There are four dengue viruses (DENV) that cause dengue fever. They are all spread by a species of mosquito known as Aedes aegypti, and more rarely by the Aedes albopictus mosquito.
The viruses jumped from monkeys to humans between 100 and 800 years ago, according to the CDC, but dengue remained a minor problem until the middle of the twentieth century.
Aedes aegypti originated in Africa, but nowadays it is found in tropical areas around the world, especially in and around areas of human population.
The virus is transmitted from an infected mosquito to a human. A mosquito bites a person who is infected with the dengue virus, and the virus is passed on when the mosquito bites someone else.
It it possible to have dengue fever more than once. A second infection carries a higher risk of developing a harsher form.
Symptoms vary depending on the severity of the disease.
Mild dengue fever
Symptoms can appear up to 7 days after being bitten by the mosquito that carries the virus.
Symptoms usually disappear after a week, and mild dengue rarely involves serious or fatal complications.
Dengue hemorrhagic fever
At first, symptoms of DHF may be mild, but they gradually worsen within a few days. As well as mild dengue symptoms, there may be signs of internal bleeding.
A person with Dengue hemorrhagic fever may experience:
Without prompt treatment, DHF can be fatal.
Dengue shock syndrome
DSS is a severe form of dengue. It can be fatal.
Apart from symptoms of mild dengue fever, the person may experience:
Without treatment, this can result in death.
The signs and symptoms of dengue fever are similar to some other diseases, such as typhoid fever and malaria. This can sometimes delay an accurate diagnosis.
The doctor will assess the symptoms and the person's medical and travel history, and they may order some blood tests to confirm the diagnosis.
Dengue is a virus, so there is no specific treatment or cure. However, intervention can help, depending on how severe the disease is.
For milder forms, treatment includes:
Preventing dehydration: A high fever and vomiting can dehydrate the body. The person should drink clean water, ideally bottled rather than tap water. Rehydration salts can also help replace fluids and minerals.
Painkillers, such as Tylenol or paracetamol: These can help lower fever and ease pain.
Non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin or ibuprofen, are not advised, as they can increase the risk of internal bleeding.
More severe forms of dengue fever may need:
Hospitalization will allow the individual to be properly monitored, in case symptoms get worse.
No vaccine can protect against dengue fever. Only avoiding mosquito bites can prevent it.
Anyone who lives in or travels to an at-risk area can use a number of ways to avoid being bitten.
Clothing: Reduce the amount of skin exposed by wearing long pants, long-sleeved shirts, and socks, tucking pant legs into shoes or socks, and wearing a hat.
Mosquito repellents: Use a repellent with at least 10 percent concentration of diethyltoluamide (DEET), or a higher concentration for longer lengths of exposure. Avoid using DEET on young children.
Mosquito traps and nets: Nets treated with insecticide are more effective, otherwise the mosquito can bite through the net if the person is standing next to it. The insecticide will kill mosquitoes and other insects, and it will repel insects from entering the room.
Door and window screens: Structural barriers, such as screens or netting, can keep mosquitos out.
Avoid scents: Heavily scented soaps and perfumes may attract mosquitos.
Camping gear: Treat clothes, shoes, and camping gear with permethrin, or purchase clothes that have been pretreated.
Timing: Try to avoid being outside at dawn, dusk, and early evening.
Stagnant water: The Aedes mosquito breeds in clean, stagnant water. Checking for and removing stagnant water can help reduce the risk.
To reduce the risk of mosquitoes breeding in stagnant water:
When camping or picnicking, choose an area that is away from still water.