Dengue fever

Quick Overview

• What is dengue fever? A virus infection transmitted by the Aedes mosquito.

• Occurrence: mainly in tropical and subtropical countries, but also (occasionally) in Europe.

• symptoms: sometimes no, otherwise typically flu-like symptoms (such as fever, headache and body aches); in complications u. a. Blood clotting disorders, vomiting, drop in blood pressure, restlessness, drowsiness

• Treatment: symptomatic with fluid intake and pain and fever; in case of complications inpatient intensive care

• Forecast: usually benign course, in children and / or secondary infections increased risk of complications
• Prevention: Avoid mosquito bites (long clothes, mosquito net, mosquito repellent etc.)

Dengue fever: infection pathways and occurrence

Dengue fever is caused by the dengue virus, which occurs in four different variants (serotypes): DENV 1-4. All are from the Aedes mosquito transmitted: most commonly by the yellow fever or tiger mosquito (Aedes aegypti or Stegomyia aegytpi), sometimes by the Asian tiger mosquito (Aedes or Stegomyia albopictus).

These mosquitoes are found mainly in urban environments or in human populated areas. They prefer to lay their eggs near water (bottles, rain barrels, buckets, etc.). If females are infected, they can transmit the virus directly to the brood. The female mosquitoes are also the ones who pass on the disease to humans. People can not be infected with each other – they serve the mosquito only as a reservoir, so as a habitat, from where they carry the virus.

Unlike flu viruses, dengue viruses are not found in the human mucosa or saliva. Dengue fever can not be transmitted by sneezing, coughing or kissing.

Occurrence of dengue fever

In Germany, the Aedes mosquito is not native because it requires at least ten degrees Celsius for wintering. At most, in the warm months, it can penetrate far into otherwise Aedes mosquito-free regions. However, global warming will allow mosquitoes to expand their habitat, experts say.

So far, if someone in this country gets the dengue fever, he has generally been infected with a stay in tropical-subtropical foreign countries. For example, in 2017, there were five cases of dengue fever in Germany after stays in Egypt.

As Germans like to travel more and more, the number of dengue fever cases that have been introduced has risen sharply in recent years. In 2015, more than 700 people in Germany were treated for dengue fever. According to the data of the infection protection law (IfSG), the most common infection countries were:

• Thailand: 29 percent
• Indonesia: 16 percent
• Brazil: 7 percent
• India: 6 percent
• Cuba, Philippines, Vietnam, Malaysia, Costa Rica, Cambodia: 3 percent each
• Others: 24 percent

Overall, dengue fever occurs in more than 100 tropical and subtropical countries, particularly in Southeast Asia, Latin America, parts of Africa, and the Western Pacific.

Dengue fever is a notifiable disease in Germany. This means that the attending physician must tell the health department in each case. This measure should help to recognize larger outbreaks as quickly as possible and to be able to take countermeasures.

Dengue fever: illnesses are increasing

Dengue fever has become very common in recent decades. In the last 50 years, the number of infected people has multiplied thirtyfold. Experts estimate that around 400 million people worldwide contract the dengue virus each year. This makes dengue fever the most mosquito-borne disease in the world.

In the meantime, it has already been discovered in Europe: For example, in October 2012, there was an outbreak of dengue fever on Madeira, a popular Portuguese holiday island off the coast of Africa. Also on Fuerteventura, in Croatia, Greece and France, the virus was already (locally) on.

Dengue fever: symptoms

The time between the bite of the Aedes mosquito and the onset of the first symptoms (incubation period) is three to 14 days. Mostly, the infection breaks out between the 4th and 7th day.

The symptoms of dengue fever are often very nonspecific and are similar to those of ordinary flu: typically, the patient has high fever (up to 40 degrees Celsius), chills, Head-, Joint and limb pain, Because of the strong muscle pain, the dengue fever is also “Bonecrusher feverThe fever is often bipedal (biphasic) .Together with the second fever thrust one can Rubella-like rash with itching occur all over the body. Other possible concomitant symptoms of dengue fever include, for example fatigue, Nausea and vomiting such as swollen lymph nodes.

Many infected persons show no symptoms (especially children).

Complications of dengue fever

In the majority of patients, dengue fever heals without further consequences. In some cases, however, there are complications: Physicians distinguish two serious disease courses, which can also be life-threatening. They occur mainly in children and adolescents under the age of 15 years and / or in patients who have already undergone dengue disease:

Dengue Hemorrhagic Fever (DHF): In the case of haemorrhagic Dengue fever, an acute fever outbreak is followed by symptoms due to a high drop in platelets (thrombocytopenia) – various types of bleeding such as pinpoint head bleeding in the skin or mucous membranes (petechiae), bleeding from the nose and gums, and gastrointestinal bleeding ( with vomiting blood and bloody stool).

Dengue shock syndrome (DSS): When the blood pressure is derailed due to the disease, the heart can no longer pump enough blood through the body. As a result, the heart rate rises sharply, yet vital organs such as the brain and kidneys are no longer adequately supplied.

Warning signs of such complications are:

• sudden abdominal pain
• repeated vomiting
• a sudden drop in body temperature to below 36 ° C
• sudden bleeding
• Confusion, restlessness or dizziness
• sudden drop in blood pressure
• fast pulse

Both complications are potentially life-threatening and must be treated in the hospital. The treacherous: They usually occur only when the patient feels better, often between the third and seventh day of the disease. For this reason one speaks in this connection also of the critical phasebecause now the course of the disease shows and the doctor must decide whether (drastic) countermeasures must be taken.

Dengue fever: treatment

There is no causal (causal) therapy for this infection. That is, the doctor can only alleviate the symptoms, but not fight the virus itself.

Dengue fever treatment does not differ significantly from that of influenza in the fever phase without complications. What is important is one adequate hydration, You can also fight the high fever and the pain analgesic and antipyretic drug like taking acetaminophen. Not suitable are painkillers and antipyretics, which interfere with the blood clotting and thus increase the tendency to bleed. These include, in particular, acetylsalicylic acid (ASA), but also ibuprofen.

As long as there are no complications, the patient does not necessarily have to go to the hospital. However, as soon as signs of bleeding or a threat of shock, inpatient treatment (possibly in the intensive care unit) is inevitable. There, the vital parameters (heart rate, respiratory rate, blood pressure, etc.) can be closely monitored. In addition, if necessary, patients are given infusions or stored blood.

Especially in the phase in which the fever subsides, the risk of complications is high. Health deteriorations should then be reported immediately to the doctor.

Dengue fever: Prevention

Although there is a vaccine against dengue fever, which is not allowed in Germany. One of the reasons: The vaccine produces antibodies that could aggravate the disease if it is infected with another dengue viral strain.

However, there are some things that can not be done to prevent a dengue fever disease. The most important thing is to protect yourself against mosquito bites when traveling to risk countries (exposure prophylaxis). For this purpose, the following protective measures are recommended:

• long pants and long sleeves
• Repellents (mosquito sprays) for application on skin and clothing
• Mosquito nets for the bed with a maximum mesh size of 1.2 mm, equivalent to approximately 200 MESH (mesh / inch²)
• Fly screens on the windows and doors (impregnated with insecticides)

Tip: If you are planning a trip to a dengue fever area, you should inform yourself about the risks and protective measures before you travel. A corresponding consultation offer travel medicine and tropical institutes.

Dengue fever: examinations and diagnosis

The main symptoms of dengue fever are in the initial phase indistinguishable from those of a normal flu. However, an appropriately specialized physician such as a tropical doctor can often already suspect an infection with “dengue fever” because of the described complaints and the information that the person was in a high-risk country. Such information is collected by the doctor during the initial consultation with the patient (anamnesis).

Also important is the physical examination, It includes:

• Temperature, pulse and blood pressure measurement
• Listening to the heart and lung sounds
• Palpation of the superficial lymph nodes
• Assessment of the pharynx and mucous membranes

The suspicion of dengue fever can be explained by a blood test confirm: A blood sample from the patient is screened for dengue viruses and specific antibodies against the pathogen. Quick tests are also available to detect specific antibodies.

In addition, the doctor looks for signs of bleeding tendency, for example in the form of bleeding gums, nosebleeds or small skin bleeding (petechiae). In this context, the so-called Tourniquet test valuable hints. It can be used to check the stability of the finest blood vessels (capillaries): A blood pressure cuff is placed on the patient’s upper arm and inflated to a value between the systolic and diastolic blood pressure. After about ten minutes, the cuff is removed, and the doctor checks if there are small bleedings (petechiae) on the forearm.

Dengue fever: disease course and prognosis

As a rule, the dengue fever is uncomplicated. Most patients recover within a few days. However, the fatigue may persist for several weeks.

An increased risk of complications with dengue fever exists in patients who are not drinking enough or younger than 15 years. Also dangerous is a secondary infection with dengue viruses:

After a dengue fever infection, one is immune to the type of dengue virus for a lifetime. But you can get infected with one of the other three types of virus and get sick again. This secondary infection is often more severe (such as haemorrhagic dengue). Experts suggest that an overreaction of the immune system is responsible for the more severe disease course. People who have ever had dengue fever must be extra careful on another tropical journey.

risk of death

In particular with dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS), timely intensive care treatment is very important. The mortality (lethality) in DHF is between six and 30 percent. Even more dangerous is the DSS: Without adequate treatment, 40 to 50 percent of patients die from this severe form of Dengue fever, On the other hand, with timely treatment, mortality drops to one percent or less.