OLIVEIRA, Márcia Cristina de Sena.; OLIVEIRA, Henrique Nunes de.; REGITANO, Luciana Correia de Almeida.; ALENCAR, Mauricio Mello de.; NÉO, Thalita Athiê.; SILVA, Ana Mary da.
Resumo:
Babesia bigemina infections were investigated in four
genetic groups of beef cattle and in Rhipicephalus (Boophilus)
microplus engorged female ticks. Blood samples and engorged
female ticks were collected from 15 cows and 15 calves of each
of the following genetic groups: Nelore (NE), ½ Angus +
½ Nelore (NA), ½ Canchim + ½ Nelore (CN) and ½ Simmental
+ ½ Nelore (SN). Microscopic examination of blood smears
and tick hemolymph revealed that merozoites of B. bigemina
(6/60 - 10%) as well as kinetes of Babesia spp. (9/549 - 1,6%)
were only detected in samples (blood and ticks, respectively)
collected from calves. Polimerase chain reaction (PCR) based
methods using primers for specific detection of B. bigemina
revealed 100% of infection in both calves and cows, regardless
the genetic group. Tick infection was detected by nested PCR
amplifications showing that the frequency of B. bigemina was
higher (P < 0.01) in female ticks collected from calves (134/
549 - 24,4%) than in those collected from cows (52/553 -
9,4%). The frequency of B. bigemina was similar in ticks
collected from animals of the four genetic groups (P > 0.05).
The larval hatching rates were significantly lower for engorged
females ticks with positive reaction for B. bigemina (53.5%)
than those with negative reaction (65.9%). There was no
difference between larval hatching rate of females ticks
collected from the four genetic groups.