The small red-backed vole, a common but inconspicuous representative of the vole, is more dangerous than many believe: namely, it transmits the dangerous hantaviruses. In Germany, the virus has only been reportable since 2001, and there were particularly high numbers of reported infections in 2007 (1,688) and 2010 (2,017). In the record year 2012, 2,824 cases were reported to the Robert Koch Institute. After that, however, the numbers dropped again; in 2016, there were only 278 reported cases. Experts estimate, however, that the number of unreported cases is far higher.
What are hantaviruses?
Infection with hantavirus can cause a sometimes severe illness. The pathogens belong to the Bunyaviridae virus group. The term hantavirus originated during the Korean War of 1950-53, when several thousand soldiers suffered from so-called Korean fever, accompanied by internal bleeding and kidney failure. The trigger was the hitherto unknown hantavirus, named after the Korean river Hantaan, where the outbreak of the severe disease began. The pathogens are now widespread throughout the world. Especially in Southeast Asia, hantaviruses are common pathogens. However, the infectious disease is not uncommon in Europe either.
Symptoms of hantavirus infection
Anyone who has flu-like symptoms over a period of more than three days may have contracted the Puumala-type hantavirus. Particularly charackteristic of hantavirus infection are signs such as:
- High fever above 38 degrees Celsius.
- Headache
- Abdominal pain
- Back pain
- Chills
- Nausea
- Possibly conjunctivitis
- Blood in the urine
Course of disease of infection with hantaviruses.
The majority of viral infections pass unnoticed, that is, the course of the disease is asymptomatic or so mild that the infection is not even noticed by the affected person. A severe course, i.e. illness with pronounced symptoms, is summarized under the term “hemorrhagic fever with renal syndrome” (HFRS): In the worst case, this means that kidney function is impaired or the kidneys are in acute failure. In addition, the liver is enlarged. In exceptional cases, there may be a life-threatening tendency to bleed.
Transmission of hantavirus
A clustered occurrence of hantavirus infections is usually associated with a proliferation of rodents. The natural hosts of hantaviruses are mice and rats. The viruses are shed by infected mice through saliva, urine, and feces. The main vectors in Central Europe are the red-backed vole, the fire mouse and the Norway rat. Human-to-human transmission or infection via pets and insects is considered unlikely. The Puumala virus spreads whenever the number of red-backed voles increases – this is the case when there is an abundance of food. People who spend a lot of time outdoors, such as foresters, forest workers, farmers, mushroom and berry pickers, as well as guests and owners of vacation homes near forests that have been empty for a long time, are considered to be particularly at risk. Because the virus is transmitted through urine and feces, dried dusty feces stirred up during sweeping can enter the respiratory tract. The same can happen when collecting or splitting wood or cleaning sheds, garages and basements where the small rodents with the reddish fur have nested.
Diagnosis of hantavirus infection
The hantavirus group includes about 30 serotypes. These are distinguishable variations of bacteria or viruses. In central and northern Europe, the most common is Puumala virus, named after the Finnish town of Puumala, where this type first appeared. Hantaviruses are detected by antibodies in the blood of the sick person. Special tests in laboratories reveal which serotypes are involved. According to the German Green Cross, only 60 to 70 percent of patients develop detectable, specific antibodies in the acute phase. Problematically, because of the low level of awareness of hantavirus infections among physicians in Europe, the diseases are sometimes even confused with appendicitis and with hepatitis or misdiagnosed as “kidney failure of unclear origin” or severe influenza.
Treating an infection with hantaviruses
A vaccine against hantaviruses does not yet exist.At best, a disease can be treated symptomatically: For example, if pain or fever occur, they can be alleviated with medication. Severe cases are treated with ribavirin, which is used for AIDS and hepatitis C, among other things, because it inhibits viral replication. If a hantavirus infection is detected, it must be reported to the appropriate health department.
Prevention of hantavirus infection.
As a preventive measure, the Robert Koch Institute recommends that a number of things be observed when cleaning rooms that have not been used for a long time and in which mice are clustered – such as barns, attics, garages, storage rooms, workshops, and also terraces:
- Provide adequate ventilation and wear respiratory protection when cleaning.
- Clean with damp cloths to stir up as little dust as possible.
- Spray feces residues with disinfectant.
- Wash your hands thoroughly after cleaning.
Dead mice should not be handled with bare hands, but with disposable gloves. You should spray them with a disinfectant, put them in a plastic bag and close it well with another plastic bag, then you can dispose of them through household waste.
