Dengue Virus: Infection, Transmission & Diseases

Dengue virus causes a disease that brings severe muscle and bone pain and fever lasting several days. This dengue fever is transmitted by various mosquitoes.

What is dengue virus?

Widespread infection is mainly in tropical and subtropical countries. Dengue viruses belong to the flavivirus genus and are divided into four subgroups (DENV-1 to DENV-4). They are usually transmitted to mammals and birds by ticks and mosquitoes (arthropods). The generic name is derived from yellow fever (Latin “flavus” – yellow). In addition to dengue fever, these viruses also cause encephalitis and meningoencephalitis as well as West Nile fever. In addition, humans can contract dengue hemorrhagic fever (dengue shock syndrome), which is life-threatening and occurs mainly in children. Fortunately, however, is not often encountered.

Occurrence, distribution, and characteristics

The vectors (vectors) of dengue fever are insects such as the yellow fever mosquito, the Asian tiger mosquito, and the Polynesian tiger mosquito. It has been observed that especially the Asian tiger mosquito has extended its range to Europe for several years. According to recent findings, some other mosquito species may also be responsible for spreading dengue fever. The viruses are passed on by the bite of infected female mosquitoes. Uninfected mosquitoes, in turn, obtain the virus by sucking blood from already infected humans. Male mosquitoes have no role in these processes because they are not bloodsuckers. Dengue virus is spread by mosquitoes primarily in urban areas, usually near human shelters. The insects prefer to set their bites in the early morning and later evening. Their eggs are very resistant and are laid in the smallest water deposits. If a female mosquito is infected with dengue virus, she passes the pathogen directly to her offspring. Dengue fever is nowadays the viral disease most frequently transmitted by mosquitoes. The distribution area of the infection extends from Southeast Asia through India, Pakistan and Afghanistan to South and Central America, Africa and Australia. The minimum temperature for mosquito survival is about 10°C. However, due to global warming, the spread of the mosquito population is facilitated. The first cases of dengue fever have already been recorded in southern France and Croatia. On the Portuguese Atlantic island of Madeira, several hundred people contracted dengue fever in 2012.

Diseases and complaints

The illness occurs a few days after infection and results in sudden, high fever of up to 40°C. The usual muscle and bone pain is often joined by joint pain and headache. The severe symptoms lead to complications when standing or walking. In addition, there is loss of appetite, diarrhea, vomiting, coughing, nausea, constipation, and sometimes swelling of the lymph nodes. At the beginning of the outbreak, the entire skin often turns reddish. The fever drops somewhat after two to three days, but then may rise again. The nose and gums may occasionally bleed. After about a week, however, all abnormalities subside in a normal course without leaving any consequential damage. Some feeling of exhaustion may remain for a few weeks. However, the severe course, dengue hemorrhagic fever, may involve severe bleeding on the skin and in the gastrointestinal tract. It is not uncommon for vomiting blood and bloody stools to follow. Bleeding in the brain or lungs is even possible. The number of blood platelets (thrombocytes) may drop abruptly. Without physician intervention, the loss of fluid and blood often leads to life-threatening shock with circulatory failure. However, these symptoms are seen in only 1 – 5 % percent of all cases. According to the World Health Organization (WHO), up to 100 million people worldwide contract dengue fever every year. In Germany, only about 300 to 600 cases occur per year. Since dengue fever can be imported from foreign travel, optimal mosquito protection is the most important preventive measure. Arms and legs should always be covered with clothing. A mosquito spray can be applied to the skin as well as clothing. In bed, a very tight mosquito net and reliable window protection are recommended. There is no specific therapeutic strategy against dengue fever.A vaccine has also not yet been introduced. Because of the severe physical pain, dengue fever is sometimes also referred to as break-bone fever. In Germany, the infectious disease is notifiable so that an epidemic can be prevented. However, direct transmission from person to person can be ruled out. Anyone affected is advised to drink plenty of fluids and to report any abnormal bleeding to their doctor immediately. In addition, medications such as aspirin or ibuprofen should be avoided, as they increase the tendency to bleed. With good medical control, dengue fever is benign and does not cause significant damage. Before any trip to high-risk areas, however, it can’t hurt to learn about current dangers and safe protection.