Diagnóstico molecular e taxas de infecção de Anaplasma marginale e Babesia bovis em rebanhos bovídeos e artrópodes parasitas na Amazônia.

Abstract

Anaplasmosis and Babesiosis are endemic diseases in cattle and buffaloes in tropical and subtropical regions of the world, and those, in the most of the time they are not differentiated and is known as cattle tick fever (CTF). In South America, both pathologies are directly related to the occurrence of the cattle tick, Rhipicephalus microplus, main vector of Anaplasma marginale, Babesia bovis and Babesia bigemina. In both hemoparasites diseases, the participation of the vertical transmission of the pathogens is considered without epidemiological importance, both in cattle and in buffaloes. We sought to establish the epidemiological participation of the transplacental transmission of A. marginale and B. bovis, as well as a participation of arthropods parasites in the epidemiology of anaplasmosis and babesiosis in bovine and buffaloes herds in Amazonia through molecular approaches. The polymerase chain reaction (PCR) and the nested PCR (nPCR) were used, respectively, for the specific diagnosis of A. marginale and B. bovis from bovine, buffalo and arthropod DNA samples collected in herds. The results showed that all bovine cows were infected by A. marginale at birth and the congenital infection rate was 81.25% (13/16). The rate of B. bovis infection in bovine cows was 93.75% (15/16) and a congenital infection rate was 81.25% (15/16). In buffaloes, the infection rate of A. marginale in the cows in the moment of birth was 61.54% (8/13) with a congenital infection rate of 23.08% (3/13). The B. bovis rate infection in cows was 53.84% (7/13) with a congenital infection rate of 30.77% (4/13). All animals were asymptomatic carriers of the agents that caused BPS. The prevalence in tick larvae was 44.4% (200/450) for A. marginale and 55.9% (247/450) for B. bovis. In hematophagous dipterans, adults of horn fly, Haematobia irritans, colletcted in cattle have a prevalence of 11.4% (27/236) for A. marginale and 9.3% (22/366) for B bovis , while in Stomoxys calcitrans flies collected on buffaloes showed an infection rate of 1.5% (1/65) for A. marginale and 12.3% (8/65) for B bovis. The observed transplacental transmission rates demonstrate that this is an important epidemiological route in bovine and buffalo herds, but their participation in the epidemiology of A. marginale and B. bovis in Brazil has been underestimated. The participation of hematophagous dipterans in the epidemiology of CTF requires further clarification, especially with regard to the viability of infection of the parasites present in the oral apparatus of these dipterans for the vertebrate host.