•  Simply emptying water isn't enough, the eggs are laid just above the waterline on the inside walls of the container
•  When the water is emptied, only the water is removed, the eggs remain attached to the container
• The eggs can survive for up to 9 months without water. Once the container fills with water again, the eggs hatch

The country has recorded more than 55,000 dengue cases so far this year (2026), with infections surging last month (in June), according to the National Dengue Control Unit's (NDCU) Disease Surveillance System (NaDSys). As of midnight on 30 June, a total of more than 54,000 dengue cases had been reported nationwide. June alone accounted for 21,565 cases by the 25th epidemiological week of 2026. The Western Province (WP) continued to carry the highest disease burden, accounting for 52.51 per cent of all reported dengue cases. The dengue death toll has risen to 32, including one maternal death reported from the Teaching Hospital, Batticaloa. According to NaDSys, 124 Medical Officer of Health (MOH) areas have been identified as high-risk areas for dengue transmission.

According to the Health Entomology Officers' Association’s (HEOA) Secretary, Buwaneka Lahiru Hewagamage, one of the primary responsibilities of Health Entomology Officers is to forecast disease outbreaks through entomological surveillance. "Our main responsibility is to predict potential disease outbreaks through entomological surveys. We are also the only group qualified to carry out the taxonomic identification of disease vectors. Health Entomology Officers are a recognised technical cadre under the Health Ministry's Paramedical Services, with a two-year higher diploma qualification. We are trained to accurately identify mosquitoes and other insects up to the species level. Another important responsibility is evaluating the effectiveness of mosquito fogging operations. We conduct the necessary tests to determine whether fogging programmes are actually effective. Our Officers also carry out insecticide susceptibility tests on all insecticides imported for mosquito control. Before any insecticide is used, we assess whether local mosquito populations remain susceptible to it. In addition, we play a key role in national mosquito control campaigns, including the three-day and seven-day mosquito control programmes conducted across the country. Our Officers carry out both pre-intervention and post-intervention surveys. Since the Government spends considerable public funds on these programmes, our findings are used to determine whether they have been successful. Only our Officers are qualified to issue technical reports evaluating the effectiveness of these mosquito control programmes. Therefore, the Officers perform a wide range of highly specialised and essential duties within the Ministry."

Following are excerpts of the interview:

With information provided by the Deputy Health Minister and the Prime Minister being misunderstood by the public, Parliament and even some health experts, could you clarify which dengue serotype is currently circulating? Also, there has been a sharp increase in the reported cases. Is this rise linked to the circulating serotype?

There are four dengue serotypes. As far as we know, the four serotypes themselves have not changed. What has changed is the dominant circulating strain. At present, it is dengue serotype two (DENV-2) that is circulating. Around 70 per cent of the blood samples tested by Medical Research Institute have been identified as DENV-2.

The major dengue outbreak in 2017 was also caused by DENV-2. However, during the past few years, most infections have been caused by serotype 3. As a result, the community has gradually developed immunity to serotype 3.

When the dominant circulating strain changes, it takes time for the community to build up immunity to the newly circulating serotype. For several years, one serotype had been predominant in the community, allowing people to develop immunity against it. That is one of the reasons why the number of dengue patients remained comparatively low in recent years.

Now that the dominant circulating strain has shifted to serotype 2, the community has not yet developed sufficient immunity against it. As a result, more are becoming infected and the number of dengue patients has increased.

What breeding habits of the dengue mosquito do people not get right and are unaware of?

A: Many still believe that the dengue mosquito breeds only in clean water. For years, public awareness campaigns have focused on this message. While it is true that the mosquito prefers clean water, what people need to understand is that it can breed in any container holding clear, stagnant water.

Public awareness should therefore focus on the fact that dengue mosquitoes can breed wherever clear water collects, regardless of the size of the container.

Even the media often show community clean-up campaigns where people are clearing drains, cutting grass or trimming trees. As a result, the public tends to associate dengue prevention with cutting vegetation and cleaning their gardens. However, that alone isn’t enough.

A dengue mosquito needs only a very small amount of water to breed. Even a puddle no larger than the size of a coin can become a breeding site. People should pay closer attention to small containers that collect clear water and remove or empty them regularly.

People also tend to focus only on cleaning their gardens. However, indoor breeding is another major issue that often goes unnoticed.

For example, mosquitoes can breed in the drip tray behind a refrigerator. Most are aware of that. However, many don’t realise that ornamental pots used to grow plants in water can also become breeding sites. Our surveillance has found that many of these containers test positive for mosquito larvae, yet, people are generally unaware that they should be emptied or cleaned.

Another common breeding site is under kitchen sinks. Water leaking from the sink can collect inside cupboards beneath it, creating hidden breeding places. These are what we call cryptic breeding sites, and they often go unnoticed. Greater public attention needs to be given to identifying and eliminating these hidden breeding places.

Another important point is that dengue mosquito eggs are highly resistant to drying out. We always advise people to remove standing water from containers. However, simply emptying the water isn’t enough.

The dengue mosquito doesn’t lay its eggs directly in the water. Instead, it lays eggs just above the waterline on the inside walls of the container. When the water is emptied, only the water is removed — the eggs remain attached to the container.

These eggs can survive for up to nine months without water. Once the container fills with water again, the eggs hatch. Many people are unaware of this, which is why simply cleaning the garden isn’t enough.

Cleaning the garden mainly removes breeding sites at the ground level. However, the dengue mosquito is highly adaptable and can easily shift to breeding sites at higher levels. Roof gutters, roof slabs and other elevated structures that collect water can become breeding places, yet, many people never inspect these areas.

Another misconception concerns the mosquito's biting habits. We often describe the dengue mosquito as a daytime biter, but, many don’t fully understand what that means.

The mosquito is most active during the day, particularly in the early morning and late afternoon. In other words, it is active when people are also active.

Many believe that sleeping under a mosquito net at night or applying mosquito repellent before going to bed is enough to prevent dengue. In reality, if repellents are used, they should also be applied during the daytime because that is when the dengue mosquito is actively biting.

These misconceptions about where the mosquito breeds and when it bites are among the reasons why dengue control continues to be such a challenge.

Who are the main offenders when you take schools, Government and private institutions, religious and public places?

During our surveillance, schools are consistently identified as the highest-risk locations for dengue breeding. They rank first among the places where mosquito breeding sites are most frequently detected.

Places of religious worship come second. In general, many religious institutions don’t receive sufficient attention when it comes to regular cleaning and dengue prevention activities.

Government institutions rank next. In many cases, people simply come to work and leave. There is often a lack of responsibility towards maintaining these premises, resulting in potential mosquito breeding sites not being properly identified and removed. As a result, these institutions have also become important mosquito breeding locations.

Another concern is that people spend a significant amount of their daytime hours in schools, places of religious worship and Government institutions. Since dengue mosquitoes are most active during the day, this increases the risk of people being bitten and contributes to the faster spread of the disease.

Do we have short-, medium- and long-term measures to control such outbreaks at least in the future?

Since cases have already been reported, we need to implement short-term measures to control the mosquito population, such as fumigation. If a large number of patients are reported from a high-risk area, fumigation can help reduce the number of mosquitoes carrying the virus in that locality.

At the same time, environmental inspections are being carried out. During these inspections, larvicides and other mosquito-control agents can be applied immediately to destroy the mosquito larvae.

We can also intensify field inspections over the next few days by deploying larger teams to inspect more premises. Community-level clean-up programmes and shramadana campaigns (voluntary community clean-ups) can also be organised.

In addition, because the number of infected mosquitoes is likely to be high, the public should be advised to use mosquito repellents and take personal protective measures.

As a medium-term strategy, proper waste management must be strengthened. Local Government authorities are responsible for waste management, while the Ministry can only provide technical guidance and support.

Unfortunately, people tend to remember to inspect their homes only when there is a dengue epidemic. Similarly, it is only then that the Government focuses on conducting environmental inspections. There’s already a circular issued by the Presidential Secretary requiring institutions to inspect their premises once a week. If these inspections were carried out consistently, outbreaks like this could be prevented.

We should also incorporate dengue prevention and awareness into the school curriculum so that children learn about the disease and its prevention from an early stage. Further, the media can play an important role in raising public awareness about the dangers of dengue.

As a long-term measure, we need to make better use of entomological surveillance data. At present, these surveys are already being carried out, and public Health Entomology Officers prepare forecasts. However, we need a national plan on how to use this data effectively to predict outbreaks and respond to them.

Another long-term solution is to consider the use of a dengue vaccine if one is recommended by the World Health Organisation (WHO). Although there is currently no WHO-recommended vaccine in use here, we understand that a dengue vaccine trial has been conducted in Sri Lanka. Based on the findings, we could consider introducing a pilot project in the future before deciding on wider use.

We can also reduce the risk of dengue by planning housing schemes and towns more carefully. They should be designed to prevent water from collecting and to allow rainwater to drain away properly, reducing mosquito breeding sites.

Ultimately, much of the responsibility lies with the public. Communities have a major role to play in dengue control. In the long-term, we need to build a culture where people take responsibility for preventing dengue in their own surroundings. That will take time, as many people don’t yet have that attitude.

Are the available legal provisions sufficient to enable the control of mosquito borne diseases?

Spot fines can currently be issued only in the WP under the Mosquito Control Statute, which applies only within the Province. It does not apply to the rest of the country because it is a Provincial Statute passed only by the Western Provincial Council.

The Law that applies across Sri Lanka is the Mosquito Control Act. There were discussions about introducing spot fines by amending this Act, but, that process hasn’t yet been completed.

There is another issue as well. The legal authority to enforce the Law has been given only to a particular group of officers. As Health Entomology Officers, we regularly carry out Breteau Index surveys, during which we inspect around 100 premises at a time. These inspections often identify mosquito breeding sites. However, we don’t have the legal authority to take further action against those responsible.

In fact, our names are not even included in the Act as authorised Officers who are allowed to enter premises. In many ways, the work we do is carried out on a voluntary basis. We are able to perform our duties largely because of the goodwill and cooperation of the community.

If Health Entomology Officers are also given the power to issue spot fines, especially during dengue outbreaks, we would be able to take immediate action. We are the Officers who deal directly with mosquito breeding sites, so we should also be given the responsibility and authority to act.

We have already made this request. However, the authority to grant these powers rests with the Director General of Health Services.

At the moment, is the Wolbachia project the only mosquito control project that we have, or are there any other similar projects underway?

The Wolbachia project is being carried out by the NDCU. We have also heard that the next phase of the project is likely to begin soon.

Another project is being carried out with the Kelaniya University using the Sterile Insect Technique (SIT). This involves using nuclear technology to make male mosquitoes sterile. The male mosquitoes are exposed to X-rays so that they can’t reproduce. They are then released into the environment, which helps reduce the mosquito population over time.

We have also suggested other methods. Mosquitoes have natural predators. During malaria control programmes, natural predators that feed on mosquito larvae were used successfully. There’s also a mosquito species called Toxorhynchites. It doesn’t bite people or spread disease. Its larvae feed on the larvae of dengue mosquitoes, helping to reduce their numbers naturally.

During a dengue outbreak, drone technology could also be used. Drones can inspect water collections in places that are difficult for people to reach. They can also be used to spray larvicides in mosquito breeding sites.

However, we don’t believe that the Wolbachia project or the SIT is the best long-term solution for a country like Sri Lanka. Our tropical climate, with frequent rainfall, creates ideal conditions for mosquitoes to breed naturally and in large numbers. For that reason, as an association, we don’t strongly recommend relying on Wolbachia or the SIT as the main approach to controlling dengue.

What is the public's attitude towards dengue control and these measures?

People believe that the Government and the Local Authorities should solve all these problems. They expect the Government and the Local Authorities to take responsibility for every aspect of dengue control.

As a result, some people even expect Government officers to visit their homes and remove mosquito breeding sites found within their own premises. This is one of the reasons why people don’t pay enough attention to preventing dengue in their own surroundings.

The views and opinions expressed in this column are those of the interviewee, and do not necessarily reflect those of this publication