Serodiagnostic methods for diagnosing larval toxocariasis

A new ELISA and western blot technique based on recombinant TES antigen and/or larval antigen for the detection of toxocariasis in humans

“…Testing of the pre-determined samples by Proto-ELISA indicated a high sensitivity of 93.1% and specificity of 94.6%, which is in accordance with the values obtained for ELISAs established in other studies and/or developed by other manufacturers (Smith and Noordin, 2006;Noordin et al, 2020). Jin et al (2013) designed an ELISA based on larval somatic antigen displaying a sensitivity of 92.2% and specificity of 86.6%.…”

“…According to Jacquier et al (1991) there are problems to exclude the presence of Toxocara antibodies in sera used for the determination of cross-reactivity, hence they might have been unrecognized by the IH-ELISA. Such polyparasitism is commonly reported in tropical regions, in which the simultaneous infection with various helminths, especially those that are soiltransmitted, represents a tremendous challenge for Toxocara serology due to cross-reactions (Smith and Noordin, 2006;Fillaux and Magnaval, 2013;Wilkins, 2014;Ma et al, 2020;Noordin et al, 2020). Nevertheless, Toxocara seronegativity in most of the IH-ELISA pre-determined potentially cross-reactive samples was also shown by the Proto-ELISA and Proto-WB.…”

“…For instance, native TES-120 is cross-reactive, whereas in Escherichia coli or Pichia pastoris recombinantly expressed protein obtains a high diagnostic specificity, possibly due to altered glycosylation (Fong et al, 2003;Fong and Lau, 2004;Mohamad et al, 2009;Wilkins, 2014). Furthermore, recombinant expression of proteins allows the production of highly purified and standardized antigens, certainly contributing to the reproducibility and reliability of serological assays (Smith and Noordin, 2006;Wilkins, 2014;Noordin et al, 2020). Another factor supporting the reliability of the Proto-ELISA is the correlation of RUs with those of the reference ELISA.…”

“…With a calculated sensitivity of 76.7%, the Proto-WB seems to be less sensitive than the Com-WB. An in-house larval TES-based WB by Magnaval et al (1991) is considered to have a 55% higher diagnostic sensitivity compared to designated commercial larval TES-ELISA kits (Gueglio et al, 1994;Courtade et al, 1995;Fillaux and Magnaval, 2013;Noordin et al, 2020). Thus, an elevated number of Toxocara-positive sera detected by the reference Com-WB, for which a comparable performance to the WB by Magnaval et al (1991) is stated in the user manual, is explainable.…”

“…In recent years, seroprevalence rates tend to increase in Europe, possibly due to increasing dog and cat populations in combination with closer human-animal relationship and a change in recreational activities with more time spent in nature (Strube et al, 2020). Noteworthily, actual Toxocara exposure might be underestimated as a considerable amount of infected persons are asymptomatic (Noordin et al, 2020) and thus not tested. Furthermore, there are gaps in the epidemiology of Toxocara spp.…”