Pilot field trial of the EG95 vaccine against ovine cystic echinococcosis in Rio Negro, Argentina: 8 years of work.

Cystic echinococcosis (CE) is endemic in the Rio Negro province of Argentina. After 30 years of control using praziquantel in dogs the transmission rate to humans and sheep has decreased significantly, however transmission persists. The objective of the study was to assess the inclusion of the EG95 for sheep in the control program and to determine the vaccine's operative feasibility in field conditions. An intervention study was defined in Rio Negro Province in Argentina comprising, in total, an area of 5820 Km2. Lambs received two vaccinations with the EG95 vaccine followed by a single booster injection when the animals were 1-1.5 years of age. Vaccination of lambs born into one trial site was introduced and continued for 8 years. Evidence for Echinococcus granulosus transmission was monitored before and after vaccination by coproantigen ELISA in faecal samples of dog, purgation of dogs to detect E. granulosus worms, necropsy on adult sheep and by ultrasound screening in children of 6-14 years old. 29,323 doses of vaccine were applied between 2009 and 2017, which a vaccination coverage of 80.1%/85.7% (57.3% average for fully vaccinated). Before the introduction of the vaccine 56.3% of the 6-year-old sheep were infected with E. granulosus at necropsy and 84.2% of the farms had infected sheep; 4.3% of the dogs were positive for E. granulosus infection using the arecoline test, and with coproELISA 9.6% of dog fecal samples were positive and 20.3% of the farms had infected dog.After the vaccine was introduced, 21.6% of sheep older than 6 years were found to be infected at necropsy and 20.2% of the farms were found to be infected; in dogs, 4.5% were found positive for E. granulosus using arecoline purgation and with coproELISA 3.7% of samples were positive, with 8.9% of farms having a positive dog. In 2016 only one case of E. granulosus infection was diagnosed by US screening in a 6-14 years old child. Included in the analysis are discussions of difficulties experienced in the field which affected correct vaccine administration as well as social features and practices that may impact on echinococcosis control and the EG95 vaccination program in Rio Negro. Vaccination of sheep with the EG95 vaccine provides a valuable new tool which improves the effectiveness of CE control activities. Vaccination was effective even in a difficult, remote environment where only approximately half the lambs born into the communities were fully vaccinated.

Pilot Field Trial of the EG95 Vaccine Against Ovine Cystic Echinococcosis in Rio Negro, Argentina: Second Study of Impact.

BACKGROUND: Cystic echinococcosis (CE) is an important zoonotic disease caused by the cestode parasite Echinococcus granulosus. It occurs in many parts of the world where pastoral activities predominate, including the Rio Negro province of Argentina. Although CE control activities have been undertaken in the western regions of Rio Negro for more than two decades, the disease continues to remain prevalent in both the human and livestock animal populations. Vaccination of animal intermediate hosts of CE with the EG95 vaccine may provide a new opportunity to improve the effectiveness of CE control measures, although data are lacking about field application of the vaccine. AIMS: Evaluate the impact of EG95 vaccination in sheep on the transmission of Echinococcus granulosus in a field environment. METHODOLOGY: Two trial sites were established in western Rio Negro province within indigenous communities. Vaccination of lambs born into one trial site was introduced and continued for 6 years. Prior to initiation of the trial, and at the end of the trial, the prevalence of CE in sheep was determined by necropsy. Weaned lambs received two injections of EG95 vaccine, approximately one month apart, and a single booster injection one year later. Vaccination was not implemented at the second trial site. A total of 2725 animals were vaccinated in the first year. Animals from this cohort as well as age-matched sheep from the control area were evaluated by necropsy. KEY RESULTS: Introduction of the vaccine led to a statistically significant in the number and size of hydatid cysts in comparison to the situation prior to the introduction of the vaccine, or compared to CE prevalence in the control area where the vaccine was not applied. The prevalence of infection in the vaccinated area was also significantly reduced by 62% compared to the re-intervention level, being lower than the prevalence seen in the control area, although the difference from the control area after the intervention was not significant possibly due to limitations in the numbers of animals available for necropsy. CONCLUSIONS: Vaccination of sheep with the EG95 vaccine provides a valuable new tool which improves the effectiveness of CE control activities. Vaccination was effective even in a difficult, remote environment where only approximately half the lambs born into the communities were fully vaccinated.

Toxocariasis: seroprevalence in abandoned-institutionalized children and infants.

Toxocariasis is an infection that has worldwide distribution. Toxocara canis is the most relevant agent due to its frequent occurrence in humans. Soil contamination with embryonated eggs is the primary source of T. canis. This study aimed to determine the seroprevalence of toxocariasis in 10-month to 3 year-old abandoned infants, considered to be at high risk because of their orphanhood status and early age. Blood samples were collected from 120 children institutionalized in an orphanage in the city of La Plata. In this study, we observed 38.33% of seropositive cases for T. canis by ELISA and 45% by Western blot techniques; significant differences among groups A (<1 year), B (1-2 years) and C (>2 years) were also found. In research group A, children presented a seropositivity rate of 23.91%, in group B of 42.85% and in group C of 56%, which indicates an increase in frequency as age advances, probably because of greater chances of contact with infective forms of the parasite since canines and soil are frequently infected with T. canis eggs. Abandoned children come from poor households, under highly unsanitary conditions resulting from inadequate or lack of water supply and sewer networks, and frequent promiscuity with canines, which promotes the occurrence of parasitic diseases. These children are highly vulnerable due to their orphanhood status and age.

Toxocariasis: seroprevalence in abandoned-institutionalized children and infants / Toxocariosis: seroprevalencia en infantes expósitos, abandonados e institucionalizados

Toxocariasis is an infection that has worldwide distribution. Toxocara canis is the most relevant agent due to its frequent occurrence in humans. Soil contamination with embryonated eggs is the primary source of T. canis. This study aimed to determine the seroprevalence of toxocariasis in 10-month to 3 year-old abandoned infants, considered to be at high risk because of their orphanhood status and early age. Blood samples were collected from 120 children institutionalized in an orphanage in the city of La Plata. In this study, we observed 38.33% of seropositive cases for T. canis by ELISA and 45% by Western blot techniques; significant differences among groups A (<1 year), B (1-2 years) and C (>2 years) were also found. In research group A, children presented a seropositivity rate of 23.91%, in group B of 42.85% and in group C of 56%, which indicates an increase in frequency as age advances, probably because of greater chances of contact with infective forms of the parasite since canines and soil are frequently infected with T. canis eggs. Abandoned children come from poor households, under highly unsanitary conditions resulting from inadequate or lack of water supply and sewer networks, and frequent promiscuity with canines, which promotes the occurrence of parasitic diseases. These children are highly vulnerable due to their orphanhood status and age.(AU)

La toxocariosis es una enfermedad presente en todo el mundo. Como causa primaria de infección se cita la contaminación de los suelos con huevos embrionados de Toxocara canis. Nuestro objetivo fue determinar la seroprevalencia de toxocariosis en niños expósitos (abandonados) de 10 meses hasta 3 años, los que se consideran de alto riesgo por su condición de orfandad y escasa edad. Las muestras de sangre fueron recolectadas de 120 niños institucionalizados en un orfelinato de la ciudad de La Plata. En este estudio, se observó un porcentaje de seropositivos para T. canis de 38,33 % por la técnica de ELISA y de 45 % por la técnica de Western blot, con diferencias significativas entre los grupos etarios estudiados (A: < 1 año, B: 1-2 años, C: > 2 años). Los niños del grupo A presentaron una frecuencia de seropositividad de 23,91 %; los del grupo B, de 42,85 % y en los niños del grupo C fue del 56 %. Esto indica un incremento de la frecuencia de presentación a medida que aumentó la edad, debido probablemente a las mayores posibilidades de contactar con estados infectantes del parásito, ya que los caninos y el suelo se hallan frecuentemente infectados por huevos de T. canis. Los niños abandonados provienen de hogares carenciados, donde a las malas condiciones de higiene resultantes de la ausencia de red de agua y cloacal se le agrega la frecuente promiscuidad con caninos, lo cual propicia la presencia de parasitosis. Sumado a la condición de desamparo, esto produce un estado de máxima vulnerabilidad.(AU)

Toxocariasis: seroprevalence in abandoned-institutionalized children and infants / Toxocariosis: seroprevalencia en infantes expósitos, abandonados e institucionalizados

Toxocariasis is an infection that has worldwide distribution. Toxocara canis is the most relevant agent due to its frequent occurrence in humans. Soil contamination with embryonated eggs is the primary source of T. canis. This study aimed to determine the seroprevalence of toxocariasis in 10-month to 3 year-old abandoned infants, considered to be at high risk because of their orphanhood status and early age. Blood samples were collected from 120 children institutionalized in an orphanage in the city of La Plata. In this study, we observed 38.33% of seropositive cases for T. canis by ELISA and 45% by Western blot techniques; significant differences among groups A (<1 year), B (1-2 years) and C (>2 years) were also found. In research group A, children presented a seropositivity rate of 23.91%, in group B of 42.85% and in group C of 56%, which indicates an increase in frequency as age advances, probably because of greater chances of contact with infective forms of the parasite since canines and soil are frequently infected with T. canis eggs. Abandoned children come from poor households, under highly unsanitary conditions resulting from inadequate or lack of water supply and sewer networks, and frequent promiscuity with canines, which promotes the occurrence of parasitic diseases. These children are highly vulnerable due to their orphanhood status and age.

La toxocariosis es una enfermedad presente en todo el mundo. Como causa primaria de infección se cita la contaminación de los suelos con huevos embrionados de Toxocara canis. Nuestro objetivo fue determinar la seroprevalencia de toxocariosis en niños expósitos (abandonados) de 10 meses hasta 3 años, los que se consideran de alto riesgo por su condición de orfandad y escasa edad. Las muestras de sangre fueron recolectadas de 120 niños institucionalizados en un orfelinato de la ciudad de La Plata. En este estudio, se observó un porcentaje de seropositivos para T. canis de 38,33 % por la técnica de ELISA y de 45 % por la técnica de Western blot, con diferencias significativas entre los grupos etarios estudiados (A: < 1 año, B: 1-2 años, C: > 2 años). Los niños del grupo A presentaron una frecuencia de seropositividad de 23,91 %; los del grupo B, de 42,85 % y en los niños del grupo C fue del 56 %. Esto indica un incremento de la frecuencia de presentación a medida que aumentó la edad, debido probablemente a las mayores posibilidades de contactar con estados infectantes del parásito, ya que los caninos y el suelo se hallan frecuentemente infectados por huevos de T. canis. Los niños abandonados provienen de hogares carenciados, donde a las malas condiciones de higiene resultantes de la ausencia de red de agua y cloacal se le agrega la frecuente promiscuidad con caninos, lo cual propicia la presencia de parasitosis. Sumado a la condición de desamparo, esto produce un estado de máxima vulnerabilidad.

Toxocariasis: seroprevalence in abandoned-institutionalized children and infants. / Toxocariasis: seroprevalence in abandoned-institutionalized children and infants.

Toxocariasis is an infection that has worldwide distribution. Toxocara canis is the most relevant agent due to its frequent occurrence in humans. Soil contamination with embryonated eggs is the primary source of T. canis. This study aimed to determine the seroprevalence of toxocariasis in 10-month to 3 year-old abandoned infants, considered to be at high risk because of their orphanhood status and early age. Blood samples were collected from 120 children institutionalized in an orphanage in the city of La Plata. In this study, we observed 38.33

of seropositive cases for T. canis by ELISA and 45

by Western blot techniques; significant differences among groups A (<1 year), B (1-2 years) and C (>2 years) were also found. In research group A, children presented a seropositivity rate of 23.91

, in group B of 42.85

and in group C of 56

, which indicates an increase in frequency as age advances, probably because of greater chances of contact with infective forms of the parasite since canines and soil are frequently infected with T. canis eggs. Abandoned children come from poor households, under highly unsanitary conditions resulting from inadequate or lack of water supply and sewer networks, and frequent promiscuity with canines, which promotes the occurrence of parasitic diseases. These children are highly vulnerable due to their orphanhood status and age.

[Coproantigens detection for the diagnosis of canine Echinococcosis in the border area of La Quiaca-Villazón]. / Detección de coproantígenos para el diagnóstico de echinococosis canina en la zona fronteriza de La Quiaca-Villazón.

Cystic Echinococcosis is a major public health issue. Immunodiagnostic techniques based on the identification of parasite antigens in dog dry faeces have been developed as alternatives for the surveillance of canine Echinococcosis. The environmental conditions favouring the parasite cycle were met in the border of La Quiaca-Villazón, given the presence of definitive (dog) and intermediate hosts (sheep and goats). The most important activity in La Puna is sheep and goat rearing; slaughtering is carried out almost exclusively in the field by sheep's owners, and preventive health measures do not apply. The aim of this study was to determine the presence of dogs parasitized by Echinococcus granulosus in this border region. A hundred and sixty eight (168) stool specimens were collected during 2006. La Quiaca samples were taken from the following selected areas: the semi-rural area of Barrios, the rural areas of Santa Catalina, Yavi Chico, El Portillo, Pumahuasi and Cara Cara and the urban area of La Quiaca; selected urban areas in Villazón and the semi-rural area of Ojo de Agua, Lampaya and Matancillas. The samples were analyzed by copro-ELISA -Western blot test. The cities of San Francisco and Barrios had a prevalence of 14.3% and 6.7%, respectively. A prevalence of 3.4% was observed in the urban area of Villazón, which indicates that dogs become infected in the rural areas and bring the risk into the city. Lampaya showed a prevalence of 30%. These findings suggest the need to implement strategies for the control of hydatidosis, both in urban and rural areas to avoid the increase and spread of Echinococcosis in the region.

Detección de coproantígenos para el diagnóstico de echinococosis canina en la zona fronteriza de La Quiaca-Villazón / Coproantigens detection for the diagnosis of canine Echinococcosis in the border area of La Quiaca-Villazón

Las técnicas de inmunodiagnóstico basadas en la identificación de antígenos parasitarios en las heces secas de los perros han sido desarrolladas para la vigilancia de la echinococosis canina. En la región fronteriza de La Quiaca-Villazón, se encontraron las condiciones ambientales que favorecerían el ciclo del parásito, dada la presencia del hospedador definitivo (perro) y de hospedadores intermediarios (ovejas y cabras). La actividad más importante de la Puna es la cría de ovinos y camélidos; la faena se realiza en el campo y a manos del dueño de los ovinos, y no se aplican medidas preventivas de sanidad. El objetivo de este trabajo fue estimar la presencia de caninos parasitados por Echinococcus granulosus en esta región. Durante el año 2006 se recolectaron 168 muestras de materia fecal. En La Quiaca se tomaron muestras de las siguientes localidades: Barrios (área semirrural), Santa Catalina, Yavi Chico, El Portillo, Pumahuasi y Cara Cara (zonas rurales) y La Quiaca (área urbana). En Villazón se seleccionó el área urbana y el área semirrural de Ojo de Agua, Lampaya y Matancillas. Las muestras se analizaron por la prueba de copro-ELISA y copro-Western blot. Las localidades de San Francisco y Barrios tuvieron una prevalencia de 14,3 % y 6,7 %, respectivamente. En Villazón se encontró un 3,4 % de prevalencia en el área urbana. En Lampaya se encontró un 30 % de prevalencia. Estos resultados sugieren la necesidad de implementar estrategias para el control de la hidatidosis, tanto a nivel urbano como rural, para evitar el aumento y la dispersión de la echinococosis en la región.(AU)

Cystic Echinococcosis is a major public health issue. Immunodiagnostic techniques based on the identification of parasite antigens in dog dry faeces have been developed as alternatives for the surveillance of canine Echinococcosis. The environmental conditions favouring the parasite cycle were met in the border of La Quiaca-Villazón, given the presence of definitive (dog) and intermediate hosts (sheep and goats). The most important activity in La Puna is sheep and goat rearing; slaughtering is carried out almost exclusively in the field by sheeps owners, and preventive health measures do not apply. The aim of this study was to determine the presence of dogs parasitized by Echinococcus granulosus in this border region. A hundred and sixty eight (168) stool specimens were collected during 2006. La Quiaca samples were taken from the following selected areas: the semi-rural area of Barrios, the rural areas of Santa Catalina, Yavi Chico, El Portillo, Pumahuasi and Cara Cara and the urban area of La Quiaca; selected urban areas in Villazón and the semi-rural area of Ojo de Agua, Lampaya and Matancillas. The samples were analyzed by copro-ELISA -Western blot test. The cities of San Francisco and Barrios had a prevalence of 14.3% and 6.7%, respectively. A prevalence of 3.4% was observed in the urban area of Villazón, which indicates that dogs become infected in the rural areas and bring the risk into the city. Lampaya showed a prevalence of 30%. These findings suggest the need to implement strategies for the control of hydatidosis, both in urban and rural areas to avoid the increase and spread of Echinococcosis in the region.(AU)

Detección de coproantígenos para el diagnóstico de echinococosis canina en la zona fronteriza de La Quiaca-Villazón / Coproantigens detection for the diagnosis of canine Echinococcosis in the border area of La Quiaca-Villazón

Las técnicas de inmunodiagnóstico basadas en la identificación de antígenos parasitarios en las heces secas de los perros han sido desarrolladas para la vigilancia de la echinococosis canina. En la región fronteriza de La Quiaca-Villazón, se encontraron las condiciones ambientales que favorecerían el ciclo del parásito, dada la presencia del hospedador definitivo (perro) y de hospedadores intermediarios (ovejas y cabras). La actividad más importante de la Puna es la cría de ovinos y camélidos; la faena se realiza en el campo y a manos del dueño de los ovinos, y no se aplican medidas preventivas de sanidad. El objetivo de este trabajo fue estimar la presencia de caninos parasitados por Echinococcus granulosus en esta región. Durante el año 2006 se recolectaron 168 muestras de materia fecal. En La Quiaca se tomaron muestras de las siguientes localidades: Barrios (área semirrural), Santa Catalina, Yavi Chico, El Portillo, Pumahuasi y Cara Cara (zonas rurales) y La Quiaca (área urbana). En Villazón se seleccionó el área urbana y el área semirrural de Ojo de Agua, Lampaya y Matancillas. Las muestras se analizaron por la prueba de copro-ELISA y copro-Western blot. Las localidades de San Francisco y Barrios tuvieron una prevalencia de 14,3 % y 6,7 %, respectivamente. En Villazón se encontró un 3,4 % de prevalencia en el área urbana. En Lampaya se encontró un 30 % de prevalencia. Estos resultados sugieren la necesidad de implementar estrategias para el control de la hidatidosis, tanto a nivel urbano como rural, para evitar el aumento y la dispersión de la echinococosis en la región.

Cystic Echinococcosis is a major public health issue. Immunodiagnostic techniques based on the identification of parasite antigens in dog dry faeces have been developed as alternatives for the surveillance of canine Echinococcosis. The environmental conditions favouring the parasite cycle were met in the border of La Quiaca-Villazón, given the presence of definitive (dog) and intermediate hosts (sheep and goats). The most important activity in La Puna is sheep and goat rearing; slaughtering is carried out almost exclusively in the field by sheep's owners, and preventive health measures do not apply. The aim of this study was to determine the presence of dogs parasitized by Echinococcus granulosus in this border region. A hundred and sixty eight (168) stool specimens were collected during 2006. La Quiaca samples were taken from the following selected areas: the semi-rural area of Barrios, the rural areas of Santa Catalina, Yavi Chico, El Portillo, Pumahuasi and Cara Cara and the urban area of La Quiaca; selected urban areas in Villazón and the semi-rural area of Ojo de Agua, Lampaya and Matancillas. The samples were analyzed by copro-ELISA -Western blot test. The cities of San Francisco and Barrios had a prevalence of 14.3% and 6.7%, respectively. A prevalence of 3.4% was observed in the urban area of Villazón, which indicates that dogs become infected in the rural areas and bring the risk into the city. Lampaya showed a prevalence of 30%. These findings suggest the need to implement strategies for the control of hydatidosis, both in urban and rural areas to avoid the increase and spread of Echinococcosis in the region.

[Evaluation of a purified antigen for the diagnosis of toxocariosis]. / Evaluación de un antígeno purificado para el diagnóstico de toxocariosis.

Toxocarosis is a zoonotic disease caused by the ingestion of infective eggs of Toxocara spp. The diagnosis is based on the detection of antibodies in serum or other biological fluids. One of the current serological techniques for the diagnosis of toxocariasis is ELISA using excretory - secretory antigens of third stage larvae (ES/L3). These antigens are glycoproteins, which originate in the secretory organs of the parasite and are non species-specific. Sera from patients with other helminthiases and non- parasitic diseases were used to evaluate the specificity of ELISA using the excretory - secretory antigen (ES/L3). The reactivity of these sera was between 11 and 70%. Western blot using patients' sera revealed that the glycoprotein triplet having a molecular weight of 120 kDa was responsible for cross-reactivity. With these results, and for the purpose of purifying the antigen, ion exchange chromatography was performed. When the sera from patients with various parasitic and non-parasitic diseases were analyzed with the purified antigen ES/ L3, they were only reactive between 10 to 20%. The sensitivity of the ELISA test determined by program Epidat 3.0 for the two antigens was 100%, but the following differences in specificity were observed: 84% for the total antigen ES/L3 and 99% for purified ES/L3. Using the ES/L3 purified antigen, it can be considered that the reactive sera, with compatible symptoms correspond to patients who are or were parasitized with Toxocara canis.

Evaluación de un antígeno purificado para el diagnóstico de toxocariosis / Evaluation of a purified antigen for the diagnosis of toxocariosis

La toxocariosis es una zoonosis causada por la ingestión de huevos infectivos de Toxocara spp. El diagnóstico de la enfermedad se basa en la detección de anticuerpos en el suero u otros fluidos biológicos. La técnica serológica más utilizada es el ELISA, que usa como antígeno los productos de excreción-secreción de larvas de tercer estadio (ES/L3). Estos productos antigénicos son glicoproteínas que se originan en los órganos secretorios del parásito y no son específicos de especie. Para evaluar la especificidad de la técnica de ELISA con el antígeno ES/L3, se emplearon sueros de personas con otras helmintiasis y con patologías no parasitarias. Se observó que estos sueros presentaron reactividad entre el 11 y el 70 % de los casos. El Western blot con suero de los mismos pacientes reveló que la glicoproteína que corresponde al triplete de 120 kDa fue la más inespecífica. Teniendo en cuenta estos resultados y con el propósito de purificar el antígeno se realizó una cromatografía de intercambio iónico. Cuando se analizaron los sueros de los pacientes con diferentes enfermedades parasitarias y no parasitarias con el antígeno ES/L3 purificado, solo fueron reactivos entre un 10 y un 20 % de ellos. La sensibilidad del test de ELISA determinada por el programa Epidat 3. 0 para los dos antígenos fue del 100 %, pero se observaron diferencias en la especificidad: para el antígeno ES/L3 total esta fue del 84 % y para el ES/L3 purificado del 99 %. Empleando el antígeno ES/L3 purificado se puede considerar que los sueros que son reactivos, en presencia de una sintomatología compatible, corresponden a pacientes que fueron o están parasitados con Toxocara canis.(AU)

Toxocarosis is a zoonotic disease caused by the ingestion of infective eggs of Toxocara spp. The diagnosis is based on the detection of antibodies in serum or other biological fluids. One of the current serological techniques for the diagnosis of toxocariasis is ELISA using excretory - secretory antigens of third stage larvae (ES/L3). These antigens are glycoproteins, which originate in the secretory organs of the parasite and are non species-specific. Sera from patients with other helminthiases and non- parasitic diseases were used to evaluate the specificity of ELISA using the excretory - secretory antigen (ES/L3). The reactivity of these sera was between 11 and 70%. Western blot using patients sera revealed that the glycoprotein triplet having a molecular weight of 120 kDa was responsible for cross-reactivity. With these results, and for the purpose of purifying the antigen, ion exchange chromatography was performed. When the sera from patients with various parasitic and non-parasitic diseases were analyzed with the purified antigen ES/ L3, they were only reactive between 10 to 20%. The sensitivity of the ELISA test determined by program Epidat 3. 0 for the two antigens was 100%, but the following differences in specificity were observed: 84% for the total antigen ES/L3 and 99% for purified ES/L3. Using the ES/L3 purified antigen, it can be considered that the reactive sera, with compatible symptoms correspond to patients who are or were parasitized with Toxocara canis.(AU)

Evaluación de un antígeno purificado para el diagnóstico de toxocariosis / Evaluation of a purified antigen for the diagnosis of toxocariosis

La toxocariosis es una zoonosis causada por la ingestión de huevos infectivos de Toxocara spp. El diagnóstico de la enfermedad se basa en la detección de anticuerpos en el suero u otros fluidos biológicos. La técnica serológica más utilizada es el ELISA, que usa como antígeno los productos de excreción-secreción de larvas de tercer estadio (ES/L3). Estos productos antigénicos son glicoproteínas que se originan en los órganos secretorios del parásito y no son específicos de especie. Para evaluar la especificidad de la técnica de ELISA con el antígeno ES/L3, se emplearon sueros de personas con otras helmintiasis y con patologías no parasitarias. Se observó que estos sueros presentaron reactividad entre el 11 y el 70 % de los casos. El Western blot con suero de los mismos pacientes reveló que la glicoproteína que corresponde al triplete de 120 kDa fue la más inespecífica. Teniendo en cuenta estos resultados y con el propósito de purificar el antígeno se realizó una cromatografía de intercambio iónico. Cuando se analizaron los sueros de los pacientes con diferentes enfermedades parasitarias y no parasitarias con el antígeno ES/L3 purificado, solo fueron reactivos entre un 10 y un 20 % de ellos. La sensibilidad del test de ELISA determinada por el programa Epidat 3. 0 para los dos antígenos fue del 100 %, pero se observaron diferencias en la especificidad: para el antígeno ES/L3 total esta fue del 84 % y para el ES/L3 purificado del 99 %. Empleando el antígeno ES/L3 purificado se puede considerar que los sueros que son reactivos, en presencia de una sintomatología compatible, corresponden a pacientes que fueron o están parasitados con Toxocara canis.

Toxocarosis is a zoonotic disease caused by the ingestion of infective eggs of Toxocara spp. The diagnosis is based on the detection of antibodies in serum or other biological fluids. One of the current serological techniques for the diagnosis of toxocariasis is ELISA using excretory - secretory antigens of third stage larvae (ES/L3). These antigens are glycoproteins, which originate in the secretory organs of the parasite and are non species-specific. Sera from patients with other helminthiases and non- parasitic diseases were used to evaluate the specificity of ELISA using the excretory - secretory antigen (ES/L3). The reactivity of these sera was between 11 and 70%. Western blot using patients' sera revealed that the glycoprotein triplet having a molecular weight of 120 kDa was responsible for cross-reactivity. With these results, and for the purpose of purifying the antigen, ion exchange chromatography was performed. When the sera from patients with various parasitic and non-parasitic diseases were analyzed with the purified antigen ES/ L3, they were only reactive between 10 to 20%. The sensitivity of the ELISA test determined by program Epidat 3. 0 for the two antigens was 100%, but the following differences in specificity were observed: 84% for the total antigen ES/L3 and 99% for purified ES/L3. Using the ES/L3 purified antigen, it can be considered that the reactive sera, with compatible symptoms correspond to patients who are or were parasitized with Toxocara canis.

Evaluación de un antígeno purificado para el diagnóstico de toxocariosis. / [Evaluation of a purified antigen for the diagnosis of toxocariosis].

Toxocarosis is a zoonotic disease caused by the ingestion of infective eggs of Toxocara spp. The diagnosis is based on the detection of antibodies in serum or other biological fluids. One of the current serological techniques for the diagnosis of toxocariasis is ELISA using excretory - secretory antigens of third stage larvae (ES/L3). These antigens are glycoproteins, which originate in the secretory organs of the parasite and are non species-specific. Sera from patients with other helminthiases and non- parasitic diseases were used to evaluate the specificity of ELISA using the excretory - secretory antigen (ES/L3). The reactivity of these sera was between 11 and 70

. Western blot using patients sera revealed that the glycoprotein triplet having a molecular weight of 120 kDa was responsible for cross-reactivity. With these results, and for the purpose of purifying the antigen, ion exchange chromatography was performed. When the sera from patients with various parasitic and non-parasitic diseases were analyzed with the purified antigen ES/ L3, they were only reactive between 10 to 20

. The sensitivity of the ELISA test determined by program Epidat 3.0 for the two antigens was 100

, but the following differences in specificity were observed: 84

for the total antigen ES/L3 and 99

for purified ES/L3. Using the ES/L3 purified antigen, it can be considered that the reactive sera, with compatible symptoms correspond to patients who are or were parasitized with Toxocara canis.

Detección de coproantígenos para el diagnóstico de echinococosis canina en la zona fronteriza de La Quiaca-Villazón. / [Coproantigens detection for the diagnosis of canine Echinococcosis in the border area of La Quiaca-Villazón].

Cystic Echinococcosis is a major public health issue. Immunodiagnostic techniques based on the identification of parasite antigens in dog dry faeces have been developed as alternatives for the surveillance of canine Echinococcosis. The environmental conditions favouring the parasite cycle were met in the border of La Quiaca-Villazón, given the presence of definitive (dog) and intermediate hosts (sheep and goats). The most important activity in La Puna is sheep and goat rearing; slaughtering is carried out almost exclusively in the field by sheeps owners, and preventive health measures do not apply. The aim of this study was to determine the presence of dogs parasitized by Echinococcus granulosus in this border region. A hundred and sixty eight (168) stool specimens were collected during 2006. La Quiaca samples were taken from the following selected areas: the semi-rural area of Barrios, the rural areas of Santa Catalina, Yavi Chico, El Portillo, Pumahuasi and Cara Cara and the urban area of La Quiaca; selected urban areas in Villazón and the semi-rural area of Ojo de Agua, Lampaya and Matancillas. The samples were analyzed by copro-ELISA -Western blot test. The cities of San Francisco and Barrios had a prevalence of 14.3

and 6.7

, respectively. A prevalence of 3.4

was observed in the urban area of Villazón, which indicates that dogs become infected in the rural areas and bring the risk into the city. Lampaya showed a prevalence of 30

. These findings suggest the need to implement strategies for the control of hydatidosis, both in urban and rural areas to avoid the increase and spread of Echinococcosis in the region.