Detection of circulating antibody of Parastrongylus cantonensis in sera with eosinophilic meningitis by dot-blot ELISA.

BACKGROUND: Eosinophilic meningitis caused by Parastrongylus cantonensis, the rat lung worm is a major public health problem in Thailand. Humans acquire this parasite by eating raw food containing infective Parastrongyliasis is dificult to make because identification of parasite materials by biopsy or chance finding is rarely possible. OBJECTIVE: Develop alternative approaches of Parastrongylus cantonensis infection employing crude antigen by dot-blot ELISA. MATERIAL AND METHOD: The investigation was carried out between October 2003 and July 2004 in Khon Kaen, which is an endemic area. One hundred thirty two serum samples from several villagers of the present study area were divided into five groups. Group 1 consisted of 30 patients with Cryptococcal meningitis, group 2 were 22 cases of Bacterial meningitis, group 3 were 32 cases of eosinophilic meningitis, group 4 were other parasitic infections (4 from Cysticercosis, 2 from Fascioliasis, 12 from Malaria), and group 5 were 30 negative healthy control. RESULTS: The result demonstrated that 26 cases of eosinophilic meningitis, were positive with Dot-blot ELISA (81.3%). None of the other groups of sample reacted with this antigen. CONCLUSION: The data obtained showed that Dot-blot ELISA has a potential for diagnosis of eosinophilic meningitis caused by Parastrongylus cantonensis.

Components of pathogenic Leptospira spp. with potentials for diagnosis of human leptospirosis.

Existing serological methods for diagnosis of leptospirosis are still unsatisfactorily due mainly to their low accuracy. In this study, serum samples of 18 clinically diagnosed-, IgM dipstick positive-, MAT positive-leptospirosis patients (group 1) were analyzed by IgG Western blotting against SDS-PAGE separated-whole cell homogenates of pathogenic and non-pathogenic Leptospira spp. belonging to 20 serovars of 15 serogroups. The samples of group 1 were collected from the patients at days 3 to 10 after the fever onset (fist samples). Second and third samples could be obtained from 4 patients. Sera of the 22 patients with other febrile illnesses (group 2) and 22 healthy counterparts (group 3) were used as patient- and normal- controls, respectively. Irrespective of the serovar or serogroup of the pathogenic Leptospira spp. used as antigen in the Western blotting, all of the 18 sera of patients with leptospirosis (group 1) gave characteristic diffuse antigen-antibody reactive bands located at approximately 35-38 and 22-26 kDa; and thus 100% diagnostic sensitivity of the Western blot assay. Some serum samples of the leptospirosis patients also reacted to components located at 80-100, approximately 70, 60, 54, and 48 kDa. More bands or the early recognized bands with increased intensity were observed when tested the second and third samples. The characteristic bands were not seen when homogenates of L. biflexa, serogroup Semaranga, serovar Patoc (saprophytic) and L. biflexa, serogroup Andamana, serovar Andamana (non-pathogenic but can infect host) were used in the assay. Sera of groups 2 and 3 did not react to the components at the seven locations implying 100% diagnostic specificity of the IgG Western blot assay. While awaiting validation with more patients' samples, the IgG Western Blot analysis aiming at the detection of the characteristic antigen-antibody reactive bands described in this study has high potential for early, rapid, simple and accurate diagnosis of human leptospirosis.