Symptoms
Uncomplicated dengue fever manifests as sudden onset and high fever that lasts for about 2-7 days. It is accompanied by headache, pain behind the eyes, nausea, nodular-spotted rash, and muscle and joint pain. Other symptoms include flushing, itching, sensory disturbances, bleeding, and petechiae. A symptomless or mild course is also possible. The infection is usually benign and lasts several days. The incubation period is 4-10 days, so the disease occurs during or shortly after travel to affected areas. Dengue fever is particularly common in tropical and subtropical regions, including South America, the southern United States, Hawaii, Cuba, the Caribbean, Madagascar, Southeast Asia, Australia, and Africa. The number of people infected is estimated to be many millions per year. In many countries, patients are travelers returning home. Figure 1 shows regions at risk of infection and the prevalence of (WHO, 2008).
Complications
When the fever begins to decrease after a few days, the disease enters the critical phase. Now the permeability of blood vessels may increase sharply, leading to shock, organ damage, and circulatory collapse due to high fluid loss. Severe internal and external bleeding is also possible, which can have a fatal outcome. This course is now known as severe dengue (formerly dengue shock syndrome, dengue hemorrhagic fever). It should be specifically noted that shock is also possible without bleeding if a lot of plasma leaks from the vessels. Other possible complications include inflammation of the brain, and involvement of the heart and liver. Fatigue and depressive states may occur during the convalescence phase and last for several weeks.
Causes
The cause of the disease is infection with dengue virus, an enveloped RNA virus of the flavivirus family, which includes, for example, TBE virus and West Nile virus. Four serotypes are known (DENV-1, 2, 3, 4). Dengue viruses are transmitted from person to person by mosquitoes of the genus during the blood meal. The main vector is , the yellow fever mosquito, which is diurnal, reproduces well in urban areas, and often lives in and around dwellings. , the Asian tiger mosquito, is another known vector, which caused the 2001 outbreak in Hawaii.
Diagnosis
Diagnosis is made in medical treatment based on the clinical picture and laboratory methods. In many countries, dengue should be considered, especially in travelers returning with fever. Because of the relatively nonspecific clinical picture, numerous differential diagnoses are possible.
Prevention
It is recommended to take various measures for prevention of insect bites. It should be noted that mosquitoes, unlike the Anopheles mosquito, are also diurnal and can live indoors. Among the recommended measures are:
- Appropriate clothing
- Repellents, e.g. DEET, insecticides.
- Rules of conduct
Various measures are also being taken to try to stop the reproduction of mosquitoes. Since 2015, a vaccine is available in some countries (eg Dengvaxia).
Treatment
To date, no specific antiviral drug exists. Treatment is symptomatic. In a severe course, hospitalization is required. For fever and pain management, acetylsalicylic acid (aspirin) and other NSAIDs are recommended to be avoided because they have blood-thinning properties and may irritate mucous membranes. Paracetamol should be used instead. Depending on the course, adequate parenteral supplementation of fluids and electrolytes is important to counteract fluid loss from the permeable vessels.
