[Immunodiagnosis in 647 suspected clinical cases of toxoplasmosis]. / Immunodiagnóstico en 647 casos clínicos sospechosos de toxoplasmosis.

Though Toxoplasma gondii can cause severe pathology in human, in most of the cases it produces only asymptomatic infection. So, it is important to dispose some methods capables to discriminate between acute and chronic infections. An indirect hemagglutination test (IHAT), dye test (DT) and complement fixation test (CFT) were performed in 647 sera from patients suspected of having toxoplasmosis infection. IHAT and DT titer > or = 4 and CFT > or = 5 were considered positive. Titers were classified as follows: low (4-16), median (64-512) and high (> or = 1000) for IHAT and DT. The pathologies for demanding these serological tests were: adenopathies (58), nephropathies (72), neuropathies (30), obstetrical problems (65), opthalmopathies (147), AIDS (237) and miscellaneous (37). Global positivity of 49.5% and 4.5% for IHAT/DT and CFT respectively were found. The positivity for the different groups were: adenopathies (48.3% and 13.8%), nephropathies (43.1% and 1.4%), neuropathies (26.7% and 3.3%), obstetrical problems (40.0% and 0.0%), ophthalmopathies (59.9% and 8.2%), AIDS (52.1% and 2.5%) and miscellaneous (40.5% and 2.7%) for IHAT/DT and CFT respectively. Low and median titers for IHAT/DT were found in 81.3% of cases. A high agreement in frequency of concordant and discordant titers of IHAT/DT and CFT, indicating a recent or acute infection was observed. This fact was more relevant in adenopathies, ophthalmopathies (uveitis) and AIDS groups.

[Diagnosis of human neurocysticercosis by ELISA-IgG using a purified antigen]. / Diagnóstico de la neurocisticercosis humana mediante ELISA-IgG usando un antígeno purificado.

An analysis of immunodiagnosis data for human neurocysticercosis (NC) by ELISA-IgG, complement fixation test (CFT) and indirect hemagglutination test (IHAT) in 67 serum samples and 54 cerebrospinal fluids (CSF) from confirmed cases of different hospitals from the Metropolitan Area of Santiago, Chile, was performed. The cut-off value was determined by using serum samples from 60 apparently healthy persons, whose absorbance values were the mean plus three standard deviations. The sensitivity of ELISA was 97.0% and 100% for serum samples and CSF respectively. This assay was considered of statistical significance (p < 0.05) when it was compared with CFT. Specificity was established by testing a purified antigen over 109 different helminthiasis serum samples, 185 neurological affections other than NC and 60 control samples. A 98.3% of global specificity was found. The use of ELISA-IgG and a purified antigen in the approach of immune diagnosis of NC is considered a useful assay, particularly if it is performed on paired serum/CSF samples.

[Diagnostic valve of ELISA-IgG for trichinosis using Melcher's antigen]. / Valor diagnóstico de la ELISA-IgG para triquinosis, usando antígeno de Melcher.

An enzyme-linked immunosorbent assay (ELISA) for trichinosis using a Melcher's antigen was developed for the detection of IgG antibodies in 41 serum samples from patients confirmed or suspected to have trichinosis by strong clinical and epidemiological evidences. ELISA- IgG was compared with a precipitin test (PT), a bentonite floculation test (BFT) and an indirect hemagglutination test (IHAT). The cut-off value was determined using serum samples from 67 apparently healthy persons employing two serum dilutions (1:100 and 1:500) with three standard deviations (SD). The sensitivity of ELISA- IgG was 97.6% and 95.2% using serum dilutions of 1:100 and 1:500 respectively, whereas the values for the other tests were: PT (92.7%), BFT (63.4%) and IHAT(85.4%). According to MacNemar test, ELISA-IgG did not present statistical significance (p > 0.05) compared with PT and IHAT, whereas all of them were different compared with BHT (p > 0.01). In order to find out the specificity of ELISA-IgG, additional 124 serum samples from individuals with other parasitoses, such as cysticercosis (31), fascioliasis (17), hydatidosis (51) and toxocariasis (25) were also tested. ELISA-IgG presented a specificity of 99.5% with both serum dilutions. The positive predictive values were 97.6 and 97.5%, whereas the negative one were 99.5 and 99.0% for 1:100 and 1:500 serum dilutions respectively. The use of ELISA-IgG and Melcher's antigen in the diagnosis of human trichinosis is discussed.

[Systemic toxocariasis in the adult patient]. / Toxocariasis sistémica en el paciente adulto.

We report a retrospective review of eight patients (one male), aged 19 to 31 years old, with systemic toxocariasis (visceral larva migrans), seen at the Salvador Hospital of Santiago. Four cases had heart involvement, three had lung involvement and in two, several organs were affected. Seven cases had leukocytosis (range 14, 5 to 160 x 10(9)/l) and all had eosinophilia (35 to 90%). Serum ELISA titers for Toxocara sp were positive in all cases, ranging from 64 to 1000. Six patients were treated with thiabendazole and one with albendazole. Steroids or hydroxiurea were administered to patients with heart failure or hyperleukocytosis. Subjects with lung involvement recovered quickly but those with cardiac compromise had a partial recovery with frequent decompensations of their cardiac failure and one death. Eosinophilia lasted up to 20 years, in spite of specific treatment. We emphasize the importance of infection prevention, accuracy of diagnosis and the severity of cardiac damage in the adult patient.

[Familial seroepidemiology of toxocariasis]. / Seroepidemiología familiar de la toxocariasis.

With the objective of defining the intrafamiliar distribution pattern of the infection and illness caused by Toxocara sp., 78 infected families (356 people) were studied for 30 months. At the same time 28 families free of infection were studied, as a control group (97 people). The socioeconomic level was analyzed according to a modified Graffar index. Contac with canine and feline pets, and antecedents of geophagia and onichophagia were found to be risk factors which would facilitate the infection. The average of persons infected, diagnosed by ELISA Toxocara test, was 2.8 per family. The importance of familiar distribution of the infection and its primary prevention is strongly stressed.