Dengue fever

introduction

Dengue fever belongs to the tropical infectious diseases and causes 50-100 million cases of illness worldwide every year, and the number is rising. Certain Mosquito species transmit the pathogen, the dengue virus, to humans.

Depending on e.g. Age and health can affect the Symptoms the disease can be very different. The spectrum ranges from mild, flu-like courses to serious, feverish episodes with involvement of several organ systems. The most feared complication is the "fatal" in approx. 30% of casesDengue shock syndrome"(DSS).

Unfortunately, it currently exists neither a vaccination, another causal therapy against dengue fever. Prophylactic is therefore primarily the Protection against insect bites in the foreground.

Sick people can only be treated symptomatically, e.g. with Fliquid and protein administration.

transmission

The disease is caused by so-called "Vectors“Transferred: Here an organism transports the pathogen from host to host. The most important vectors of the dengue virus are the females of the Egyptian and Asian tiger mosquitoes (lat .: Stegomyia aegypti and Stegomyia albopticus). It is usually easy to recognize due to its striking, black and white patterned drawing!

With one prick, they can easily deliver the virus into the human bloodstream. Conversely, non-infected mosquitoes can ingest the pathogen from a sick person.

Since the diurnal insects multiply in stagnant water, extinction is extremely difficult. Even small puddles or water-filled containers (e.g. bottles) are sufficient. The rate of spread is particularly high in densely populated residential areas.

In contrast to other tropical infectious diseases such as Ebola, the person-to-person transmission of dengue fever is an absolute rarity! It is therefore not necessary to isolate the affected patient.

They find out, which symptoms you can use to recognize a bite from the Asian tiger mosquito.

distribution

Dengue is in more than 100 countries subtropical and tropical Asia, in Australia, Central- and South America, Oceania, Africa and in the Caribbean spread. Due to the increasing spread of the tiger mosquito, however, the disease can also be expected to spread in Europe in the future. There was already a major outbreak on the in 2012 Portuguese island of Madeira. Also in South France and Croatia cases have been reported.

Because of the increasing long-distance tourism, the number of "imported“Dengue cases: While 60 cases were reported in Germany in 2001, in October 2010 there were already 387 cases. This was particularly popular among travelers returning home India and South East Asia (Thailand, Vietnam, Philippines, Malaysia and Indonesia) affected.

Symptoms

Basically you can choose between three gradient forms distinguish the disease: That flu-like dengue fever (DF), the severe dengue hemorrhagic fever (DHS) and the dangerous Dengue shock syndrome (DSS). Age, nutritional status, state of health, gender and probably genetic predisposition of the patient also seem to play an important role in the severity of the disease.

If those affected are also under a Second infection suffer from the virus repeatedly, is one of the two severe manifestations of dengue fever (DHS and DSS) all the more likely.

Small children often have a high fever lasting 1-5 days at the beginning.

Only in older children and adults can the typical, bimodal fever Observe: After an initial, short-lasting fever with sudden normalization, a second rise in fever follows, which usually lasts longer. Many sufferers complain of headaches, especially in the forehead and eye area, accompanied by nausea and abdominal pain.

In the vernacular, dengue fever is often called "Bone breaker fever“Referred to as the sick under extreme painful move- and Body aches Suffer. Sometimes a knottier, spottier Rash can be observed.

In the first few weeks of the disease, there may be swelling of the lymph nodes all over the body, as well Paresthesia (lat .: Dysesthesia) come.

Heavier gradients lead to a Coagulation disorderso that nasal, skin- and Mucosal bleeding occur. If the bleeding is heavy, there may be a lack of volume in the blood vessels dangerous Cause shock. In this case one speaks of the life-threatening dengue shock syndrome (DSS).

The preliminary stage, that Dengue hemorrhagic fever (DHF), occurs when the following 4 criteria are met:

1. fever
2. Platelet deficiency (lat .: Thrombocytopenia)
3. Destruction of red blood cells (lat .: hemolysis)
4. Loss of fluid through the Capillary, also "Capillary leak" called

root cause

Dengue viruses belong to the family of Flaviviruses, similar to e.g. the causative agents of yellow fever, TBE or Japanese Encephalitis (Please also read: Vaccination against Japanese encephalitis).

A total of four different types of dengue virus (DEN 1-4) infect humans, with type DEN 2 having the highest disease value.

Unfortunately, the exact mechanism of the disease has not yet been clarified. Put simply, the viruses penetrate human cells and use their mechanisms to spread further in the organism. Our body then releases various messenger substances, enzymes, inflammation mediators and activators, which are then released 3-12 days after infection (incubation period) lead to the classic dengue fever.

Structures of the human immune system, the immunoglobulins or antibodies, seem to play an important role, particularly in the more severe manifestations, DHS and DSS.

You can find a detailed overview of all tropical diseases under the article: Overview page on tropical diseases

Diagnosis

Fever after being in the tropics is not a rare symptom and can be found in around 20% of all those returning sick. Unfortunately, almost express themselves all typical tropical diseases have a more or less pronounced fever, so that a detailed medical examination and questioning is required when diagnosing dengue fever.

E.g. detailed travel descriptions, schedule the complaints or similar symptoms in fellow travelers provide valuable information. Often can over Insect bites or Freshwater contact to be reported.

In addition to questioning the patient (anamnese), the attending physician thoroughly examines sick patients. For example, a Enlargement of the liver and or spleen (lat .: Hepato,- Splenomegaly) and the very poor general condition be trend-setting. Unfortunately, most complaints, such as Skin rash or swelling of the lymph nodes, also with other tropical diseases, so that they are often considered to be too unspecific.

In order to make an exact diagnosis, modern laboratory medicine is indispensable today. With a simple blood sample, various methods can be used that are suitable for the detection of dengue fever (Virus isolation, antigen and antibody detection, PCR).

therapy

Currently still exists no causal therapy of dengue fever, so that treatment must be purely symptomatic. In this way, the complaints of those affected can be alleviated, however, a cure cannot yet be achieved through medical measures become.

Since the circulatory function is to be regarded as unstable in many patients, treatment is usually carried out in hospital. There you can use intravenous access („drip") either Volume and protein infusions, as well as Fever reducers administered.

Strict bed rest and monitoring of the so-called "Vital signs", Namely heart and Respiratory rate, Blood pressure and Body temperature, are also part of the therapy. Medicines can also be used to relieve pain. It is important to ensure that no acetylsalicylic acid-containing preparations such as aspirin, as they "blood thinning“Have properties and that Risk of bleeding would further strengthen.

prophylaxis

First and foremost, that includes prophylaxis the Protection against insect bites. Both Protective clothing as well as so-called "Repellants". Light-colored, strong and long-sleeved clothing can protect the skin. Since the tiger mosquito can even bite through certain clothing, one should impregnation should also be considered. It is important to note that the vectors of dengue fever, different from the malaria transmitting Anopheles mosquito, diurnal are! Still one should Mosquito net at night be attached.

In addition to the protective clothing mentioned, the use of Repellents or. Insect repellants. Applied to vulnerable, exposed skin areas such as arms, legs and face, they offer relatively safe protection against insect bites. The most common insect repellants include e.g. Diethyltoluamide or Icaridin.

In pregnant women and Toddlers The products may only be able to with restrictions be used. Simultaneous use of a suncream is possible - however, the sunscreen must be used first and then the insect repellent spray.

Unfortunately, it still exists today no effective vaccination against dengue fever. As a possible vaccine would have to work against all four types of the virus, development is extremely difficult. Because after one survived infection becomes the patient only immune against the type of virus that infected him.

Currently there are several promising vaccines in the testing phase. However, a breakthrough is not expected in the near future.

forecast

Overall, dengue has one favorable forecast. Through supportive measures like Hydration and Lowering of fever, most cases can be cured in western countries. With heavy variants, especially the Dengue shock syndrome, is the Mortality around 30% but significantly higher. In countries without adequate medical care, however, milder forms such as dengue hemorrhagic fever (DHF) lead to death.

Decisive factors such as Age and State of health prior to infection, also determine the individual prognosis.