THEILERIOSIS IN GOAT & SHEEP
Dr Ajeet sharan,TVO,Gomoh
Theileriosis is tick borne disease of sheep and goats, cattle, buffalo and wild ruminants caused by species of protozoa in the genus Theileria. In sheep and goats, the infections are caused by T. hirci and T. ovis.
Theileria hirci is the cause of an acute and highly fatal disease of sheep and goats . The subacute and chronic forms have also been reported. Mild infection in noted young lambs and kids.
Theileria ovis causes a milk disease in sheep and goats; a disease from which they rapidly recover.
⭕Transmission :
The thick vector is unknown in Theileria hirci infection, although Hyalomma spp. are suspected.
🔴Sources of the agent
⭕Theileria parva/East Coast fever (ECF):
➡️Sporozoites in salivary glands of infected Rhipicephalus appendiculatus ticks
➡️Schizonts occur in spleen, lymph nodes and whole blood (lymphoblasts) from ECF-infected
animals; experimental transmission to cattle is erratic
⭕Theileria annulata/Tropical theileriosis (TT):
➡️Sporozoites in salivary glands of infected Hyalomma spp. ticks
➡️Schizonts occur in spleen, lymph nodes, liver and whole blood (mononuclear cells) from TT infected animals; transmission by inoculated schizonts occurs readily to cattle
⭕theileria orientalis/Oriental theileriosis (OT)-Theileria-associated bovine anaemia (TABA)
➡️Sporozoites in salivary glands of infected Haemaphysalis spp. ticks
➡️ Schizonts can be detected transiently in the lymph nodes, spleen and liver. Piroplasms can
be detected in the erythrocytes at approximately 10 days post inoculation.
⭕theileria lestoquardi/Malignant ovine theileriosis (MOT)
➡️Sporozoites in salivary glands of infected Hyalomma spp. ticks
➡️ Schizonts occur in lymph nodes, spleen and liver. The schizonts produce many merozoites
that are released after lymphocyte disruption, enter the erythrocytes and transform to
piroplasms with ring, dot and rod forms
•⭕theileria uilenbergi and Theileria luwenshuni
➡️Sporozoites in salivary glands of infected Haemaphysalis spp. ticks
➡️Schizonts can be detected in lymph nodes, spleen and liver. Piroplasms can be detected in the erythrocytes
🔴antemortem findings :
In acute form
1. Morbidity rate of 100 % and mortality of 46 – 100 %
2. Fever (40°C – 41°C)
3. Loss of appetite and listlessness
4. Increased heart rate and difficult breathing
5. Edema of the throat and subsequent death
6. Hyperaemia of the conjunctiva and nasal discharge
7. Swollen superficial lymph nodes
8. Atony of the rumen in the chronic form
9. Mild fever, anaemia, icterus, weakness and emaciation
🔴postmortem findings :
1. The lesions are basically similar as those observed in bovine Theileriosis (T. parva).
2. Edema of the lungs
3. The yellowish-brown liver may be increased in size and shows soft and friable consistency.
4. Enlarged haemorrhagic lymph nodes and enlarged spleen
5. Kidney infarcts
6. Petechial haemorrhage in subcutaneous, subserosal and submucosal tissue
🔴Differential diagnosis
• Heartwater
• Trypanosomosis
• Babesiosis
• Anaplasmosis
• Malignant catarrhal fever
• Contagious bovine pleuropneumonia
• The parasites must also be differentiated from other species of Theileria
🔴Management
Immediately reducing pressure on the affected animals. This can be achieved by:
Once a day milking
Minimised handling
When bringing into the shed, let them go at their own pace (don’t push them)
Good quality feed
🔴Treatment
Treatment options for benign theileriosis are limited to supportive care and symptomatic treatment.
Blood transfusion has been performed occasionally on valuable animals. Animals improve following transfusion but it is expensive and not practical if multiple animals are involved.
Most importantly, stress and movement of affected animal should be minimised or their reduced ability to transport oxygen throughout the body may lead to collapse. They should be rested, nursed and given high quality feed. Handling of affected cattle should be avoided where possible; if movement or yarding is necessary, move animals slowly.
A number of chemicals are known to work against the parasite, including buparvaquone (BPQ).
Of the few drugs that could potentially be used against Theileria orientalis infections, the most promising is buparvaquone (BPQ), which has been used effectively against exotic Theileria parasites.
Reference-On request.
