Overview
Dengue is a viral infection spread by the bite of infected Aedes mosquitoes. These mosquitoes bite mainly during the day and breed in standing water in and around homes. In India, cases usually rise during and after the monsoon.
Many infections cause no symptoms or only a mild illness, and most people who fall ill recover in about a week. A small number develop severe dengue, in which fluid leaks out of the blood vessels and serious bleeding can occur. Severe dengue is a medical emergency.
Symptoms
Symptoms usually begin 4 to 10 days after the mosquito bite and last 2 to 7 days. They can include:
- High fever
- Severe headache
- Pain behind the eyes
- Muscle, joint and bone pain
- Nausea and vomiting
- Skin rash
- Swollen glands
The warning signs of severe dengue usually appear as the fever settles, often in the day or two after it comes down. This period needs the closest watch, even if the person seems to be improving.
When to see a doctor
See a doctor for a high fever during the dengue season, so that blood tests can be done and the illness monitored.
Infants, pregnant women and people who have had dengue before are at higher risk of severe illness.
Causes
Dengue is caused by the dengue virus, which has four closely related types. A mosquito picks up the virus when it bites an infected person and passes it on when it bites someone else. Dengue does not spread through touch, coughing or sharing food.
Recovery protects against that one type only, so a person can get dengue more than once.
Risk factors
- Living in or travelling to an area where dengue is common
- The monsoon and post-monsoon months
- Standing water near the home, in coolers, pots, tyres, tanks and open containers
- A previous dengue infection, which raises the risk of severe dengue
Complications
Severe dengue can cause:
- Leakage of fluid from the blood vessels, leading to dangerously low (shock)
- Fluid build-up in the chest or tummy, with difficulty breathing
- Serious bleeding
- Damage to organs such as the liver
With early recognition and proper hospital care, most people with severe dengue recover.
Prevention
- Emptying and cleaning coolers, flower pots and water containers every week
- Keeping water tanks covered, and clearing away items that collect rainwater
- Wearing clothes that cover the arms and legs
- Using mosquito repellent on exposed skin
- Using window screens, and mosquito nets when sleeping during the day
A person who has dengue should also be protected from mosquito bites, so that the virus is not passed on to others in the household.
Diagnosis
Dengue cannot be confirmed from symptoms alone, because other fevers such as malaria, typhoid and chikungunya can look similar. Blood tests can detect the virus or the body's antibodies to it.
Doctors also follow the blood count, including and the haematocrit (how concentrated the blood is), often with repeat tests, to pick up early signs of severe dengue.
Treatment
There is no specific antiviral medicine for dengue. Treatment supports the body while it clears the infection. For most people this means:
- Rest
- Plenty of fluids, such as water, (ORS), soups and fruit juice
- Paracetamol, the usual choice for fever and pain
People with warning signs or severe dengue are treated in hospital, with careful fluid replacement through a drip and close monitoring.
Myths and facts
Things people often say about this. Open each one to see what is true.
Myth“Papaya leaf juice, goat's milk or kiwi fruit cures dengue and brings the platelets back up.”What is true?
Fact
There is no medicine or home remedy that cures dengue. Care means rest, plenty of fluids and paracetamol for fever, along with watching closely for the warning signs and having the blood tests a doctor advises.
Myth“Dengue spreads from person to person, so the patient must be kept away from the family.”What is true?
Fact
Dengue does not spread directly from one person to another. It passes through the bite of an infected mosquito, so the family does not need to keep away. The patient should be protected from mosquito bites, so that mosquitoes do not carry the virus on to others.
Myth“Dengue mosquitoes bite at night, so a net at bedtime is enough.”What is true?
Fact
The mosquitoes that spread dengue bite mainly during the day. Covering the arms and legs, using repellent and clearing standing water around the home matter through the daytime too.
Myth“Once you have had dengue you cannot get it again.”What is true?
Fact
Dengue is caused by four related viruses, so it is possible to get it more than once. A later infection carries a higher risk of severe dengue, so a fever afterwards needs prompt medical attention.
Myth“The fever has come down, so the danger is over.”What is true?
Fact
The warning signs of severe dengue usually appear in the day or two after the fever settles. That is the period to watch most closely, even when the person seems to be getting better.
Questions to ask your doctor
Tick the ones you want answered and take them with you.
Common questions
Which medicine is safe for fever in dengue?
Paracetamol is the usual choice for fever and pain in dengue, taken as directed by a doctor or the label. Aspirin and ibuprofen-type painkillers (NSAIDs) should be avoided unless a doctor advises otherwise, because they can increase the risk of bleeding.
Can I get dengue a second time?
Yes. There are four types of dengue virus, and infection with one type protects against that type only. A second infection carries a higher risk of severe dengue, so it needs prompt medical attention.
Is there a vaccine for dengue?
Dengue vaccines have been approved in some countries for certain groups of people. Availability and eligibility differ from place to place, so a doctor can give current advice. Avoiding mosquito bites remains the main protection.
