Trypanosomes in cattle in southern Ontario

Area of Science:

• Veterinary Parasitology
• Protozoology
• Animal Health

Background:

• Trypanosomiasis is a significant concern in livestock globally.
• Previous research has documented Trypanosoma theileri in cattle, but other species remain less characterized in North America.
• Holstein cows are a prevalent dairy breed, making them important subjects for disease surveillance.

Purpose of the Study:

• To investigate the prevalence and species of trypanosomes in Holstein cows in southern Ontario.
• To characterize a novel, small trypanosome species found in cattle.
• To assess the viability of trypanosomes under controlled conditions.

Main Methods:

• Blood samples were collected from 274 Holstein cows of various ages in southern Ontario.
• Trypanosome species were identified morphologically and through inoculation into chick embryos.
• The survival of Trypanosoma theileri in refrigerated blood was evaluated.

Main Results:

• Trypanosomes were identified in 155 (56.6%) of the 274 cows sampled.
• Two species were found: Trypanosoma theileri and a smaller species resembling T. uniforme.
• The incidence of infection varied significantly between herds, ranging from 8% to 85%.
• Epimastigotes from both species successfully produced morphologically identical blood forms in chick embryos.
• Trypanosoma theileri demonstrated survival for at least two weeks in refrigerated blood (4-5°C).

Conclusions:

• This study confirms the presence of Trypanosoma theileri and reports the first North American detection of a small trypanosome species, morphologically similar to T. uniforme, in Holstein cattle.
• The findings highlight the need for further investigation into the epidemiology and potential impact of these trypanosomes in Canadian cattle populations.
• The successful experimental transmission and survival data provide a basis for future research on vector competence and disease transmission dynamics.