etiology, local names, definition, transmission, source of infection, epidemiology, pathogenesis, clinical signs, diagnosis, differential diagnosis, treatment prevention and control

1. Faculty of Veterinary Medicine &
Animal Husbandry
Somali National University
Mogadishu, Gaheyr Campus
Nov. 03. 2019
INFECTIOUS DISEASES II (Protozoal Diseases)
THEILERIOSIS

3. Theileriosis are those tick-borne protozoan
diseases associated with Theileria spp.
 In North Africa, 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 East Africa .

4.  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
(Transstadial Transmission).

7. 4) Lymphocyte  lymphoblast (enlarged
lymphocyte) and…
3) Sporozoite enters
lymphocyte (WBC)  schizont
6) 10-15 days post-
infection, schizont 
merozoite (invades
erythrocyte (RBC))
1) Sporozoites produced
in tick salivary glands
2) Sporozoites transfer to
ungulate if tick is attached
for 48-72 hrs
5) …divides with schizont inside  2 infected daughter cells
7) In RBC,
merozoite 
piroplasm (infect
ticks)
8) RBCs
ingested by
nymphs during
feeding
Incubation Period
Experimentally Infected: 8-12 days
Naturally Infected: up to 3 weeks
9) Once in gut, undergoes
sexual reproduction 
motile stage, moves to
tick’s salivary gland
* 5-8 days post-infection:
found in lymph nodes
* Schizonts increase 10-
fold every 3 days

8. Pathogenesis
Tick inoculation of sporozoites lymphocytes
in local lymph node schizonts lymphoid
proliferation merozoites erythrocytes
piroplasms ticks.
 Damage mainly by schizonts.

9.  Swelling of the draining lymph node, usually the
parotid.
 Generalized lymphadenopathy.
 Fever 40 – 41o C

11.  Poor condition and severe lymphadenopathy in heifer

12. Lacrimation and corneal opacity

13. Dyspnea

14. Diarrhoea

15. Recumbency

16. Death usually within three weeks of
infection

17.  In case of Equine theileriosis there is fever,
anaemia, jaundice and haemoglobinuria.
Jaundice in a horse’s eye

18. 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.

19.  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 tract.
 The carcass is emaciated and hemorrhages are evident in a
variety of tissues and organs.

20. The Ln. is enlarged and diffusely pale, and
contains numerous petechiae.
Pulmonary emphysema and edema
Multiple pale foci on the cortical
surface of the kidney are
lymphoid infiltrates.

21. Emaciated Carcass
Kidney, There are multiple petechiae on
the surface of the cortex. The lymph
node near the hilus is markedly enlargedHydropericardium
Emaciated Carcass

22.  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.

23. 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.

24. 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.

25. In the field, diagnosis is usually achieved by finding
Theileria parasites in Giemsa-stained blood smears and
lymph node needle biopsy smears

26. Theileria Piroplasmosis
Lymphoblasts containing
Theileria parasites

27.  The indirect fluorescent antibody test is of value in
detecting cattle which have recovered from ECF.

28. Differential diagnosis
1. 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.

29. 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.

31. Control
Integrated approach involving resistant
animal breeds.
Vaccination by infection-and-treatment
methods.

32.  Strategic application of
acaricides.

33. Dipping

34. Recommended actions if theileriosis is suspected
• Notification of authorities
Theileria species not reported in Somalia ;
however, Th. parva, is exotic. East Coast fever
and diseases caused by other exotic Theileria
spp. must be reported to state or federal
authorities immediately upon diagnosis or
suspicion of the disease.