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La equinococosis quística (EQ) es una zoonosis parasitaria causada por Echinococcus granulosus sensu lato. Técnicas inmunodiagnósticas como Western blot (WB) o el enzimoinmunoensayo (ELISA), con distintos antígenos, pueden ser aplicadas al diagnóstico de la EQ ovina con fin tales de vigilancia epidemiológica en programas de control. Sin embargo, hay limitación para su uso por la existencia de reacción cruzada antigénica entre diferentes especies de taeniidaes presentes en el ovino. A pesar de ello se ha postulado la utilidad de establecer sistemas de vigilancia basados en la identificación de infección presente en un establecimiento ganadero, a lo que se denomina Unidad Epidemiológica (UE). Una nueva técnica diagnóstica de ELISA ha sido desarrollada y validada utilizando el antígeno EgAgB8/2 recombinante, para detección de anticuerpos contra E. granulosus, estimándose una DO 0.496 como el valor de corte que optimiza la sensibilidad y especificidad. Para la determinación de la infección en UE se construyó un modelo bayesiano ejecutado con un algoritmo de cadena de Markov Monte Carlo que permitió definir los tamaños de muestra para diferentes prevalencias esperadas para asegurar que al menos dos de las muestras sean verdaderamente positivas. De tal forma, el sistema puede ser usado para identificar la prevalencia de la infección en el área bajo control medida como porcentaje de UE con ovinos infectados (infección presente) o identificar individualmente las UE con transmisión presente, dada por la existencia de corderos infectados, sobre las que se deben intensificar las medidas de control.

Equinococosis quística (EQ) es una enfermedad zoonótica causada por el estadío larval del complejo Echinococcus granulosus sensu lato. En el año 2009 en la Provincia de Rio Negro se agregó la vacunación de corderos con EG95, la desparasitación de perros con praziquantel lográndose disminuir la prevalencia de la infección en los diferentes hospederos. Sin embargo, los estudios de impacto señalaron la necesidad de mejorar la comprensión de la epidemiologia local. Objetivo: identificar causas que pueden generar aun infección en los perros Materiales y métodos: se determinó la prevalencia de EQ en caprinos y ovinos adultos mediante necropsia y por serología (ELISA). El análisis epidemiológico se completó con una encuesta a los productores sobre hábitos de faena para consumo. Resultados: Mediante serología. las diferencias en la tasa de infección entre ovinos vacunados y no vacunados resulto significativa (p=0.0004); entre ovinos no vacunados y cabras no vacunadas resulto significativa (p= 0.0013) y entre ovejas vacunadas y cabras no vacunadas resultaron no significativas (p= 0.254). Mediante necropsia las diferencias en la tasa de infección entre ovinos vacunados y no vacunados resulto significativa (p=0.0016); entre ovinos no vacunados y cabras no vacunadas resulto significativa (p= 0.0016 y entre ovejas vacunadas y cabras no vacunadas resultaron no significativas (p= 0.23). El relevamiento de la faena de animales para consumo en 41 productores mostro que 21 faenan en promedio 18 cabras mensuales y entre 36 faenan 35 ovejas viejas mensuales Conclusión: El diseño y la implementación del programa resultaron costo – efectivas, en tanto ha podido sostenerse a través del tiempo demostrando impacto en la disminución de la prevalencia en los distintos hospedadores

Cystic echinococcosis (CE) is a zoonosis caused by species of the complex Echinococcus granulosus, sensu lato in their larval stage. It is an endemic disease in the province of Río Negro, where lamb vaccination with EG95 was incorporated in 2009 with very good results: in fact, it contributed to a significant drop in prevalence of infection in diverse hosts. However, impact studies have revealed the need to improve understanding of local epidemiology. The objective was to identify causes which can still generate infection in dogs. In indigenous reserves comprised within the area of lamb vaccination with 3 doses of EG95, prevalence in adult caprines and ovines was determined by necropsy and serology (ELISA). Through serology, infection rates in vaccinated and non-vaccinated ovines were significantly different (p= 0.0004), as well as between non-vaccinated ovines and goats (p= 0.0013); on the other hand, infection rate differences between vaccinated sheep and non-vaccinated goats turned out non-significant (p= 0.254). Through necropsy, such difference between vaccinated and non-vaccinated ovines turned out significant (p= 0.0016); between non-vaccinated ovines and non-vaccinated goats, it proved non-significant (p= 0.23). With reference to epidemiology and control along the period 2018-2022, vaccination strategy was maintained, and 2 extra deworming tasks were introduced, performed by the vaccination team. Assessment of animal slaughter for consumption in 41 producers showed that 21 of them slaughter a monthly average of 18 goats, and 36 in all slaughter 35 old sheep. Design and implementation of programme resulted cost-effective, since it was possible to maintain them over time, with clear impact on prevalence decrease in diverse hosts. [ABSTRACT FROM AUTHOR]

Cystic echinococcosis (CE) is a parasitic zoonosis caused by Echinococcus granulosus sensu lato. Immunodiagnostic techniques such as Western blot (WB) or enzyme-linked immunosorbent assay (ELISA), with different antigens, can be applied to the diagnosis of CE sheep for epidemiological surveillance purposes in control programs. However, its use is limited by the existence of antigenic cross-reactivity between different species of taeniidae present in sheep. Despite this, the usefulness of establishing surveillance systems based on the identification of infection present in a livestock establishment, known as the Epidemiological Unit (UE), has been postulated. A new ELISA diagnostic technique has been developed and validated using the recombinant EgAgB8/2 antigen for the detection of antibodies against E. granulosus, estimating an OD 0.496 as the cut-off value that optimizes diagnostic sensitivity and specificity. To determine the infection in the EU, a Bayesian model was built, executed with a Monte Carlo Markov chain algorithm, which allowed defining the sample sizes for different expected prevalences to ensure that at least two of the samples are truly positive. In this way, the system can be used to identify the prevalence of infection in the area under control measured as a percentage of EU with the presence of infected sheep (infection present) or individually identify the EU with present transmission, given by presence of infected lambs, on which control measures should be intensified. [ABSTRACT FROM AUTHOR]

Cystic echinococcosis 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 is to assess the impact of the inclusion of the EG95 vaccine in sheep in the control program. The vaccine was applied to lambs from communities of native peoples which included 70 producers (Anecón Grande, Mamuel Choique, Nahuel Pan y Río Chico Abajo). From 2009 on, lambs received two doses of the EG95 vaccine when they were 30 and 60 days of age, followed by a single booster injection when the animals were 1 year of age. The transmission of Echinococcus granulosus was assessed through necropsy in mature sheep, Arecoline test and coproantigen test in dogs and register of new clinical cases in inhabitants of the area. A total of 29.323 doses of EG95 vaccine were applied to lambs in the 2009-2017 period, working with 4 groups of 2 veterinaries each, covering 83.5% with one doses, 80.1% with two doses and 85.7% with three doses. Before the vaccine was introduced, in necropsy of sheep of 6 years old showed that 45.7% were infected with E. granulosus. The rate decreased to 21.1% in 2006. The number of cysts per animal decreased from 1.4% to 0.3. The number of producers with infected animals decreased from 84.2% to 22.2%. The humoral response to the vaccination, in field conditions, showed an increased in antibodies with the second dose, reaching its maximum after the booster at one year of age for many years and keeping constant. In dogs, 4.7% was found positive using arecoline purgation and 20.3% of the farms were infected using coproantigen test. The impact assessment showed a 5.6% of dogs positive to the arecoline test. Only a new case of echinococcosis was detected in kids with a 10 cm cyst, and its origin was probably before the vaccination. EG95 vaccine has been effective to prevent the infection in ovines up to six years of age, in spite of the difficulties of achieving better coverage. The transmission to dogs and human beings has to be determined. [ABSTRACT FROM AUTHOR]