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

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

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

Comparación de la infección por trypanosoma cruzi en niños menores de 10 años de la V Región Chile: 1982-1995 / Comparison of trypanosoma cruzi infection in less than 10 year old children from the V Región Chile: 1982-1995

Evaluation of desinsectation programs carried out in the two health services from the V region, was undertaken by comparing serologic prevalences of T. cruzi infection age groups exposed to the risk of infection in rural areas during the antivectorial campaign activities (1982 vs 1995). Thus, were studied 2,193 blood samples from children under 10 years of age, proceeding from six chagasic endemic provinces in which antitriatomic domiciliary insecticide sprayings had been performed. Indirect hemagglutination and ELISA tests were carried out to each of the blood samples. A total de 42 (1,9 percent) children resulted positive. As an five counties no positive cases were detected in the last five years it is possible to assume that vector trasmission of T. cruzi should have been interrupted in them. When comparing prevalences existing in 1982 with the present ones, it is possible to observe a 63,5 percent of reduction of transmission in the V region, been this reduction higher in the Aconcagua Health services with 79,6 percent and lower in the Viña del Mar - Quillota Health Service with 55,6 percent. According to these results, comparison of prevalence of T. cruzi infection in children less than 10 year old in diverse periods, allows evaluate the vectorial control of Triatoma infestans programs

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

Situación epidemiológica de la enfermedad de Chagas en el área endémica de la II Región de Antofagasta, Chile / Epidemiological situation of Chagasï disease in the endemic area from the II Region of Antofagasta, Chile

During 1997 a seroepidemiological study on Chagas' disease was carried out in 18 localities of three provinces (Tocopilla,El Loa and Antofagasta) of Region II (20º 56'-26º south lat.; 70º 38'- 67º west long.), in order to asses the impact of the control program against triatoma infestans launched in 1988, based on insecticide spraying of dwellings. By means of ELISA and an indirect hemagglutination test for chagas' disease blood samples from 1,034 children under 10 years of age were examined, arising a 0.5 por ciento (3 cases) positivity. Test resulted positivite in 2 (0.9 percent) children from the locality of San Pedro de Atacama and 1 (0.4 percent) from Calama city, all in the age group 6-10 year -old. However, none of their dwellings were found infested with T.infestants. These result indicate that the control program has a good possibility to prevent new human infections. It is advisable to continue the seroepidemiological and entomological vigilance and remark the necessity of increasing the effort in the study of transmission through other routes, to adopt or reinforce the pertinent preventive measures

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

Rendimiento del xenodiagnótico y el PCR para evaluar el tratamiento quimioterápico específico de la enfermedad de Chagas en niños / Yielding of skin diagnosis and PCR for the evaluation of specific chemotherapy of Chagas's disease in children

Amplification by the polymerase chain reaction (PCR) of Trypanosoma cruzi kinetoplastic DNA was used to enhance sentitivity in the detection of the parasite in blood, with the ultimate goal of improving the parasitological diagnosis of Chagas' disease in 0-10 year-old infected children. Twenty eight children were evaluated by using xenodiagnosis (XD) and PCR. Whereas XD detected 75,0 percent of the cases PCR was positive in 96,8 percent. The usefulness of the PCR was further investigated in the 28 children who have received specific treatment with nifurtimox. Negativetion of XD after three and six months post treatment respectively. These observations suggest that PCR is the most sensitive and quick technique available for direct detection of T. cruzi in chagasic children and that it can be a very useful tool for the follow-up of infected subjects after specific chemotherapeutical treatment

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

Tendencia actual de la epidemiología de la triquinosis humana en Chile / Present trends of human trichinosis epidemilogy in Chile

Surveillance of the epidemiology of human triquinosis in Chile has been maintained during the last 30 years by the Department of Parasitology. Incidence and prevalence have been followed-up by analysing Ministry of Health annual reports and periodical phototrichinoscopic examination of diaphragm samples from individuals autopsied at the Santiago Medico Legal Service. A decrease has been observed on: incidence from 1.4 per 100.000 in the 1960s to 0.7 in the 1980s down to 0.3 in 1993 and 1994 and to 0.5 in 1995, and prevalence from 3.4 percent 2.8 percent, 2.0 percent and 0.8 percent in 1972, 1982, 1992 and 1997 respectively. A predominance of the prevalence in the groups of more age, with the observation of calcified Trichinella spiralis larvae should be indicating a decline of new infections in the general population. This decrease of frequence of human trichinosis in Chile is possible due to the interaction of two main factors, efficacy and higher implementation of control measures and significant advances in porcine technology with a resulting provision to consumers of pork from young animals practically trichinosis free

Enfermedad de Chagas: impacto del programa de control del triatoma infestans en la comuna de Alto del Carmen provincia de Huasco III Región Atacama de Chile / Chagas' disease: impact of triatoma infestans control program in Alto del Carmen of Huasco, III region Atacama, Chile

A control program of triatoma infestans has been carried out in Alto del Carmen, an endemic chagasic rural county in the III Region, Chile. The program started in 1988 with an attack phase consisting in a masshouse spraying with residual insecticide, followed by an entomological surveillance phase with health education for community participation and vector detection in eventually reinfested houses. A yearly evaluation in 1992, 1993, 1994 and 1995 was carried out in order to determine the effectiveness of vector control activities. In 1992, 24,1 percent of dwellings was infected, whereas in 1993, 1994 and 1995 the infestation rates were 3,9 percent, 2,8 percent and 4,0 percent respectively. The similar infestation rates found in 1993, 1994 and 1995 suggest passive dispersion of triatomas from areas without suveillance. Additionally, in 1994, 110 (16,0 percent) out of 688 examined people resulted serologically positive. It is noteworthy that all of the children in the 0-4 year age group, born after the attack phase, resulted serologically negative. This fact may indicate the interruption of vectorial transmission of Chagas's disease in Alto del Carmen county. It is concluded that the control activities perfored in the county constitute god strategies to the Nacional Program of Control of triatoma infestans, but for the sucess of such a program it is necessary to integrate the effort of all endemic areas with an active community participation

Detección de marcadores parasitarios y virales en embarazadas adolescentes y sus recién nacidos de riesgo / Detection of parasitary and viral markers in pregnant adolescent women and their newborns in risk

Las embarazadas adolescentes constituirían por su condición etárea una población de alto riesgo de infección por agentes relevantes en el binomio madre-hijo. Se investigó en 139 embarazadas adolescentes, la prevalencia de anticuerpos anti Toxoplasma gondii, Trypanosoma cruzi, Virus hepatitis B (VHB), citomegalovirus (CMV), Virus rubéola (VR) y Virus de la Inmunodeficiencia humana (VIH), así como la presencia de marcadores de infección en sus recién nacidos (RN) de riesgo. Se utilizaron las técnicas de Sabin y Feldman, fijación del complemento, ELISA, hemoaglutinación indirecta y xenodiagnóstico. Se detectó 30.9 por ciento de seropositivas para T. gondii, siendo estas madres y sus RN IgM negativos. Se detectaron dos madres con Acs anti T. cruzi (1.4 por ciento) y uno de los RN presentaba parásitos circulantes. En relación al estudio virológico, se detectó un 93,5 por ciento de madres seropositivas para CMV siendo sus RN IgM negativos, un 90,6 por ciento de las adolescentes eran antirrubéola positivas y se detectó un caso de adolescentes positiva para VIH. Las prevalencias establecidas en este grupo de embarazadas, no son significativamente diferentes a las encontradas en la población general de embarazadas

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

Epidemiología de la enfermedad de Chagas en Chile: seguimiento serológico de 1.906 habitantes de un área rural endémica de la IV región, 1991-1993 / Epidemiology of Chagas' disease in Chile: serological follow-up of 1.906 inhabitants from an endemic rural area in IV región, 1991-1993

The IV region (29º 30' -32º 13' south lat.) is located in the center of the geographical area of distribution of Chagas' disease in Chile. Triatoma infestans is the main and almost exclusive vector of trypanpsoma cruzi in this country. The mean prevalence rate of T. cruzi human infection in urban and periurban sections of IV region is 24,7 percent. To assess the impact of anti-T. infestans activities, by means of health education and sprayings of dwellings with insecticides, carried out in the IV Region since 1980, during january-february (summer) a serological follow-up to residents from 46 rural chagasic localities was performed. An indirect hemagglutination test and an indirect immunofluorescence test were done to each of the surveyed persons. In 1991, 303 (15.9 percent) out of 1,906 examined people resulted serologically positive. In 1992, previous discarding the positive individuals found in 1991. 1,334 persons were examined resulting positive 9 (0.7 percent). In 1993, 1,398 persons were surveyed and 26 (1.9 percent) were positive. It is neteworthy that none of these 35 positive persons had been surveyed in 1991, being difficult to assert if any was positive before. Two infants, daughters of positive mothers, serologically positive at the beginning, changed to negative in the following survey, indicatins that it was passive transfer of maternal specific antibodies. According to the results of this study, it is concluded that dwelling spraying with persistent-activity insecticides against T. infestans and health education are good tools in the control of T. cruzi human infection, particularly when the involved community participates

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

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