Bovis ISSN 2398-2993

Bovine Petechial Fever

Synonym(s): Ondiri disease

Contributor(s): , Veronica Fowler

Introduction

  • Cause:
    • Bovine petechial fever (BPF) is caused by the rickettsial parasite, Ehrlichia ondiri.
    • An as yet unidentified biting arthropod, possibly a tick of restricted distribution, is thought to be the vector of the disease.
  • Signs:
    • Fluctuating pyrexia, lethargy, lacrimation, milk drop in lactating dairy cows, petechial hemorrhages in mucus membranes, epistaxis, melena, abortion may occur in pregnant animals and anaemia may be so severe cattle may die up to 4 weeks post infection.
    • Unilateral edema of the conjunctivae is peculiar for BPF (poached egg eye) and may be accompanied by blood in the anterior chamber of the eye.
  • Diagnosis:
    • Clinical signs coupled with the recent movement of cattle to forest edges within BPF endemic regions allows for a presumptive diagnosis. However BPF cannot be definitively differentiated from a range of other diseases (eg Rift Valley Fever, Trypanosomosis, Theileriasis, Heartwater) and poisoning (Bracken fern poisoning) based on clinical signs alone.
    • Definitive diagnosis can be achieved using a range of methods.
  • Treatment: experimental infections suggest that oxytetracycline and dithioemcarazone are useful whilst clinical signs persist. Both are ineffective in advanced disease. Recovered animals develop immunity which can last for at least 2 years.
  • Prognosis: guarded (mortality ca. 50%) unless therapy is instigated early in the disease process. If signs of hemorrhage are already present, the disease is invariably fatal.

Pathogenesis

Predisposing factors

General

  • Grazing thick scrubland or the edge of forested areas at 1500-3000m altitude in East Africa.
  • Presence of wild bushbuck. 

Specific

  • New naïve cattle recently introduced to endemic regions.
  • Characteristically disease occurs in cattle which have broken out from fenced pastures and grazed the adjacent bushland.
  • Disease incidence appears to increase during the wet season.

Pathophysiology

  • The highest levels of infective rikettsial bodies are found in the blood, subsequent to endothelial cell degeneration and blood leakage. 
  • This accounts for the petechial hemorrhages and ecchymosis of mucus membranes associated with the disease.

Timecourse

  • The duration of clinical disease is up to 10 days.

Epidemiology

  • Clinical disease is most commonly observed in  naïve, non-indigenous cattle recently introduced to endemic regions.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMed Resource.
  • Davies F G (1993) Bovine petechial fever (Ondiri disease). Veterinary Microbiology (34) pp 103-121.
  • Snodgrass D R, Karstad L H & Cooper J E (1975) The role of wild ruminants in the epidemiology of bovine petechial fever. J Hyg (Lond) 74 (2) pp 245-50. 
  • Krauss H, Davies F G, Odegaard O A & Cooper J E (1972) The morphology of the causal agent of bovine petechial fever (Ondiri disease). J Comp Pathol 82 (3) pp 241-6.
  • Dawe P S, Ohder H, Wegener J & Bruce W (1970) Some observations on bovine petechial fever (Ondiri disease) passaged in sheep. Bull Epizoot Dis Afr 18 (4) pp 361-8.

Other sources of information

  • Radostits O M, Gay C C, Blood D C & Hinchcliff K W (2005) Diseases of the cardiovascular system. In: Veterinary Medicine. 9th Edn. W B Saunders, Philadelphia, pp 1276-1277.


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