Trypanosomosis by Trypanosoma (Megatrypanum) vivax in Ruminants in Brazil: Epidemiology, Clinical Signs, Pathology, Diagnosis, and Control.

In Brazil, Trypanosoma vivax was identified between 1970 and 1984 in buffalo, cattle, and sheep in northern Brazil. In the 1990s, the disease was diagnosed in the Pantanal of Mato Grosso. Currently, the disease is considered in enzootic stability in both regions. From 2006 to 2018, outbreaks of the disease associated with the presence of horseflies (Tabanidae) and stable flies (Stomoxys calcitrans) or transmitted by needle and syringe reuse were diagnosed in sheep, goats, and cattle during the rainy season in the semiarid region of Northeast Brazil, a region considered to have enzootic instability. Since 2013, numerous outbreaks have been diagnosed associated with oxytocin inoculation to induce milk letdown in dairy cows. Most outbreaks occur in cattle transported from areas of enzootic instability to areas of stability, or vice versa. Serological, parasitological, and molecular techniques have identified T. vivax in asymptomatic animals in all Brazilian regions. For disease prophylaxis, it is important not to reuse syringes and needles when administering medication and to avoid transporting animals during periods of insect abundance. It is also necessary to avoid the use of oxytocin or adopt safe injection practices, using disposable or disinfected needles and syringes only for cows with ineffective milk ejection.