Hantavirus infections in Germany, the year 2010
04. August 2010: This year a total of 1,318 laboratory confirmed cases of hantavirus disease were registered until August 4, the majority of them in Baden Württemberg (739) and Bavaria (249), followed by Northrhine-Westphalia (98), Hesse (94), and Lower Saxony (76) (Robert Koch-Institut: SurvStat, http://www3.rki.de/SurvStat, as per August 4, 2010). So far, the highest number in Germany occurred in 2007; in the subsequent years 2008 and 2009 the numbers were considerably lower with 243 and 181 cases, respectively (Fig. 1).
Currently, no reliable statement can be made on the reasons for the considerable increase in notified cases this year (and in 2007). One factor may be the strong increase in the number of bank voles due to a beech mast last year. For elucidation, a cooperation project has been started to conduct long-term studies on the population dynamics of bank voles, the presence of Puumalavirus (one of the three hantavirus types in rodents in Germany) in the bank vole population and the incidence of human infections. One of the aims of these investigations is to develop a long-term monitoring program for early detection of signs of an increased infection risk for the human population. Project partners are the Julius Kühn-Institute, the Friedrich-Loeffler-Institut, the Robert Koch-Institute, the National Consiliary Laboratory for Hantaviruses at the Institute of Virology of the Charité, the State Health Agency Baden-Württemberg, the Bundeswehr Institute for Microbiology and the Büsgen-Institut of the University of Göttingen.
Hantaviruses count among the „emerging viruses“, their significance as human pathogenic agents is increasing. As zoonotic agents, hantaviruses are transmitted from animals to humans. Infections of humans with hantaviruses are usually transmitted by virus-contaminated excretions of infected rodents which are inhaled by humans; in rare cases the pathogens can also be transmitted by the bite of an infected animal. In addition to rodents, other small mammals (insectivores such as shrews and moles) may act as hantavirus reservoirs.
In Germany, 3 rodent-associated virus types occur. The Puumalavirus transmitted by bank voles (Figure 2A) is responsible for the majority of hantavirus infections and for the currently observed increased case numbers in Southern and Western Germany. In the North and East of the country, the Dobrava-Belgrade-Virus transmitted by the striped field mouse (Figure 2B) also causes human infections. In addition, the Tulavirus occurs in Germany which is transmitted by the common vole (Figure 2C) and presumably also by the field vole. It is assumed that this agent does not or only very rarely cause symptoms of disease in humans.
Typically, the clinical course of a hantavirus infection is characterized by high fever, headaches, backaches and abdominal pain, drop in blood pressure and kidney disorders. In some cases, extrarenal manifestations of a hantavirus infection can be observed, mainly accompanying hepatitis or involvement of the lung. Many cases of disease, however are not recognized as such, either because an infectious cause for kidney failure is not considered or the technical preconditions for virus diagnostics are not available.
Persons who live in the known endemic areas and who have contact with rodents and their excretions due to their profession or their living conditions have an increased risk of infection. Risk factors for transmission of hantaviruses from the reservoir animal to humans are outdoor activities (forest, field, construction sites), forest and park areas in the immediate vicinity of living quarters as well as increased contact to mice and their excretions. As so far no protective vaccination and no causative antiviral therapy are available, exposure prophylaxis is of utmost importance.
The best protection from infections is to avoid contact with the excretions of rodents. This includes keeping mice away from living quarters and their closer environment (e.g. by avoiding the accumulation of food waste close to residential buildings). Also farmers and stud workers should thoroughly prevent mice from settling and eliminate mouse nests in the animal houses (please use gloves and masks, avoid to disperse mouse excretions, disinfection).
An infection risk also arises from re-opening and cleaning summer houses after the winter; these should be aired out thoroughly prior to cleaning (if necessary by applying the same safety measures as in animal houses).
For further information please refer to the information sheet „Wie vermeide ich Hantavirusinfektionen“ (How to avoid hantavirus infections) and to the links below:
- www.rki.de > Infektionskrankheiten A-Z > Hantavirus-Infektionen
- Detlev H. Krüger (IMV, Charité Berlin)
- Rainer G. Ulrich (FLI, Greifswald-Insel Riems)
- Jens Jacob (JKI, Münster)