Incidência de Anaplasma marginale, Babesia bigemina e Babesia bovis em bezerros no semiárido paraibano

First report of the presence of Anaplasma marginale in different tissues of the stable-fly Stomoxys calcitrans (Linnaeus, 1758) in Rio de Janeiro state, Brazil

Stomoxys calcitrans is a cosmopolitan hematophagous insect with significant veterinary importance. Besides causing great stress with its bites, the fly is a mechanical vector of several pathogens of the most diverse phylogenetic groups to their hosts. The objective of this study was to test for the presence of Anaplasma marginale in stable flies collected at three points inside the campus of the Federal Rural University of Rio de Janeiro (UFRRJ), Seropédica, Rio de Janeiro, Brazil. The collected flies were dissected and separated into three parts - heads, carcass and guts - which were individually submitted to A. marginale specific semi nested PCR gene amplification. A total 150 samples of 50 flies were assayed and 11.33% were positive with predominant presence in guts. In parallel, 6 F1 colony S. calcitrans flies fed with bovine blood were also investigated, being all positive for the presence of the bacteria. This is the first report of the presence of A. marginale in S. calcitrans at Rio de Janeiro state, actually in Brazil, indicating that the epidemiological importance of this vector in the transmission of diseases with great economic impact must not be ignored.

Correlation between Rhipicephalus microplus ticks and Anaplasma marginale infection in various cattle breeds in Brazil

The tick Rhipicephalus microplus is responsible for the transmission of Anaplasma marginale, which causes hemolytic anemia, abortion, decreased production, and mortality in cattle in Brazil. However, A. marginale can also persist in cattle herds without any clinical signs. This study investigated the relationship between the number of ticks present on each cattle and the circulating number of A. marginale msp1β gene copies in the blood of Brangus and Nellore cattle reared in the Brazilian Cerrado through a year period. Twenty-three animals (11 Brangus and 12 Nellore) were raised for 12 months with ticks counted every 18 days, and blood collected every 36 days. Blood sera was used for total antigen iELISA, genomic DNA was extracted from whole blood by the phenol/chloroform method and then analyzed by PCR to confirm A. marginale presence with the msp5 gene. Positive samples were quantified by qPCR using msp1β gene. Brangus cattle presented 4.5 fold more ticks than Nellore group. Although Brangus cattle carried a higher overall A. marginale msp1β gene presence than Nellore cattle, no relationship of tick count and copy number could be achieved due to high variability in copy number. Moreover, both breeds showed similar weight gain and a similar serological pattern throughout the year. None of the animals showed any clinical signs of anaplasmosis during the experimental period, indicating that a low level of tick infestation may be sufficient to maintain a stable enzootic situation.