Dengue Fever – Time to Protect Your Home

Dengue is a mosquito-born viral infection, causing a severe flu-like illness and, sometimes causing a potentially lethal complication called severe dengue. A warning has been issued by the Department of Disease Control at the Ministry of Public Health following at least 15 deaths with conditions expected to be very severe this rainy season.

Department director-general Dr Suwanchai Wattanayingcharoenchai said that the number of dengue fever patients from January 1 to July 8 was 25,708 people, while 15 people have died. The most affected were in the 15-24 age group, followed by those 10-14 years and 25-34 years.

“This fever has spread across the country,” he said. “Chaiyaphum has the most dengue fever patients, followed by Rayong, Khon Kaen, Mae Hong Son and Nakhon Ratchasima.”  He forecast that the number of dengue fever patients would increase, adding that the Thai Meteorological Department said many areas would face heavy rain, which will enable mosquitoes to lay eggs in water-filled containers or areas holding water.

“Therefore, the department would like to advise people to eliminate mosquito breeding sites by keeping their clothes inside wardrobes, disposing of garbage regularly, closing the lid of water-filled containers, and changing water in pots or vases every week,” he said.  “These recommendations will help people to avoid contracting dengue fever, the Zika virus or the Chikungunya virus.”

He added that people can prevent mosquito bites by also wearing long-sleeved shirts and long pants, using various types of mosquito repellents such as lemongrass or other chemicals, and sleeping under a mosquito net.

A person infected by the dengue virus presents with severe flu-like symptoms. The contamination, also called ‘break-bone’ fever affects infants, children and adults alike and has no known cure. The appearance of dengue fever varies according to the age of the patient.

The disease is endemic throughout the country in the rainy season in both urban and rural areas, with elevated risk in the northeastern part of the country.  The region has an infection rate of 25.67 patients per 100,000 of the population which is the highest in the country, according to Thailand’s Bureau of Epidemiology.  During January 1 and May 25, 2020, the Bureau reported 14,136 patients with Dengue fever, which accounts for 21.28 per 100,000 of Thailand’s overall population. 

Aedes aegypti, the mosquitoes responsible for dengue fever, can also spread yellow fever and Zika virus.   The viruses are passed on to humans through an infective female which mainly acquires the virus while feeding on the blood of an infected person.  The virus infects the mosquito mid-gut and subsequently spreads to the salivary glands over a period of 8-12 days. After this incubation period, the virus can be transmitted to humans during probing or feeding. Immature mosquitos are found in water-filled habitats, mostly in artificial containers closely associated with human dwellings and often indoors.

Flight range studies suggest that the female spend their lifetime in or around the houses where as adults and they may fly distances of 400 metres. These mosquitos are small and dark in colour, approximately 4 to 7 millimetres in length with typical white markings on the legs and thorax. 

Thailand hospitals may offer a dengue vaccine, however this is not suitable for everyone and a doctor’s consultation is essential.  A key factor is a history of dengue infection in the past; if you never have dengue infection before, a vaccination is unlikely to be recommended.

The World Health Organization (WHO) only recommends vaccinations for people aged 9-45 years old who live in the dengue endemic area and not for travelers or foreigners living in Thailand. 

There is no specific treatment for Dengue virus. Using mosquito repellents, insect screens for all doors and windows and being vigilant in removing any water stagnation are important for the prevention of the disease.  Households should ‘survey’ the home environment, both outdoors, under cover or inside the home.  Look for and remove or cover any containers that could hold water.  It may also be timely to remind the neighbours for the well-being of the wider community.