Babesiosis
Babesiosis is a disease caused by parasites that lodge inside the red blood cells of animals. It is distributed in tropical and subtropical regions of the world, where the ticks that transmit it are also found. In Mexico, Babesia bovis and Babesia bigemina cause the disease in cattle, while Babesia vogeli affects dogs.
Babesias destroy red blood cells and impair the animal's health, which can lead to death.
Clinical signs
The main sign of the disease is a high fever (39.5–41°C). Animals also suffer from anemia, weakness, yellowing of the mucous membranes, depression, reddish urine, increased respiratory rate, abortions in pregnant females, and death.
Infections caused by Babesia bovis may present with nervous signs, such as incoordination and coma.
Clinical signs appear two to three weeks after the bite of a tick infected with Babesia.
Transmission
A tick bite is necessary for an animal to become ill. The disease can also be acquired by sharing needles between animals, sharing surgical equipment, or receiving blood transfusions.
Babesia is acquired by an adult tick after biting an infected and/or sick animal. Once the tick detaches from the cattle, the parasites travel to the female's ovaries and infect the eggs. This means that the next generation of ticks will be infected with Babesia and can transmit the disease to cattle; this phenomenon is known as transovarial transmission.
Disease management
Cattle are resistant to the disease for the first 9 months of age, meaning they rarely show clinical signs during this period.
In areas where the relationship between ticks, disease, and cattle is very close, a phenomenon called enzootic stability occurs. This phenomenon is characterized by the absence of clinical signs in animals but the parasite circulating in the herd.
This enzootic stability can be broken if animals are not infected during their resistance window. A decline in tick populations can lead to a breakdown in enzootic stability in an area. Climate change and the use of acaricides are factors that modify the number of ticks circulating in the environment.
For this reason, it is necessary to diagnose the disease before the animals' resistance period ends, in order to take corrective actions to prevent the disease in animals.