Dengue Cases Surge in Singapore: What You Need to Know About DENV-3

Introduction

Part I: What is DENV-3

• DENV-3, The New Dengue Strain that is Causing an Outbreak
• Other Factors that Contribute to the Spike in Dengue Cases in Singapore

Part II: What Happens When You Contract Dengue?

• What are the Symptoms of Dengue?
• Who is at Risk of Severe Dengue Infections?
• How is Dengue Treated?
• Prevention & Control: Is There a Vaccine to Dengue?

Part III: How Can You Help in the Fight Against Dengue

• What Makes You Attractive to Mosquitoes
• What Makes Your Home Attractive to Mosquitoes
• Practical Measures to Remove Mosquito Breeding Sites at Home
• How to Protect Your Household Against Mosquito Bites

Part IV: What Should You Expect from a Mosquito Control Company?

• What to Look for in a Pest Control Company
• What Happens in Mosquito Control
• Mosquito Control: Can You Only Do One?
• Mosquito Treatment: Cost & Frequency
• Why Mosquito Control is a Long-Term Commitment

The warm and humid weather, the occasional rainy nights, the rise of an unfamiliar dengue strain, and the recently concluded circuit breaker could all have resulted in the alarming surge of dengue cases in Singapore since the start of the year.

While the year kicked off with an average of 300-400 dengue cases a week, it is been a different story in May when the numbers have started to range between 500 and 800. In the first week of June, Singapore already saw over 10,000 cases and a fear that the number of weekly cases could exceed historical high unless immediate and collective action is taken.

In a previous post, we talked about how to prevent mosquitoes from breeding. Today, we will discuss in-depth the one reason why we are seeing more dengue cases lately: DENV-3.

Part I: What is DENV-3?

Dengue fever is a mosquito-borne disease that triggers symptoms that can develop into a potentially fatal complication called severe dengue. Four related viruses called DENV-1, DENV-2, DENV-3, and DENV-4 carried by infected mosquitoes are the main cause. Known as serotypes, they interact differently with our antibodies.

Historically, the DENV-1 and DENV-2 have been the dominant strains of dengue in Singapore. . In early January, the dengue virus serotype 3 (DENV-3) was detected in large dengue clusters in Singapore. In a statement, the NEA said that because the city has not seen a DENV-3 outbreak in the past three decades, the immunity for the virus is low. Therefore, communities are more susceptible to transmission of the virus.

DENV-3, The New Dengue Strain that is Causing an Outbreak

This circulating virus is the type most associated with diseases during primary infection, thus a fear the present outbreak could lead to severe cases that have a fatality rate of 2-5%.

While it happens, the previously dominant serotypes is predicted to return at some point in the future as dengue outbreaks generally occur every 2-4 years. Aside from the surfacing of a less common dengue strain, other factors could have contributed to the jump in cases.

Other Factors that Contribute to the Spike in Dengue Cases in Singapore

Warmer Weather

The warmer temperature in Singapore has accelerated the life cycle of the Aedes mosquito and shortened incubation period for the dengue virus. This situation is further exacerbated by the occasional rainfall that provides mosquitoes with favourable breeding conditions.

Traditional Dengue Peak Period

Singapore has already entered the traditional dengue peak season—from June to October. Ahead of that, the country has already recorded twice as many infections compared with the same period last year. This has led to authorities anticipating the worst dengue outbreak for the last seven years.

Circuit Breaker Period

During the two-month circuit breaker and post circuit breaker, which forced the majority of people to stay more at home to fight against COVID-19, authorities saw an increase in the presence of Aedes mosquito larvae in both homes and construction sites. This places workforce at risk as Aedes Mosquitoes are active in the daytime as we work.

Construction Sites & Indoor Gardens

With the temporary closure of construction sites, there is a twofold increase in the presence of Aedes mosquito larvae in these areas. It is not the only effect of the COVID-19 pandemic. Indoor gardening among homes further attracted mosquitos that seeks carbon dioxide from our exhalation.

Low Herd Immunity

As there has been a switch in dominant serotype, fewer people have been infected in the past thus the low levels of immunity and absence of vaccination against DENV-3 within a population. This results in lowered herd immunity and hence a higher rate of transmission, wherein children are at the highest risk of contracting the disease.

Urban Density

The drastic urbanisation in Singapore has created new habitats for mosquitoes to breed. The closer proximity between humans has also provided them with more blood meals in shorter distances. With their receptors and tracking ability, it is not a problem for mosquitoes to find their hosts.

Poor Mosquito Prevention

All these factors, accompanied by poor mosquito prevention, may have all led to the rise in dengue cases in Singapore. There is an urgent call for community efforts to keep our homes, gardens, and shared facilities free from mosquito breeding sites.

Some of the steps the National Environmental Agency (NEA) is taking to reduce the spread of dengue include laying traps for mosquitoes and releasing Wolbachia-infected male Aedes mosquitoes that would cause female mosquitoes to lay eggs that do not hatch.

However, these efforts would not be enough without everyone’s contribution. As homeowners, it is our responsibility to pay close attention to any mosquito breeding spots and the adult mosquitoes around you as well as to take the necessary steps to prevent and remove them.

Part II: What Happens When You Contract Dengue?

About 400 million dengue infections occur worldwide every year, with about 96 million resulting in illnesses. It is endemic in Singapore but is also prevalent in other Southeast Asian countries and tropical areas of the world and has been steadily increasing in Latin America and the Caribbean.

When a person infects with dengue, the virus will circulate in their blood for 2-7 days, at about the same time they develop a fever. After the first symptoms appear, which can be anywhere from 4-5 days or a maximum of 12 days, the infected person can transmit the virus through Aedes mosquitoes.

What are the Symptoms of Dengue?

The symptoms of dengue can vary differently—about 40-80% of all infections are asymptomatic while others develop mild to severe symptoms that can include a high fever of 40°C accompanied by two of the following symptoms:

These symptoms can last anywhere from 2-7 days following an incubation period of 4-10 days after the bite from a dengue-infected mosquito. Aside from these, severe dengue can potentially lead to fatal complications resulting from plasma leaking, fluid accumulation, severe bleeding, respiratory distress, or organ failure. These include:

These warning signs can occur 3-7 days after the first symptoms in conjunction with a decrease in temperature. Immediate medical care is crucial to avoid further complications and risks of death.

Who is at Risk of Severe Dengue Infections?

Multiple exposures to dengue can increase the risk of severe dengue. Other factors that could increase that risk which includes chronic diseases such as asthma, anaemia, and diabetes.

Also called dengue haemorrhagic fever (DHF), severe dengue is a syndrome that mostly affects children below 10 years old. It is generally manifested by abdominal pain, haemorrhage (bleeding), and/or circulatory collapse (shock).

How is Dengue Treated?

There is no specific treatment for dengue fever. Patients with mild to no symptoms should seek medical advice, rest and drink plenty of fluids to stay hydrated. They can take paracetamol to bring down fever and reduce muscle and joint pains. However, it is recommended to avoid aspirin and ibuprofen as they can increase the risk of bleeding. For severe dengue cases, immediate medical care is necessary.

Prevention & Control: Is There a Vaccine to Dengue?

In 2016, the Health Sciences Authority (HSA) approved the use of Dengvaxia in Singapore, a dengue vaccine. However, it is not part of the national immunisation program and administered only to people when the benefits outweigh the risks.

Therefore, the most effective method of mosquito control and preventing dengue transmission is to disrupt the life cycle of mosquitoes. These days, pest control is performed using an integrated pest management approach—a strategy that uses a combination of techniques such as biological control, habitat manipulation, lifestyle modification, and use of resistant varieties.

It focuses on long-term prevention, which means pesticides are used when necessary and in a manner that minimises risks to human health, non-target organisms and the environment, overall.

Part III: How Can You Help in the Fight Against Dengue

Dengue infections in Singapore are rising, even as the world is battling against the COVID-19 pandemic. According to the NEA, there has not been an outbreak of DENV-3 here in the past three decades and given the low herd immunity, it could lead to more severe cases.

What is worse is that both dengue and COVID-19 share similar symptoms such as muscle and body pain, fever, fatigue, and headache thus, making it difficult to differentiate between the two viral diseases.

Therefore, with the global focus and resources allocated to containing the COVID-19 virus, a valuable contribution you could make is to remain vigilant and keep yourself from adding to the numbers. One way to do so is to address anything that makes you and your home attractive to mosquitoes.

What Makes You Attractive to Mosquitoes

Mosquitoes are attracted to humans for several reasons. Besides attracted by the body heat and the carbon dioxide we exhale, other factors that can make them more attracted to one than the other includes:

• Sweat: Mosquitoes are attracted to sweat, which includes the scent of lactic acid. Therefore, when you exercise or perspire more, you are marginally more attractive to this pest.
• Blood Type: A study demonstrated that blood type O attracted more mosquitoes than other blood types A, B, and AB. However, it is only slightly more attractive than blood type A.
• Pregnancy: Some people produce more heat when they are pregnant, overweight, or exercising and these conditions make them more attractive to mosquitoes that are capable of picking up sensory information.
• Alcohol Drinking: There is an observation that participants who consumed a bottle of beer were more attractive to mosquitoes. It is believed to be the increase in body temperature and the alcohol content in sweat.
• Dark-Coloured Clothes: Mosquitoes have exceptionally poor eyesight but they will use silhouettes to zero in on their target hence their attraction to dark clothing

Read also: What are other factors that can make you attractive to mosquitoes.

What Makes Your Home Attractive to Mosquitoes

Mosquitoes naturally live and reproduce in certain areas, but there are just factors that can make an environment more preferable to breed. By keeping an eye out for the presence of these offenders in your property and removing them, you will be one-step closer to keeping mosquitoes at bay.

Stagnant Water

Mosquitoes require stagnant water to lay their eggs and anything from the water in a plant pot to a coin size or puddle can turn into a breeding ground if you are not careful.

What You Can Do:

Inspect for any stagnant water. Remove any junk that could hold in rainwater including old tyres, cans, and old buckets. For pools, ponds, or fountains, make sure that they are cleaned regularly and the filters are properly functioning.

Shade

Where do mosquitoes go during the day? As it turns out, they do not like the drying heat the sun gives off. So, to avoid that, they tend to seek shade under decks and porches as well as vegetation like bushes, grass, and low-hanging tree branches.

What You Can Do:

As mosquitoes thrive in dense and shaded areas provided by overgrown vegetation, make sure to keep them trimmed and neat. You should deprive them of areas where they have prime access for shelter and protection

Blocked Drains

Blocked drains and drainage systems are some other sources of stagnant water that could invite mosquitoes to hang around and lay eggs in your yard. If your drains are blocked, it is only a matter of time to create the perfect ground for mosquitoes.

What You Can Do:

You can avoid this situation by keeping your gutters clear and your drains maintained. Remove any debris such as leaves and branches on your drainage and make sure to have them repaired in case of blockage.

Open Doors & Windows

There are plenty of ways that mosquitoes can enter your home. Firstly, the most obvious of which is through your open doors and windows. Secondly, while you may have screens installed, there may have entries or may be left open at most time, rendering them useless in keeping mosquitoes away. Finally, The ingoing and outgoing home activities invite opportunities for mozzies to enter through those opening and closing.

What You Can Do:

The best practice is to install high-quality screens on your doors and keep them closed at all times. Check the mesh often to make sure no defects or rips where mosquitoes can squeeze through.

Gardens & Indoor Plants

Mosquitoes are not directly attracted to gardens, flowers, and plants but to the moisture, shade and carbon dioxide they may provide. Overwatering your plants have the tendency to create unwanted standing water that may serve as a breeding ground for mosquitoes.

What You Can Do:

Do not overwater your plants to avoid this risk. Furthermore, make sure that the water pan beneath stays dry as well because mosquitoes can breed in the littlest puddle of water available to them.

Practical Measures to Remove Mosquito Breeding Sites at Home

With all these in mind, the best way to get rid of mosquitoes and prevent the diseases through their bites is to make our homes as uninviting as possible to mosquitoes. Below are some of the ways:

• Clean drains and gutters to prevent blockage
• Remove old tyres and other items that can hold unnecessary water
• Discard all empty plastic bottles, wrappers, pots, containers, old toys, etc.
• Replace water in bird baths at least twice a week
• Clean out pet food and water dishes regularly
• Do not leave trashcan lids open and make sure water does not collect inside
• Fix water leaks and broken pipes that can create unnecessary moisture

How to Protect Yourself & Your Household against Mosquito Bites

In terms of protecting your family from mosquito bites, the best thing you can do is to make sure we are not attractive to mosquitoes and more importantly, keep them from getting into your home in the first place.

• Protect yourself against mosquitoes. Keep your temperature as cool as possible, wipe off your sweat, cover as much skin as possible—wear long sleeveless and pants, particularly when outdoors.
• Use insect sprays and repellents that contain DEET or picaridin, both inside and outside your home. There are plenty of mosquito repellents commercially available including mosquito coils, plug-in mosquito zappers, sprays, etc.
• Install screens on windows, doors, as well as on vents and other potential mosquito entries. The mesh screens should be small enough to keep mosquitoes out or if possible, other smaller biting insects as well—sand flies, for instance.
• In case you find or suspect that mosquito larvae are present in your property, call a reputable pest control specialist. A few precautions can lower your risk of attracting mosquitoes. If they have already invaded your property, it is time to call the professionals.

Part IV: What Should You Expect from a Mosquito Control Company?

The best pest control in Singapore is one that uses a combination of treatments to break the mosquito life cycle: prevent larvae from becoming adult mosquitoes that breed, bite, and potentially carry diseases.

What to Look for in a Pest Control Company

Regardless of how urgent your pest problem is, take time to look for a local pest control company that is reputable, knowledgeable, and ultimately one that meets your standards.

• License - Make sure that the company you are hiring is licensed and certified to conduct pest control. This service is not a job for everyone and thus requires ongoing training—a proof of this training is licensing and certifications.
• Experience - How long has the pest control company been in the field? How have they dealt with cases similar to yours? It will not matter if they have addressed rodent infestations successfully in the past if you have a mosquito problem.
• Presentation - While a presentable uniform and a company vehicle do not guarantee great pest control service, you should be wary of one who does not at least demonstrate such level of professionalism.
• Commitment - Pest control is a long-term and ongoing process and a good pest control company should be able to advise you on preventative measures to prevent reinfestation. It is also recommended if they have follow-up services to offer after the initial job has been carried out.
• Review - The best way to find out what a local pest control company can provide is to check out their customer reviews. Often, the most honest people to tell you about a business are the customers themselves.

Read also: Factors that make a good pest control service in Singapore.

At Rentokil Singapore, we offer one-time or monthly treatments to provide your family with protection against mosquitoes, the potential dengue virus they bring and other mosquito-borne diseases—Zika, West Nile Virus, yellow fever, Chikungunya, etc.

What Happens in Mosquito Control

Our treatment plan starts with a thorough inspection of your property by a team of highly-trained pest control specialists to identify mosquitoes and locate the places they breed in and around your home. Upon completion, we will outline a mosquito treatment plan that’s appropriate for you, which primarily covers two methods of mosquito control:

Fogging - Fogging is done mainly to control adult mosquitoes. It’s essential to fog at the right time which is when the mosquitoes are more active—at night, dusk, or dawn—to ensure more effective control. At Rentokil Singapore, we offer water-based fogging which is a more eco-friendly option than the traditional oil-based solution.

Larviciding - Larvae control is just as important as fogging as mosquitoes breed rapidly under favourable conditions. In larviciding, active ingredients are released in mosquito breeding sites to eliminate larvae. We handle these solutions with care and ensure that a thorough inspection is conducted before carrying out the treatment.

In addition to these traditional methods, we also engage a smart control solution that leverages on mosquito behaviour: In2Care Mosquito Trap.

This water-filled trap works by attracting adult female mosquitoes to lay their eggs. When they do, the eggs will not hatch as they are destructed by the larvicide in the water. Afterwards, they would fly out of the trap to continue searching for other places to lay their eggs in. However, they are now carrying the active ingredient thus, contaminating other breeding sites. The infected mosquitoes will then be killed approximately within 7-14 days.

Read more about this innovative mosquito trap here.

Mosquito Control: Can You Only Do One?

As is generally known, mosquitoes have four life stages: egg, larva, pupa, and adult. Perhaps less known is that every stage has a corresponding method of control.

While fogging is by far the most recognised form of mosquito control, the fact remains that eradicating mosquitoes in their every life stage is key to integrated pest control management. This is particularly true at a time when we require a robust approach to protecting public health against the dengue outbreak.

With all these said, exactly how often should you engage mosquito treatments? How much does mosquito control cost?

Mosquito Treatment: Cost & Frequency

How often should you schedule pest control?

As a pest control specialist in Singapore, we offer one-time, weekly, fortnightly, or monthly services. We always recommend having regular mosquito inspection to keep mosquitoes from gaining a foothold in your property. Depending on conditions and situations, frequency may differ. Firstly, an acute infestation that happens. Secondly, a heavy infestation that is not under control and require intensive treatments. Thirdly, pandemic or endemic crisis that requires step up programme such as dengue or Zika outbreak. Finally, is there is environmental changes such as nearby construction works that requires additional protection.

Concerning the pest control prices in Singapore, it is determined by several factors:

• Coverage Area
• Frequency
• Level of Treatment
• Use of Eco-Friendly Solutions
• Use of Additional Protection

Read more on the average cost of pest control in Singapore.

Why Mosquito Control is a Long-Term Commitment

Mosquito control is essential on a public level due to the vector potential that exists from mosquitoes in transmitting dengue, among other diseases, and causing an outbreak.

Given their ability to reproduce quickly, a long-term and regular commitment to mosquito control is essential to reduce their damage to our health, economy, and lifestyle.

With several years of industry experience and accreditations, working with us at Rentokil Singapore means that your pest control requirements are addressed with utmost commitment and professionalism.

Ready to get started? Get safe and targeted treatments today from Rentokil Singapore. Contact us at (65) 6347 8138.