Tularemia (rabbit fever)

Francisella tularensis

Changed on: 17.12.2020
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Tularemia (rabbit fever, deer fly fever, Ohara's disease) is an infectious disease caused by the bacterium Francisella tularensis. The pathogen can be transmitted from animals to humans.

Occurrence

Entire northern hemisphere.

Reservoir

Hares and rodents. Ectoparasites, especially ticks, play an important role as vectors.

Mode of transmission

Tularemia is transmitted via direct contact and smear infection or splashes of pathogen-containing liquids (especially handling raw meat from field hares), but also through tick or insect bites. Infections via dust or droplets can occur while skinning or cutting infected field hares and while working with agricultural products such as hay, straw, grain or sugar beet if they are contaminated with excrements or carcasses of mice. Transmission through contaminated food or water is possible.

Incubation period

Up to 14 days, usually three to five days.

Symptoms

In most cases a painless ulcer develops at the contact point. Frequent symptoms are fever, headache, aching limbs and painful swelling of regional lymph nodes. The course of the disease can vary between different symptoms such as pharyngitis, vomiting, diarrhoea or abdominal pain. Sick rabbits may show unusual movements and a lack of escape behaviour.

Therapy

The disease can be treated with antibiotics.

Prevention

Sick, killed or dead hares must not be skinned, should only be touched with gloves and packed safely immediately.

Situation in Austria

In Austria, a total of 57 cases of human tularemia were reported between 2015 and 2019; the exact transmission route is unknown in most cases.

In the northeast of Austria there is an active tularemia occurence, which is connected to endemic areas in Slovakia and the Czech Republic along the rivers March and Thaya. Sporadic cases of tularemia also occur in other areas of Austria. For example, there is another endemic area in southern Burgenland and neighbouring Styria, where tularemia has been repeatedly detected in field hares. Cases of tularemia in field hares and humans have also been detected sporadically in Upper Austria. In 2018, an endemic occurrence of tularemia was also detected in western Austria, with an accumulation of deaths among field hares in Salzburg and Vorarlberg (see Figure 1).

Professional information

Veterinary Medicine

Francisella tularensis subspecies holarctica Biovar II (erythromycin resistant) is endemically widespread in the east of Austria. In western Austria Biovar I (erythromycin sensitive) of the subspecies holarctica is found in addition to Biovar II. The different distribution areas of biovars I and II in Western and Eastern Europe overlap in Western Austria, where rabbits and rodents (Lagomorpha and Rodentia) are considered reservoir animals of tularemia.

Ectoparasites, especially ticks, play an important role as vectors in maintaining the natural occurance. Francisella tularensis subspecies holarctica, which occurs in Europe, North America and Japan, and subspecies mediaasiatica, which occurs in Central Asia, usually cause less severe, localised diseases in humans. Life-threatening, generalised forms of the disease are possible when infected with the highly virulent subspecies tularensis, which occurs predominantly in North America.

Transmission occurs through contact and smear infection or splashes of pathogen-containing fluids (especially while handling raw meat from field hares), but also through tick bites or insect bites. Dust or droplet infection can also occur during skinning or cutting of infected field hares and during work with agricultural products such as hay, straw, grain or sugar beet if they are contaminated with excrements or carcasses of mice.

Symptoms

The clinical picture is very diverse, depending on the transmission route and the point of entry of the pathogen. While in the case of an infection by field hares the ulceroglandular or glandular form with inflammation of the lymph nodes of the upper extremities is usually observed, the entry site of the pathogen in the case of transmission by arthropods is more likely to be in the area of the lower extremities. Diseased brown hares can show unusual movements and a lack of escape behaviour.

Prevention and control

Sick, killed or dead hares as well as hunted hares with pathological changes in the internal organs must never be thrown away or buried, but should be sent to the IVET in Mödling for examination or disposed in a way to prevent spreading of the disease. Since hares with chronic renal entularaemia excrete the bacteria with urine over a long period of time, hunters in endemic areas should pay more attention to killing sick animals with unusual behaviour to prevent further spread of the pathogen. Sick, killed or dead field hares must not be skinned, but should only be touched with gloves and securely packed immediately to prevent infection of humans through inhalation of pathogen-containing dust or contact with fur, blood or excrements.

Contact, forms

Institute of Veterinary Medicine Mödling

Robert Koch-Gasse 17
2340 Mödling

Phone: +43 50 555-38112
Fax: +43(0)5 0555 38529
E-Mail: vetmed.moedlingno@Spam@agesno.Spam.at

Downloads

    Erstmalige Isolierung von Francisella tularensis subsp. holarctica Biovar II und Brucella suis Biovar 2 beim Rotfuchs in Österreich (5.70 M)
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    Zur Überwachung der österreichischen Tularämie- und Brucellose-Naturherde mit dem Rotfuchs (Vulpes vulpes) als Bioindikator (201 K)
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    Epidemiological study of Francisella tularensis ssp. holarctica Biovar II srains in Austria from 1995 to 2010 (905 K)
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