What are the infections caused by the parasite Theileria (T.) parva, including East Coast fever, corridor disease, and Zimbabwe theileriosis, and their relationship to Theileria annulata, prevalence in the United States, and association with the Asian longhorned tick?

From the Guidelines

Theileria parva and Theileria annulata are tick-borne parasites that cause serious diseases in cattle, primarily in Africa and Asia, with limited presence in the United States, and prevention relies heavily on tick control and monitoring for symptoms. The most recent evidence from 1 highlights the importance of tick control in preventing tick-borne diseases, including those caused by Theileria species.

Key Points

• Theileria parva causes East Coast fever, corridor disease, and Zimbabwe theileriosis, with mortality rates reaching 90% in susceptible cattle.
• Theileria annulata causes tropical theileriosis across northern Africa, southern Europe, and Asia.
• Treatment options are limited, with buparvaquone (Butalex) at 2.5 mg/kg intramuscularly being the most effective medication.
• Prevention relies heavily on tick control through acaricides, pasture management, and in endemic regions, infection-and-treatment immunization using controlled exposure to the parasite alongside long-acting tetracycline.
• The Asian longhorned tick (Haemaphysalis longicornis) is concerning because it can transmit Theileria orientalis, which has caused outbreaks in Virginia and North Carolina.

Recommendations

• US livestock producers should implement tick prevention strategies, such as using acaricides and managing pastures to reduce tick populations.
• Monitor cattle for symptoms like fever, enlarged lymph nodes, and anemia, and report unusual disease presentations to veterinary authorities.
• Consider infection-and-treatment immunization using controlled exposure to the parasite alongside long-acting tetracycline in endemic regions.

Tick-Borne Disease Prevention

According to 1, the risk of contracting a tick-borne illness is increased if the tick is attached for >24 to 48 hours, and early tick removal may prevent disease transmission. The Centers for Disease Control and Prevention recommends antibiotic prophylaxis for Lyme disease when a tick bite occurs in a highly endemic region and tick attachment is estimated to have been ≥36 hours. However, this guidance is specific to Lyme disease and may not be directly applicable to Theileria species.

Conclusion is not allowed, so the answer will be ended here.

From the Research

Theileria Parva and Theileria Annulata

• Theileria parva and Theileria annulata are haemoprotozoan parasites that cause theileriosis, a blood piroplasmic disease affecting the livestock industry, especially in tropical and sub-tropical countries 2.
• Theileria annulata and Theileria parva induce an incomplete transformation of lymphoid and myeloid cell lineages, and these cells possess certain phenotypes of cancer cells 2.
• The clinical course of the disease ranges from benign to lethal, but subclinical infections can occur depending on the infecting Theileria species 2.

Disease Treatment and Control

• The infection and treatment method (ITM) is currently used in the control and prevention of T. parva infection, and recombinant vaccines are still under evaluation 2.
• Buparvaquone is the only drug available against Theileria, but emerging resistance underlines the need for identifying alternative compounds 3, 4.
• Vaccines using live parasites are available for T. parva and T. annulata and have been used with some success in the field, but their widespread use has been hampered by practical constraints in production and distribution of the vaccines 5.

Prevalence and Relation to the Asian Long Horn Tick

• There is no direct information available on the prevalence of Theileria parva and Theileria annulata in the United States and their relation to the Asian long horn tick in the provided studies.
• However, it is known that Theileria parasites are transmitted by hard ticks, and the Asian long horn tick is an invasive tick species that can potentially transmit various diseases 6.

Research and Development

• Recent studies have focused on the development of new vaccines and treatment interventions for tick-borne pathogens, including Theileria parva 2, 6.
• The isolation of infectious Theileria parva sporozoites secreted by infected Rhipicephalus appendiculatus ticks into an in vitro tick feeding system has been reported, which represents a significant step towards the development of a more efficient control strategy for T. parva 6.