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Objective. To compare the performance of polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) tests for diagnosing Echinococcus granulosus in dog feces among national reference laboratories in Argentina, Chile, Peru, and Uruguay. Methods. National laboratories affiliated with the Ministry of Health/Agriculture of each country exchanged panels of 10 positive/negative samples obtained from their regular national surveillance programs in November 2015 – November 2016. All laboratories applied PCR; two also applied ELISA techniques. Sensitivity and specificity were determined for each laboratory and concordance of results among the laboratories was evaluated by Cohen Kappa coefficient. Results. Poor concordance (3 of 10 paired comparisons had values of Kappa > 0.4), low sensitivity and specificity across all laboratories, and poor performance of both techniques in detecting E. granulosus in canine feces was demonstrated in this study. An ex-post comparison of the laboratories’ test protocols showed substantial heterogeneity that could partially explain poor concordance of results. Conclusion. The results underscore the heterogeneity of canine echinococcosis diagnosis across the region and indicate possible sources of variability. Efforts to standardize canine echinococcosis testing must be included in the plan of action for the Regional Initiative for the Control of Cystic Echinococcosis. Future comparisons with fecal samples of known parasite load are needed.

En la Provincia de Río Negro, Argentina, se presentaron casos humanos de síndrome pulmonar por hantavirus (SPH) en la región de la cordillera andino patagónica. El virus Andes ha sido identificado en la región, tanto en el roedor Oligoryzomys longicaudatus como en seres humanos, demostrándose la transmisión principalmente del roedor al hombre y la factibilidad de la transmisión de persona a persona. El objetivo del presente trabajo es presentar nueva información sobre especies de roedores portadores de hantavirus en Argentina, su prevalencia de anticuerpos para hantavirus (período 1999-2001) y la relación del tamaño de las poblaciones de roedores y su seroprevalencia con la ocurrencia de casos humanos (período 1996-2001). Para ello, se procedió a la colocación de 3973 trampas para captura viva de roedores, tipo sherman en seis operativos efectuados entre octubre de 1999 y mayo de 2001. Se obtuvieron muestras de sangre de los roedores las que fueron procesadas mediante enzimoinmunoensayo con antígenos elaborados a partir de virus Andes. Una síntesis de los resultados indica 397 roedores capturados, con un éxito de trampeo del 10% y una prevalencia de anticuerpos contra hantavirus del 1.0%. Se observaron importantes diferencias en las especies capturadas en cada una de las regiones. Se capturaron O. longicaudatus y A. Olivaceus seropositivos y O. flavescens y C. Laucha potencialmente portadores de hantavirus Se registraron 6 casos humanos en el período 1993-1995 (correspondientes a estudios retrospectivos), 21 casos se notificaron en el período 1996-1998 y 6 en el período 1999-2001 Se analiza la correlación entre ocurrencia de casos humanos, seroprevalencia en roedores y éxito de trampeo.In the Province of Río Negro, Argentina, human cases of hantavirus pulmonary syndrome (HPS) have occurred in the region of the Patagonian Andean range. The Andes virus has been identified in the region, both in the rodent Oligoryzomys longicaudatus and in human beings, demonstrating mainly transmission from rodents to human and the possibility of person-to-person transmission. The goal of this paper is to present new information on hantavirus rodent carrier species in Argentina, the prevalence of antibodies to hantavirus (1999-2001 period) and the relationship of the rodent population size and seroprevalence with the occurrence of human cases (1996-2001 period). To this end, a total of 3,973 Sherman type traps for capturing live rodents were placed in six campaigns from October 1999 to May 2001. Rodent blood samples were obtained and processed by means of enzymoimmunoassay with antigens developed from the Andes virus. A summary of results indicates 397 captured rodents, with a 10% trapping success rate and a 1.0% prevalence of antibodies to hantavirus. Considerable differences were observed in species captured in each region. Seropositive O. longicaudatus and A. olivaceus specimens, as well as potential hantavirus O. flavescens and C. laucha carriers, were captured. Six human cases were recorded during the 1993-1995 period (corresponding to retrospective studies), while 21 cases were reported in 1996-1998 and 6 in 1999-2001. The correlation between occurrence of human cases, seroprevalence in rodents and trapping success is analyzed.

There is little information on the humoral response of sheep experimentally infected with Echinococcus granulosus. Thus, the objective of this study was to evaluate this response and measure its evolution. Doses of 10, 100, 1000 and 10000 E. granulosus eggs were prepared and inoculated via intraruminal puncture. Blood samples were obtained before inoculation and every 48 h after inoculation, until they became seropositive. Thereafter, they were taken monthly for the first year and then every three months until 1700 days of observation had been completed. An ELISA test, with total hydatid fluid antigen, was used for immunodiagnosis. The average optical density of the 12 inoculated sheep was found to be above the mean cutoff value 10 days after inoculation, went on increasing until 180 days after inoculation and remained above the cutoff level until the end of the observation period. This confirms that the antibody response of sheep to E. granulosus infection occurs before production of hydatid fluid and that activation, mobilization and establishment of oncospheres in the tissues generates a persistent response from the host's immune system.