Dengue in Myanmar

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Dengue in Myanmar is a real problem. In 2018, a total of 3649 cases of dengue fever were recorded across Myanmar with 187 deaths. As of 19 June 2019, 12 people have died of dengue fever, while a total of 3144 cases have already been recorded. This number is already more than 86% of the total dengue cases reported in 2018.

Risk of Dengue in Myanmar

Myanmar is at risk of dengue transmission as the weather is conducive for the breeding of the vector (an organism that transmits a pathogen or disease). Transmission of the disease takes place all-year-round but peaks during the rainy season which takes place from May to October.

Dengue Fever

Dengue fever is caused by 4 types of viruses, namely DENV-1, DENV-2, DENV-3, and DENV-4. Infection with the viruses may be asymptomatic (producing or showing no symptoms) in some individuals but in others the symptoms will develop between 4 to 7 days after bitten by the vector.

The symptoms include recurring fever, pain behind the eyes, muscle, joint, bone pain, severe headache, and skin rash with red spots.

Dengue fever is not usually fatal, but may progress to a fatal complication known as Dengue Hemorrhagic Fever (DHF). Symptoms of DHF includes severe abdominal pain, diarrhea, vomiting, convulsions, bruising and uncontrolled bleeding. DHF can also lead to high fever that last from 2 to 7 days and circulatory collapse known as Dengue Shock Syndrome.

Transmission of Dengue virus

There are 3 main components that must be present in the transmission dengue virus and they are the virus, human as well as the vector. The disease vectors for dengue in Myanmar are Aedes aegypti and Aedes albopictus. Both species of mosquitoes are able to transmit other diseases such as yellow fever, chikungunya and Zika fever.

The transmission cycle of dengue starts when a female Aedes mosquito bites a person infected with dengue virus. The mosquito picks up the virus and virus incubation takes place for 4 to 10 days before the mosquito can transmit the virus for the rest of its life by biting other humans.

Aedes mosquitoes play a crucial role in the transmission and incubation of dengue virus. They can be found in the tropical and subtropical regions which cover the Americas, Europe, Africa, Asia and the Indian subcontinent. Aedes mosquitoes are holometabolous (undergo complete metamorphosis). This means that they undergo 4 stages in their life, namely the egg, larva, pupa and adult stages.

A female Aedes mosquito lays about 100 eggs each time. Eggs are laid in clean water found in both natural and man-made containers. The eggs are able to resist desiccation (the state of extreme dryness) for more than six months and will hatch in one day as soon as they are submerged in water.

After hatching, a mosquito larva will develop into pupa in as little as 5 days. After spending 2 to 3 days as a pupa, a flying adult mosquito will emerge hence the entire life cycle completes in approximately 8 to 10 days.

Only female mosquitoes bite as they need blood meal for the development of eggs and they usually bite during the day. Aedes mosquitoes are exophagic and exophilic which mean that they prefer to feed and rest outdoor.

As mentioned earlier, all 3 components involved in the transmission of dengue virus must be present for the disease to spread therefore we only need to target one of the component to stop the transmission.

Since the use of vaccines for dengue virus is limited and subjected to many restrictions, the most effective and efficient way to control the transmission of dengue virus remains to target the vector – Aedes mosquitoes.

Control of Dengue in Myanmar

The control measures for mosquitoes can be divided in to 3 main types, namely biological, physical and chemical.

Biological control involves the use of biological agents such as predators and pathogens to suppress the population of pests. Bacillus thuringiensis israelensis (Bti) is a type of bacteria that produces toxin and kills mosquito larvae, while having no effect to other non-target organisms. It can be used to control mosquito larvae at sensitive locations including drinking water.

Besides Bti, Gambusia affinis or mosquito fish has been used to control the breeding of mosquitoes in drains and ponds. The advantages of this type of control methods are that they are target-specific and more environmentally friendly.

Physical control of mosquitoes involves source removal, exclusion and trapping. Removal of breeding sites of mosquitoes helps to control the population of mosquitoes. Mosquitoes breeding can occur in still water bodies found in items such as discarded containers, tires or locations such as clogged drains and uneven surfaces.

Exclusion of mosquitoes can be done by keeping them out using physical barriers such as mosquito screens and nets. Physical barriers prevent adult mosquitoes from entering premises and prevent them from biting humans. Some examples of traps that are used in mosquito control are ovitraps which trap the eggs and gravid traps which target egg-laying female mosquitoes.

Mosquito control is most conventionally done using chemical methods. Chemicals are used to control the larvae and adults. Larviciding can be done at breeding sites to kill larvae and control of adult mosquitoes is usually carried out using thermal fogging and misting method.

Thermal fogging produces insecticide particles that are small enough to be carried in the air and reach flying mosquitoes. Misting produces insecticide droplets that may suspend in the air and kill mosquitoes that touch them when they fly through.

Reduce mosquito bites

Besides suppressing the population of mosquitoes, efforts can be made to reduce mosquito bites. Here are some tips to reduce mosquito bites:

1.       Use insect repellents

2.       Wear protective clothing

3.       Avoid peak mosquito hours

4.       Keep air circulating

5.       Sleep under mosquito net

6.       Get rid of stagnant water

7.       Keep landscape and home clean

To read more about prevention of mosquito bites, click here.

Mosquitoes are present everywhere around us so controlling them can be a challenge. The fight against dengue in Myanmar will succeed with public awareness and collective efforts from everyone including home owners and pest control operators. Everyone needs to be vigilant about the occurrence of dengue and Aedes mosquitoes so that the outbreak of dengue in Myanmar can be prevented.

In Titan, our pest control experts provide a variety of mosquito control services like thermal fogging, misting and larviciding to make sure that mosquito populations are under control. To understand more about the pest control services that Titan provides, click here.

Krystian -