Tropical theileriosis
Also called Tick fever (Theileria annulata), East Coast fever in Africa
A tick-borne blood parasite disease of cattle and buffalo that causes high fever, swollen lymph nodes and anaemia.
Cause and spread
- Cause
- The protozoal parasites Theileria annulata (tropical theileriosis) and Theileria parva (East Coast fever), spread by ticks.
- How it spreads
- By ticks that carry the parasite from animal to animal; it is not spread by casual contact. Hyalomma ticks carry T. annulata and Rhipicephalus ticks carry T. parva. Blood transfer by shared needles can also spread it.
Signs to watch for
- High fever, loss of appetite and weakness
- Swollen lymph nodes (glands in front of the shoulders)
- Pale or yellow gums, anaemia and weight loss
- Fall in milk yield
- Small bleeding spots on the gums and eyes, and discharge from the nose
- Difficulty breathing in the final stages
Many diseases look alike. Only a laboratory test can tell them apart, so please see a veterinarian for any sick animal.
How it is diagnosed
A stained blood smear shows the parasites in red blood cells, and a smear from a swollen lymph node shows the parasite stages in white cells. PCR detects the parasite's genes and can find infection when few parasites are seen. A blood count shows anaemia.
- Usually the first testBlood Smear ExaminationLooks for the parasite inside red blood cells.
- Usually the first testBasic Haemoparasite Panel (CBC + Blood Smear) (panel)Blood count and blood smear together.
- Confirms the diseaseTheileria PCRDetects the parasite's genes, even when few parasites are in the blood.
- Confirms the diseaseBovine Haemoparasite PCR ProfileTests for Theileria, Babesia, Anaplasma and Trypanosoma at once.
- Supports the diagnosisComplete Blood Count (CBC)Shows anaemia and changes in white cells.
Prevention and control
- Control ticks with acaricides and good grazing management
- Avoid sharing needles and blood between animals
- Check animals regularly for ticks during the tick season
- Vaccines exist in some countries; ask your veterinarian
Where this information comes from
- Theileriosis: Theileria parva and Theileria annulata (factsheet) · Center for Food Security and Public Health, Iowa State University
General information for animal owners and veterinarians, last checked October 2026. It does not replace the advice of your veterinarian, who should decide which tests and treatment your animal needs.