title: Pilot Field Trial of the EG95 Vaccine Against Ovine Cystic Echinococcosis in Rio Negro, Argentina: Second Study of Impact.
abstract: 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.
  
  
  OBJECTIVE
  Evaluate the impact of EG95 vaccination in sheep on the transmission of Echinococcus granulosus in a field environment.
  
  
  METHODS
  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.
  
  
  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.
authors.affiliation: Facultad de Ciencias Veterinarias, Universidad Nacional de La Pampa, General Pico, Argentina; Escuela de Veterinaria, Universidad Nacional de Río Negro, Choele Choel, Argentina.
authors.forename: Edmundo
authors.initials: E
authors.lastname: Larrieu
authors.affiliation: Ministerio de Salud, Provincia de Río Negro, Viedma, Argentina.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Mujica
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Werribee, Australia.
authors.forename: Charles G
authors.initials: CG
authors.lastname: Gauci
authors.affiliation: Departamento de Parasitología "INEI- ANLIS", Buenos Aires, Argentina.
authors.forename: Katherina
authors.initials: K
authors.lastname: Vizcaychipi
authors.affiliation: Ministerio de Salud, Provincia de Río Negro, Viedma, Argentina.
authors.forename: Marcos
authors.initials: M
authors.lastname: Seleiman
authors.affiliation: Ministerio de Salud, Provincia de Río Negro, Viedma, Argentina.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Herrero
authors.affiliation: Ministerio de Salud, Provincia de Río Negro, Viedma, Argentina.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Labanchi
authors.affiliation: Ministerio de Salud, Provincia de Río Negro, Viedma, Argentina.
authors.forename: Daniel
authors.initials: D
authors.lastname: Araya
authors.affiliation: Ministerio de Salud, Provincia de Río Negro, Viedma, Argentina.
authors.forename: Luis
authors.initials: L
authors.lastname: Sepúlveda
authors.affiliation: Ministerio de Salud, Provincia de Río Negro, Viedma, Argentina.
authors.forename: Claudia
authors.initials: C
authors.lastname: Grizmado
authors.affiliation: Ministerio de Salud, Provincia de Río Negro, Viedma, Argentina.
authors.forename: Arnoldo
authors.initials: A
authors.lastname: Calabro
authors.affiliation: Ministerio de Salud, Provincia de Río Negro, Viedma, Argentina.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Talmon
authors.affiliation: Centro de Virología Animal (CEVAN), Instituto de Ciencia y Tecnología / Cesar Milstein-CONICET, Buenos Aires, Argentina.
authors.forename: Thelma Verónica
authors.initials: TV
authors.lastname: Poggio
authors.affiliation: Escuela de Veterinaria, Universidad Nacional de Río Negro, Choele Choel, Argentina.
authors.forename: Pablo
authors.initials: P
authors.lastname: Crowley
authors.affiliation: Departamento de Parasitología "INEI- ANLIS", Buenos Aires, Argentina.
authors.forename: Graciela
authors.initials: G
authors.lastname: Cespedes
authors.affiliation: Departamento de Parasitología "INEI- ANLIS", Buenos Aires, Argentina.
authors.forename: Graciela
authors.initials: G
authors.lastname: Santillán
authors.affiliation: Facultad de Ciencias Veterinarias, Universidad Nacional de La Pampa, General Pico, Argentina.
authors.forename: Mariela
authors.initials: M
authors.lastname: García Cachau
authors.affiliation: Facultad de Ciencias Veterinarias, Universidad Nacional de La Pampa, General Pico, Argentina.
authors.forename: Roberto
authors.initials: R
authors.lastname: Lamberti
authors.affiliation: Facultad de Ciencias Veterinarias, Universidad Nacional de La Pampa, General Pico, Argentina.
authors.forename: Lilia
authors.initials: L
authors.lastname: Gino
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Werribee, Australia.
authors.forename: Meritxell
authors.initials: M
authors.lastname: Donadeu
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Werribee, Australia.
authors.forename: Marshall W
authors.initials: MW
authors.lastname: Lightowlers
mesh_terms: D000818:Animals; D000947:Antigens, Helminth / Q000008:administration & dosage / Q000276:immunology*; D001118:Argentina; D018562:Disease Transmission, Infectious / Q000517:prevention & control*; D004443:Echinococcosis / Q000453:epidemiology / Q000517:prevention & control / Q000635:transmission / Q000662:veterinary*; D048209:Echinococcus granulosus / Q000276:immunology; D015801:Helminth Proteins / Q000008:administration & dosage / Q000276:immunology*; D007115:Immunization Schedule; D059208:Parasite Load; D015995:Prevalence; D012756:Sheep; D012757:Sheep Diseases / Q000453:epidemiology / Q000469:parasitology* / Q000517:prevention & control* / Q000635:transmission; D016896:Treatment Outcome; D014612:Vaccines / Q000008:administration & dosage* / Q000276:immunology*
chemical_list: D000947:Antigens, Helminth; C446034:EG95 protein, Echinococcus granulosus; D015801:Helminth Proteins; D014612:Vaccines