Asian Longhorned Tick and Theileria orientalis: A Growing Risk for PA Cattle

Asian Longhorned Tick

(Haemaphysalis longicornis; also known as ALT)

• Invasive species first recognized in the United States in 2017
• Prefers feeding on livestock
• Females reproduce without a male, so a single tick can start a new population
• The population is nearly 100% female, so all ticks can lay eggs, resulting in massive population explosions

Theileria orientalis genotype Ikeda

• Blood-borne parasite of cattle transmitted by ALT
• Infected cattle often show no signs of disease, but some will develop severe anemia causing weakness, jaundice, and pale gums
• Clinical signs are the same as those of anaplasmosis

No treatment available, and infection is considered lifelong; supportive care may help recovery

Preventing T. orientalis Transmission

1. If the established herd is T. orientalis-negative, test new cattle before entry to avoid purchasing positive animals
2. Treat new cattle with antiparasitics to reduce entry of new ticks
3. Ensure proper nutrition to strengthen immunity and prevent clinical disease

Tick Management

1. Eliminate or fence off tall grass and brushy areas on pasture to reduce tick exposure
2. Send ticks or photographs of ticks to the Insect Identification Lab at Penn State
3. Talk with your veterinarian about using systemic parasite control products for better coverage

Testing

1. Knowing herd status will allow for easier decisions when moving cattle
2. Work with your veterinarian to test animal status by PCR at the PA Animal Diagnostic Laboratory System

Managing Cattle Movement Amid T. orientalis Ikeda Concerns

Considerations for buying and selling safely

With T. orientalis genotype Ikeda, buying a positive animal can sometimes pose risks but at other times can be the safer choice. Use the guide below to help you decide.

Established Herd: NEGATIVE
Newly Purchased Animal: NEGATIVE

1. This is a SAFE movement of cattle
2. A quarantine is still recommended
3. Discuss retesting with your veterinarian if the source herd has any Theileria-positive animals
4. Treating purchased animals with parasiticide may help reduce the risk of ALT entry

Established Herd: POSITIVE
Newly Purchased Animal: POSITIVE

1. This is a SAFE movement of cattle
2. A quarantine and/or additional testing is still recommended for other diseases
3. Discuss herd parasiticide treatments with your veterinarian to help manage ALT populations

Established Herd: NEGATIVE
Newly Purchased Animal: POSITIVE

1. There is an INCREASED RISK in this movement of cattle
2. The established herd is at risk of disease
3. If any of the following are present, Theileria could spread quickly in the herd:
   • ALT present and cattle on pasture
   • Needles are used on multiple animals before being discarded
4. The following reduce the risk of disease transmission:
   
   • ALT not present or cattle kept in confinement
   • Strict single-use of needles

Established Herd: POSITIVE
Newly Purchased Animal: NEGATIVE

1. There is an INCREASED RISK in this movement of cattle
2. The newly purchased animal is at risk of disease
3. If any of the following are present, Theileria could spread quickly in the herd:
   
   • ALT present and cattle on pasture
   • Needles are used on multiple animals before being discarded
4. The following reduce the risk of disease transmission:
   
   • ALT not present or cattle kept in confinement
   • Strict single-use of needles

Resource

Rainey T, Occi JL, Robbins RG, and Egizi A. "Discovery of Haemaphysalis longicornis (Ixodida: Ixodidae) parasitizing a sheep in New Jersey, United States." Journal of Medical
Entomology 55 (3): 757–759.

Prepared in collaboration by Penn State Extension and the Pennsylvania Department of Agriculture.