Congenital Chagas disease (CChD) has been reported in different countries, mostly in Latin America. In 1987 a fatal case of CChD of second generation (CChDSG) was published. Within a period of six months - 1989-1990 - two cases of CChDSG were diagnosed and studied in the city of Santiago. Two premature newborns, sons of two sisters, with moderate liver and spleen enlargement, were found to have positive serology for Chagas disease and xenodiagnoses. The mothers, urban residents all their lives, without antecedents of triatomine bugs contact or blood transfusions, showed positive serology and xenodiagnoses. Their mother (grandmother of the infants), lived 20 years in a Northern rural Chagas disease endemic locality, in a triatomine infested house. Afterwards, she moved to Santiago, where she married and has resided up to now. Serology and xenodiagnoses were also positive. All the Trypanosoma cruzi infected individuals were successfully treated with nifurtimox.

La enfermedad de Chagas congénita ha sido reportada en diferentes países, en su gran mayoría de Latinoamérica. En 1987 un caso fatal de enfermedad de Chagas congénita de segunda generación fue publicado. En 1989-1990 dos casos de enfermedad de Chagas congénita de segunda generación fueron diagnosticados y estudiados en la ciudad de Santiago. Dos recién nacidos prematuros, hijos de dos hermanas, con moderado aumento del hígado y del bazo, presentaron serología para enfermedad de Chagas y xenodiagnósticos positivos. Las madres, residentes urbanas toda su vida, sin antecedentes de contacto con triatominos ni transfusiones de sangre presentaron serología y xenodiagnósticos positivos. La madre de ellas (abuela de los niños) nació y vivió 20 años en una localidad rural de endemia chagásica, en una casa infestada con triatominos. Posteriormente, se trasladó a vivir a Santiago, donde se casó y ha residido hasta el presente; su serología y xenodiagnóstico fueron positivos. Todas las personas infectadas con Trypanosoma cruzi fueron tratadas exitosamente con nifurtimox.

San Juan de la Costa County (40º 45' South lat., 73º 19' West long.) is located in the Osorno province, South of Chile. Its population is 11,445. The basic economic activities are agriculture,cattle raising, fishery, timber production and manufacture of wood and coal. According to official reports, the incidence of human hydatidosis in Chile and Osorno province, in 1999, was 1.8 and 12.5 per 100,000 respectively. In order to contribute to a better knowledge of the epidemiology of human hydatidosis, an indirect hemagglutination test (IHAT) and ELISA IgG for hydatidosis were performed to 533 randomized people. Three (0.56%) resulted positive. Parallelly, a socio-epidemiological survey on hydatidosis was carried out: the majority of people had some basic knowledge about some aspects of hydatidosis transmission. Some considerations on the corresponding prophylatic measures are mentioned.

An indirect hemagglutination test (IHAT) and an ELISA test for trichinosis using as antigen a larvae soluble fraction from Trichinella spiralis was carried out for the detection of IgG, IgM and IgA specific antibodies in 113 serum samples from patients confirmed or suspected to have trichinosis by strong clinical and epidemiological evidences (Group I). The same tests were also performed on 110 serum samples corresponding to patients without strong evidences of having trichinosis (Group II). In Group I the corresponding sensitivities for RHAI, ELISA IgG, ELISA IgM, ELISA IgA were: 82.3-85.8-88.5 and 88.5% respectively. Seventeen patients were tested again a week after the first analysis (10 of them corresponded to negative ones), increasing the positivity: 23.5-100.0;35.3-100.0;41.2-100.0 and 41.2-100.0% for RHAI, ELISA IgG, ELISA IgM and ELISA IgA, respectively. Other two patients were followed-up for 5 years. IHAT and ELISA IgG remained positive, whereas ELISA IgM and ELISA IgA were constantly negative betweeen 17 and 32 months in one case, and between 48 and 60 months in the other (this last one had presented a severe clinic disease). In the group II, four patients were positive with IHAT, however only one for ELISA IgA, the latter also presented ELISA IgM near the cut off. The use of ELISA IgG, ELSIA IgM and ELISA IgA in the immunodiagnosis of trichinosis is discussed.

Toxoplasmosis, a world-wide zoonotic infection, is generally asymptomatic and benign in immunocompetent individuals, but it can be serious in immunodeficiencies particulary in patients with acquired immunodeficiency syndrome and in children infected in utero. So, it is important to dispose methods which permit discriminate between recent and chronic infections. In order to contribute to improve the diagnosis of toxoplasmosis ELISA IgG, IgM, IgA and ELISA IgG avidity were performed in 15 and 24 sera from patients suspected of having acute and chronic infection respectively, according dye test (DT) titres. ELISA IgG was positive in both groups, ELISA IgM was positive in 78.6 and 58.3% respectively, while ELISA IgA was positive in 85.7 and 33.3% of recent and chronic group respectively. In those sera with low IgG avidity ( 18.8%) we found specific IgM in 71.5 and 4.2% and IgA in 78.6 and 0.0% of recent and chronic groups respectively. Parallely, 208 sera samples were clasified according to the results of DT, indirect hemagglutination and complement fixation tests in the following groups: acute (97), intermediate (36), chronic (35) and negative (40). The results were: acute (96.9-64.9-55.6 and 65.9%); intermediate (97.2-63.8-44.4 and 47.2%); chronic (45.7-42.8- 5.7 and 34.3%) for IgG, IgM, IgA and low IgG avidity respectively. The use of both acute markers, IgA and low IgG avidity in the diagnosis of toxoplasmosis is discussed.

An ELISA test for trichinosis using as antigen a larvae soluble fraction from Trichinella spiralis was carried out for the detection of IgMand IgA specific antibodies in 45 serum samples from patients confirmed or suspected to have trichinosis by strong clinical and epidemiological evidences. All the patients had positive serology detected by precipitin test, bentonite floculation test, indirect hemagglutination test and ELISA IgG test. The cut-off value was determined using two criteria. Criterion A was determined in each plate, using three positive controls and two negative ones; the average of the negative controls and the weakest positive control, muliplied by a 1.2 factor was, considered the cut-off value. Criterion B was determinated using the average plus three standard deviations from 64 apparently healthy persons serum samples. In both cases, three serum dilutions (1:10, 1:100 and 1:500) were used. The sensitivity of ELISA IgM was 100.0, 93.3 and 82.2% using serum dilutions of 1:10, 1:100 and 1:500 respectively (criterion A) and 100.0, 97.8 and 95.6% for the same dilutions (criterion B), whereas the values for ELISA IgA were: 100.0, 91.1 and 86.7% (criterion A) and 100.0, 100.0 and 91.1%(criterion B). In order to find out the specificity of ELISA IgM and ELISA IgA, additional118 serum samples from individuals with other parasitoses, such as cysticercosis (18) hydatidosis (39), fascioliasis (12), toxocariasis (30), Chagas' disease(12) and individuals with non-specif eosinophilia (7), were also tested. ELISA IgM presented a specificity of 92.3, 93.4 and 97.3% (criterion A) and 96.2, 97.8 and 97.8% (criterion B) whereas the results for ELISA IgA were 97.8, 98.9 and 99.4% (criterion A) and 98.4% for the 1:10 and 1:100 dilutions and 100.0% for the 1:500 dilution (criterion B). The positive predictive values of ELISA IgM were 76.3, 77.8 and 88.1% (criterion A) and 86.5, 91.7 and 91.5% (criterion B) whereas the negative ones were 100.0, 98.3 and 95.7% (criterion A) and 100.0, 99.4 and 98.9% (criterion B). The positive predictive values of ELISA IgA were 91.8, 95.3 and 97.5% (criterion A) and 93.8, 93.8 and 100.0% (criterion B) whereas the negatives ones were: 100.0, 97.8 and 96.8% (criterion A) and 100.0, 100.0 and 97.8%(criterion B). The use of ELISA IgM and ELISA IgA in the immunodiagnosis of trichinosisis discussed.