Alicia Perez

Portadores asintomaticos de hidatidosis: epidemiologia, diagnostico y tratamiento

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 Río 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).

Control program of hydatid disease in the province of Río Negro Argentina.: 1980-1997

La hidatidosis constituye un serio problema de Salud Publica en la Provincia de Rio Negro, Argentina. Los factores que han motivado esta situacion incluyen una economia rural basada en la ganaderia ovina extensiva, bajas condiciones socioculturales en una porcion importante de la poblacion rural, habitos de faenamiento domiciliario de ovinos adultos para consumo humano con entrega de las visceras resultantes del acto para consumo de los perros e infraestructura de faena en pequenas comunidades rurales altamente deficiente. Esta situacion ha promovido la instrumentacion de un programa de control basado en la desparasitacion canina sistematica con praziquantel, la vigilancia con arecolina, la educacion sanitaria, el control de faena, la legislacion y la atencion de las personas. El programa, puesto en marcha en 1980, cubrio inicialmente con acciones sistematicas 51.479 km2, alcanzandose en 1992 120,013 km2 bajo control. 11.915 canes rurales han recibido 1,870,423 comprimidos de praziquantel con coberturas que en promedio fueron del 65%. Se efectuaron 21.444 controles de materia fecal canina mediante la dosificacion con bromhidrato de arecolina, (control anual del 11,2% de los canes bajo programa). La prevalencia equinococcosica inicial era de 41,5%, siendo en 1996 del 2,9%. La hidatidosis ovina, por su parte, presenta una disminucion acentuada de la prevalencia, ubicandose en 1996 en el 5,5%. En relacion a hidatidosis humana, 1,720 casos nuevos fueron diagnosticados en toda la provincia en el periodo 1980/1996, el 31,4% de los cuales correspondieron a infectados asintomaticos, mediante encuestas serologicas o ecograficas (48.826 encuestas serologicas a poblacion escolar y a pobladores rurales adultos y 2.762 encuestas ultrasonograficas). El numero de casos humanos nuevos en el grupo de edad 0-10 anos presenta una disminucion del 77% desde la puesta en marcha del programa. Por el contrario, zonas no tratadas muestran una tendencia estable en la aparicion de casos humanos nuevos. En el periodo 1980/1986 se produjeron 581 casos nuevos en las areas bajo programa, mientras que en el periodo 1990/1996 el numero de casos nuevos fue de 275. Las encuestas ultrasonograficas en poblacion asintomatica, por su parte, arrojaron tasas de positividad del 5,5% (1984), 4,1% (1986) y 2,1% (1996). El modelo desarrollado, basado en una estructura de ejecucion descentralizada, con activa participacion comunitaria, seleccion de tecnologias sencillas y enfoque de riesgo; sustentado en el tiempo sobre la base de una firme decision politica de continuidad programatica y a su bajo costo operativo habria en tal sentido, modificado la capacidad de reproduccion del parasito.

Pilot field trial of the EG95 vaccine against ovine cystic echinococcosis in Rio Negro, Argentina: Early impact and preliminary data

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 vaccines 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.

Evaluation of the losses produced by hydatidosis and cost/benefit analysis of different strategic interventions of control in the Province of Rio Negro, Argentina

Los programas de control de la hidatidosis requieren de la elaboracion de ecuaciones costo/beneficio para la justificacion tecnica del mantenimiento de su fuente de financiamiento. Asi, el objetivo del presente trabajo es analizar los costos para los servicios de salud de la Provincia de Rio Negro, Argentina, la atencion medica de los casos economicamente alternativas futuras en las estrategias de control. Para ello se obtuvo informacion de casos humanos atendidos en tres hospitales, tratados con metodos quirurgicos convencionales, con quimioterapia y con PAIR (puncion, aspiracion, inyeccion y reaspiracion), procediendose a valorizar las practicas medicas efectuadas. Se estimaron asimismo costos del programa de control basado en la desparasitacion de perros y de programas alternativos basados en diagnostico masivo en personas mediante ecografia y serologia, y tratamientos no convencionales. Se estimmo un costo de tratamiento de US

HANTAVIRUS PULMONARY SYNDROME IN THE PROVINCE OF RIO NEGRO, ARGENTINA, 1993-1996

4.511 por paciente, US

Vigilancia de la equinococosis quística en perros y niños en la provincia de Río Negro, Argentina

5.936 en cirugia convencional, US

Ultrasonographic diagnosis and medical treatment of human cystic echinococcosis in asymptomatic school age carriers: 5 years of follow-up

1988 en PAIR y US

Diagnosis of cystic echinococcosis on sheep farms in the south of Argentina: areas with a control program.

1.350 en quimioterapia con albendazol. Los costos globales de atencion medica para 1997 fueron estimados en US

VIGILANCIA EPIDEMIOLOGICA DE LA EQUINOCOCCOSIS QUISTICA EN PERROS, ESTABLECIMIENTOS GANADEROS Y POBLACIONES HUMANAS EN LA PROVINCIA DE RIO NEGRO

293.215, resultando un 77% inferiores a 1980. Se estimaron los costos operativos del programa tradicional de control en US

Hantavirus antibodies in rodents and human cases with pulmonary syndrome, Rio Negro, Argentina.

440000 y uno alternativo basado en diagnostico y tratamiento en US