the prevention and control of dengue fever in Việt Nam.

A notable characteristic of dengue is that it is transmitted through disease-carrying mosquitoes. This is a difficulty because no specific antiviral medication is currently available to treat the disease while the vaccine is being researched on a small scale and has yet to be made available. Therefore, the treatment depends on the nature of the condition, the physical fitness attributes of the patient and the capability of health facilities, which vary.

The overall strategy to combat dengue as recommended by WHO and the health ministry focuses on preventive measures, which involve killing colonies of mosquitoes transmitting the disease.

One of the commitments of the National Dengue Fever Prevention Programme is periodical supervision and prompt zoning of breakout areas. Regarding periodical supervision, the faculty here has been carrying out regular administration check-ups. For example, as you can see, most of our personnel are in Hưng Yên right now, supervising units in Vĩnh Phúc, Hải Phòng, Thanh Hóa, and Nghệ An, areas that currently have outbreaks.

After the outbreak, areas have been outlined and the mosquitoes have been collected, we give localities recommendations and work in close collaboration with them to effectively tackle these hotspots. With the insects we have collected from the outbreak sites, in this case, the mosquitoes, we will begin identifying their species and sensitivity to chemicals, looking out for sites or species that are resistant to insecticides. Then, we will test different chemicals to find the most effective one for said species, recommending them to the infected localities, at the same time assisting local medical staff in order to fully address the outbreak.

Lê Trung Kiên, head Of Experimental Chemistry of the National Institute Of Malariology, Parasitology and Entomology. — VNS Photo Vân Nguyễn

Could you elaborate on sensitivity testing?

Sensitivity testing refers to the process of collecting and multiplying the mosquitoes and then putting their offspring, which we call F1, into contact with chemicals. Insecticide-resistant mosquitoes will not die when they come into contact with the chemicals. This means that the mosquito population will not be affected when we spray these chemicals in the locality. When we find a species of chemical-resistant mosquitoes, we will choose a different chemical, one that has the ability to kill said mosquitoes and recommend those chemicals to localities for them to effectively apply in the prevention process.

What are the major challenges in dengue fever prevention and treatment now?

Currently, people of all ages can catch dengue fever. This means that infants all the way to elderly people are all at risk of contracting the disease. Infections are concentrated in the demographic most susceptible, although this changes over time. In this case, dengue fever generally affects adults. However, there have been outbreak sites with most children having contracted the disease since they are not able to take the same precautions as most adults can.

A big challenge right now is carrying out these procedures following the recent COVID-19 pandemic. There have been issues regarding the shortage of medical and chemical supplies, as well as the medical staff. Many faculty members and collaborators very familiar with the terrain and disease prevention procedures have now retired from the workforce, due to health and other personal issues. That is a major obstacle in dengue fever prevention.

How has Việt Nam cooperated with the international community in fighting dengue fever?

Instructions from the Ministry of Health, especially those pertaining to the limiting of dengue fever outbreaks currently, have now received input and support from the World Health Organization. For example, the WHO supplies us with the paper used to test the specimens’ sensitivity to chemicals  and share the results with other countries in Southeast Asia and the world. Then, we can form a network to stop the outbreak of dengue fever everywhere.

Also, we have collaborated with other global organisations in order to research and share data, finding methods of preventing the outbreak of diseases transmitted through vectors, such as malaria and dengue fever. For example, we have collaborated with ACT Malaria, the US, the UK and Japan in order to find solutions to prevent the spread of outbreaks. This collaboration has spanned many years and has brought very fruitful results in the development of new insecticides, procedures, and solutions to prevent malaria and dengue fever.

A woman in the southern province of Đồng Tháp covers a water container to prevent mosquito breeding. — VNA/VNS Photo

What are your predictions about the development of dengue fever in Việt Nam in the future?

Regarding the current dengue fever outbreak, the Government and the Ministry of Health have provided guidance and hosted conferences, simultaneously alerting all 63 provinces to take measures in preventing the spread of the disease.

However, with the volatile weather conditions and changes in disease cycles we are experiencing, there will be many factors that we feel are still difficult for the disease to be put under control. Therefore, according to instructions from the Ministry of Health, specialists will maximise coordination with medical personnel across the country, from provinces and cities all the way down to wards and villages, to carry out and maintain the prevention and control of dengue fever in our country. — VNS