RESUMO
The persistence of Babesia bovis and B. bigemina infection in Friesian cows, following vaccination with attenuated live vaccines, was assessed by subinoculation of blood into splenectomized calves. Subinoculation tests showed that B. bigemina persisted in two out of 20 cows vaccinated 10 and 46 months previously, and that B. bovis persisted in 11 out of 22 cows vaccinated 10 to 47 months previously. Antibody was detected in five B. bigemina - and 15B. bovis -vaccinated cows. Parasites of both species persisted among the serologically negative cows, whereas blood obtained from serologically positive cows failed to transmit infection. It is concluded that in the absence of reinfection Friesian cattle may spontaneously eliminate B. bigemina and B. bovis infection after various periods following vaccination.
Assuntos
Babesia bovis/imunologia , Babesiose/imunologia , Doenças dos Bovinos/parasitologia , Vacinas Protozoárias/imunologia , Vacinação/veterinária , Animais , Anticorpos Antiprotozoários/sangue , Babesiose/sangue , Babesiose/prevenção & controle , Bovinos , Doenças dos Bovinos/imunologia , Feminino , Parasitemia/sangue , Parasitemia/parasitologia , Parasitemia/veterinária , Esplenectomia/veterinária , Vacinas Atenuadas/imunologia , Vacinas Atenuadas/normasRESUMO
Forty Friesian one-year-old calves were vaccinated simultaneously with live Babesia bovis and B bigemina vaccines. Three groups of 10 calves each were treated with two, three or four doses of 20 mg kg-1 long-acting oxytetracycline (OTC/LA) at six- to seven-day intervals starting from day 6 after vaccination. Ten animals remained untreated. The treated calves showed considerably fewer days of patency and higher packed cell volumes than the vaccinated untreated calves. All calves developed serum antibodies to both parasites following vaccination. Five months later the 40 vaccinated and 30 new calves were challenged with syringe-transferred virulent parasites of both species. The vaccinated calves showed no parasites or clinical manifestations while calves of the new group exhibited severe clinical babesiosis. These results show that when OTC/LA is administered following anti-babesial vaccination, parasitaemia and red blood cell destruction are significantly reduced without, however, inhibiting the development of immunity.