Dengue fever (DF) (ICD-10-GM A97: dengue) is an infectious disease that occurs primarily in tropical and subtropical regions. It is caused by dengue viruses (DENV). The disease belongs to the viral hemorrhagic fever group. Dengue virus belongs to the flaviviruses (“flavivirosis”) and is divided into four different serotypes. The flavivirus family belongs to the list of arboviruses transmissible to humans by arthropods (arthropods). Humans represent the most relevant pathogen reservoir. Dengue fever is the most rapidly spreading arbovirus infection worldwide. Occurrence: The major endemic areas are South Asia (India, Sri Lanka), Southeast Asia (Brunei, Indonesia, Cambodia, Malaysia, East Timor, Philippines, Singapore, Thailand, Vietnam), southern China (Guangdong), Japan (Tokyo, in Yoyogi Park), the Pacific islands, New Guinea, Egypt, tropical Africa (eg. e.g., Kenya, Tanzania, Uganda, Ivory Coast, Senegal, Angola, Malawi), Brazil, Colombia, Venezuela, and the Caribbean. Epidemics first occurred in Nepal (up to mid-mountain elevations) in 2004. The first cases of autochthonous dengue fever have occurred in southern Europe (France, Croatia). Due to increased travel activity, there is an increase in infections imported to Germany. Seasonal accumulation of the disease: The risk of contracting dengue fever varies seasonally in the endemic areas. More infections occur during the rainy season (humid heat). The pathogen is transmitted (infection route) by day-active mosquitoes of the species Aedes (mainly Aedes aegypti/African tiger mosquito, also Aedes albopictus/Asian tiger mosquito). The yellow fever mosquito Aedes aegypti has the greatest transmission potential. Human-to-human transmission: No. The incubation period (time from infection to onset of disease) is usually 4-7 (max. 14) days. In dengue fever, the following courses can be distinguished:
- Classic dengue fever
- Mild atypical dengue fever, also called “five-day fever”.
- Dengue hemorrhagic fever (DHF) – especially in children and after secondary infection.
Incidence peak: dengue hemorrhagic fever mainly affects children under 15 years of age. The incidence (frequency of new cases) of dengue virus infection in travelers returning from endemic areas is 10.2 to 30 cases per 100,000 inhabitants per year. It is the most common imported infectious disease in Germany. The World Health Organization (WHO) estimates that there are approximately 400 million infections worldwide each year. The disease leaves a long-lasting, serotype-specific immunity. However, cross-immunity exists only for a short time. Course and prognosis: Most infected persons are asymptomatic or develop only a mild fever. The initial infection is flu-like, occasionally with exanthema (skin rashes), and resolves without complications after about 14 days. Some may develop sudden high fever (up to 40°C, 48-96 hours) after an average of 3-7 days, with a brief drop in fever on day 3-4 (often but not always biphasic), headache, lymphadenopathy (enlargement of lymph nodes), conjunctivitis (inflammation of the conjunctiva), photophobia (sensitivity to light), myalgia (muscle pain), and possibly a fine truncal exanthema (skin rash), maculopapular (blotchy and with papules, i.e. with vesicles) occur.In the case of a renewed infection with another serotype, more severe, sometimes lethal (fatal) courses usually occur. They are characterized by diffuse bleeding (dengue hemorrhagic fever) and/or circulatory failure (dengue shock syndrome). The severe course of secondary infection is attributed to infection-associated antibodies (ADEs). These courses are also observed mainly in children living in endemic areas. Approximately 6% of all symptomatic dengue virus infections in endemic areas are thought to lead to complications. The lethality (mortality in relation to the total number of people infected with the disease) is 6 to 30 % in the severe forms. Vaccination: A tetravalent vaccine with all four dengue serotypes was approved by the Commission for the Protection against Sanitary Risks (COFEPRIS) in Mexico in 2015 for dengue fever worldwide. It is also used in Brazil, Thailand and the Philippines. Depending on the study, protection rates range from 20 to 60 percent.Note: The vaccine manufacturer warns that people who have never contracted dengue should not get vaccinated against dengue. The reason is that vaccination produces infection-amplifying antibodies (ADEs) that make people who become infected with dengue viruses more likely to develop dengue hemorrhagic fever.The EU Commission allows the above-mentioned tetravalent vaccine for people between the ages of 9 and 45 who have already had a dengue infection and who reside in endemic areas. In Germany, notification is mandatory in cases of suspected illness, illness, and death from virus-induced hemorrhagic fever, as well as in cases of pathogen detection with acute infection, according to the Infection Protection Act (IfSG).
