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Fil: Crowley Pablo, Uiversidad Nacional de Rio Negro, Escuela de Veterinaria, Rio Negro, Argentina Fil: Labanchi Jose Luis, Universidad Nacional de Rio Negro, Escuela de Veterinaria, Rio Negro, Argentina Fil: Dade Mertin, Universidad Nacional de Rio Negro, Escuea de Veterinaria, Rio Negro Fil: Daniele Martin, Universidad Nacional de Rio Negro, Escuela de Veterinaria, Rio Negro Fil: Calabro Arnoldo, Ministerio de Salud, Salud Ambiental, Rio Negro Fil: Grizmado Claudia, Ministerio de Salud, Salud Ambiental, Rio Negro Fil: Ochoa Alexis, Universidad Nacional de Rio Negro, Escuela de Veterinaria, Rio Negro Fil: Hernandez Paula, Ministerio de Salud, Salud Ambiental, Rio Negro Fil: Arezo Marcos, Ministerio de Salud, Salud Ambiental, Rio Negro Fil: Larrieu Edmundo, Universidad Nacional de Rio Negro, Escuela de Veterinaria, Rio Negro Chagas is an endemic epidemic disease of vector transmission in the Province of Rio Negro caused by Trypanosoma cruzi, transmitted by triatomines. The Chagas control program certified, through serological and entomological indicators, the interruption of vector transmission throughout the provincial territory. However, in recent years, conditions have been generated that may allow the re-emergence of the disease, such as the eventual domiciliation of wild vinchucas such as T patagonico. The objective was to evaluate the epidemiological situation of the vector through studies of home and peri-home infestation by triatomines and to carry out resistance analyzes to insecticides that were applied for many years in control. As a result, 143 homes were evaluated and 66 light traps were placed. In the intra-domicile all the dwellings were negative, with 3 being positive in the peri-domicile (2.1%) with captures of T-infestans and T. patagonica. No triatomines were captured with the light traps. The captured triatomines were T. infestans and T. patagonica, which were all negative for T. cruzi. Insecticide resistance studies showed that the colonies are still susceptible to deltamethrin. Chagas es una enfermedad endemoepidémica de transmisión vectorial en la Provincia de Rio Negro causada por Trypanosoma cruzi, transmitido por insectos vectores denominados triatominos (vinchucas). El programa de control de Chagas certifico, a través de indicadores serológicos y entomológicos la interrupción de la transmisión vectorial en todo el territorio provincial. Sin embargo, en los últimos años se han generado condiciones que pueden posibilitar la reemergencia de la enfermedad, tal como la eventual domiciliación de vinchucas silvestres como Triatoma patagónica. El objetivo fue evaluar la situación epidemiológica del vector mediante estudios de infestación domiciliaria y peri domiciliaria por triatominos y efectuar análisis de resistencia al principal insecticida que fue aplicado durante muchos años en control. Como resultado se evaluaron 143 viviendas y se colocaron 66 trampas de luz. En el introdomicilio todas las viviendas resultaron negativas, resultando 3 positivas en el peri-domicilio (2.1%) con capturas de T- infestans y T. patagonica. Con las trampas de luz no se capturaron triatominos. Los insectos capturados fueron T. infestans y T. patagonica los que resultaron todos negativos a T. cruzi. Los estudios de resistencia a insecticidas mostraron que las colonias siguen siendo susceptibles a deltametrina.

In December 2019, an outbreak of a novel zoonotic coronavirus began, called SARS-CoV-2 or COVID-19, which reached pandemic dimensions on March 11, 2020. By March 3, it had already entered República Argentina, while on March 9 the first case occurred in the Province of Rio Negro. In this province, 823 cases were identified with 41 deaths and 602 recovered cases by June 30, giving rise to successive intervention strategies to prevent its arrival in some places without viral circulation, to control outbreaks occurred and, when this objective was achieved, to avoid reintroduction. Among all measures, those related to non-pharmaceutical Interventions or NFI based on Primary Health Care and One Health with integrated participation among health agents of the First Level of Care, veterinary public health and medical areas of the Departments of Activities for the Area and Its Primary Health Care Centers and epidemiology services are a central, highly effective and essential strategy to cut the transmission chain and decrease the agent’s reproductive capacity (R0) to a value

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.

Background Cystic echinococcosis (CE) is a parasitic zoonosis caused by infection with the larval stage of Echinococcus granulosus (s.l.). This study investigated the prevalence and potential risk factors associated with human CE in the towns and rural areas of Ñorquinco and Ramos Mexia, Rio Negro province, Argentina. Methods To detect abdominal CE cysts, we screened 892 volunteers by ultrasound and investigated potential risk factors for CE using a standardized questionnaire. Prevalence ratio (PR) with 95% confidence intervals (CI) was used to measure the association between CE and the factors investigated, applying bivariate and multivariate analyses. Results Abdominal CE was detected in 42/892 screened volunteers (4.7%, 95% CI 3.2–6.1), only two of whom were under 15 years of age. Thirteen (30.9%) CE cases had 25 cysts in active stages (CE1, CE2, CE3a, according to the WHO Informal Working Group on Echinococcosis [WHO-IWGE] classification). The most relevant risk factors identified in the bivariate analysis included: living in rural areas (P = 0.003), age > 40 years (P = 0.000), always drinking water from natural sources (P = 0.007), residing in rural areas during the first 5 years of life (P = 0.000) and having lived more than 20 years at the current address (P = 0.013). In the multivariate final model, the statistically significant risk factors were: frequently touching dogs (P = 0.012), residing in rural areas during the first 5 years of life (P = 0.004), smoking (P = 0.000), age > 60 years (P = 0.002) and living in rural areas (P = 0.017). Conclusions Our results point toward infection with CE being acquired since childhood and with constant exposure throughout life, especially in rural areas with a general environmental contamination. Graphical Abstract

Cystic echinococcosis (CE), caused by Echinococcus granulosus, is a chronic and debilitating zoonotic larval cestode infection in humans, which is principally transmitted between dogs and domestic livestock, particularly sheep. Human CE occurs in almost all pastoral communities and rangeland areas of the underdeveloped and developed world. Control programmes against CE have been implemented in several endemic countries to reduce or eliminate the disease. New Zealand and Tasmania are examples of some of the first programmes to be undertaken (in insular territories) and which were very successful in the elimination of CE. The advent and proven effectiveness of praziquantel, plus the experience of insular models, produced high expectations for rapid advances in a second generation of control programmes undertaken in continental areas (Argentina, Uruguay and Chile). Nevertheless, only moderate gains in CE control have been made and the impact on prevalence among humans has been slight. A major impediment to the adoption of procedures that were successful in New Zealand and Tasmania has been the requirement to administer praziquantel to dogs in rural areas eight times per year over numerous years. In addition, there have been clear technological improvements made in the diagnosis of canine echinococcosis for surveillance, the genetic characterization of parasite strains and in vaccination against CE infection in livestock. In order to establish new paradigms and appropriate combinations of control strategies, we have carried out a review and discussion of the available control tools and control models. Control strategies must be suitable and sustainable to benefit the Echinococcosis-endemic areas primarily, which at the same time are the poorest regions of the world.

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.

Background Rio Negro Province is endemic for cystic echinococcosis (CE). A CE control program includes early diagnosis in humans. During 1980-1996, screening was done with serology and surgery was the unique choice of treatment. Since 1997, ultrasound (US) has been the method of choice for screening, and new choices of treatment for asymptomatic carriers are discussed in the CE guidelines. Methods Between 1997 and 2016, 42 734 abdominal USs were performed, 192 new asymptomatic cases were diagnosed and underwent a protocol according to the size, location and type of cyst. Treatment options included active surveillance (US monitoring, 83 [43.3%]), antiparasitic (albendazole, 92 [47.9%]) and surgery (17 [8.8%], including percutaneous treatment). Results After 7.7 y of follow-up, of the cases under active surveillance, 28 (33.7%) had to change treatment: 5 (6%) to surgery and 22 (26.5%) to albendazole. Of the patients treated with albendazole, 3 (3.2%) were operated on and 13 (14%) were treated with a second cycle of albendazole. Conclusion As a result of the present study, resolution of CE in a non-surgical way with albendazole is confirmed to be effective in asymptomatic carriers with CE1 or CE3a cysts. An update eliminates the strategy of active surveillance in type CE1 cysts

Background: Cystic echinococcosis (CE) is a parasitic zoonosis caused by infection with the larval stage of Echinococcus granulosus sensu lato This study investigated the prevalence and potential risk factors associated with human CE in the towns and rural areas of Ñorquinco and Ramos Mexia, Rio Negro province, Argentina. Methods: In order to detect abdominal CE cysts, we screened 892 volunteers by ultrasound and investigated potential risk factors for CE using a standardized questionnaire. Bivariate and multivariate analyses were used to estimate the Prevalence Ratio (PR) and their 95% CIs of the association between CE and the factors investigated. Results: Abdominal CE was detected in 42/892 screened volunteers (4.7%, CI 3.2-6.1), only two of who being under 15 years of age. Thirteen CE (30.9%) cases had 25 cysts in active stages (CE1, CE2, CE3) The most relevant risk factors identified in the bivariate analysis included: live in rural area (p=0.003), age >40 years (p=0.000), drinking always water of natural source (p=0.007), residing in rural areas during first five years of life (p=0.000) and live more than 20 years at your current address (p=0.013). In the multivariate model, statistically significant risk factors were: frequently touch dogs (p=0.012), residing in rural areas during first five years of life (p=0.004), smoking (p=0.000), age > 60 years (p­­=0.002) and live in rural areas (p=0.017).Conclusions: our results point toward infection with CE being acquired since childhood and with constant exposure throughout life, especially in rural areas with a general environmental contamination

The analysis of zoonotic disease risk requires the consideration of both human and animal geo-referenced disease incidence data. Here we show an application of joint Bayesian analyses to the study of echinococcosis granulosus (EG) in the province of Rio Negro, Argentina. We focus on merging passive and active surveillance data sources of animal and human EG cases using joint Bayesian spatial and spatio-temporal models. While similar spatial clustering and temporal trending was apparent, there appears to be limited lagged dependence between animal and human outcomes. Beyond the data quality issues relating to missingness at different times, we were able to identify relations between dog and human data and the highest ‘at risk’ areas for echinococcosis within the province., Author summary This work focuses on utilizing animal disease data to try and inform our understanding of the spread of diseases in humans. We implement predictive models to estimate the relationship between the distribution of disease in animal populations and the distribution of disease in human populations. Development of a better understanding of this relationship could inform animal and public health interventions aiming to mitigate against human disease before it spreads. Missing data and limited data resources made discovery of these relationships difficult, but we fit multiple model types to try and identify any connection between these two populations. We found specific areas with elevated risk of human disease and changes in disease risk over time. Finally, there was some indication of an association between previous years’ levels of animal disease and human disease when using animals as covariables.

Cystic echinococcosis is endemic in the Rio Negro province of Argentina and, for this, a control program using praziquantel in dogs was developed from 1980. The transmission rate to humans and sheep has decreased significantly, however transmission persists. In 2009 the vaccination of sheep with EG95 was incorporated in some areas of the province. The objective of the study was to evaluate the humoral responses to the vaccine EG95. Lambs received two vaccinations with the EG95 vaccine followed by a single booster injection when the animals were 1-1.5 years of age. Blood samples from 6 vaccinated groups and 4 no vaccinated sheep were obtained for determination of antibody titles against EG95 protein. Anti-EG95 responses were determined as described by Heath and Koolaard, 2012. Responses were evaluated from 331 animals. Median ELISA absorbance values in vaccinated group was 0.828, and in non-vaccinated groups was 0.218. EG95 antibody responses in sheep from different cohorts of non-immunized control groups and vaccinated groups reveal the sustained increase in response seen in animals following the third immunization. (p< 0.0001). Significant differences are also evidenced in ANOVA test (p< 0.001). An anti-EG95 antibody response was induced in all groups of immunized sheep, 4 times higher (0.828) than the mean observed in the control groups (0.218). Data described here indicate that following a third vaccination with the EG95 vaccine at 1 year of age the specific IgG responses detected in the serum of sheep increased to a level greater than that seen following the second immunization and that this response was maintained longitudinally over time, for at least 5 years. Fil: Larrieu, Edmundo Juan. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; Argentina. Universidad Nacional de Río Negro; Argentina Fil: Poggio, Thelma Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ciencia y Tecnología "Dr. César Milstein". Fundación Pablo Cassará. Instituto de Ciencia y Tecnología ; Argentina Fil: Mujica, Guillermo. Provincia de Río Negro. Ministerio de Salud; Argentina Fil: Gauci, Charles G.. University of Melbourne; Australia Fil: Labanchi, Jose Luis. Provincia de Río Negro. Ministerio de Salud; Argentina Fil: Herrero, Eduardo. Provincia de Río Negro. Ministerio de Salud; Argentina Fil: Araya, Daniel. Provincia de Río Negro. Ministerio de Salud; Argentina Fil: Grizmado, Claudia. Provincia de Río Negro. Ministerio de Salud; Argentina Fil: Calabro, Arnoldo. Provincia de Río Negro. Ministerio de Salud; Argentina Fil: Talmon, Gabriel. Provincia de Río Negro. Ministerio de Salud; Argentina Fil: Crowley, Pablo Ernesto. Universidad Nacional de Río Negro; Argentina Fil: Santillán, Graciela. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbran". Departamento de Parasitología; Argentina Fil: Vizcaychipi, Katherina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbran". Departamento de Parasitología; Argentina Fil: Seleiman, Marcos. Provincia de Río Negro. Ministerio de Salud; Argentina Fil: Sepulveda, Luis. Provincia de Río Negro. Ministerio de Salud; Argentina Fil: Arezo, Marcos. Provincia de Río Negro. Ministerio de Salud; Argentina Fil: García Cachau, Mariela Alejandra. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; Argentina Fil: Lamberti, Roberto. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; Argentina Fil: Molina, Leonardo. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; Argentina Fil: Gino, Lilia Mabel. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; Argentina Fil: Donadeu, Meritxell. University of Melbourne; Australia Fil: Lightowlers, Marshall W.. University of Melbourne; Australia

Cystic echinococcosis (CE), a parasitic zoonosis with substantial human health and economic consequences, is highly endemic in Rio Negro Province, Argentina. The objective of this study was to estimate the direct and indirect human and livestock-associated monetary losses attributable to CE, in Rio Negro Province, for the year 2010. Human costs were estimated using data obtained from hospital chart reviews, patient interviews, and government reports. Livestock-associated losses were estimated using data from government reports and scientific publications. Spreadsheet models were developed utilizing Latin Hypercube sampling to account for uncertainty in the input parameters. In 2010, the estimated total cost of CE, in Rio Negro Province, ranged from US$4,234,000 (95% credible interval [CI]: US$2,709,000-US$6,226,000) to US$5,897,000 (95% CI: US$3,452,000-US$9,105,000), with livestock-associated losses representing between 80% and 94% of the total losses, depending on whether non-healthcare-seeking human cases were included and if livestock slaughter values were adjusted to account for underreporting. These estimates suggest that CE is responsible for considerable human and livestock-associated monetary losses in Rio Negro Province. Stakeholders and policymakers can use these data to better allocate public health and agricultural resources for this region.

Cystic echinococcosis (CE) is a parasitic zoonosis caused by Echinococcus granulosus. The control program of CE of Rio Negro province, Argentina, involves annual surveillance using ultrasound (US) screening in school children, and five-year cross-sectional surveys to detect livestock farms with parasitized dogs by coproELISA with confirmation tests (Western Blot or PCR). Control program is based on deworming of dogs with praziquantel and the aim is to identify areas at risk of Cystic echinococcosis transmission to humans, using all available data sources. The information was spatially distributed in 13 program areas and, at a smaller geographical scale, in 80 Primary Health Care Centers. CoproELISA surveys involved three randomized sampling periods (2003-05, 2009-10, 2017-18), with 1790 canine fecal samples. The US surveys were conducted in 2003-08, 2009-16 and 2017-18 in 34,515 children. Heat maps were created at the smallest geographic scale with QGIS 3.4.6. For the consecutive sampling periods, prevalence of positive canine fecal samples from livestock farms were 14.7, 12.1 and 7.8%, respectively, and children prevalence was 0.4, 0.2 and 0.1%, respectively. The study has been developed on a scale according to which the temporal-spatial distribution of CE allows to adjust control strategies in those areas of potential transmission of the zoonosis to humans.

To investigate the epidemiology of human toxocariasis in a steppe environment, a field survey was carried out in three provinces of Argentina's Patagonia (Chubut, Neuquen, and Rio Negro) among 114 rural subjects residing in estancias (cattle- or sheep-breeding ranches). Overall seroprevalence was 31.6%, and the contamination rate of soil by Toxocara eggs was 35.1%. Bivariate and multivariate analyses were performed for various exposure variables and also for the De Martonne aridity-humidity index. Multivariate analysis revealed that the seroprevalence rate was found to be inversely correlated with age but was positively linked to De Martonne index. These findings suggest that the harsh climatic conditions existing in Argentina's Patagonia would inhibit embryonation of eggs in the soil, thus lowering the transmission of human toxocariasis.

Immunodiagnosis in sheep presents problems of sensitivity and specificity, limiting its applicability in surveillance systems. The objective of this study was to develop a sensitive, specific and accessible technique for diagnosing cystic echinococcosis in naturally infected sheep and to evaluate the validity of necropsy as a reference test. A total of 247 sheep were studied at slaughterhouses, confirming the parasitological diagnosis with histology. Serum was processed with enzyme immunoassay (EIA) using three antigen preparations: total hydatid liquid (LHT), purified fraction of LHT (S2B) and purified lipoprotein (B). Western Blot (WB) was used as a control. EIA proved effective for differentiating Echinococcus granulosus from larval stage of Taenia hydatigena and intestinal cestodes in all three antigen preparations. Serums from macroscopically negative sheep were reactive to EIA and positive with WB. In the whole flock, sensitivity was 89.2% for LHT, 80.0% for S2B and 86.4% for B. Sensitivity in lambs was 78.6% for LHT, 75.0% for S2B and 64.3% for B. Macroscopic diagnosis at the time of slaughter was found to have limitations as a reference test for immunodiagnosis of cystic equinococcosis in sheep, so it was necessary to include histology and WB as reference tests. LHT was the antigen preparation of greatest value and EIA proved to be a sensitive and specific technique, adequate for surveillance systems and for evaluating control programmes.

In 2000 Guarnera et al. proposed using ELISA in canine faeces collected from the ground to detect dogs infected with Echinococcus granulosus, thus determining sheep farms with active transmission. The objective was to evaluate the prevalence of E. granulosus infection in sheep farms of the Patagonia. Sheep farms were randomly selected in the Provinces of Río Negro, Chubut, Neuquén, Santa Cruz and Tierra del Fuego (areas with control programs) and La Pampa (comparison area). From one to three samples of fecal matter were obtained for each sheep farm, which were processed by means of copro-ELISA test with confirmation of positive samples by copro-Western blot. A total of 1042 samples were obtained from 352 sheep farms, 26 (7.3%) proving positive. Of these 5 (6.3%) were from La Pampa, 9 (13.8%) from Neuquén, 4 (4.7%) from Río Negro, 2 (2.9%) from Chubut, 1 (5.9%) from Santa Cruz and 5 (13.9%) from Tierra del Fuego. The identification of parasitized dogs is an essential activity upon which rests the strategy of control and surveillance. Arecoline tests or coproantigen test with fecal matter obtained directly from the dog contribute information on individual prevalence, while the use of coproantigens detected in ground-collected samples transfers the dog unit of observation to units of greater epidemiological value. In the present experience, the technique employed seems promising for its application in systems of epidemiological surveillance of cystic echinococcosis and in drawing a baseline on which to measure the progress of control programs in the Argentine Patagonia in subsequent years.

In 2000, two cases of human trichinellosis were detected in the Sierra Grande area of Rio Negro province, Argentina. As part of an investigation of the aetiology of these cases, 300 pigs slaughtered for consumption in the area between 2000 and 2002 were checked for Trichinella infection, by artificial digestion of a muscle sample. Twelve (5.6%) - four (7.3%) of the 55 checked in 2000, five (4.8%) of the 105 investigated in 2001, and three (2.1%) of the 140 investigated in 2002 - were found infected. Blood samples were collected from other pigs aged6 months old, so that sera could be tested, in ELISA and by western blotting, for anti- Trichinella antibodies. Of the 181 animals checked in the initial serological survey, 36 (19.9%) were found seropositive for Trichinella. When 35 of the seronegative pigs were re-checked 6 months later, three (8.6%) were found to have seroconverted. Four (15.4%) of 26 local rodents, caught in Sherman-type traps, were also found positive when checked for infection by artificial digestion. It appears that about 20% of pigs in the study area are infected each year, this high level of transmission being sustained by a high prevalence of infection in the local rodent populations.

In this work, the impact of a hydatidosis control programme for dogs on the intermediate ovine host was specifically analysed to determine the levels of prevalence achieved and the dynamics of parasite transmission, as well as to evaluate the quality of diagnostic systems in slaughterhouses. A field study was conducted in four slaughterhouses (Valcheta, Los Menucos, Jacobacci, Bariloche) that process animals coming from all the departments within the work area. The control programme for dogs entailed treating dogs with 5 mg/kg praziquantel at 2-month intervals for 20 years. Sample size was determined with a 10% error margin and a 95% significance level. Harvested viscera (liver, lungs, kidneys) were preserved in 5% formaldehyde and sent to the laboratory for diagnostic confirmation of both positive and negative specimens. The 61% initial prevalence dropped to 18.3% at the end of the 10-year period, observed differences proving significant (Chi-square=15.454, P=0.00). There were statistically significant increases in infection prevalence with age (Pearson’s Chi-square=133.61, P=0.00). Overall, 37.2% of hydatidosis cases diagnosed in slaughterhouses were considered non-hydatid by histological study. On the other hand, 1.1% of those diagnosed as healthy were found to be infected with hydatidosis. The number of hydatid cysts per animal increased with age: 0.04 in lambs and 1.22 in adults (linear regression equation, −0.0539+0.0127×age), whereas the average for the whole period was 3.7% in lambs and 20.5% in adults. Viability studies indicated that 63.8% of parasitised animals had viable cysts, out of which 53.3% were fertile. Diagnosis of infection in sheep made by means of an adjusted statistical design and with histological confirmation of the presumptive diagnosis made in slaughterhouses demonstrated the flaws of the official systems for epidemic surveillance of hydatidosis. However, there was no overall significant difference in slaughterhouse and laboratory data. Ro was 0.53 and could imply a decrease in reproductive capacity of the parasite and steady state extinction.

Until a short time ago, hydatidosis was considered a pathology that could only be resolved surgically. However, in recent years progress has been made with the epidemiology, diagnosis, and treatment of the disease, and new information on the natural history of hydatidosis has helped define new criteria for its treatment. It is now known that as many as 67% of the carriers of liver cysts who are asymptomatic remain so throughout their lives. This situation produces special results in immunologic testing. Enzyme-linked immunosorbent assay (ELISA) has a sensitivity of 63% and a specificity of 97% with asymptomatic carriers, while the double diffusion arc 5 test (DD5) achieves a sensitivity of only 31% with the same population. On the other hand, imaging studies based on ultrasonography have become the method of choice to detect asymptomatic carriers. Ultrasonography studies are 49% to 73% more sensitive than serological tests, and they can even be used as a part of epidemiological surveillance systems and to monitor control programs. Treatment schemes have also been modernized. Treating asymptomatic carriers chemotherapeutically with albendazole produces favorable results in as many as 69% of cases, while such minimally invasive surgical treatments as puncture-aspiration-injection-reaspiration (PAIR) reduce average cyst volume by as much as 66%. These factors have made it possible for hospital services in the province of Rio Negro, Argentina, to establish a treatment scheme for asymptomatic carriers. It is based on the monitoring of small cysts (type Ia on the modified Gharbi scale); initial treatment with albendazole, followed by PAIR if there is no response, in larger or more complex cysts (types Ib, II, and III); and follow-up of inviable or dead cysts (types IV and V).

Early in 1995 the first case of Hantavirus Pulmonary Syndrome was serologically confirmed in El Bolsón (Province of Río Negro, Argentina), corresponding to the third outbreak reported in Argentina. A total of 26 cases of HPS related to the Andean region of Rio Negro Province, were reported from 1993 to 1996, 17 in El Bolsón, 4 in San Carlos de Bariloche, and 5 in Buenos Aires. The incidence rate was 5.03 x 100000 with a mortality rate of 51.85 x 100. The occurrence of cases was mainly seasonal, with a significantly greater number in the spring, and the persons affected mainly lived in urban or periurban areas. In four cases, the affected individuals were members of a couple, spouses or live-in contacts. Seven cases were Health workers (physicians, nurses or administrative staff). Twelve cases were related among them, due to an outbreak of 80 days. Two of them did not visit the Andean region. A total of 139 rodents were captured and seven of them, Olygoryzomys longicaudatus, were found to be serologically positive. The possibility of infection by contact with rodents or fecal matter is being analyzed and also hypothesis related with interhuman transmissionEm 1995, o primeiro caso de Síndrome Pulmonar pelo Hantavírus (HPS) foi sorologicamente confirmado em El Bolsón (Província de Rio Negro, Argentina), correspondendo ao terceiro surto relatado na Argentina. Um total de 26 casos de HPS relacionados com a região Andina, Província de Rio Negro, foram relatados de 1993 a 1996, 17 em El Bolsón, 4 em São Carlos de Bariloche e 5 em Buenos Aires. O índice de incidência foi de 5,03 x 100.000 com índice de mortalidade de 51,85 x 100. A ocorrência de casos foi principalmente sasonal, com números significativamente maiores na primavera, e as pessoas afetadas viviam principalmente nas áreas urbanas e periurbanas. Em 4 casos, os indivíduos afetados eram membros de um casal, esposas ou viviam em contato. Sete casos eram trabalhadores da Saúde (médicos, enfermeiras e pessoal administrativo). Doze casos estavam relacionados entre si, devidos a um surto de 80 dias. Dois deles não visitaram a região Andina. Um total de 139 roedores foram capturados e sete deles, Olygoryzomys longicaudatus, foram sorologicamente positivos. A possibilidade de infecção por contato com roedores ou fezes está sendo analisada e também a hipótese de transmissão interhumana

Although cystic echinococcosis (CE) is an important public health problem in Rio Negro Province, current epidemiological data for CE, in this region of Argentina, are not available. Therefore, a community-based study, which incorporated diagnostic imaging and a questionnaire, was conducted in Ingeniero Jacobacci, a small town in southern Rio Negro Province. This study sought to assess the prevalence of human CE, in the study population, and to evaluate epidemiologic factors associated with CE transmission within the study area. Of the 560 individuals who volunteered to participate in the study, 189 (34%) were children and 371 (66%) were adults. All study participants were screened for CE using abdominal ultrasound scanning, with CE-positive or suspect individuals also receiving thoracic radiographs. The overall prevalence of CE was 7.1% (40/560), with 1.6% (3/189) of children, and 10% (37/371) of adults diagnosed as CE-positive. Although 92.5% (37/40) of the CE-positive individuals had only hepatic lesions, two participants had both hepatic and pulmonary lesions, and one participant had a single renal lesion. Approximately 92% (340/371) of the adult study participants completed the questionnaire, which was used to identify factors associated with an increased risk for human infection. Age, level of education, dog ownership, and contact with sheep were found to be significantly associated with CE status. This study demonstrated that CE continues to be highly endemic in this region of Rio Negro Province, Argentina. In addition, community-based ultrasound screening surveys are a noninvasive, effective approach to case detection at the community level.

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 for sheep in the control programme, including analysis of the vaccine's operative feasibility in field conditions. The vaccine was applied in an area comprising four communities of native people including 79 farms with 3146 lambs and 311 dogs in total. Seventy one farms were designated as control areas where no vaccinations were undertaken while vaccinations of lambs undertaken on 91 farms. Lambs received two vaccinations with the EG95 vaccine followed by a single booster injection when the animals were 1-1.5 years of age. Farm locations were defined using GPS coordinates for the houses. Evidence for Echinococcus granulosus transmission was monitored by coproantigen ELISA on samples of dog faeces, by E. granulosus-specific PCR using soil samples, and anti-E. granulosus antibody assessments in sera from 2 to 4 teeth lambs, purgation of dogs to detect E. granulosus worms and necropsy on adult sheep. Before the vaccine was introduced, 26.2% of sheep with 2-4 teeth were positive using ELISA/WB, the prevalence decreased to 7.8% at the third year following use of the vaccine. Necropsy of animals older than 6 years (not vaccinated) showed that 66.1% of animals were infected with E. granulosus. In dogs, 4% was found positive for E. granulosus using arecoline purgation and 24.7% of the farms were infected using coproELISA/WB. During the first year of vaccination 2721 lambs received the first vaccine dose and 2448 received a booster. In the second year 2138 lambs were initially vaccinated and 1745 received a booster, and 1308 animals received the third dose. During the third year 1110 lambs received the first dose from which 539 received a booster and 723 animals received the third dose. An analysis of advantages and limitations of the diagnostic techniques used and the ability of the geospatial analysis to detect risk area are included. Based in the immunodiagnostic techniques, the EG95 vaccine has been able to prevent the infection in animals up to 3 years old. Also, the difficulties in the field for the correct vaccine administration and the social features and habits that may impact on echinococcosis control are included in the analysis.

Cystic echinococcosis (CE) is a chronic, complex and neglected disease caused by the larval stage of Echinococcus granulosus. The effects of this neglect have a stronger impact in remote rural areas whose inhabitants have no chances of being diagnosed and treated properly without leaving their jobs and travelling long distances, sometimes taking days to reach the closest referral center. Background In 1980 our group set up a control program in endemic regions with CE in rural sections of Rio Negro, Argentina. Since 1997, we have used abdominopelvic ultrasound (US) as a screening method of CE in school children and determined an algorithm of treatment. Objectives To describe the training system of general practitioners in early diagnosis and treatment of CE and to evaluate the impact of the implementation of the field program. Materials and Methods In 2000, to overcome the shortage of radiologists in the area, we set up a short training course on Focused Assessment with Sonography for Echinococcosis (FASE) for general practitioners with no previous experience with US. After the course, the trainees were able to carry out autonomous ultrasound surveys under the supervision of the course faculty. From 2000 to 2008, trainees carried out 22,793 ultrasound scans in children from 6 to 14 years of age, and diagnosed 87 (0.4%) new cases of CE. Forty-nine (56.4%) were treated with albendazole, 29 (33.3%) were monitored expectantly and 9 (10.3%) were treated with surgery. Discussion The introduction of a FASE course for general practitioners allowed for the screening of CE in a large population of individuals in remote endemic areas with persistent levels of transmission, thus overcoming the barrier of the great distance from tertiary care facilities. The ability of local practitioners to screen for CE using US saved the local residents costly travel time and missed work and proved to be an efficacious and least expensive intervention tool for both the community and health care system., Author Summary Cystic echinococcosis (CE) is an important and widespread disease that affects sheep, cattle, and humans living in areas where sheep and cattle are raised. CE is highly endemic in rural sections of Rio Negro, Argentina, where our group is based. However, it requires continuous monitoring of both populations with human disease best assessed by means of ultrasound (US) screening. This is challenging in remote rural areas due to the shortage of imaging specialists. To overcome this hurdle, we set up a two-day training program of Focused Assessment with Sonography for Echinococcosis (FASE) on CE for family medicine practitioners with no previous experience in US. After the course, they were equipped with portable US scanners and dispatched to remote rural areas in Rio Negro where they screened patients, located and staged the cysts and decided on the treatment with the help of surgeons and radiologists in local tertiary care centers. The need to travel to referral hospitals for traditional surgical interventions was therefore limited to a few cases. US was instead brought to rural areas thereby extending affordable healthcare to people who would otherwise not have access to it.

Cystic echinococcosis (CE) is one of the most prevalent zoonoses in Argentina, Brazil, Chile, Peru, and Uruguay. Control programs in South America were originally modeled after programs developed in insular territories, such as Tasmania and New Zealand. The advent and proven effectiveness of praziquantel, plus the experience of insular models, produced high expectations for rapid advances; however, after 30 years of praziquantel use, no endemic area in South America has obtained eradication. In fact, only modest gains in CE control have been made and impact on prevalence among humans has been slight. A major impediment has been the infrastructure needed to administer praziquantel to dogs in rural areas 8 times per year over numerous years, a requirement for rapid attack stage 1. Such an infrastructure has not been financially or politically sustainable in endemic areas, which tend to be the poorest. On the other hand, certain areas in Argentina have had success with simple and economically viable alternatives. Based primarily on continuous field work supported by the local community, these strategies have significantly decreased transmission to humans, the health sector's main objective. In addition, new possibilities and tools, such as the EG95 vaccine, are being evaluated; as are early detection and treatment of asymptomatic carriers.

Liver hydatidosis is the most common clinical presentation of cystic echinococcosis (CE). Ultrasonographic mass surveys have demonstrated the true prevalence, including the asymptomatic characteristic of the majority of cases, providing new insight into the natural history of the disease. This raises the question of whether to treat or not to treat these patients, due to the high and unsuspected prevalence of CE. The high rate of liver/lung frequencies of cyst localization, the autopsy findings, and the involution of cysts demonstrated in long time follow-up of asymptomatic carriers contribute to this discussion. The decision to treat an asymptomatic patient by surgery, albendazole, or puncture aspiration injection and re-aspiration or to wait and watch, is based on conflicting reports in the literature, the lack of complications in untreated patients over time, and the spontaneous disappearance and involution of cysts. All these points contribute to difficulties of individual clinical decisions. The patients should be informed of the reasons and the risks of watchful/waiting without treatment, the possibility of complications, and the risks of the other options. As more information on the natural history of liver hydatidosis is acquired, selection of the best treatment will be come easier. Without this knowledge it would be very difficult to establish definitive rules of treatment. At present, it is possible to manage these patients over time and to wait for the best moment for treatment. Follow-up studies must be conducted to achieve this objective.

Cystic echinococcosis is an endemic disease in the Province of Rio Negro, Argentina. Ultrasound surveys carried out in 1984 found prevalence rates of 5.6% in children between 6 and 14 years of age. Objective To describe and to evaluate the results of the strategy applied in school children by hospital services of the Province of Rio Negro with regard to diagnosis, treatment and monitoring of cystic echinococcosis and to evaluate simultaneously the results of the control program against cystic echinococcosis. Materials and methods In 1997 ultrasound was chosen to carry out population surveys and the medical treatment criteria for the detected cases were standardized. The population under study involved 5745 students in the first survey and 22,793 in subsequent studies. The detected cases were classified according to Gharbi's scheme. A treatment algorithm was defined based only on monitoring (“watch and wait”), albendazole, surgery (open or laparoscopic) or mini-invasive procedures, according to type, location and size of the cyst. Information was also obtained on cases notified to the Health System between 1980 and 2008. Results In the first survey, 70 carriers (1.2%) were detected; of these, 25 started albendazole treatment (35.7%) and only 3 (4.3%) underwent surgery. Ten years after treatment, 60.1% of 42 cases, presented Types IV and V cysts and 14.5% presented total involution of their cysts. In subsequent studies, 87 (0.4%) cases were detected, 49 of which started albendazole treatment (56.3%) and 9 underwent surgery (10.3%). The incidence rate of cystic echinococcosis cases decreased from 38 × 100,000 in 1980 to 3.7 × 100,000 in 2008. Discussion A strong decrease in cystic echinococcosis was obtained although persistent levels of transmission were maintained. The cases produced under these conditions are diagnosed by means of ultrasound surveys and are treated using a plan based on albendazole and monitoring by the Health System during a period of 10 years.

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., Author Summary Hydatid disease, otherwise known as cystic echinococcosis (CE), is caused by Echinococcus granulosus. The disease is common in many pastoral areas, including parts of the Rio Negro province of Argentina, and is formally recognised by the WHO as a Neglected Tropical Disease. We undertook the first scientific evaluation of the EG95 vaccine against transmission of hydatid disease in a field situation. Sheep in remote indigenous communities of Rio Negro were vaccinated over a six year period. Young lambs received two injections of vaccine and a single booster injection as one year old sheep. A similar region acted as a control where vaccination was not implemented. Evaluation of the outcomes of vaccination revealed a significant, 62% decrease in the prevalence of hydatid infection in 6 year old sheep. Our study provides a template for the application of vaccination in future efforts to control transmission of E. granulosus and reduce the burden of human disease caused by the parasite.

Hydatidosis is a zoonosis produced by a parasite, Echinococcus granulosus, of high prevalence in Argentina, Uruguay, Chile, Peru and the south of Brazil, producing high losses for cattle raising and for health systems. Man acts as a host for the metacestode and is infected when ingesting fertile eggs adhering to the anus or hair of parasitized dogs or by ingestion of vegetables or water polluted with canine feces. Major epidemiological risk factors are: to slaughter sheep in the household, to cohabit with a great number of dogs during the first years of life, to have a history of hydatidosis cases in the family nucleus, to use non-potable water and to be in contact with parasitized dogs. It has been estimated that over 2000 new human cases are reported every year in the region, with rates of incidence ranging from 41 per 100,000 in the Patagonian region in southern Argentina, 80 per 100,000 in the XI Region of Chile, up to 100 x 100,000 in the Flores Department of Uruguay. Successful programs based on systematic canine deparasitation with praziquantel have been developed in Uruguay, Chile and Argentina, with diverse organization models. Traditionally, cystic echinococcosis has been regarded as a disease requiring surgical resolution. However, during the last years alternative methods have been developed including chemotherapeutic treatment with albendazol and minimally invasive surgical procedures such as echo-assisted puncture (PAIR). The Ministers of Agriculture and Health attending the XII RIMSA approved Resolution RIMSA12.R7 requesting the Pan American Health Organization (PAHO) to strengthen cooperative actions and coordination among countries and their institutions in matters related to hydatidosis control and prevention. In implementing this directive, the PAHO through the Program of Veterinary Public Health and its specialized center, the Pan American Center of Foot-and-Mouth Disease (PANAFTOSA), initiated actions to consolidate efforts carried out throughout the continent for hydatidosis control, establishing the mechanisms of collaboration among countries that have been developing control actions and drawing up a strategy of joint action aimed to strengthen and to support the actions \\ overall thrust.

Hydatidosis or cystic echinococcosis (CE) caused by Echinococcus granulosus is endemic in the Province of Rio Negro, Argentina. The objective of this investigation was to evaluate the results of a program carried out in endemic areas of the Province of Rio Negro, Argentina, in the years 1997-2002. Abdominal ultrasonography was used, classifying the cases detected according to WHO guidelines. A treatment algorithm was defined which included observation, albendazol therapy, PAIR or surgery, according to cyst type and size. A total of 5745 schoolchildren were evaluated, detecting hydatid cyst carriers in 70 (1.2%). Of these; 40 (57.1%) were included in follow-up protocol, 25 (35.7%) in treatment protocol with albendazol, 2 (2.9%) with PAIR and 3 (4.3%) with conventional surgery. After a mean of 44 months, among 25 cases treated with albendazol, in 2 (8%) cysts underwent total involution, in 17 (68%) they presented positive changes, in one (4%) they remained unchanged and in 4 (16%) they progressed to type II, while 1 (4%) displayed negative evolutionary changes. Out of 39 cases under observation alone protocol, in 8 cases (21%) cysts underwent total involution, in 7 (18%) they presented positive changes, in 11 (28%) they remained unchanged, in 2 (5%) they progressed to Type II and in 11 (28%) they presented negative evolutionary changes and had to be included in the other protocol types. In this study, conventional surgery, was applied to 10% of detected cases. The combination of ultrasonographic screening and albendazol treatment showed promising results.

In 1984 the prevalence of cystic echinococcosis (CE) in Rio Negro province in central Argentina reached alarming levels, with almost 6% of children aged 7-13 years infected with the causative agent, Echinococcus granulosus. Although the control activities developed between 1980-2000 have now lowered the prevalence of infection in this age-group to 1.1%, transmission of E. granulosus has clearly not ceased. The aim of the present study was to identify possible flaws in the control programme and the risk factors associated with CE. The 24 cases and 66 controls used were identified during a survey of the 1,070 schoolchildren attending 12 schools in Ingeniero Jacobacci, Rio Negro province. In interviews based around a standardized questionnaire, the adult female with responsibility for each subject (usually the mother but sometimes a grandmother or guardian) was asked 70 questions about the child and his or her immediate family, their contact with dogs and relevant environmentmental factors, and their level of contact with the control programme. Univariate and multivariate analyses were used to determine odds ratios (OR) and their 95% confidence intervals (CI). The main risk factors found to be significantly associated with CE were having a family member with the disease (OR = 3.11; CI = 0.92-10.47), spending the first years of life surrounded by a large number of dogs (OR = 2.11; CI = 1.2-3.5), and having a father who slaughtered sheep at his workplace (OR = 1.14; CI = 1.04-1.24). Obtaining drinking water from a tap (OR = 0.28; CI = 0.08-1.01) also remained in the final model, as a protective factor.

Epidemiological surveillance for hydatidosis is based on initial determination and follow-up of the infestation rate in man, sheep and dogs. The use of ultrasonography (US) as a screening method has demonstrated its usefulness in detecting asymptomatic human carriers of abdominal hydatidosis. To evaluate the contribution of US to epidemiological surveillance within the framework of disease control programs, we performed 719 US studies in school children from 7 to 13 years of age, in rural areas of Rio Negro, Argentina, subjected to canine deparasitization during 1984/1986 and 1997/1998. In the first period, 15/268 (5.6%), while in the second, 5/451 (1.1%) carriers were detected (P < 0.0004). The average diameter of the cysts was 4.71 cm in 1984/1986 and 2.14 in 1997/1998. US as a mass screening method allows evaluation of early changes in human prevalence rates, closely related to infestation rates in sheeps and dogs, thus providing a sensitive indicator of the evaluation of control programs.

Hydatidosis (cystic echinococcosis) constitutes a serious public health problem in the Province of Rio Negro, Argentina. In the present work it was intended to evaluate the prevalence of the canine echinococcosis in rural areas of the Province of Rio Negro and studied the reinfection rate in dogs after treatment with Praziquantel during the period 1980–1997. A total of 496 dogs were studied in 18 canine concentrations in order to establish the initial prevalence rate which was 42.3%. From 1980 onward dogs should have been systematically treated with anthelmintic every 2 months in rural areas and every 6 months in urban areas. We estimated that approximately 65% of dogs were treated. To determine the reinfection rate, 476 dogs (1984) and 598 dogs (1996) were studied after anthelmintic treatment during two sequential time periods (0–45; 46–90 days). In both cases treated animals were compared with untreated dogs. Prevalences were 3.5%, 6.7% and 21.3% in 1984 and 0.8%, 4.0% and 10.0% in 1996. For the purpose of surveillance a total number of 21,444 dogs were studied during 18 years. Prevalence of Echinococcus granulosus decreased significantly in the first year from 42.3% to 6.1%.

Los programas de control de la hidatidosis requieren de la elaboración de ecuaciones costo/beneficio para la justificación técnica del mantenimiento de su fuente de financiamiento. Así, el objetivo del presente trabajo es analizar los costos para los servicios de salud de la Provincia de Río Negro, Argentina, la atención médica de los casos económicamente alternativas futuras en las estrategias de control. Para ello se obtuvo información de casos humanos atendidos en tres hospitales, tratados con métodos quirúrgicos convencionales, con quimioterapia y con PAIR (punción, aspiración, inyección y reaspiración), procediéndose a valorizar las prácticas médicas efectuadas. Se estimaron asimismo costos del programa de control basado en la desparasitación de perros y de programas alternativos basados en diagnóstico masivo en personas mediante ecografía y serología, y tratamientos no convencionales. Se estimmó un costo de tratamiento de US$ 4.511 por paciente, US$ 5.936 en cirugía convencional, US$ 1988 en PAIR y US$ 1.350 en quimioterapia con albendazol. Los costos globales de atención médica para 1997 fueron estimados en US$ 293.215, resultando un 77% inferiores a 1980. Se estimaron los costos operativos del programa tradicional de control en US$ 440000 y uno alternativo basado en diagnóstico y tratamiento en US$ 260.218. Se analizan relaciones costo/beneficio para cada una de las estrategias planteadas.

Percutaneous puncture-aspiration-injection-reaspiration (PAIR) of hydatid liver cysts, was performed in 38 patients 14-80 years old, with a total of 60 liver hydatid cysts. After aspiration under computed tomography guidance, hypertonic saline was injected into the cystic cavities of patients as a scolecidal agent. No major complications were associated with the procedures. In the follow-up period of 18 months, control CT scans of 35 cysts revealed a gradual decrease in cyst size with a mean volume reduction of 66%. Complications included two cases of urticaria, one case of anaphylaxis and one subcapsular hematoma. No mortality occurred. It is concluded that percutaneous aspiration and hypertonic saline injection for liver hydatid cysts appears to be an effective form of treatment and may eventually prove to be an alternative to surgical intervention.

The aim of this study was to determine the outcome of asymptomatic liver hydatid cysts in a cohort of 33 out of 59 carriers by evaluating clinical and ultrasonographic (US) changes 10-12 years after initial diagnosis.We compared US features and cyst size with the original descriptions from 1984-1986. Patients were questioned about hydatid-related symptoms and signs.Thirty-three of the 59 carriers could be reevaluated, five (15.2%) of whom had undergone surgery without presenting symptoms, while of 28 unoperated cases, 21 (75%) remained asymptomatic. Of the unoperated cases evaluated by US, in 8/14 (57.1%) there were no modifications in cyst size during the 10-12-year period, in five (35.7%) growth was slight (3 cm) and in one (7.1%) the cyst grew 4 cm. Mean cyst growth in all 14 cases was 0.7 cm.Despite the limited number of cases, our results show that most asymptomatic liver hydatid cases (75%) remain symptom-free for more than 10 years, regardless of cyst size or type. We believe that such carriers are at low risk of developing complications, so that it is difficult to establish specific rules for their therapy, if any. Longitudinal follow-up of larger series of asymptomatic hepatic hydatidosis cases is essential to gain a deeper insight into the natural history of such patients, and to draw up comprehensive guidelines for treatment.

En la República Argentina, la hidatidosis constituye un serio problema que afecta a la salud publica y tiene graves repercusiones socioeconómicas. Las fuertes corrientes urbanisticas han traido consigo el traslado de algunas costumbres rurales hacia los centros poblados. A partir ae ello la hidatidosis en las areas endêmicas ha adquirido importância como zoonosis urbana. Si bien las cifras de infección canina halladas (1.12%) son significativamente inferiores que en las áreas rurales de la misma región, la capacidad potencial de infectar al hombre es muy superior en canes domiciliados en áreas de gran densidad demográfica. Las altas tasas de infección humana halladas son demostrativas de los aspectos señalados. In Argentina hydatidosis is a serious problem of Public Health with socioeconomic effects Strong urbanistic populational streams brought from the country local habits to urban areas. Hydatidosis became them an urban zoonosis. In spite of data on canine infection found (1.12%) are lower than those found in rural areas from the same region, the potential capacity to infect humans is higher in dogs from areas of high demographic density. The high incidences of human infections found are in accordance with this idea.

El desarrollo de equipos ultrasonográficos portátiles ha permitido incorporar esta técnica a los métodos de detección precoz de la Hidatidosis Humana. En esta experiência fueron efectuadas 690 ecografias, hallándose un 5.51% de imágenes compatibles en población general y un 12.24% en grupos de riesgo (convivientes de casos operados). Se observo una disminución significativa de los porcentajes de infección en el hombre en población general en Ias áreas bajo programa de control, utilizándose Ias encuestas ecográficas para esta determinación. Se concluyó sobre la posibilidad de incorporar la ecografía a los sistemas de vigilância epidemiológica de la hidatidosis humana. The development of small ultrasonographic equipment has permitted to incorporate this technique to the methods of early detection of Human Hydatidosis. 689 ecographies were carried out in this experience, and 5.51% of compatible images in the whole population, and 12.24% in groups of risk (those living together with the operated ones) were found. It was observed a significant decrease in the infection percentages in man in the whole population of areas under Control Program, using the ecographic screening. In conclusion, ecography might be incorporated to the epidemiologic surveillance system of human Hydatidosis.

Programmes for the control of hydatidosis caused by Echinococcus granulosus in Argentina use an enzyme immunoassay (EIA) as a screening test for population surveys aimed at detecting asymptomatic patients. Persons thus selected are referred to health centres for the arc 5 double diffusion test and imaging techniques. One of the most costly procedures of these surveys is the collection of blood samples under field conditions; the possibility of collecting dry blood samples on filter paper was therefore investigated. In a survey of 497 rural inhabitants of an endemic area, the same number of hydatidosis cases (22) were identified by EIA using (i) serum samples and (ii) capillary blood samples obtained by finger prick and collected on filter paper. The latter system was both simpler and cheaper.

This study presents new evidence as to the usefulness of ultrasound scanning in field conditions, to screen out hydatidosis in endemic areas, and to compare its detection capability with serological methods. It also intends to demonstrate that for an efficient rural ultrasound screening, neither an experienced ultra sonographer nor expensive and sophisticated equipment is necessary, it can be done by suitably trained personnel (eg, nurse, public health worker), using basic equipment, without public health installations or electricity, thus making it a feasible, simple, fast, and cheap screening method for hydatidosis.