Detection of Trypanosoma cruzi in untreated chronic chagasic patients is improved by using three parasitological methods simultaneously.

OBJECTIVES: This study compared three parasitological methods applied simultaneously in individuals with untreated chronic Chagas' disease in order to determine their individual and combined performances. METHODS: From a total of 100 chronic chagasic patients from endemic areas of Chile, with informed consent, we extracted 2 mL of peripheral venous blood for PCR (PCR-B) and applied two xenodiagnosis (XD) boxes with seven uninfected Triatoma infestans nymphs each for microscopic examination and PCR of faecal samples of the triatomines fed on each patient (PCR-XD). The PCR-B and PCR-XD reactions were performed with oligonucleotides 121 and 122, which anneal to the four constant regions of the minicircles of Trypanosoma cruzi kinetoplasts. The 330 bp PCR product was analysed by electrophoresis in a 2% agarose gel and visualized by staining with ethidium bromide. RESULTS: PCR-B detected T. cruzi in 58% of the cases, while PCR-XD proved to be more sensitive than XD (67% versus 14%, respectively) (P = 0.0001). There was no difference between the detection power of PCR-B and PCR-XD (P = 0.222). The percentage detected as positive was much greater when the three tests were considered (84%) (P = 0.00001). CONCLUSIONS: The simultaneous application of more than one technique for the parasitological diagnosis of Chagas' disease in untreated individuals increases the possibility of detection of T. cruzi.

Analysis of Toxoplasma gondii surface antigen 2 gene (SAG2). Relevance of genotype I in clinical toxoplasmosis.

Toxoplasma gondii is one of the most successful protozoan parasites given its ability to manipulate the immune system and establish a chronic infection. It is a parasite with a significant impact on human health, mainly in immunocompromised patients. In Europe and North America, only a few clonal genotypes (I, II and III) seem to be responsible for the vast majority of Toxoplasma infections. Surface antigen 2 gene (SAG2) has been extensively used for genotyping T. gondii isolates. The analysis of this locus reveals that in Northern hemisphere, human disease causing isolates are mainly type II, whereas T. gondii isolated from different animals are both type II and III. Since the immune response depends on parasite genotype, it seems relevant to characterize parasites producing human toxoplasmosis in different geographical areas. The growing information about the prevalent T. gondii genotypes in South America mostly refers to domestic animals. This is the first report of genetic characterization of T. gondii isolates from clinical samples in Chile, South America. All the samples analyzed corresponded to SAG2 type I isolates, and they differ from classic SAG2 type I by genetic polymorphisms. This study contributes to the scarce available information on T. gondii at South America, and reinforces an emerging concept suggesting that SAG2 type I, rather than II, parasites are a frequent cause of clinical toxoplasmosis in this continent.

Enfermedad de Chagas crónica en Chile. Experiencia de intervención educativa / Chronic Chagas disease in Chile: educational intervention

Las diversas inquietudes planteadas por pacientes chagásicos crónicos en relación a su condición clínica, motivaron a un grupo de parasitólogos a diseñar un programa de intervención educativa. Participaron en forma voluntaria 72 pacientes, 32 hombres y 40 mujeres, procedentes de zona de alta y baja endemia chagásica de Chile. La metodología docente consistió fundamentalmente en: aplicación de test diagnóstico y de conocimientos adquiridos; sesiones teóricas que abordaron seis temáticas relacionadas; actividades prácticas tutoriales; utilización de material audiovisual e impreso; atención personalizada por médico parasitólogo (posterior a la intervención educativa y con los antecedentes serológicos, electrocardiográficos y parasitológicos previamente determinados) y evaluación de la actividad educativa por parte de los pacientes. Un mayor conocimiento previo y adquirido se observó en chagásicos crónicos procedentes de zonas endémicas. Todos demos-traron un alto grado de interés y participaron activamente de las actividades programadas. La metodología utilizada, el trabajo tutorial de pequeño grupo y la atención-orientación individual por parte del médico parasitólogo, facilitaron el proceso de enseñanza-aprendizaje. Se concluye que la intervención educativa responde a muchas de las interrogantes respecto de la afección, permite al paciente reconocer el rol que le cabe como protagonista de su propio bienestar y lo transforma en un eficaz agente en el control de la enfermedad de Chagas.

Strongyloidosis no autóctona en Chile: descripción de un brote familiar / Non autochthonous strongyloidosis in Chile: report of a familiar outbrake

Se presenta un brote familiar de stron-gyloidosis que afectó a inmigrantes peruanos que habían llegado a Chile en noviembre del año 2001. En marzo del 2002, se confirmó en el Laboratorio de Parasitología Básico-Clínico de la Facultad de Medicina de la Universidad de Chile que el caso índice presentaba infección por Strongyloides stercoralis. Correspondía a una menor de 11 años que estaba siendo estudiada en el Hospital Roberto del Río por artritis reumatoide juvenil. Además de esta patología la niña refería leves molestias abdominales, siendo derivada a nuestra unidad, donde se le efectuó un examen parasitológico seriado de deposiciones (EPSD), observándose abundantes larvas rabditoides de S. stercoralis, por lo cual se procedió a estudiar al grupo familiar integrado por los padres y una hermana. A todos ellos se les efectuó EPSD e inmunodiagnóstico mediante ELISA para detectar anticuerpos anti S.stercoralis. Resultaron positivos para ambos exámenes la madre y las dos hijas. El padre fue negativo. Se decidió tratar con ivermectina y controlar los resultados del tratamiento anti-parasitario al grupo familiar al cabo de un año. Después de ese periodo permanecía positiva serológicamente, solamente la hermana del caso índice debido a que no ingirió los medicamentos de la manera indicada.

Infecciones por protozoos y helmintos intestinales en pre-escolares y escolares de la Comuna de Colina, Santiago, Chile, 2003 / Intestinal protozoa and infections in pre-school and elementary school-children from colina county, Santiago, Chile, 2003

En mayo de 2003 se efectuó una encuesta epidemio-parasitológica en pre-escolares y escolares de la Escuela San Vicente de Lo Arcaya de Colina, comuna semirural de la Provincia de Santiago ubicada en la Región Metropolitana de Chile. Hay que destacar que los niños estudiados eran asintomáticos. Los elementos parasitarios más frecuentemente encontrados fueron: Blastocystis hominis - en hombre y mujeres respectivamente - 38,8 por ciento y 44,4 por ciento, Giardia intestinalis con 9,5 por ciento y 16,2 por ciento y Enterobius vermicularis con 12,9 por ciento y 10,0 por ciento. Cryptosporidium parvum no fue encontrado y ELISA para Strongyloides stercoralis resultó positiva en un niño.

[Current epidemiological situation of trichinosis in Chile. 1991-2000]. / Situación epidemiológica actual de la triquinosis en Chile. 1991-2000.

BACKGROUND: Human and animal trichinosis has been recorded in Chile since the late XIX century and is irregularly distributed along the country. From high rates of infection in the early 1900, the frequency of this parasitosis in man has progressively decreased. AIM: To describe and discuss the epidemiological situation of trichinosis in Chile during the decade 1991-2000. MATERIAL AND METHODS: Human infection was assessed using annual incidence and lethality reports provided by the Ministry of Health, periodic photostrichinoscopies in corpses of non selected individuals autopsied at the Medico Legal Service and periodic national serologic surveys. The advise of one of the authors in an epidemic that occurred in 1999 in the VIII Region was also used. Animal infection was assessed using the annual prevalence of infection in pigs slaughtered in abattoirs, furnished by the Ministry of Health. RESULTS: A total of 631 clinical cases with 4 deaths (0.6%) was recorded. A decline in the incidence, from 0.7 x 100,000 in 1991 to 0.2 x 100,000 in 2000 was recorded. The higher frequency of the parasitosis was observed in the Metropolitan, VI, VIII and X regions. Although human trichinosis has been observed in all seasons, its frequency increases in close relation with the higher pork consumption in cold seasons (45.8% in winter and 37.5% in spring). There has been a decrease of infection rates in pigs from 0.17@1000 in 1991 to 0.04@1000 in 1998-2000. CONCLUSIONS: The incidence and prevalence of trichinosis shows a constant decline in Chile. Considering the geographical characteristics of Chile, it is possible that an undetermined number of pigs are home reared and butchered without veterinary control, constituting an important source of human trichinosis.

Inmunodiagnóstico de la triquinosis humana / Inmunodiagnosis of human trichinosis

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 1). The same test were also performed on 110 serum samples corresponding to patients without strong enidences of having trichinosis (Group II). In Group 1 the correponding sensitivities for RHAI, ELISA IgG, ELISA IgM, ELISA IgA were: 82.3-85.8-88.5 and 88.5 percent 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 percent 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, ELISA IgM and ELISA IgA in the immunodiagnosis of trichinosis is discussed

Estudio seroepidemiológico de la toxoplasmosis humana en Osorno, X Región, Chile, 1998 / Seroepidemiological survey of human toxoplasmosis in Osorno, X Region, Chile, 1998

A serological survey was carried out in Osorno X Región, Chile (40º 21'-40º 46' south lat, and 73º 26'-72º-46' west long.). An indirect hemagglutination test (IHAT) for toxoplasmosis was performed to 305 persons, 160 blood donors and 145 with sexuallly transmitted diseases (STD).The age the surveyed persons (167 males and 138 females) varied between 10 and 72 years. IHAT titers >16 were considered as positive. The general prevalence was 20.3 percent, 21.2 percent in blood donors and 19.3 percent in persons with some STD, with no differences between males and females. However, significant differences between males and females with STD were found (35.6 percent and 8.1 percent respectively). No differences between urban and rural inhabitants were found, with a slight higher prevalence in the urban ones. No antibodies against toxoplasma gondii were detected in six AIDS patients. The importance of performing toxoplasmosis immnuodiagnosis and individual profilaxis to avoid the infection in high risk group are recommended

Inmunodiagnóstico en 647 casos clínicos sospechosos de toxoplasmosis / Immunodiagnosis in 647 clinical cases of toxoplasmosis suspected

Though Toxoplasma gondii can cause severe pathology in human, in most of the cases it asymptomatic infection. So, it is important to dispose some methods capables to discriminate 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 > the same as 4 and CFT > the same as 5 were considered positive. Titers were classified as follows: low (4-16), median (64-512) and high (> the same as 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 positvity of 49.5 percent and 4.5 percent for IHAT/DT and CFT respectively were found. The positvity for the different groups were: adenopathies (48.3 percent and 13.8 percent), nephropathies (43.1 percent and 1.4 percent), neuropathies ,(26.7 percent and 3.3 percent), obstetrical problems (40.0 percent and 0.0 percent), ophthalmopathies (59.9 percent and 8.2 percent), AIDS (52. 1 percent and 2.5 percent) and miscellancous (40.5 percent and 2.7 percent) for IHAT/DT and CFT respectively. Low and median titers for IHAT/DT were found in 81.3 percent 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

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

An analysis of inmunodiagnosis data for human neurocysticercosis (NC) by ELISA-IgG, complement fixation (CSF) from confirmed cases of different hospitals from the metrolitan 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 desviations. The sensitivity of ELISA was 97,0 percent and 100 percent for serum samples and CSF respectively. This assay was considered od statistical significance (p< 0,05) when it was compared with CFT. Specificity was stablished by testing a purified antigen over 109 different helminthiasis serum samples, 185 neurological affections other than NC and 60 control samples. A 98,3 percent of global specificity was found. The use of ELISA-IgG and a purified antigen in the approach of inmune diagnosis of NC is considered a useful assay, particularly if it is perfomed on paired serum/CSF samples.

Seroepidemiology of human toxoplasmosis in Chile

En este trabajo se revisa, se amplia y se analiza en conjunto una crise serie e encuestas seroepidemiologicas sobre toxoplasmosis efectuadas en Chile entre 1982 y 1994, utilizando la reaccion de hemaglutinacion indirecta (RHAI). El estudio incluyo 76.317 personas aparentemente sanas de diferentes edades (0,57 por cento de la problacion total del pais), procedentes de 309 localidades urbanas y rural-periurbanas...

Epidemiología de la enfermedad de Chagas en Chile: frecuencia de infección humana por trypanosoma cruzi por grupos de edad y por regiones / Epidemiology of Chagas's disease in Chile: frequency of trypanosoma cruzi human infection by age groups and regions

Chagas's disease is endemic in rural-periurban sections of the northern half of Chile which includes the first seven political-administrative regions of the country (18º30'-34º36' South lat.). Data concerning to the results of an indirect hemagglutination test for Chagas's disease performed to 15,418 rural-periurban and 45,119 urban inhabitants from the chagasic endemic regions are presented migrations from rural-periurban to urban areas have contributed to the dissemination of trypanosoma cruzi infection. General rates of infection for rural-periurban (r-p) and urban (u) sections were 16,7 for percent and 1,9 for percent respectively. The higher prevalence rates were detected in region III with 27,2 for percent (r-p) and 3,9 (u) and Region IV with 24,7 for percent (r-p) and 3,5 for percent (u), while the lower prevalence rates corresponded to Region VI with 7,0 for percent (r-p) and 0,8 for percent (u). Serological positivity increased parallelly with age in all regions

Valor diagnóstico de la ELISA-IgG para triquinosis usando antígeno de Melcher / Diagnosis value of ELISA-IgG for human trichinosis by using Melcher's antigen

An enzyme-linked inmunosorbent 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 as determined using serum samples from 67 apparently healthy persons employing two serum dilutions (1:100 and 1:500) with three standard desviations (SD). The sensitivity of ELISA-IgG was 97,6 for percent and 95,2 for percent using serum dilutions of 1:100 and 1:500 respectively, whereas the values for the other tests were: PT (92,7 for percent), BFT (63,4 for percent) and IHAT (85,4 for percent). According to MacNemar test, Elisa-IgG did not present statistical significance (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 for percent with both serum dilutions. The positive predictive values were 97,6 and 97,5 for percent, whereas the negative one were 99,5 and 99,0 for percent 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

Epidemiología de la triquinosis en Chile: estudio de la prevalencia mediante reacciones inmunodiagnósticas / Epidemiology of trichinosis in Chile: study of prevalence by immunodiagnostic reactions

In the period 1983-1994 a series of seroepidemiological surveys by using immunodiagnostic tests for trichinosis, was carried out in 138 localities and health institutions and health institutions from the 13 regions of the country. Thus, a total of 12,882 randomly selected persons, with different sex and age distribution, were submitted to precipitin test and indirect hemagglutination test for trichinosis. One hundred and ninety one (1.5 percent) persons resulted positive for trichinosis. Higher rates of infection were observed in central and southern Chile. No differences of positivity, according to age sex, but constant increase parallel to age of the individual were detected. The general prevalence rate of infection of 1.5 percent is in reasonable accordance with the prevalence of 2.0 percent found in human corpses in 1992

Evaluación de la ELISA IgG, usando un antígeno purificado en el diagnóstico de la hidatidosis humana / Evaluation of ELISA IgG test using a purified antigen in the human hydatidosis diagnosis

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of IgG antibodies to purified sheep hydatic cyst fluid antigen in 56 sera of confirmed cases of hydatidosis. The cut-off value was determined using serum samples from 80 healthy persons, employing two serum dilutions (1:100 and 1:500) with two and three standard desviations (SD). This assay was compared with the indirect hemaglutination test (IHAT). The sensitivity of ELISA-IgG was 94,3 for percent, for hepatic cysts and 92,9 for percent, for pulmonary cysts, whereas the values for IHAT were 77,1 and 64,3 for percent, respcetively. According to Mac Nemar test, both thod presented statistical significance (p < 0,05). In order to find out the specificity, additional 70 serum samples from individuals with other parasitoses, such as cysticercosis (30), trichinosis (26) and fascioliasis (14) were also tested, IHAT presented a specificity of 92,7 for percent and for ELISA-IgG the specificity using a cut-off of average + 3 SD was 99,3 and 100,0 por percent with sera dilution of 1:100 and 1:500 respectively when a cut-off of average +2 SD was considered, we found a specificity of 91,3 and 97,3 por percent, for 1:100 and 1:500 dilutions. The use of ELISA-IgG and purified antigen in the diagnosis of human hydatidosis is discussed

Brote de triquinosis en la comuna de Purranque X Región, Chile: octubre/noviembre 1992 / Outbreak of trichinosis in Purranque county X Region, Chile: october/november 1992

An outbreak of trichinosis occurred in Purranque county, X Region, Chile, between october and november of 1992, which involved 36 persons. The incubation period, determinated by the clinical picture and laboratory assays, fluctuated between 10 and 12 days, myalgias (88,9 for percent) and palpebral oedema (86,1 por percent) were the most important symptoms, followed by fever (44,4 for percent) and headache (33,3 for percent). Eosinophils count ranged from two to 42 for percent the first week, and this value raised to 55 for percent the second week of the outbreak. Anti-trichinella spiralis antibodies were determinated by some serological tests such as: precipitin test (PT), bentonite flocculation test (BFT) and indirect hemagglutination test (IHAT) in sera IHAT (21,4 for percent) and BFT (3,6 for percent). After 15 days, the three tests were perfomed in sera from 12 patients. At that time, the positivity was elevated in all of them: PT (100,0 for percent), BFT (66,7 for percent) and IHAT (91,7 for percent). It is believed that the outbreak had its origin in infected pork meat that was consumed raw or insufficiently cooked without a previous veterinary inspection

Comparación de la frecuencia de alteraciones electrocardiográficas en grupos de personas aparentemente sanas con serología positiva para enfermedad de Chagas, para toxoplasmosis o para ambas parasitosis / Comparison of the frequence of electrocardiographical alterations in groups of apparently healthy persons with positive serology for Chagas'disease, for toxoplasmosis or for both parasitoses

Comparison of the frequence of electrocardiographical alterations in groups of apparently helathy persons with positive serology for Chagas disease, for toxoplasmosis or for both parasitoses

Estudio seroepidemiológico de la hidatidosis y triquinosis humana, mediante la reacción de hemaglutinación indirecta, en la Comuna de San Juan de la Costa: Osorno, X Región, Chile; 1990-1991 / Seroepidemiological study of human hydatidosis and trichinosis, by means of indirect hemagglutination reaction, in San Juan de la Costa County, X Region, Chile: 1990-1991

San Juan de la costa County (40-45' South lat., 73-19' West long) is located in the Osorno province, South of Chile. Its population is 8,486 inhabitants. The basic economic activities are agriculture, cattle raising, timber production and manufacture of wood and coal. According to official reports, the incidence of human hydatidosis and trichinosis in this locality in 1989 were 24 and 59% respectively. In order to contribute to a better knowledge of the epidemiology of human hydatidosis and trichinosis in San Juan de la Costa County, an indirect hemagglutination test (IHAT) for these parasitoses was performed to 511 randomized people. Nine (1.8%) individuals resulted positive for hydatidosis and twenty four (4.7%) were positive for trichinosis. Some considerations on the corresponding phrophylactic meaures are proposed

Epidemiología de la toxoplasmosis en Chile: VI prevalencia de la infección humana, investigada por medio de la reacción de hemaglutinación indirecta, en las regiones VII, VIII y IX / Epidemiology of toxoplasmosis in Chile: VI. Prevalence of human infection, investigated by means of an indirected hemaglutination test, in regions VII, VIII and IX

In presecuting the investigations on the epidemiology of toxoplasmosis in Chile, a new series of serological surveys has been performed during 1982-1989 in 10 urban and 25 periurban-rural localities form the regions VII, VIII and IX of the country [34-41'-39-38' South lat.]. In 9.758, randomly selected, apparently helathy persons, and indirect hemagglutination test [IHAT] for toxoplasmosis was carried out. The age of these individuals [4.203 males and 5.555 females] varied between 4 and 84 years. The exmined persons represent a 0.33% of the total population of the three studied regions. IHAT titers of 1:> ou = 16 were regarded as positive. The global prevalence for positive IHAT was 45.5% [50.5% in men and 41.7% in women]. A higher proportion of positive tests was observed in urban areas [47.0%] than in periurban-rural sections [33.3%]. An increasing prevalence with age was also observed. Only 5[0.05%] persons had IHATtiters higher than 1:1000