Dengue fever

Dengue fever is a mosquito-borne disease caused by the dengue virus. It is common in tropical and subtropical areas. Most people who get dengue fever either have no symptoms or only mild ones. Symptoms usually start 3 to 14 days after being infected and can include a high fever, headache, vomiting, muscle and joint pains, and a skin rash. People usually feel better in two to seven days.

In a small number of cases, dengue can become severe. This can cause bleeding, low levels of blood cells called blood platelets, and problems with blood pressure. Dengue is spread by female mosquitoes of the Aedes genus, especially Aedes aegypti.

There is no special medicine to cure dengue fever. Treatment focuses on helping with pain and keeping people hydrated. Getting enough fluids is very important, especially in severe cases. There are vaccines to help prevent dengue, but they work best in people who have already had the disease once.

Dengue fever has been known since 1779 and is now found in over one hundred countries. Because of climate change, it is moving into new areas, including parts of Europe and the southern United States. In 2023, more than 5 million infections and over 5,000 deaths were reported, though many more cases likely went unnoticed.

Signs and symptoms

Most people who get dengue fever don't feel sick, or they only have mild symptoms like a simple fever. About 80% of cases are like this. A smaller number, about 5%, can get very sick, and for a few, it can be dangerous.

Symptoms usually start showing up 3 to 14 days after being bitten by a mosquito that carries the virus. Common signs of mild dengue include sudden fever, headaches, pain in muscles and joints, feeling sick, throwing up, swollen glands, and a rash. If it gets worse, symptoms can include severe stomach pain, throwing up a lot, breathing fast, bleeding from the gums or nose, feeling very tired, and pale skin.

The illness usually has three stages: a fever stage, a critical stage, and a recovery stage. The fever stage lasts a few days and includes high fever, pain, and headaches. Most people start to get better in about a week. But in some cases, symptoms can suddenly get much worse and become very dangerous. This is called severe dengue and can cause serious problems like internal bleeding and damage to organs. Signs to watch for include severe stomach pain, trouble breathing, and bleeding from the nose or gums.

Recovery usually takes a few more days, and people often feel much better quickly. It's important to watch for warning signs and get help if needed.

Cause

Virology

Main article: Dengue virus

Dengue virus is a tiny germ carried by mosquitoes. It belongs to a group of germs that also cause yellow fever, West Nile fever, and Zika. The virus has four different types, and each type can make people sick in similar ways.

Transmission

The dengue virus is spread mainly by certain mosquitoes, especially ones called Aedes aegypti. These mosquitoes like to bite people at dawn or dusk but can bite at any time. When an infected mosquito bites a person, it can pass the virus to them. The virus can also spread through infected blood or during organ donations, though this is less common.

Risk factors

Getting bitten by an infected mosquito is the main way people catch dengue. This is more likely in places where the disease is common, especially where there are many people, poor cleanliness, and standing water where mosquitoes breed. Wearing long clothes, using mosquito nets, and applying insect repellent can help prevent bites.

Having certain health conditions like asthma or diabetes can make dengue worse. Getting infected with one type of the virus gives protection from that type, but not others. Getting infected with a different type later can increase the chance of severe illness.

Mechanism of infection

When an infected mosquito bites a person, the virus enters the skin and infects cells there. It then spreads to other parts of the body through the immune system. This can cause fever, pain, and other symptoms. In severe cases, the virus can affect many body parts, leading to low blood pressure and bleeding problems.

Diagnosis

Mild cases of dengue fever can look like other common diseases such as Influenza, measles, chikungunya, and zika. These diseases are often found in the same warm areas of the world and can even happen at the same time. If someone gets a fever after visiting tropical or subtropics areas, doctors might think about dengue fever.

There are some warning signs that the illness could become serious, like stomach pain, throwing up a lot, swelling, bleeding, feeling very tired, and an enlarged liver. These signs can also be seen in other diseases like malaria. Blood tests can help confirm if someone has dengue fever. Special tests can find parts of the virus during the early days of the illness, and later tests can detect antibodies in the blood.

Prevention

Mosquito control

Main article: Mosquito control

The biggest danger from dengue fever comes from mosquito bites. This risk is highest in places where the disease is common, especially where many people live close together and where standing water collects, providing a place for mosquitoes to breed. You can lower your risk by wearing long sleeves and pants, using nets when you rest, and applying insect repellent like DEET. Treating clothes, nets, and tents with a special liquid called permethrin can also help.

Keeping your home safe includes using screens on doors and windows, using air conditioning, and regularly cleaning out any containers that can hold water, like buckets or flower pots.

The best way to control the main dengue mosquito is to remove places where it can lay eggs. This means getting rid of open water sources or, if that’s not possible, adding special substances to stop the mosquitoes from growing. Community efforts, like clearing gutters and drains and keeping yards free of standing water, are very important.

Vaccine

Main article: Dengue vaccine

As of March 2026, there are two vaccines that help protect against dengue. Dengvaxia became available in 2015 and works for people aged 6 to 45 years. It needs to be given three times, six months apart. However, it should only be given to people who have already had dengue before.

Qdenga was approved in late 2022 and can be given to children as young as four years old, even if they have never had dengue before. It is given in two doses, three months apart.

In 2025 and 2026, health programs in big cities were expanded to give more people the dengue vaccine, based on early success in reducing serious cases of the disease.

Treatment

As of July 2024, there is no special medicine to treat dengue fever.

Most people with dengue fever feel only a little sick, and they get better in a few days without any special treatment. For mild fever or pain, acetaminophen (also called Tylenol) can be used. However, medicines like aspirin, ibuprofen (such as Advil or Motrin IB), and naproxen sodium (like Aleve) should not be used because they can make bleeding more likely.

For people who are a bit sicker but can still drink, go to the bathroom, and do not show warning signs, careful monitoring at home is advised. Supportive care, such as taking pain medicine, drinking fluids, and resting in bed, is recommended.

Severe dengue is a serious condition that needs immediate care at a hospital, sometimes in intensive care. Warning signs include dehydration, low platelets, and rising hematocrit. Treatment may involve fluids given through a vein and, if needed, transfusions with platelets or plasma.

Prognosis

Most people with dengue get better and don't have any lasting issues. Severe cases can be serious, but with proper care, the chances of serious problems are very low. Younger children and older adults may face more challenges if they get very sick from dengue.

Epidemiology

See also: Dengue fever outbreaks

Dengue fever is found in over 100 countries, and cases appear on every continent except Antarctica. Areas like the Americas, Southeast Asia, and the Western Pacific are affected the most. It is hard to know exactly how many people get sick because many cases are mild and not noticed. About 3.9 billion people live in areas where they can catch dengue. Each year, around 390 million people get infected, and some of these cases can become severe.

Dengue is mostly found in cities where a special type of mosquito, called Aedes aegypti, lives close to people and breeds in small pools of water. These mosquitoes prefer humans and like to live near homes. In rural areas, other mosquitoes can also spread the disease. The number of dengue cases has gone up a lot in recent years because these mosquitoes are spreading to new places due to growth in cities, more people, and warmer temperatures.

Climate change is helping dengue spread. Warmer weather makes mosquitoes live faster and breed more, and it creates more places for them to lay eggs. This change lets dengue appear in new areas, including places that used to be too cold. To stop dengue, it is important to remove standing water, improve city planning, and work together across different areas like health and the environment.

History

The first known mention of a sickness that might have been dengue fever appeared in ancient China during the Jin dynasty, describing a "water poison" linked to flying insects.

The main mosquito that spreads dengue spread from Africa between the 1500s and 1800s, partly because of trade and movement of people. There were reports of illnesses similar to dengue long ago in places like Jakarta, Cairo, and Philadelphia. Dengue likely stayed present in many warm, busy cities during the 1800s and early 1900s, even if big outbreaks were rare. The disease spread more widely during and after World War II, partly because of war disruptions and growing cities in Southeast Asia. Severe forms of the disease were first noted in the Philippines in 1953 and later became a leading cause of illness in children across that region.

In Central and South America, efforts to stop the disease-winning mosquitoes stopped in the 1970s, and dengue returned in the 1980s, causing many outbreaks. Today, dengue continues to affect more people worldwide as the mosquitoes that carry it spread to new areas, partly because of climate change and urban growth.

Etymology

The word "dengue" entered English from West Indian Spanish, which took it from an East African word meaning "cramp-like seizure." Early names for the disease included "break-bone fever" because of the severe muscle and joint pains it causes. The term "dengue fever" became common use after 1828.

Research directions

Researchers are studying how dengue fever develops in people and learning more about the mosquitoes that spread it. They are also working on better ways to diagnose the disease so doctors can treat it faster. Scientists are trying to create medicines that target specific parts of the virus.

Besides the vaccines that are already available, many new vaccine options are being tested. Scientists are also creating special lab tools, like Organ Chips and Lab-on-Chips, to better understand how dengue affects the body.

Society and culture

When there is an outbreak of dengue fever, more blood is needed, but fewer people can donate blood because they might have the virus. People who have had dengue cannot donate blood for at least six months.

Each year on June 15, many countries celebrate International Anti-Dengue Day. This idea started in 2010, with the first event in Jakarta, Indonesia, in 2011. Other events took place in Yangon, Myanmar, in 2012, and in Vietnam in 2013. The goal is to teach people about dengue and to get help to stop the disease. The Philippines has a dengue awareness month every June since 1998. India also marks a National Dengue Day each year on May 16.

Persistent symptoms from dengue can make life harder for patients, lower their ability to work, and increase costs for healthcare. One study found that dengue cost the world about US$8.9 billion in 2013.