Theileria causes disease in domestic and wild animals as a parasite on ticks. Millions of animals are at risk every year. This parasite has the capability of causing a worldwide food shortage and total devastation to poor farmers in the Third World. According to the Department of Animal Biotechnology, ” At least five species of Theileria (T. parva, T. annulata, T.taurotragi, T. velifera and members of the T. sergenti/ orientalis / buffeli group) have been found to infect cattle. Theileria parasites enter the bovine host during tick feeding as sporozoites, which rapidly invade mononuclear leukocytes.”
These six or more species of theileria are carried by the host tick, which differs from region to region. The tropical theileriosis affects cattle in tropical and sub-tropical regions of the world: North Africa, Southern Europe, through the Middle East and across Southern Asia. Theileria annulata is a protozoan parasite that passes through known stages as it develops in leukocytes and erythrocytes of the mammal host, causing acute illness, including death.
East Coast Fever Theileria parva was first described in 1992 in Zimbabwe. The symptoms in both infections are very similar, including anorexia, nasal discharge, diarrhea, fluid in and around the lungs, and anemia. The parasites from both species cause the white blood cells to divide, allowing the parasites to divide, growing much like cancerous tumors. In some cases, the red blood cells are also affected.
Fever usually begins seven to ten days after cattle are infected. Death can occur between 17 to 25 days – depending upon the cattle stock – after an infected tick begins to feed on the cattle. Animals that manage to recover are immune to re-infection by the same strain of parasite, but may be susceptible to another strain.
The theileria parasite is not the only parasite carried by ticks in these regions of the world. Farmers, large cattle ranchers, and individuals fight a constant battle to beat back the ticks with poisons that the ticks become immune to quickly. There is even a species of the theileria that affects humans.
Other species of theileriases affect sheep and goats. Two species have been identified in which the incidence of death is as high as 100 percent. T. lestoquardi is found in Southern Europe, Africa, and throughout Asia. T. orientalis is found in the Far East where death is rare, but chronic anemia is common in infected animals.
The livestock industry is vital in the agricultural economies of the countries affected by these parasites. Farmers in these regions can not afford the expensive vaccine that was registered by the governments of Kenya, Malawi and Tanzunia in May of 2010. Medication like buparvaquone yields a 90 to 98 percent recovery if administered quickly enough. The cost of medicine is outside the reach of most farmers. Catching the infection soon enough is difficult due to the difference in life stages of the parasite as it multiplies throughout the host animal.
Native cattle appear to have a better resistance to the parasites than the dairy breeds brought in from other countries to cross-breed in an effort to satisfy the need for meat and dairy production in endemic areas.
There are non-profit agencies and Trusts that are constantly seeking information that may provide the answers to this devastating parasite. Any answer must be economically feasible for individuals and small holder farmers. The answer must be practical and include a means of destroying host ticks without harming the environment.
Sources: Merck Veterinary Manual
Theileria
