Histophilosis, or Histophilus somni–associated disease, is a common disease in North American cattle. It also has been reported to occur sporadically in beef. Histophilus somni is a Gram-negative bacterium that is associated with a disease complex (termed histophilosis) that can produce several clinical syndromes. Histophilus somni (H. somni) is a Gram-negative bacterium currently classified as a member of the Hae- mophilus-Actinobacillus-Pasteurella group. Clinical.

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Young growing cattle age months are most commonly infected and show clinical signs. Colonies with characteristics of H.

Address all correspondence and reprint requests to Dr. Reproductive tract swab samples were collected from 74 histpohilus bighorn sheep Ovis canadensis nelsoni captured in southern Nevada as part of a health-monitoring program. It is also harbored in their reproductive tracts and has been associated with reproductive failure in domestic sheep and cattle. Biberstein 7 found that organisms in these 3 species share several characteristics; however, growth of only H.

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Therefore, it could be that the H. Affected animals will be febrile, off-feed, show labored breathing, etc. Isolated colonies were removed with a sterile inoculation loop, and the underlying medium was evaluated for evidence of lytic activity of the test isolates in comparison with that produced by M.

The disease was characterized by meningitis, ecchymotic hemorrhage on serous membranes of subcutaneous tissues and muscles, necrotic foci in the liver, bacterial thrombosis, and necrotizing vasculitis. CummingsKaren F. Wildlife biologists and diagnosticians should be aware of the potential of these organisms to cause disease in bighorn sheep and of growth characteristics that may hinder laboratory detection. None of the tissue sections were immunohistologically positive for M.

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Gross lesions of cattle with TME may be difficult to see and can be highly variable. Because this proposal is not fully accepted, we are using herein the more usual name, Haemophilus somnus.

Int J Syst Bacteriol. Metaphylaxis has also been used to uistophilus H. Nei M, Li W-H. Pathogenic or nonpathogenic H. Certain virulence factors play a role in the disease process as well. In conclusion, persuasive evidence that H. The profiles of major outer membrane proteins and antigens for all of the isolates were predominantly similar, although differences that may be associated with the host—parasite relationship and virulence were detected.

Microthrombi were detected in alveolar septa of most of the lungs, and 3 lambs had occasional vascular thrombi in the brain.

Histopyilus Haemophilus somnus pneumonia in calves and immunoperoxidase localization of bacteria. Use of a polymerase chain reaction method to detect the leukotoxin gene lktA in biogroup and biovariant isolates of Pasteurella haemolytica and P. The strains with low amounts could have low expression, or the IgBPs may have been shed from their surfaces.

Lack of these cardinal characteristics, as described for domestic-livestock isolates 10could result in lack of detection and identification of the organism. Biberstein 7 reported that H.

Haemophilus somnus (Histophilus somni) in bighorn sheep

These lambs had been submitted for necropsy after sudden illness or death, with or without prior depression, stiffness, or fever. Treatment for all forms of the disease complex have often been with oxytetracycline. Weiser histophulus, Bruce C. Immunoglobulin-binding activity among pathogenic and carrier isolates of Haemophilus somnus. Antigenic profile with Western blot testing of the isolates after exposure to convalescent-phase serum from 2 calves with experimental Haemophilus somnus infection.

Abstract Respiratory disease and poor lamb recruitment have been identified as limiting factors for bighorn-sheep populations. The progression of disease sonni calves with myocarditis is also very rapid and sudden death may be the only clinical sign. Although all but 1 of the bighorn isolates and 2 of the domestic-sheep isolates produced identical biochemical utilization reactions that were characteristic of biovariant 4, the bighorn-sheep isolates lacked the yellow pigmentation and CO 2 requirement of the domestic-livestock isolates.


Significant vasculitis was not recognized except in areas of severe inflammation.

It is also a common commensal in the upper respiratory tract, prepuce, hisfophilus vagina of clinically healthy cattle 3. Post mortem examination of cattle that have suffered from H. Radostits OM et al. This may be explained by the fact that bovine H.

Respiratory infection somi precedes infection of other organ systems. Bacterial meningitis and encephalitis in ruminants. Growth inhibition zones for all of the isolates equaled or exceeded those published for all of the antibiotics with the exception of isolatewhich had a zone indicative of intermediate sensitivity to tetracycline, and isolates andwhich had zones indicative of resistance to clindamycin.

Involvement of the central nervous system, whereby blood flow to the spinal cord and brain is affected, results in a syndrome known as thromboembolic meningoencepahlitis TEME. Haemophilus somnus myocarditis in a feedlot steer.

If calves are to be vaccinated it should be performed prior to entry into the feedlot. Similar organisms were isolated from lung tissue of the 2 Rocky Mountain bighorn sheep that died with evidence of pneumonia in and Bacterial culture remains the gold standard for diagnosing H.

Epidemiology of Haemophilus somnus in young rams. Isolate identification a Geographic location Animal species; b anatomic site Associated clinical condition A.