Dengue Fever and Related Illnesses

Quick Overview

What is dengue fever?

Dengue fever is a mosquito-borne infection that causes a severe flu-like illness, and sometimes a potentially lethal complication called Dengue Hemorrhagic Fever (DHF). Dengue is caused by four closely related virus serotypes.

According to the World Health Organization, 2.5 billion people, i.e. two fifths of the world's population, are now at risk of dengue fever. The WHO estimates that there may be 50 million cases of dengue infection every year. Dengue fever is found in tropical and sub-tropical climates worldwide, mostly in urban and semi-urban areas. The disease is now endemic in over 100 countries in Africa, the Americas, the Eastern Mediterranean, southeast Asia and the Western Pacific, the latter two being the most seriously affected.

Chikungunya is an mosquito-borne virus that is transmitted to humans by virus-carrying Aedes mosquitoes. Symptoms are quite similar to the ones provoked by dengue fever; chikungunya manifests itself with an acute fever which lasts two to five days, followed by arthritic and joint pain. Chikungunya is rarely life-threatening, but joint pain may persist for weeks or even months. The virus is endemic in tropical Africa and Asia.

There is no preventive immunisation, and no specific treatment exists, but appropriate medical care may save the lives of patients. Without proper treatment, Dengue Hemorrhagic Fever fatality rates can exceed 20%.

Immunity

An attack of dengue fever creates a lifetime immunity to the particular serotype to which the patient was exposed, but there is no cross immunity. Any person infected once by chikungunya acquires durable immunity; however, joint pain may persist or reappear.

Risks for Travellers

Vectors

Both dengue fever and chikungunya are mosquito-borne illnesses. Dengue fever is transmitted to humans by the Aedes aegypti or more rarely the Aedes albopictus mosquito, which feed during the day. Chikungunya is transmitted to humans by the Aedes albopictus mosquito, which is active during the day, especially around sunrise and sunset.

High-risk populations

People living in or visiting areas where Aedes mosquitoes live, which includes most tropical urban areas of the world, are considered to be at risk. Usually, children, pregnant women, the elderly, and persons with weak immune systems may develop a more serious form of the disease. Concerning dengue fever, the disease is more likely to be severe or fatal in children under 15.

What are the consequences of dengue fever?

Incubation period

The first symptoms of dengue fever usually occur within 3 to 14 days after exposure. For chikungunya, the incubation period is usually 4 to 7 days.

Main symptoms of dengue fever

The clinical features of dengue fever vary according to the age of the patient. Infants and young children may have a fever with rash. Older children and adults may have either a mild fever or show classic signs which can be incapacitating, such as abrupt onset of higth fever, headaches, pain behind the eyes, nausea, muscle and joint pains, and rash.

Dengue Hemorrhagic Fever (DHF) is a potentially deadly complication that is characterized by high fever, often with enlargement of the liver, and in severe cases hemorrhaging. The illness often begins with a sudden rise in temperature accompanied by flu-like symptoms. The fever usually continues for two to seven days and can be as high as 41°C, possibly with convulsions and other complications.

Symptoms of chikungunya are quite similar to those of dengue fever, associated with severe and long-lasting joint pain.

Prevention and Treatment

Prevention

There is no vaccine for dengue fever or chikungunya. If you are travelling or living in areas where mosquito-borne diseases are endemic, you must take all precautions in order to avoid mosquito bites. Be aware that the risk of being bitten by mosquitoes indoors is reduced by the use of air conditioning and screened doors and windows. Travellers can avoid bites by properly applying mosquito repellents to exposed skin and should remember that clothing decreases the risk of being bitten.

Treatment

There is no specific treatment for dengue fever, DHF or chikungunya.

For DHF, appropriate medical care, provided by experienced physicians or nurses who understand the effects and progression of the disease, can decrease the mortality rate from over 20% to less than 1%.

Be aware that aspirin and non-steroidal anti-inflammatory drugs (ibuprofen) should be avoided as these drugs may worsen the tendency to bleed associated with some of these infections. Patients may be given preparations of paracetamol.