Geographic DistributionThe distribution of ECF is strictly associated with the distribution of the vector tick species. In the case of Rhipicephalusappendiculatus, the area extends from southern Sudan to South Africa and as far west as Zaire.
The dominating pathological lesion is generalized lymphoid proliferation resulting from uncontrolled proliferation of T-Iymphocytes containing schizonts.This is followed later by necrosis of infected lymphoblasts induced by cytotoxic T-Iymphocytes. The severe lymphocytolysis often leads to immunosuppression.
Turning sickness: an aberrant form of theileriosis in which parasitized lymphocytes cause emboli and hemorrhagic infarcts in central nervous tissue.
Bovine, lung. The lung tissue is diffusely tan-brown, and lobules are non-collapsed and rubbery (interstitial pneumonia).The node is enlarged and diffusely pale, and contains numerous petechiae.Bovine, kidney. The multiple pale foci on the cortical surface are lymphoid infiltrates.
Bovine, kidney. There are multiple petechiae on the surface of the cortex. The lymph node near the hilus is markedly enlarged.
Koch’s blue bodies: sporozoites enter the lymphocytes.
Treatment with these compounds is highly effective when applied in the early stages of clinical disease but is less effective in the advanced stages in which there is extensive destruction of lymphoid and hematopoietic tissues.
Infect animal with the sporozoite form of the parasite while at the same time treating the cattle with an antibiotic drug to lessen the severity of the infection.
Theileriosis are those tick-borne protozoandiseases associated with Theileria spp. In Sudan, most cases of Bovine theileriosis are caused by Th. annulata (tropical or Mediterranean theileriosis) and Th. mutans (benign theileriosis), and Th. parva (ECF) may exist in Southern Sudan.
Theileriosis of sheep and goat are caused by Th. hirci (Th. lestoquardi - Malignant ovine theileriosis) and Th. ovis (mild theileriosis). Equine theileriosis are caused by Th. equi. Transmission: Stage to stage (Transtadial Transmission).
5) …divides with schizont inside 2 infected daughter cells 6) 10-15 days post- infection, schizont merozoite (invades erythrocyte (RBC))4) Lymphocyte lymphoblast (enlargedlymphocyte) and… * 5-8 days post-infection: found in lymph nodes * Schizonts increase 10- fold every 3 days3) Sporozoite enters 7) In RBC,lymphocyte (WBC) schizont merozoite piroplasm (infect ticks) 2) Sporozoites transfer to ungulate if tick is attached for 48-72 hrs 1) Sporozoites produced in tick salivary glands 8) RBCs ingested by nymphs during feeding Incubation Period 9) Once in gut, undergoes sexual reproduction Experimentally Infected: 8-12 days motile stage, moves to Naturally Infected: up to 3 weeks tick’s salivary gland
PathogenesisTick inoculation of sporozoites lymphocytesin local lymph node schizonts lymphoidproliferation merozoites erythrocytespiroplasms ticks. Damage mainly by schizonts.
Swelling of the draining lymph node, usually the parotid. Generalized lymphadenopathy. Fever 40 – 41o C
Poor condition and severe lymphadenopathy in heifer
Death usually within three weeks of infection
In case of Equine theileriosis there is fever, anaemia, jaundice and haemoglobinuria. Jaundice in a horse’s eye
Occasional cases of brain involvement occur and are characterized by circling, hence turning sickness or cerebral theileriosis due to the presence of schizont in the cerebral capillaries.
Splenic enlargement. Severe pulmonary emphysema and edema along with hydrothorax and hydropericardium. Generalized lymphoid hyperplasia. Small lymphoid nodules (the so-called pseudo-infarcts) are present in liver, kidney, and alimentary track. The carcass is emaciated and hemorrhages are evident in a variety of tissues and organs.
Pulmonary emphysema and edema The Ln. is enlarged and diffusely pale, and contains numerous petechiae. Multiple pale foci on the cortical surface of the kidney are lymphoid infiltrates.
Emaciated Carcass Kidney, There are multiple petechiae on the surface of the cortex. The lymph node near the hilus is markedly enlarged Hydropericardium
East Coast Fever only occurs where R. appendiculatus is present, although occasionally outbreaks such areas have been recorded due to the introduction of tick-infected cattle from an enzootic area.
In sick animals, macroschizonts are readily detected in biopsy smears of lymph nodes and in dead animals in impression smears of lymph nodes and spleen.
There are two types of schizonts (Koch’s Blue Bodies)• Macroschizont: one with large chromatin granules gives (8-16 macromerozoites).• Microschizont: one with small chromatin granules gives (50-120 Micromerozoites) (Sexually differentiated) and infect RBCs.
In the field, diagnosis isusually achieved by findingTheileria parasites inGiemsa-stained bloodsmears and lymph nodeneedle biopsy smears
The indirect fluorescent antibody test is of value in detecting cattle which have recovered from ECF.
Differential diagnosis1. Heartwater because of pulmonary edema and hydrothorax. Examination of brain smears and lymph node or spleen impression smears can differentiate between the two diseases.2. Trypanosomiasis because of edema, lymphadenopathy, and anemia. Blood and lymph node smear examination will normally differentiate between the two diseases.3. Babesiosis and anaplasmosis because of anemia. These diseases can easily be differentiated from theileriosis on examination of blood smears.4. Malignant catarrhal fever because of lymphadenopathy and corneal opacity. Examination of blood and lymph node smears will clearly differentiate between the two diseases.
Treatment Tetracyclines have a therapeutic effect if given at the time of infection but they are of no value in the treatment of clinical cases.
Recommended actions if theileriosis is suspected• Notification of authoritiesTheileria species including Th. annulata have beenreported in Sudan; however, Th. parva, is exotic.East Coast fever and diseases caused by otherexotic Theileria spp. must be reported to state orfederal authorities immediately upon diagnosis orsuspicion of the disease.