Detection of Trypanosoma vivax by PCR in a dairy establishment in the province of Santa Fe. Case report.

LIHUE NADIA GONZALEZ; EMMANUEL ANGELI ; SELVA MACHADO ; MARCELO RUIZ ; ROXANNA ZIMMERMANN ; FABIÁN AGUIRRE ; MARIO LAPILLI ; IVÁN MANCIPAR ; IVAN BONTEMPI; MARTIN ALLASSIA

Ciudad Autonoma de Buenos Aires

Congreso; International Congress on Tropical Veterinary Medicine; 2018

Society for Tropical Veterinary Medicine

Trypanosomosis is one of the most significant infectious threats to cattle, being Trypanosoma vivax (T. vivax) the most important causative agent. T. vivax is detected in wild and domestic ungulate animals, including bovines, buffaloes, goats and sheep. Clinically, T. vivax is characterized by fever, anemia, wasting, nervous disorders, and even death, although it can also be subclinical. In South America, T. vivax is mainly transmitted mechanically by hematophagous diptera of the family Tabanidae. In Argentina it was diagnosed for the first time in the north of the country in the province of Formosa, and now it was also reported in the province of Chaco and Córdoba. The present work aims to communicate our findings of T. vivax in bovines of a dairy establishment located in the rural area of San Jerónimo del Sauce, Province of Santa Fe. In June 2018, 8 bovine whole blood samples were sent to the Laboratory of Clinical Analysis of the Animal Health Hospital (FCV UNL) for the diagnosis of Anaplasmosis. The dairy establishment has 240 Holstein cows, and in the course of one month, six had died, after experiencing weight loss, production decrease, and decubitus. One sample was positive to Trypanosoma sp. by microscopy. After 5 days, blood was taken from five animals of the same farm (4 animals with clinical signs and 1 healthy animal) and clinical parameters were evaluated. These samples were subjected to molecular diagnosis by PCR mutiplex, to determine the presence of Trypanosoma spp., T. vivax, T. cruzi and T. evansi and A. marginale DNA. Two were positive for Trypanosoma, resulting to be the T. vivax species. Microscopical observation of Trypanosoma parasites in blood could not always be achieved in animals with the highest degree of anemia or with hyperthermia at the time of extraction, which could be explained by oscillations of parasitemia. One of the T. vivax-positive animals did not present clinical signs, and had not been treated with parasiticide agents. This indicates the presence of asymptomatic carrier animals, which could develop the disease in the face of decreased immunity (nutritional stress, climate, transport), increased production requirements (peak production, late gestation). In conclusion, we have been able to identify cases of cattle infected with T. vivax in the province of Santa Fe, being a province that is further south than the previously reported affected area. This indicates that trypanosomosis is spreading in Argentina, highlighting the need of future prevalence studies to determine the current distribution of the parasite.