RESUMO
Background: Today only indirect fluorescent antibody assays (IFAs) are commercially available to detect antibodies against Babesia divergens in humans. IFA is subjective and requires highly experienced staff. We have therefore developed an enzyme-linked immunosorbent assay (ELISA)-based method for measuring anti-B. divergens immunoglobulin G antibodies in human blood samples. Methods: Crude merozoite extract from in vitro cultures of a new B. divergens isolate was used in ELISA to detect antibodies in different sets of samples: Borrelia burgdorferi-positive samples, healthy individuals, tick-bitten individuals including follow-up samples 3 months later, positive control samples from patients with an active Babesia infection, and samples from malaria-endemic regions. As a reference, IFA was used to detect antibodies in the tick-bitten samples. Western blot was used to evaluate reactions against specific bands in extracts with/without parasites. Results: Using IFA as the reference method, the sensitivity and specificity of the ELISA were 86% (12/14) and 100% (52/52). There was a very high correlation (r = -0.84; P = .0004) between IFA dilution factors and ELISA absorbances among the samples classified as positive. Five percent of the B. burgdorferi-positive samples were judged as weakly positive and 5% as strongly positive in our ELISA. Western blot showed that the immunodominant antigens (â¼120â kDa) were from merozoites and not from erythrocytes. Conclusions: This ELISA can detect antibodies directed against B. divergens, and it can be a useful and easy assay to handle compared with IFA. The ELISA can also measure high and low levels of antibodies, which could give insight into the recency of a B. divergens infection.
RESUMO
Background: For the most important and well-known infections spread by Ixodes ticks, Lyme borreliosis (LB) and tick-borne encephalitis (TBE), there are recommendations for diagnosis and management available from several health authorities and professional medical networks. However, other tick-borne microorganisms with potential to cause human disease are less known and clear recommendations on diagnosis and management are scarce. Therefore, we performed a systematic review of published studies and reviews focusing on evaluation of laboratory methods for clinical diagnosis of human tick-borne diseases (TBDs), other than acute LB and TBE. The specific aim was to evaluate the scientific support for laboratory diagnosis of human granulocytic anaplasmosis, rickettsiosis, neoehrlichiosis, babesiosis, hard tick relapsing fever, tularemia and bartonellosis, as well as tick-borne co-infections and persistent LB in spite of recommended standard antibiotic treatment. Methods: We performed a systematic literature search in 11 databases for research published from 2007 through 2017, and categorized potentially relevant references according to the predefined infections and study design. An expert group assessed the relevance and eligibility and reviewed the articles according to the QUADAS (diagnostic studies) or AMSTAR (systematic reviews) protocols, respectively. Clinical evaluations of one or several diagnostic tests and systematic reviews were included. Case reports, non-human studies and articles published in other languages than English were excluded. Results: A total of 48 studies fulfilled the inclusion criteria for evaluation. The majority of these studies were based on small sample sizes. There were no eligible studies for evaluation of tick-borne co-infections or for persistent LB after antibiotic treatment. Conclusions: Our findings highlight the need for larger evaluations of laboratory tests using clinical samples from well-defined cases taken at different time-points during the course of the diseases. Since the diseases occur at a relatively low frequency, single-center cross-sectional studies are practically not feasible, but multi-center case control studies could be a way forward.
