Overview
Mosquitoes, not person-to-person contact, transmit dengue: it spreads only through infected mosquitoes. There is rarely direct transmission between people, such as from mother to child during pregnancy. A previous dengue infection significantly increases the likelihood of a severe, life-threatening illness if exposed to a different strain. Treatment involves managing symptoms, rest, hydration, and paracetamol, with avoidance of ibuprofen or aspirin to prevent bleeding. Hospitalization might be necessary if severe symptoms develop.
What is dengue?
Dengue, also known as break-bone fever, is a viral disease transmitted to humans by infected mosquitoes. It predominantly occurs in tropical and subtropical zones rather than in temperate regions. Dengue fever results from bites by mosquitoes carrying one of four dengue virus types (DENV). These viruses are primarily found in tropical and subtropical areas, including Central and South America, Africa, parts of Asia, and the Pacific Islands.
Most people infected with dengue do not exhibit symptoms. When symptoms occur, they often include high fever, headache, body aches, nausea, and rash. The majority recover within one to two weeks. However, some cases progress to severe dengue, potentially needing hospitalization. Dengue is not contagious between people, except through vertical transmission from mother to child during pregnancy. Symptoms tend to be mild during the first infection; however, subsequent infections with a different DENV strain increase the risk of serious complications.
In severe cases, dengue can be deadly. You can reduce your risk of dengue by avoiding mosquito bites, especially during the daytime. Dengue is treated with pain management, as there is currently no specific cure for the disease.
What is the mode of transmission for dengue?
Transmission through the mosquito bite
The dengue virus is transmitted to humans through the bites of infected female Aedes aegypti mosquitoes. Other species within the Aedes genus can also serve as vectors, but their role is usually secondary to Aedes aegypti.
After feeding on a person infected with DENV, the virus replicates initially in the mosquito’s midgut and then spreads to other tissues, including the salivary glands. The time from virus ingestion to transmission to another host is known as the extrinsic incubation period (EIP). This period typically lasts around 8–12 days at temperatures between 25 °C and 28°C. Factors such as temperature variations, virus genotype, and initial viral load can influence the length of the EIP, affecting how soon a mosquito becomes infectious. Once it is capable of transmitting the virus, the mosquito can do so for the remainder of its life.
Human-to-mosquito transmission
Mosquitoes can acquire DENV by biting viremic people, including symptomatic dengue patients, pre-symptomatic individuals, and asymptomatic carriers without any signs of illness.
Transmission from humans to mosquitoes can occur as early as 2 days before symptoms begin and up to 2 days after the fever subsides.
The risk of mosquito infection increases with high viremia and high fever in the patient. Conversely, elevated levels of DENV-specific antibodies are associated with a lower risk of mosquito infection. Most individuals are viremic for approximately 4–5 days, although viremia can last up to 12 days.
After feeding on a person infected with DENV, the virus replicates initially in the mosquito’s midgut and then spreads to other tissues, including the salivary glands. The time from virus ingestion to transmission to another host is known as the extrinsic incubation period (EIP). This period typically lasts around 8–12 days at temperatures between 25 °C and 28°C. Factors such as temperature variations, virus genotype, and initial viral load can influence the length of the EIP, affecting how soon a mosquito becomes infectious. Once it is capable of transmitting the virus, the mosquito can do so for the remainder of its life.
Maternal transmission
DENV mainly spreads between humans through mosquito vectors. However, evidence also shows maternal transmission from a pregnant mother to her baby. Although vertical transmission rates are generally low and rare, they seem to vary depending on the timing of the infection during pregnancy. If a mother contracts dengue during pregnancy, the baby may be at risk of pre-term birth, low birthweight, and fetal distress.
Other methods of transmission
Rare cases of transmission through blood products, organ donation, and transfusions have been reported. Similarly, the virus has also been transmitted transovarially within mosquitoes.
What are the common symptoms of dengue?
Dengue often does not cause noticeable symptoms. When symptoms do appear, they usually start 4 to 10 days after a mosquito bite. Some symptoms resemble the flu and include:
- A very high temperature
- An intense headache
- Pain behind your eyes
- Muscle and joint pain
- Feeling ill or being unwell
- Swollen lymph nodes
- A blotchy rash consisting of flat or slightly raised spots – this can cover large areas of your body.
Severe dengue
While some individuals may develop a more severe form of dengue a few days after symptoms first appear, this is rare. You might begin to feel better as your fever decreases, but approximately 24 to 48 hours later, more serious symptoms could emerge.
Symptoms of severe dengue include:
- Severe abdominal pain
- Constantly getting sick
- Rapid breathing
- Bleeding gums or nose bleeding
- Extreme fatigue (tiredness)
- Being unable to relax or sit still (restlessness)
- Blood in your vomit or stool
Is dengue more deadly than malaria?
No. Although only a small percentage of those infected with either disease die from it, malaria is more lethal than dengue worldwide.
Approximately 400 million people worldwide get dengue each year, with around 40,000 fatalities, representing about 0.01%. Meanwhile, roughly 271 million people contract malaria annually, and about 627,000 of them die, which is approximately 0.3%.
Keep in mind that the severity of diseases can vary significantly across different regions. Children in Africa face a higher risk of dying from malaria, whereas dengue predominantly impacts people in Asia.
What causes dengue fever?
Dengue fever is caused by one of four dengue viruses. When a mosquito infected with the dengue virus bites you, the virus can enter your bloodstream and replicate. Both the virus and your immune system’s response can cause you to feel sick.
The virus can damage parts of your blood that form clots and provide structure to your blood vessels. This, along with certain chemicals produced by your immune system, can cause your blood to leak out of your vessels and lead to internal bleeding. This may result in life-threatening symptoms of severe dengue.
What are the risks of developing dengue?
A previous infection with DENV increases the risk of developing severe dengue in an individual.
- Urbanization, mainly when it occurs rapidly and without planning, is connected to dengue transmission. This is influenced by social and environmental factors such as denser populations, increased human mobility, access to dependable water sources, and water storage methods.
- Community risks for dengue are also influenced by community knowledge, attitudes, and practices related to the disease, since exposure is closely connected to behaviors like water storage, keeping plants, and protecting against mosquito bites. Regular vector surveillance and control measures, combined with targeted community engagement, greatly enhance resilience.
- Vectors are capable of adapting to different environments and climates. The interaction among the dengue virus, the host, and the environment is constantly changing. Consequently, disease risks may fluctuate and evolve in response to climate change in tropical and subtropical areas, particularly when urbanization and population movement are also increasing.
How is dengue diagnosed?
Laboratory and point-of-care diagnostics are crucial for controlling and managing dengue. However, global disparities in laboratory infrastructure pose significant challenges. Diagnostic algorithms, testing strategies, and methods vary depending on the resources available in each country’s laboratory system. The range of available tests, including nucleic acid amplification tests (NAATs), enzyme-linked immunosorbent assays (ELISAs), and rapid diagnostic tests (RDTs), widely varies in quality and effectiveness.
Laboratory testing for arboviruses during the first week of illness can be conducted using direct detection methods, such as virus isolation, molecular detection of nucleic acids, or antigen testing, including rapid diagnostic tests (RDTs).
What are the treatments for dengue?
Most people with dengue start to feel better after a few days. Although there is no specific treatment for dengue, you can relieve your symptoms by:
- Resting.
- Drinking plenty of fluids helps stay hydrated and maintain health.
- Taking paracetamol to reduce your fever and relieve any pain.
- Avoid using anti-inflammatory painkillers like ibuprofen or aspirin. These can lead to bleeding issues if you have dengue.
- If you have severe dengue, you will need to stay in the hospital until you recover.
There is no direct cure for dengue; however, pain management is possible with medications such as paracetamol (acetaminophen). It is advisable to avoid non-steroidal anti-inflammatory drugs like ibuprofen and aspirin, as they can raise the risk of bleeding.
What are effective ways to reduce my risk of dengue fever?
The best way to reduce your risk of dengue fever is to prevent mosquito bites. These steps include:
- Use EPA-registered insect repellents with 20% to 30% DEET or other proven ingredients to deter Aedes mosquitoes.
- Cover exposed skin when outdoors. Mosquitoes carrying dengue are more active during the day, particularly in the early morning and late afternoon.
- Remove standing water from containers like buckets, barrels, bird baths, and old tires that can hold rainwater. Also, fill low spots where water tends to collect.
- Prevent mosquitoes from entering your home by fixing screen holes and closing windows and doors whenever possible.
- Use mosquito netting during the night in regions where dengue is common.
- If you are pregnant, avoid traveling to regions where dengue fever is common, if feasible.
- Before you depart, check with the CDC for any ongoing illness outbreaks at your destination.
- Two vaccines are available, but only one is accessible in the U.S. They are recommended for children in regions where dengue is common. However, adults at higher risk for dengue may also be eligible.
What are the ways to prevent dengue?
If you are more likely to become seriously ill from dengue, it may be advisable to avoid traveling to countries where the infection is prevalent.
To lower your risk of dengue, protect yourself from mosquito bites by using:
- Clothing that covers most of your body;
- Mosquito nets, ideally treated with insect repellent, should be used when sleeping during the day.
- Window screens.
- Mosquito repellents that include DEET, Picaridin, or IR3535
- Coils and vaporizers.
Tips to prevent mosquitoes from breeding:
- Implement environmental management and modification practices to prevent mosquitoes from accessing egg-laying habitats.
- Dispose of solid waste correctly and eliminate artificial habitats that can collect water
- Weekly, cover, empty, and clean domestic water storage containers.
- Use suitable insecticides on outdoor water storage containers.
If you contract dengue, it is essential to:
- Rest
- Drink plenty of fluids.
- Use acetaminophen (paracetamol) to manage pain.
- Avoid NSAIDs such as ibuprofen and aspirin, as they raise the risk of bleeding.
- Watch for severe symptoms and contact your doctor immediately if you notice any.
When should you seek emergency help?
Symptoms of dengue can worsen rapidly, sometimes within just a few hours. Severe dengue is a medical emergency. About 1 in 20 people who get dengue will develop severe dengue. Severe dengue can lead to shock, internal bleeding, and death.
Warning signs are symptoms that indicate a person may be at an increased risk of severe dengue. If you or a family member exhibits any of these signs, please visit a local clinic or emergency room immediately.
- Abdominal pain or tenderness
- Vomiting at least 3 times within 24 hours
- Nose or gum bleeding
- Vomiting blood or blood in the stool
- Feeling very tired or uneasy
Conclusion:
Dengue fever, although rarely fatal, remains a significant public health issue in tropical and subtropical regions, caused each year by Aedes mosquitoes. Most people recover with rest, fluids, and paracetamol. Still, a second infection with a different virus strain significantly increases the risk of severe dengue, a serious and sometimes deadly condition characterized by bleeding, shock, and organ failure. Unlike malaria, which causes more deaths worldwide, dengue’s severity is worsened by urbanization, climate change, and inadequate mosquito control. There is no specific cure or widely available vaccine, making prevention essential. Eliminate standing water, use effective repellents, and avoid bites during the day to reduce the risk of mosquito bites. Recognizing warning signs early and seeking prompt medical care can save lives. Ultimately, controlling dengue requires ongoing community efforts, vigilant surveillance, and responsible individual actions, simple steps that can interrupt transmission cycles and protect vulnerable populations. If you feel sick or notice any signs of dengue, get medical advice immediately.
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Frequently Asked Questions
What symptoms and effects are common if you have dengue fever?
Most dengue fever cases exhibit either no symptoms or mild ones, but a more severe form can occasionally occur, necessitating prompt medical attention.
Are you able to survive dengue fever?
Most people recover from dengue fever without any long-term complications. If you experience symptoms of dengue, there is roughly a 1 in 20 chance that it could develop into severe dengue. However, with prompt treatment at a hospital or medical facility, the chances of recovery from severe dengue are over 99%.
Is it possible to contract dengue fever multiple times?
Since there are at least four different dengue virus strains, it is possible to get dengue multiple times. Usually, you develop immunity to the first strain you encounter, which prevents reinfection with that same strain. However, you can still contract any of the other three strains later. In fact, having dengue more than once increases your risk of severe illness. A previous infection with one strain can lead to antibody-dependent enhancement (ADE) during a future infection with a different strain. This process involves existing antibodies helping the new virus to replicate more effectively, which results in a stronger immune response and a higher risk of severe dengue.
How should I take care of myself if I have had dengue?
If you previously had dengue, your risk of severe illness increases if you encounter a different strain later. Consult your doctor about vaccination options and take additional precautions to prevent mosquito bites, particularly in regions where dengue is widespread.
Could dengue fever cause complications during my pregnancy?
If you are pregnant and contract dengue fever, it could lead to miscarriage, low birth weight, or premature delivery. Taking preventive measures against dengue during pregnancy is crucial to protect both your health and your baby’s development.
