A 3D approach to be safe from Dengue

During 2021, Thailand saw roughly 10,600 cases of Dengue infections, which increased by roughly 350% in 2022 and 1200% in 2023. Experts believe that these numbers will rise in the future due to a combination of increased temperatures, increasing population density in concentrated urban settlements, and the evolving nature of the mosquitoes, among other reasons. It is already proven by the fact that it is now considered endemic in more than 100 countries, many of which had no previous history of the disease, writes Uttam Ghimire of Stockholm Environment Institute (SEI) Asia Centre

Dengue—a term you’ve likely heard many times in recent years—is a viral disease transmitted by the female Aedes aegypti mosquito. This mosquito bites a Dengue-infected human, becomes infected, and transmits it to healthy humans for its remaining life period (typically 3-4 weeks).

In typical cases, Dengue may be asymptomatic or cause mild illness. Still, for patients with a prior history or other chronic diseases, it significantly increases the risk of health complications and, in some cases, death. Unlike flu, where getting the disease improves the human body’s immunity for the next time, the Dengue virus infection provides limited immunity for recurring infections.

With the exacerbation of its drivers and disparities in healthcare and health information access, the incidence of Dengue and associated health complications is thus likely to continue rising. What can we do to contain the increasing cases of Dengue? Given the rising rate of infection, we cannot wait for global climate action to slow down global warming or expect a different population setting. However, we think that with simple 3 Ds of household measures, which we discuss below, the risk and exposure of Dengue can be reduced.

Decrease breeding grounds. A common understanding of the Dengue-transmitting mosquito is that it is typically found in tropical countries and thrives in high humidity and temperatures. While this is true, Dengue outbreaks can occur anywhere and anytime when mosquitoes are active. Therefore, the most effective strategy for reducing Dengue incidences is to eliminate the breeding grounds of these mosquitoes, as they prefer to lay eggs in shallow, clean, stagnant water near human dwellings.

Mosquito eggs are usually laid above the waterline in inconspicuous locations such as potholes in the road, tires, plastic containers, bird baths, flowerpots, water storage jars, and air conditioners. These eggs can hatch into larvae within a day when containers fill with water, either from rainfall or human activities. If there is no rain or human-induced water addition, these eggs can survive up to nine months, demonstrating the adaptability of these mosquitoes.

The larvae then develop into pupae and eventually mature into adult mosquitoes, which emerge from these breeding sites and can contract and transmit Dengue. The larvae-to-adult mosquito transformation takes approximately 5-6 days, during which they are completely aquatic, depending entirely on water availability for survival.

Therefore, we should be aware of places where water collects around our homes and workplaces and refresh stagnant water every 2-3 days. If larvae are found in one water container, we should diligently search for other potential sources and thoroughly drain them. When disposing of larvae and pupae, it’s important to do so carefully and avoid mixing them with other water sources. Water containers should be emptied, cleaned, and scrubbed periodically.

Abandoned tires, which are often black and difficult to drain, are particularly favored by these mosquitoes and should be stored or disposed of properly. Similarly, plastic cups and packets that may collect rainwater or dewdrops in garbage dumps can provide potential breeding sites. They should not be left to accumulate within half a kilometer of our residences. Potholes around our homes should be filled to prevent rainwater accumulation, and storm drains should be properly covered.

Diminish exposure. The Dengue-transmitting mosquito is a daytime feeder, with peak biting times in the morning and evening. Therefore, it is crucial to remain vigilant during these hours. Wearing long-sleeved clothes, using mosquito repellents, and staying alert in high-risk scenarios (such as during the peak outbreak months of June to September in South Asia) are essential measures to take at home. Installing window and door screens, ensuring adequate ventilation, and using mosquito nets not only reduces the risk of contracting Dengue but also other mosquito- and insect-borne illnesses.

It takes approximately a week for the mosquito to become infective after biting an infected person. Thus, the risk of exposure remains high for an extended period, even when no infected person is nearby. The mosquito that transmits Dengue is small and dark-colored, identifiable by white bands on its legs and silver-white patterns on its body. Family members, especially children, should be educated and encouraged to report sightings of similar mosquitoes in the household. Additionally, it’s important to inform neighbors about these mosquitoes because experts suggest they operate within a radius of 400-500 meters, necessitating collective efforts to reduce their impact.

Doctors and experts know the best. If someone becomes infected with Dengue or suspects they have contracted it, they should seek professional medical assistance immediately. A simple blood test can confirm the presence of Dengue, and preventive quarantine measures should be taken. In many countries like Nepal, this testing is free whereas in other countries like Thailand, Dengue specific insurances are popular.

Hospital admission may be necessary to manage severe symptoms, which is crucial for vulnerable populations such as children, elderly individuals, pregnant women, and those with chronic health conditions. Infected individuals should take appropriate quarantine measures to minimize mosquito contact and help contain outbreaks.

While some emerging vaccines have shown preventative properties in reducing fever and hospitalization due to Dengue, medical experts have recommended that they be used only in certain cases and upon their consultation. If people detect larvae and are worried about the type of mosquito, they should also seek the help of exterminators with more ground knowledge on using environmentally friendly and effective practices, as old practices like pouring kerosene or fumigation might create even more serious environmental issues.

While following this 3D approach does not guarantee immunity from Dengue, studies and experts suggest that it significantly reduces the risk of contracting the disease.