Objective—To quantify the number of horses with Corynebacterium pseudotuberculosis infection identified in the United States from January 2003 through December 2012.
Sample—State veterinary diagnostic laboratory records of 2,237 C pseudotuberculosis culture-positive samples from horses.
Procedures—44 state veterinary diagnostic laboratories throughout the United States were invited by mail to participate in the study. Data requested included the number of C pseudotuberculosis culture-positive samples from horses identified per year, geographic location from which the C pseudotuberculosis culture-positive sample was submitted, month and year of sample submission, breed and age of horses, and category of clinical manifestation (ie, internal infection, external infection, or ulcerative lymphangitis).
Results—Of the 44 invited laboratories, 15 agreed to participate and provided data on affected horses from 23 states. The proportion of C pseudotuberculosis culture-positive samples submitted during 2011 through 2012 (1,213/2,237 [54%]) was significantly greater than that for the period from 2003 through 2010 (1,024/2,237 [46%]). Corynebacterium pseudotuberculosis was recovered from horses in states where the disease has not been previously recognized as endemic. Affected horses were identified year-round. The greatest proportion of C pseudotuberculosis culture-positive samples was identified during November, December, and January (789/2,237 [35%]). No significant association between the clinical form of disease and age or breed of horse was observed.
Conclusions and Clinical Relevance—The occurrence of C pseudotuberculosis infection in horses increased during the 10-year period, and affected horses were identified throughout the United States. Further studies to determine changes in annual incidence and to identify potential changing climatic conditions or vector populations associated with disease transmission are warranted to help control the occurrence and spread of C pseudotuberculosis infection in horses.
Objective—To evaluate effects of high incubation temperatures on results of protozoal culture and real-time PCR testing for Tritrichomonas foetus inoculated in a commercially available self-contained culture media system.
Design—In vitro experimental study.
Sample—2 strains of T foetus (1 field isolate from the University of California-Davis and 1 field isolate from the Texas Veterinary Medical Diagnostic Laboratory).
Procedures—2 sets of 36 dual-chamber media pouches were inoculated with T foetus (36 sample pouches/strain) and incubated at temperatures of 37.0°C (98.6°F), 46.1°C (115.0°F), or 54.4°C (130.0°F) for 1, 3, 6, or 24 hours. Six uninoculated media samples in pouches stored at 37.0°C for the entire treatment period were used as negative controls. Pouches were removed from incubators and stored at 22.2°C (72.0°F) until all treatments were complete. Samples were submitted to a diagnostic laboratory for protozoal culture and real-time PCR testing.
Results—T foetus was detectable microscopically in inoculated pouches incubated at 37.0°C regardless of exposure time, whereas those incubated at 46.1°C yielded T foetus after 1 and 3 hours only, and those incubated at 54.4°C yielded T foetus after 1 hour only. Testing via real-time PCR assay yielded positive results for all inoculated media samples and negative results for all uninoculated control samples.
Conclusions and Clinical Relevance—Samples collected into the self-contained culture media system for T foetus testing via culture alone should be protected from high temperatures. Realtime PCR amplification may be a more reliable method for identification of the organism if storage and transport temperatures cannot be controlled.