FAQ on the Hanta virus

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1. What are Hanta viruses?

Hanta viruses are viruses belonging to the Hantaviridae family. They cause illnesses that primarily affect the kidneys and also the lungs. These are known as zoonoses, i.e. infections that are transmitted from animals to humans.

Each Hanta virus is typically associated with a specific rodent species as its reservoir. The animals themselves usually do not become ill, but excrete the virus in their urine, faeces and saliva.

In humans, hantaviruses can cause different clinical presentations depending on the virus species:

• In Europe and Asia, this usually involves kidney involvement (haemorrhagic fever with renal syndrome, HFRS, or the milder ‘nephropathia epidemica’).
• In North and South America, primarily Hanta virus Cardiopulmonary Syndrome (HCPS) with severe lung disease.

2. How are Hanta viruses transmitted?

Hanta viruses are not usually transmitted from person to person. The main route of infection is transmission from rodents to humans.

Typical routes of transmission are:

• Inhalation of dust contaminated with dried rodent urine, faeces or saliva (for example, when sweeping, mucking out, or clearing out sheds, attics or garages).
• Less commonly, bite injuries from infected rodents.

For the Hanta viruses types found in Europe, the following applies:

Human-to-human transmission has not yet been proven.

An exception is the Andes Hanta virus in South America. Here, human-to-human transmission has been reported in rare cases.

3. Where do Hanta viruses occur?

Hanta viruses occur worldwide. They can be found wherever the respective rodents that serve as reservoirs live.

• In Europe, the Puumala virus plays a particularly significant role; its main host is the bank vole.
• In Germany, infections with the Dobrava-Belgrade virus, which is transmitted by the common vole and the yellow-necked vole, also occur rarely.

In Germany, Hanta virus diseases occur more frequently in certain regions:

• Lower Saxony (Osnabrück)
• North Rhine-Westphalia (Cologne)
• Baden-Württemberg and Bavaria

The number of reported cases varies from year to year. Following ‘bumper years’ with particularly abundant beech nuts or acorns, there is often an increase in rodent populations and, consequently, more Hanta virus infections in humans.

4. What are the symptoms of a Hanta virus infection?

Symptoms usually begin suddenly after an incubation period of around 2 to 4 weeks. The course of the illness can vary greatly: from unnoticed or flu-like infections to severe illness.

Common general symptoms:

• Sudden onset of high fever
• Severe headaches, back pain and aching limbs
• Abdominal pain, nausea, vomiting
• A pronounced feeling of illness and weakness

Typical organ involvement (Europe):

• Kidneys: protein and blood in the urine, reduced urine output, up to acute kidney failure, which may require dialysis.
• Blood vessels and blood clotting: tendency to bleed, petechiae (pinpoint haemorrhages in the skin).

In North and South America (HCPS), severe lung disease is the main feature, with shortness of breath, cough and pulmonary oedema. These courses can be life-threatening.

However, many infections in Germany are mild or even asymptomatic and therefore go undetected.

5. How is a Hanta virus infection diagnosed?

Suspicion arises from:

• the symptoms (sudden fever, pain, kidney problems)
• appropriate exposure (contact with rodents, spending time in woodland and rural areas, clearing out barns, sheds or attics)

Confirmation is carried out in the laboratory mainly by:

• serological tests: detection of antibodies (IgM, IgG) against Hanta viruses in the blood, for example using ELISA, immunoblot or immunofluorescence
• PCR: In the early phase of the disease, the viral genome can be detected directly using molecular biological methods (polymerase chain reaction).

In Germany, acute Hanta virus infection is a notifiable disease. Certain specialised laboratories, such as national reference centres or consultative laboratories, assist with diagnosis and typing.

6. How is Hanta virus disease treated?

There is currently no standard therapy with antiviral drugs that targets all hantaviruses. Treatment is therefore primarily supportive and depends on the severity of the illness.

Typical measures:

• Close monitoring of circulation, kidney function and fluid balance
• Pain and fever management
• Adequate fluid intake (intravenously if necessary)
• In cases of severe kidney damage: dialysis
• In severe cases: treatment in an intensive care unit

Early diagnosis and prompt hospitalisation in complicated cases are crucial.

7. Is there a vaccine against Hanta viruses?

In some Asian countries, vaccines against certain types of Hanta virus (for example, against the Hantaan virus) are authorised and are used particularly in high-risk groups.

In Europe and Germany:

• there is no authorised vaccine against hantaviruses.

The most important protection currently consists of behavioural measures that minimise contact with infectious rodent dust.

8. How can you protect yourself against Hanta viruses?

The aim is to avoid contact with rodents and their excrement or to make such contact as safe as possible.

Important protective measures:

In and around the house

• Store food and animal feed in well-sealed containers.
• Store rubbish in such a way that it does not attract rodents.
• Seal openings in the house (cracks, gaps) as rodent-proof as possible.
• Detect rodent infestations early and have them professionally controlled.

When tidying and cleaning (e.g. cellars, attics, sheds, hunting huts)

• Ventilate rooms well before sweeping or cleaning.
• Avoid raising dust: instead of dry sweeping, wipe carefully with a damp cloth.
• Wear disposable gloves and, if possible, a close-fitting face mask (e.g. FFP2) if heavily soiled areas are expected.
• Do not disturb rodent droppings or nests; instead, carefully pick them up with damp paper and dispose of them in a sealed bag.

Outdoors

• When carrying out activities in areas with high rodent populations (e.g. woodwork, hunting, forestry work), ensure you wear protective gloves.
• Choose and store tents, sleeping areas and food in such a way that rodents cannot easily access them.

As a general rule: if you suddenly develop a fever and severe pain following contact with rodents or their habitat, you should seek medical advice and mention the possible contact.

9. Further information

• WHO https://www.who.int/news-room/fact-sheets/detail/hantavirus
• EDCD https://www.ecdc.europa.eu/en/hantavirus-infection

• Robert Koch Institute (RKI) – Hantavirus disease

  https://www.rki.de/DE/Themen/Infektionskrankheiten/Infektionskrankheiten-A-Z/H/Hantavirus/hantavirus-node.htmlrki