Francisella tularensis

From Cow
Culture of Francisella tularensis

Francisella tularensis is a Gram-negative endosymbiontic bacteria which causes Tularaemia in cattle and other animals including humans in the northern hemisphere[1][2].

F. tularensis is antigenically related to Brucella spp and is a parasite transmitted by Dermacentor andersoni, D. variabilis, Amblyomma americanum, Chrysops discalis.

Clinical signs

Cattle are often subclinically infected, and merely serve as intermediate hosts for the vector ticks and flies. In acute affected cattle, disease is characterised by fever, lethargy, anorexia, joint stiffness and anorexia.

Postmortem examinations in cattle usually reveal miliary, off-white necrotic lesions affecting the liver, spleen, lung, and lymph nodes.

Diagnosis

Diagnosis is based on presenting clinical signs supported by laboratory isolation and identification of Francisella spp organisms.

Direct or indirect fluorescent antibody test and ELISA can be supportive ion a diagnosis. PCR testing are required for definitive diagnosis[3].

Treatment

Streptomycin, gentamicin, chloramphenicol and tetracyclines are reportedly effective at clearing bacteraemia.

Following recovery, a stable immunity of long duration develops.

References

  1. Mörner T & Sandstedt K (1983) A serological survey of antibodies against Francisella tularensis in some Swedish mammals. Nord Vet Med 35(2):82-85
  2. Baldridge GD et al (2009) Transovarial transmission of Francisella-like endosymbionts and Anaplasma phagocytophilum variants in Dermacentor albipictus (Acari: Ixodidae). J Med Entomol 46(3):625-632
  3. Skottman T et al (2007) Simultaneous real-time PCR detection of Bacillus anthracis, Francisella tularensis and Yersinia pestis. Eur J Clin Microbiol Infect Dis 26(3):207-211