East Coast Fever (ECF)

by Country Vet

East Coast fever (ECF) is a tick-transmitted protozoan disease of cattle characterized by high fever, dyspnea , lymphadenopathy and high mortalities. It affects cattle in East and Central Africa, particularly in Kenya, Uganda, Tanzania, Rwanda, Burundi and Malawi.

Etiology

The disease causing agent, Theileria parva is an apicomplex protozoan parasite. Classic East Coast Fever occurs in East Africa and is associated with T. parva transmitted from cattle to cattle by the brown ear tick, Rhipicephalus appendiculatus. ECF also occurs either as Corridor disease in eastern and southern Africa or as January disease in central Africa.

Occurrence

ECF affects mainly cattle but also buffalo, and occurs in countries in eastern, central, and southern Africa. Its occurrence is related to the distribution of the vector tick which has been recorded from large areas extending from southern Sudan in the north to western Zambia and eastern Zaire in the west, and to Mozambique and Zimbabwe in the south.

The disease is prevalent throughout the wetter areas favoring the development of the tick, but is absent from the wet highlands in the horn of Africa. It has been eradicated from southern Africa up to the Zambezi River. The endemic scenarios range from a stable situation with high prevalence of herd infection but low fatality rates (endemic stability), to a low prevalence/high fatality scenario (endemic instability).

Endemic stability develops in indigenous zebu cattle exposed to constant tick challenge as in wetter areas whereas endemic instability is seen with commercial production systems utilizing imported breeds or crossbreeds and in areas with a unimodal rainfall pattern that restricts tick activity. Epidemics occur when there is a breakdown in tick control especially during the rainy season or when susceptible animals are introduced into an endemic area.

Transmission

The vector of ECF is Rhipicephalus appendiculatus and in the field, the disease occurs only where this tick is found, save for Corridor disease which may be transmitted by R. zambeziensis. Other species of Rhipicephalus and Hyalomma spp. can transmit ECF experimentally, but they are not significant.

Economic Importance

ECF has a major impact on cattle production in eastern, central, and southern Africa. The disease is cause for death of large heads of cattle. Serious losses occur in exotic and indigenous cattle, mainly from reduced production of milk and meat due to morbidity and mortality, as well as from the heavy costs incurred in implementing effective tick control.

Clinical Signs

The first clinical signs of ECF in cattle appear 7 to 15 days following the attachment of infected ticks. These signs include:

  • Generalized lymphadenopathy involving superficial subcutaneous lymph nodes such as the parotid, prescapular and prefemoral lymph nodes.
  • One or 2 days later, there is fever, depression, anorexia, and a drop in milk in dairy animals. In later stages, there may be nasal and ocular discharges, dyspnea, generalized lymph node enlarge­ ment, and splenomegaly. In severe cases, cliarrhea occurs, sometimes with dysentery; but usually only late in the course of the disease. Emaciation, weakness, and recumbency lead to death from asphyxia in 7-10 days.
  • Terminally, there is often a frothy nasal discharge. Occasional cases of brain involvement occur and are characterized by circling, hence ‘turning sickness’ or cerebral theileriosis.

Differential Diagnoses

  1. Corridor disease
  2. Mediterranean or tropical theileriosis
  3. Heartwater
  4. Trypanosomosis
  5. Babesiosis
  6. Anaplasmosis,
  7. Malignant catarrhal fever

Control

  • Vaccination-Animals are inoculated with a potentially lethal dose of infective sporozoite stabilate prepared from ticks and treated either simultaneously with a drug.
  • Vector control using acaricides-Organochlorides, organophosphorus , Synthetic pyrethroids and Amitraz, are applied in dips, spray races, or by hand spraying.

Always Contact your veterinarian whenever your identify abnormal behavior in your cows. Timely consultation and prompt treatment ultimately influences the prognosis.

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