East Coast fever

Clinical signs and diagnosis

Mortality can be up to 100%, with death occurring around 18–30 days after the initial attachment of infected ticks, because the incubation required is around 10–25 days, and the parasite spreads quickly and is rather aggressive.

Clinical signs include fever and enlarged lymph nodes near the tick bites.

Smears and stains can also be done to check for the parasite. Schizonts (meronts, or segmentors) can be found in infected lymphocytes. Pathology includes anorexia, dyspnea, corneal opacity, nasal discharge, frothy nasal discharge, diarrhea, pulmonary edema, leukopenia, and anemia. Endemic cattle given medication sometimes recover to varying degrees, or death follows due to blocked capillaries and parasites infecting the central nervous system. Cattle in endemic areas which survive infection become carriers.

For diagnosis, post mortem findings are characteristic and mainly include damage to the lymphoid and respiratory systems.

Treatment and control

One study using the medicinal plant Peganum harmala showed it to have a lifesaving effect on cattle infected with East Coast fever.

The classical treatment with tetracyclines (1970–1990) cannot provide efficiency above 50%.

Since the early 1990s, buparvaquone has been used in bovine theileriosis with 90 to 98% recovery.

Other than buparvaquone, another chemotherapeutic option is parvaquone, e.g. Clexon. Halofuginone lactate has also been shown to have an 80.5% efficacy against Theirelia parva parva infections. The ultimate factor that causes death is pulmonary edema. In May 2010, a vaccine to protect cattle against East Coast fever reportedly had been approved and registered by the governments of Kenya, Malawi and Tanzania. This consists of cryopreserved sporozoites from crushed ticks, but it is expensive and can cause disease.

Control of the disease relies on control of ticks of domestic animals. This is a major concern in tropical countries with large livestock populations, especially in the endemic area. Pesticides (acaricides) are applied in dipping baths or spray races, and cattle breeds with good ability to acquire immune resistance to the vector ticks are used.

Future treatment and control research will be informed by Gardner et al 2005's genome and protein expression and Bishop et al 2005's expression-by-stage and antigen results.

History

This disease was first reported in southern Africa, south of the Zambezi river, in 1902. It became known as East Coast fever after it was determined that the disease had originated in cattle imported from the East Coast of Africa.

References

References

1. (2008). "Climate change and the tick-borne disease, Theileriosis (East Coast fever) in sub-Saharan Africa". Journal of Arid Environments.
2. (September 2014). "Protecting Africa's cattle with a live vaccine: An East Coast fever impact narrative". International Livestock Research Institute.
3. (June 2016). "The biology of ''Theileria parva'' and control of East Coast fever - Current status and future trends". Ticks and Tick-borne Diseases.
4. (7 September 2012). "Epidemiology of East Coast fever (Theileria parva infection) in Kenya: past, present and the future". Parasites & Vectors.
5. (1992). "The Epidemiology of Theileriosis in Africa". Academic Press.
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9. (March 2008). "Effect of Peganum harmala (wild rue) extract on experimental ovine malignant theileriosis: pathological and parasitological findings". Onderstepoort J Vet Res..
10. ILRI. "Treatment of East coast Fever using Clexon in Uganda".
11. PubMed. (June 1987). "Clinical Trial of Halofuginone Lactate for the Treatment of East Coast Fever in Kenya". Vet. Rec..
12. (2010-05-07). "Cattle disease vaccine launched 30 years after invention".
13. (2015-02-16). "Understanding the Basis of Parasite Strain-Restricted Immunity to ''Theileria parva''". [[Annual Reviews (publisher).
14. (1992). "The epidemiology of theileriosis in Africa". Academic Press.