Dengue Fever (Breakbone Fever)
What Is Dengue Fever (Breakbone Fever)
Dengue fever (DF) is a mosquito-transmitted viral disease that is also known as “breakbone fever” because it causes severe joint and bone pain, among other symptoms. There are four types of dengue fever (dengue-1, -2, -3, -4), and the same viruses are responsible for dengue haemorrhagic fever (DHF) (see symptoms section). Dengue epidemics can be explosive and may affect a high percentage of the population, but fatalities in the absence of DHF are rare.
Between World War II and about 1970, severe dengue epidemics were recorded in only 9 tropical countries; now the disease occurs routinely in more than 100 countries. Dengue viruses cause more than 100 million infections per year around the world and result in more than 500,000 hospitalizations, most of them children. It causes fewer deaths—25,000 per year—than malaria, but its prolonged illness keeps people from work and affects both personal incomes and national economies.
How Do You Get Dengue Fever (Breakbone Fever)?
Dengue fever is transmitted by the bite of mosquitoes that are infected with the virus. In particular, a day-biting species of mosquito is the most common transmitter. This mosquito has increased biting activity for 2 hours after sunrise and several hours before sunset. The species is found in both rural and urban settings.
Susceptibility and Resistance
Everyone can get dengue fever, but children usually have a milder disease than adults. Recovery from infection with one type of dengue provides lifelong immunity against that type but does not provide protection against other types. Immunity against one type may actually exacerbate subsequent infections, as well as increase the likelihood of getting DHF during subsequent infections.
What Are The Symptoms?
Dengue fever is characterized by the sudden onset of fever lasting 3 to 5 days (rarely more than 7), intense headache, muscle and joint pain, pain behind the eye, loss of appetite, gastro-intestinal disturbances, and small fine rash appearing around the time the fever subsides. Dark-skinned people usually have no visible rash. Minor bleeding, such as gum bleeding or nosebleeds, may occur at any time during the fever. Adults with underlying conditions may experience heavy bleeding, such as gastro-intestinal haemorrhage in peptic ulcer cases or excessive menstrual bleeding. Prolonged fatigue and depression are sometimes associated with recovery from dengue infections.
Dengue haemorrhagic fever (DHF) is a serious and sometimes fatal complication of dengue infection. The patient’s condition may suddenly deteriorate due to the onset of increased vascular permeability (internal seepage of blood from the blood vessels into the tissues) with hypotension (loss of blood pressure) and shock. The patient may experience marked weakness, restlessness, facial pallor, severe abdominal pain, and cool extremities. The death rate can be as high as 40 to 50 percent in untreated cases; however, adequate treatment and fluid replacement can reduce the death rate to 1 to 2 percent.
Personal preventative measures include protecting against mosquito bites by using screening and bed nets, protective clothing, and insect repellents. If possible, stay in air conditioned or well-screened houses and avoid being outdoors at dawn, dusk, and early evening when mosquitoes are often biting.
There is no specific treatment for dengue fever. The only treatment available includes supportive measures to relieve symptoms, such as controlling the fever and adequate fluid intake.
Where Does It Commonly Occur?
The worldwide distribution of dengue fever virus (DF) closely follows the distribution of the two mosquito types that transmit the disease. All four dengue virus types are now widespread in most countries in the tropics.
In Asia, dengue viruses are highly prevalent in southern China and Hainan, Vietnam, Laos, Cambodia (Kampuchea), Thailand, Myanmar (Burma), India, Pakistan, Sri Lanka, Indonesia, the Philippines, Malaysia and Singapore, and with lower occurrence in Papua New Guinea, India, Bangladesh, Nepal, Taiwan and much of the Pacific. Some of the dengue virus types have also circulated in Queensland, northern Australia, since 1981.
Dengue fever is also prevalent in Africa. In recent years, outbreaks have occurred in large areas of West Africa, on the east coast of Africa from Mozambique to Ethiopia, and on offshore islands such as the Seychelles and Comoros, with a small number of dengue fever and dengue haemorrhagic fever-like cases reported from Saudi Arabia.
In the Americas, successive introduction and circulation of all four types of the dengue virus in the Caribbean and Central and South America have occurred since 1977. More recently small outbreaks have occurred in Texas, Key West and southern Florida. As of the late 1990s, two or more dengue viruses are periodically common in Mexico, all of the Caribbean, and Central and South America. Epidemics may occur wherever infected mosquitoes are present, whether in urban or rural areas.