Dengue viruses belong to the family of Flaviviridae (RNA viruses) and the group of arboviruses. These are viruses transmitted by arthropods (such as mosquitoes, sand flies and ticks). There are four different serotypes (DEN-1, DEN-2, DEN-3 and DEN-4), which are distributed over various geographic regions. The virus occurs in more than 100 tropical and subtropical countries, but can also be found in other regions, such as the Canary Islands. The yellow-fever mosquito Aedes aegypti is one of the most frequent carriers of the pathogen. Besides dengue, it can also carry and transmit Chikungunya, Zika and yellow-fever viruses. Approximately 50 million people are infected with the dengue virus every year. Dengue is one of the most common viral diseases brought back by travellers to tropical regions.
The dengue virus is transmitted by mosquitoes; it cannot be transmitted from person to person. The virus is usually transmitted from mosquito to human during the day, in the early morning hours, or at dusk by a female Aedes aegypti mosquito that has previously bitten a person infected with dengue. The bite can cause the pathogens to enter the human body, where they then multiply further. Mosquitoes remain infectious throughout their lives and pass the pathogens on to their offspring. In climates with high temperatures, for example in the tropics, mosquitoes multiply particularly quickly. They need only very small accumulations of water as breeding places, and they can be found, for example, in discarded bottles, plastic containers or coconut shells.
The incubation period of dengue fever is three to 14 days. The illness can take various forms, ranging from mild flu-like symptoms such as fever, headaches and aching limbs to life-threatening conditions, including shortness of breath, circulatory collapse or vomiting of blood. The dangerous forms usually occur in conjunction with haemorrhagic dengue fever (DHF) and dengue shock syndrome (DSS). Depending on the degree of the disease, fever is often accompanied by severe fatigue, chills, gastrointestinal tract bleeding and occasional conjunctivitis. The fever usually lasts three to four days and is accompanied by a slowed pulse. Skin rashes, lymph node and spleen swelling, joint and muscle pain are other possible symptoms. A few days after the patients’ fever has gone down, their temperature may rise again, often accompanied by large patches of skin rash. Mild bleeding of the skin and mucous membranes is also possible. It can take several weeks for patients to recover from the infection. If the episode is weak, the disease lasts about three days, and the symptoms are significantly less pronounced.
According to the Protection against Infection Act, suspected disease, disease episodes and death from dengue fever with haemorrhagic activity must be reported. If diagnosed early and treated appropriately, the mortality rate can be reduced as low as 1%. The only way to prevent the spread or an epidemic of the dengue virus in countries with poor hygiene conditions is to systematically eliminate mosquitoes, for example, by using insecticides on a large scale.
The necessary spectrum of activity against dengueviruses is: limited virucidal