Bovine petechial fever

From Cow
Sudden death attributed to bovine petechial fever

Bovine petechial fever (BTF), also known as Ondiri disease, is a rickettsial disease of cattle in Kenya, East Africa which results in sudden death in cattle with significant economic impact[1].

Cause

BTF is caused by Ehrlichia ondiri, an intracellular rickettsia, believed to be endemic and thought to be transmitted by ticks, biting insects, and mites[2].

Infection is thought to be initiated by arthropod bites, which leads to dissemination via endothelial cell invasion[3].

Clinical signs

BPF is characterized by fever, lethargy and widespread petechiation of mucous membranes. Marked conjunctival edema and hemorrhage (“poached egg eye”) are characteristic in some severe cases. Pregnant cows may abort.

Diagnosis

Diagnosis is based on presenting clinical signs and supportive blood tests which show marked pancytopenia. Organisms can be demonstrated in Giemsa-stained smears of blood or spleen.

At necropsy, widespread serosal and mucosal hemorrhages and edema are accompanied by lymphoid hyperplasia. Organs frequently affected include the heart, alimentary tract from the forestomach to the colon, liver, gall bladder, kidneys, and urinary bladder.

A differential diagnosis would include Rift Valley fever, acute Trypanosoma spp infection, acute Theileria spp infection, Heartwater, hemorrhagic septicemia, and bracken fern poisoning.

Treatment

Dithiosemicarbazone and tetracyclines have been used successfully to treat early experimental cases but are ineffective in advanced cases. The former is said to be more effective.

Following recovery from the disease, affected cattle are immune against experimental challenge for about 2 years[4].

Control of this disease requires elimination or reduction of arthropod parasites and immunisation[5].

References

  1. Davies G (1993) Bovine petechial fever (Ondiri disease). Vet Microbiol 34(2):103-121
  2. Snodgrass DR (1975) Pathogenesis of bovine petechial fever. Latent infections, immunity, and tissue distribution of Cytocetes ondiri. J Comp Pathol 85(4):523-530
  3. Kiptoon JC & Mugera GM (1983) Invasion of capillary endothelial cells by Ehrlichia ondiri. Vet Rec 112(3):59-60
  4. Merck Vet Manual
  5. Young AS et al(1992) Immunisation of cattle against theileriosis in Nakuru District of Kenya by infection and treatment and the introduction of unconventional tick control. Vet Parasitol 42(3-4):225-240