New methods for the diagnosis of Babesia bigemina infection

Abstract

Accurate diagnosis of Babesia bigemina infection, an economically important tick-transmitted protozoan parasite of cattle, is essential in the management of disease control and in epidemiological studies. The currently used methods of diagnosis are blood smear examination and serological tests which include agglutination and immunofluorescence tests. These tests have been used in the fild but because they lack sensitivity and specificity, newer and improved methods of diagnosis are being developed. The quantitative buffy coat (QBC) method, using microhaematocrit tubes and acridine orange staining allows rapid and quicker diagnosis of B. bigemina and other blood parasites compared to light microscopic examination of stained smears. Parasite specific monoclonal antibodies have been used in antigen/antibody capture enzymelinked immunosorbent assays with greater sensitivity and specificity than previously described serological tests. Similarly, DNA probes, derived from a repetitive sequence of the B. bigemina genome, offer a method of detecting very small numbers of parasites which are undetectable by conventional microscopy. An extrachromosomal DNA element, present in all the tick-borne protozoan parasites so far tested, provides an accurate means of differentiating mixed parasite populations in infected animals. These improved methods will greatly facilitate epidemiological studies.

Development of an enzyme-linked immunosorbent assay for detection of antibodies to Babesia bigemina in cattle

“…Cross-reaction of antibodies to B. bovis is an added complication in regions where the two parasites occur simultaneously (Morzaria et al 1992; de Vos and Jorgensen 1996). Enzyme-linked immunosorbent assays (ELISAs) have been successfully developed for the detection of antibodies to other Babesia species (Wright 1990;BoÈ se et al 1995), but several complicating factors have impeded the development of an assay for B. bigemina.…”

“…Reviews by Palmer (1991), Morzaria et al (1992) and El-Ghaysh et al (1996) have concluded that a sensitive and speci®c test for antibodies to B. bigemina would require puri®ed antigen and/or monoclonal antibodies (MoAbs). Morzaria et al (1992) described an ELISA based on a 200-kDa parasite antigen that was in the early stage of development, but that assay required the use of antigen-and antibody-detection ELISAs together to improve its sensitivity beyond that of the IFAT. In a recent review of serological tests for diagnosis of babesiosis, BoÈ se et al (1995) concluded that existing serological tests for B. bigemina were inadequate and that the development of an improved test was a priority.…”

Tristeza Parasitária em bovinos do semiárido pernambucano

“…Informações sobre a epidemiologia de doenças transmitidas por carrapatos, especialmente sobre a dinâmica de transmissão da infecção por este vetor, são essenciais para elaboração de eficientes estratégias de controle (Morzaria et al 1992). No Brasil, escassos estudos têm sido realizados utilizando carrapatos na detecção da infecção por Babesia spp.…”

Validation of a Competitive Enzyme-Linked Immunosorbent Assay for Detection ofBabesia bigeminaAntibodies in Cattle

“…Other serological methods that have been developed and utilized in the past include an indirect immunofluorescence assay (6) and a number of ELISA-based formats (4,17). Although these assays allow the detection of infected cattle, they all have limitations in specificity, sensitivity, and reliability to some degree; and the indirect immunofluorescence assay requires subjective interpretation and low throughput.…”