Tularemia in rabbits
Esther van Praag, Ph.D.
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The bacterium Francisella tularensis leads to the
development of acute blood poisoning in hares, in rabbits and in other
animals like birds. Man can also be infected.
Rabbits, hares and rodents are most sensitive to the bacterium and the
disease is fatal for them. It is
suspected that the lagomorph species are responsible for the epidemic spread
of the diseases in some regions. Tularemia occurs on the
American continent, in Russia and in Scandinavia. There are nevertheless
regions in Western Europe where the bacterium is endemic such as Alsace,
France. The bacterium is spread by blood-sucking insects (lice, ticks, flies,
mosquitoes) but can also be spread by skin contact, through respiration or by
contaminated food.
Francisella sp.,
which has been classified with the bacterial family of Brucella sp. and Pasteurella
sp., is a tiny, Gram negative,
immobile and aerobic coccobacillus. The most virulent strains are mainly
observed in the USA. The disease is rarely seen in rabbits, and contamination from a
domestic rabbit to a human being has not been described so far. Clinical signs and diagnosisThe initial first clinical signs include a decrease
appetite, depression, ataxia (blocked ability to coordinate movements) and a
certain inclination to remain together with other rabbits. Further
characteristics of tularemia are the presence of skin abscesses and infection
of the lymphatic glands (nodular form of the disease). In severe cases, the
disease can be accompanied by pneumonia and septicemia Since the time between infection and the death of the
rabbit is rapid, tularemia is usually diagnozed after the death of the animal
only. An autopsy shows the presence of bleedings in the pleura
and an accumulation of blood in the lungs. The liver is enlarged and the
presence of blood clots is observed in this organ as well as in the spleen.
The lymph nodes are usually swollen. This disease is very contagious to human beings, and
extra safety measure must be taken during the treatment and the lab work. Francisella sp. grows only on a
special medium, e.g. the blood cystine medium. A further analytical tool is
the ELISA test. TreatmentAs
in human beings, streptomycin or other aminoglucoside antibiotics are given
to the rabbit. The advantage of tetracycline antibiotics is that it can be
administrated orally, but often, the disease is recurrent after the treatment
is halted. Further information1. Frolich K, Wisser J, Schmuser H,
Fehlberg U, Neubauer H, Grunow R, Nikolaou K, Priemer J, Thiede S, Streich
WJ, Speck S. Epizootiologic and ecologic investigations of European brown
hares (Lepus europaeus) in selected populations from
Schleswig-Holstein, Germany. J Wildl Dis. 2003; 39:751-61. 2. Garcia del
Blanco N, Gutierrez CB, de la Puente VA, Rodriguez Ferri EF. Biochemical characterization of Francisella tularensis
strains isolated in Spain. Vet Rec. 2004; 154:55-6. 3. Lepitzki, D. A., A. Woolf, and M.
Cooper. 1990. Serological prevalence of tularemia in cottontail rabbits of
southern Illinois. J. Wildl. Dis. 26:279–282. 4. Morner T, Mattsson R, Forsman M,
Johansson KE, Sandstrom G. Identification and classification of different
isolates of Francisella tularensis. Zentralbl Veterinarmed B. 1993;
40:613-20. 5. Morner T. The ecology of tularaemia.
Rev Sci Tech. 1992; 11:1123-30 6. Manning, P J, Ringer DH, Newcomer,
CE, The Biology of the Laboratory Rabbit. (1994). Academic Press, New York,
New York. |
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