Situación epidemiológica actual de la triquinosis en Chile 1991-2000 / Epidemiology of trichinosis in Chile from 1991 to 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 percent) 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 percent in winter and 37.5 percent in spring). There has been a decrease of infection rates in pigs from 0.17 percento in 1991 to 0.04 percento 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

Utilidad diagnóstica de ELISA IgG, IgM, IgA y ELISA avidez de IgG en toxoplasmosis reciente y crónica / Diagnostic utility of ELISA IgG, IgM, IgA and ELISA IgG avidity in recent and chronic toxoplasmosis

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, IgG, IgM, IgA and ELISA IgG, avidity were performed in 15 and 24 sera from patients suspectec 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 percent respectively, while ELISA IgA was positive in 85,7 and 33,3 percent of recent and chronic group respectively. In those sera with low IgG avidity (18,8 percent) we found specific IgM in 71,5 and 4,2 percent and IgA in 78,6 and 0,0 percent of recent and chronic groups respectively. Parallelly, 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 percent); intermediate (97,2-63,8-44,4 and 47,2 percent); chronic (45,7-42,8-5,7 and 34,3 percent) 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

Hidatidosis en Chile: seroprevalencia y estimación del número de personas infectadas / Human hydatidosis in Chile: seroprevalence and an estimate of the number of infected people

Chile is located in the southwestern border of South America. The country is 4,329 km long and 96-342 wide. From north to south it is divided into five marked different biogeographical zones: deserts, steppes, bushes, forests (cattle raising) and austral (sheep raising). Population (june 1999) 15,017,760 (14,6 percent rural). Human hydatidosis is endemic in Chile. According to Ministry of Health information about 320 cases are registered each year. In order to find out the likely prevalence of human hydatidosis in Chile, a series of serosurveys was carried out in 1988-1997 throughout the total country. By using the indirect hemagglutination reaction and ELISA for hydatidosis (test with good sensibility and specificity) 60,790 unselected apparently healthy persons: 41,399 from urban areas (16,428 blood donors, 13,894 delivering mothers and 11,077 middle grade schoolchildren) and 19,361 from rural areas from randomly selected family groupings were studied. A total individuals 82 (136/100,000) resulted positive: 36 (87/100,000) urban and 46 (241/100,000) rural, being the prevalence higher in rural areas, particularly in the southern austral zone (mean 1068/100,00). These figures agree with those observed in clinical epidemiological studies. In conformity with the present results, in the whole country 17,002 individuals should have hydatidosis: 10,318 urban and 6,784 rural. All these possible infected people, not necessarily should present pathology in the future, as it has been observed in autopsies from unselected individuals, performed at the Medico Legal Service in Santiago, in whom 71,3 percent of diagnosed hydatidosis with hydatid cysts in many different locations, was an autopsy finding

Estandarización de ELISA IgM e IgA para el inmunodiagnóstico de la triquinosis humana / Standarization of ELISA IgM and IgA for inmunodiagnosis of human trichinosis

An ELISA test for trichinosis using as antigen a larvae soluble fraction from trichinella spiralis was carried out for the detection of IgM and 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 tes 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 halthy 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 percent using serum dilution of 1:10, 1:100 and 1:500 respectively (criterion A) and 100,0, 97,8 and 95,6 percent for the same dilutions (criterion B), whereas the values for ELISA IgA were: 100,0 91,1 and 86,7 percent (criterion A) and 100,0 100,0 and 91,1 percent (criterion B). In order to find out the specificity of ELISA IgM and ELISA IgA, additional 118 serum samples from individuals with other parasitoses, such as cysticercoss (18) hydatidosis (39), fascioliasis (12), toxocariasis (30), Chagaïs disease (12) and individuals with non specif eosinophilia (7), were also tested. ELISA IgM presentes a specificity of 92,3, 93,4 and 97,3 percent (criterion A) and 96,2, 97,8 and 97,8 percent (criterion B) whereas the results for ELISA IgA were 97,8, 98,9 and 99,4 percent (criterion A) and 98,4 percent for the 1:10 and 1:100 dilutions and 100,0 percent for the 1:500 dilution (criterion B). The positive predictive values of ELISA IgM were 76,3, 77,8 and 88,1 percent (criterion A) and 86,5, 91,7 and 91,5 percent (criterion B) whereas the negative ones were 100,0, 98,3 and 95,7 percent (criterion A) and 100,0, 99,4 and 98,9 percent (criterion B). The positive predictive values of ELISA IgA were 91,8, 95,3 and 97,5 percent (criterion A) and 93,8, 93,8 and 100,0 percent (criterion B) whereas the negatives ones were: 100,0, 97,9 and 96,8 percent (criterion A) and 100,0, 100,0 and 97,8 percent (criterion B). The use of ELISA IgM and ELISA IgA in the inmunodiagnosis of trichinosis is discussed

Infección chagásica en donantes de sangre de hospitales de las regiones endémicas de Chile (1982-1987): transcendencia epidemiológica del problema / Chagasic infection in blood donors from hospitals in endemic regions of Chile (1982-1987). Epidemiological transcendence of the problem

La enfermedad de Chagas, producida por el Trypanosoma cruzi y transmitida por triatominos hematófagos, existe en América desde el sur de Estados Unidos hasta Chile y Argentina. Existe en sectores rurales y periurbanos de la mitad norte de Chile, siendo su prevalencia del 16,9%. Constantes migraciones rural-urbanas han contribuído a su propagación hacia sectores urbanos. Para investigar el impacto de dichas migraciones sobre la población susceptible de donar sangre y el probable incremento del riesgo de transmisión del T. cruzi vía transfusional se efectuaron encuestas seroepidemiológicas en donantes de 22 hospitales de la mitad norte de Chile. Mediante la reacción de hemaglutinación indirecta se examinaron 16.841 donantes encontrándose un 2,7% de positividad, porcentaje que permitió estimar que habría 126.477 potenciales donantes de sangre infectados por T. cruzi en los sectores urbanos estudiados. Estos hechos refuerzan la necesidad que en bancos de sangre de las regiones endémicas del país se efectúe rutinariamente serología para enfermedad de Chagas, para adoptar o reforzar medidas preventivas pertinentes