BREATHITT VETERINARY CENTER DIAGNOSTIC ROUNDS


Teileria orientalis Ikeda in Western Kentucky Cleon G. Hendricks, DVM, MPH, Assistant Professor Breathitt Veterinary Center ~ Murray State University


In mid-October, a referring veterinarian in West-Central Kentucky submitted a spleen and whole blood sample (in Ethylenediaminetetraacetic Acid [EDTA]/ “purple top” tube), from a 10-year-old female cow that died suddenly. Suspicious of anaplasmosis, the referring veterinarian also submitted serum and whole blood from an 8-year-old living herd-mate. Histopathology was requested on the spleen. Polymerase Chain (PCR) and complement-enzyme linked immuno-sorbet assay (CELISA) for anaplasmosis were requested on serum and blood samples, respectively.


Histologic examination on a cross section of the spleen revealed moderate number of neutrophils mixed with cellular debris and variably size aggregates of dark brown to gold granular material. Few macrophages contained this material within their cytoplasm. Histologic findings were reported as moderate multifocal fibrino-necrotitzing splenitis. PCR and CELISA for anaplasmosis were negative. Te attending pathologist offered to send whole blood samples to Virginia Tech Animal Laboratory Services (ViTALS) for duplex PCR testing, targeting Teileria orientalis and Anaplasma marginale. Results detected Teileria orientalis in the samples. Cycle threshold values (Ct values) and genotyping were not provided. Te samples were neg- ative for Anaplasma marginale. Upon receipt of the results, the referring veterinarian and State Veterinarian were notified.


Discussion: Lifecycle, transmission, clinical signs, testing, control measures and tick identification/submission were covered in the Summer 2022 issue of KVMA by Drs. Laura Kennedy and Michelle Arnold (University of Kentucky Veterinary Diagnostic Laboratory—UKVDL). Tis article can be found at http://www.modern- pubsonline.com/0A41ltr/Summer2022/html/index.html?page=49. Te aim of this communication is to reiterate the emerging risk this pathogen poses to the state’s cattle in- dustry. An infographic complementing this communication can be distributed to clients in order to promote awareness and management practices concerning this emerging threat.


Teileria orientalis is a vector-borne protozoan hemoparasite transmitted by the Asian Longhorn Tick (ALT), Haemaphysalis longicornis.1 First encountered in Virginia, sightings of the ALT range as far west as Missouri, as far north as New York, and as far south as Georgia.2


has a history of negatively impacting the cattle industry in the Asian-Pacific region.1 the organism is the sporozoite, which infects lymphocytes.1,4


schizonts (or “Koch’s bodies”); schizonts rupture, releasing merizoites that infect erythrocytes.4


Anemia, weakness, pallor, increased respiratory rate, elevated heart rate, fever, and jaundice are a few clinical signs of infection.1,3


calves and pregnant heifers at highest risk for infection.1,3


Approximately 5% of infected animals demonstrate severe clinical signs and death, with Transmission of Teileria orientalis from the ALT


to the cow can take up to 72 hours after attachment and feeding, but is accelerated during high environ- mental temperatures.3


infections occur within 3 weeks of naive cattle arriving to an endemic area. Under ideal conditions, infected ticks can survive on pastures for up to 2 years.1,3


Prevention is multimodal, involving physical inspection, pesticide application, wildlife avoidance, perim- eter awareness (avoiding wooden areas), and pasture maintenance. Te Virginia Cooperative Extension provides an excellent resource for managing ALTs.5


PCR is the gold standard for diagnosing Teileria orientalis. In addition to molecular testing, evaluation of a fresh blood smear is a quick, and low cost method that might assist in verifying the presence of the organism. Infected red blood cells harbor merozoites, characterized by variably centered, 1-2.5um wide signet-ring to comma shaped, to tear shaped, purple organisms (piroplasms).1,4


It is important to know


that both pathogenic and nonpathogenic forms of Teileria exhibit similar microscopic characteristics.4 30 KVMA News


Continued on pg. 31 Te incubation period is thought to be as long as 14 days post infection. Reported


Te most virulent strain is the Ikeda, which Te infectious stage of


Within the lymphocyte, the sporozoites form


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