A person can contract dengue fever multiple times.

Associate Professor Tran Dac Phu, Director of the Department of Preventive Medicine (Ministry of Health), said that many people have the mindset that once they get dengue fever, they don't have to worry about getting it again. In reality, a person is at risk of contracting dengue fever four times with four different types, and each subsequent infection is usually more severe than the previous one.

Associate Professor Tran Dac Phu stated that a person is at risk of contracting dengue fever multiple times, with different serotypes. (Photo: H. Hai)

According to Associate Professor Phu, dengue fever is an acute infectious disease that can cause epidemics, caused by the Dengue virus with four pathogenic types designated as D1, D2, D3, and D4. Because the immunity acquired after contracting the disease is specific to each type, people can contract dengue fever a second or third time from different virus types.

"Once you've contracted a strain like D1, you'll have lifelong immunity to it. Subsequent infections tend to be more severe than previous ones," Associate Professor Phu said.

Where do mosquitoes that transmit dengue fever prefer to live?

The disease is spread when Aedes mosquitoes bite infected individuals and then transmit the virus to healthy people through their bites.

Many people mistakenly believe that mosquitoes in cattle sheds cause dengue fever. In reality, those are mosquitoes that transmit other diseases, while dengue mosquitoes prefer to live near humans, sheltering right next to them. The two types of mosquitoes that transmit dengue fever are Aedes aegypti and Aedes albopictus, with Aedes aegypti being the primary vector.

Female Aedes mosquitoes bite humans during the day, with the most intense biting occurring in the early morning and late evening. They typically perch in dark corners and crevices of houses, on clothing, bedding, clotheslines, and other household items. Aedes mosquitoes lay their eggs and breed primarily in containers of clean water in and around the house, such as water tanks, jars, pots, wells, tree hollows, and other objects or discarded items containing water, such as flower vases, water bowls on shelves, car tires, coconut shells, etc. They do not breed in stagnant ponds or sewers with foul-smelling water. Aedes mosquitoes thrive during the rainy season, when the average temperature exceeds 20ºC.

In Vietnam, nearly 60,000 cases of dengue fever have been recorded since the beginning of the year, with over 50,000 requiring hospitalization and 18 deaths. Compared to the same period in 2016, the number of hospitalized cases increased by 9.7%. However, the majority of cases are still concentrated in the South (64.4%) and Central regions (19.9%) of the total number of cases nationwide, as these areas have been endemic for many years.

The northern region has a lower incidence rate (12.4%), however, there has recently been an increase in the number of cases in Hanoi (Hanoi ranks 3rd nationwide in absolute number of cases, and 19th in the number of cases per 100,000 people).

Regarding the opinion that mosquito spraying is not thorough enough, Associate Professor Phu stated that all mosquito-killing chemicals available on the market have been licensed by the Ministry of Health. However, spraying requires the cooperation and consent of the people.

“For example, in a four-story house, when spraying insecticide, all floors must be sprayed. Spraying only the first floor as a precaution, neglecting the upper floors, is ineffective because mosquitoes fly and move around. Spraying also needs to be carried out in all houses in the same area. But the most fundamental measures are preventing mosquitoes from laying eggs and breeding larvae to effectively prevent dengue fever,” Associate Professor Phu said.

Therefore, every citizen and family needs to cover all water containers tightly to prevent mosquitoes from laying eggs inside.

Weekly measures to eliminate mosquito larvae/pupae include: releasing fish into large water containers; washing and cleaning medium and small water containers, turning over empty containers; changing the water in flower vases; adding salt or oil to water bowls placed under cupboard legs. Remove waste materials and natural water pockets where mosquitoes can lay eggs, such as bottles, broken glass, coconut shells, broken pottery, old tires, bamboo hollows, leaf sheaths, etc.

"If your house has water storage tanks on the upper floors, check them carefully because if the lid is turned off, it will become a breeding ground for mosquito larvae and pupae, as it is a preferred place for mosquitoes to lay their eggs," Associate Professor Phu advised.

To date, thanks to the vigorous implementation of the mosquito larva eradication campaign in all communes and wards, and proactive chemical spraying, over 96% of detected dengue fever outbreaks have been treated.

According to Dantri