| Abstract: | Taeniasis/cysticercosis caused by Taenia solium is a frequent parasitic infection of the human brain in most of the world. Rapid and simple screening tools to identify taeniasis and cysticercosis cases are needed for control programs, mostly to identify tapeworm carriers which are the source of infection and need to be treated, or as tools for point-of-care case detection or confirmation. These screening assays should be affordable, reliable, rapid, and easy to perform. Immunochromatographic tests meet these criteria. To demonstrate proof of principle, we developed and evaluated two magnetic immunochromatographic tests (MICTs) for detection of human Taenia solium taeniasis antibodies (ES33-MICT) and neurocysticercosis antibodies (T24-MICT). These assays detected stage-specific antibodies by using two recombinant proteins, rES33 for detection of taeniasis antibodies and rT24H for detection of cysticercosis antibodies. The sensitivity and specificity of the ES33-MICT to detect taeniasis infections were 94.5% and 96%, respectively, and those of the T24-MICT to detect cases of human cysticercosis with two or more viable brain cysts were 93.9% and 98.9%, respectively. These data provide proof of principle that the ES33- and T24-MICTs provide rapid and suitable methods to identify individuals with taeniasis and cysticercosis.Humans can be infected with both the adult worm and larval forms of the cestode Taenia solium, causing taeniasis and cysticercosis, respectively. Humans, who are the only definitive host for the adult tapeworm, develop taeniasis after eating raw or undercooked pork infested with the larval stages of the parasite. Both pigs and humans can develop cysticercosis by ingesting eggs passed in the feces of a tapeworm carrier. Consequently, cysticercosis can be acquired under any variety of cultural and socioeconomic conditions where there is close contact with a taeniasis carrier. Because tapeworm-infected humans are the only source of transmission of both human and pig cysticercosis, diagnosis and treatment of taeniasis are crucial for control and elimination of cysticercosis in both humans and pigs (18). Therefore, accurate and rapid diagnostic methods to identify tapeworm carriers are critical tools needed in cysticercosis/taeniasis control and elimination programs. Although diagnosis of porcine or human cysticercosis is not crucial in the context of control programs, the availability of rapid diagnosis for human cysticercosis would be useful for estimating the burden of disease and for determining seroprevalence rates in pigs.Diagnosis of taeniasis usually is established by microscopic observation of T. solium eggs in stool specimens, but this method is insensitive and cannot differentiate between T. solium and Taenia saginata ova. Other methods to detect taeniasis include coproantigen detection methods, which are more sensitive than microscopy, and serodiagnosis of taeniasis by the use of excretory-secretory proteins in an enzyme-linked immunoelectrotransfer blot (EITB) (1, 14, 23). Two specific T. solium excretory-secretory (TSES) proteins, ES33 and ES38, were identified for specific taeniasis serodiagnosis. Recombinant forms of ES33 and ES38 (rES33 and rES38) have been evaluated, and the diagnostic performances of these two proteins were determined to be comparable (11).The gold standard for serological identification of cysticercosis is the EITB, which relies on antibody reactivity with seven diagnostic lentil lectin purified glycoproteins (LLGP) (20). Recombinant or synthetic peptide forms of these proteins are now available (7-9), and after comparing the performances of these diagnostic proteins, rT24H (which corresponds to a 24,000-Da protein of the LLGP extract) (9) was identified as the recombinant protein with the best sensitivity and specificity for detecting neurocysticercosis cases (11).The gold standard tests described above are not field friendly, not widely available, and do not exist in point-of-care formats. In contrast, lateral flow immunochromatographic tests, can be used at the point of care and in settings with minimal infrastructure (5, 21). Lateral flow methods have been used for several decades for clinical and veterinary diagnosis (16). In conventional lateral flow assays, reactions are detected visually, generating a qualitative result, or with a detection device that measures reflectance, contrast, color change, or fluorescence (16). Several studies have demonstrated that magnetic particle-labeled detection systems have the potential to improve lateral flow assay sensitivity and to provide a means of quantification (12, 17, 25). In this study, we describe the development and evaluation of two magnetic immunochromatographic tests (MICTs) for serologic detection of taeniasis (based on rES33 antigen) and cysticercosis (based on the rT24H antigen). |
