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

• Published in: Acta tropica 2013-08, Vol.127 (2), p.143-151
• Main Authors: Larrieu, Edmundo, Herrero, Eduardo, Mujica, Guillermo, Labanchi, Jose Luis, Araya, Daniel, Grizmado, Claudia, Calabro, Arnoldo, Talmon, Gabriel, Ruesta, Guillermo, Perez, Alicia, Gatti, Antonio, Santillán, Graciela, Cabrera, Marta, Arezzo, Marcos, Seleiman, Marcos, Cavagión, Laura, Cachau, Mariela García, Alvarez Rojas, Cristian A., Gino, Lilia, Gauci, Charles G., Heath, David D., Lamberti, Roberto, Lightowlers, Marshall W.
• Format: Article
• Language: English
• Subjects: adults; Animals; arecoline; Argentina - epidemiology; Control; Diagnosis; Dog Diseases - epidemiology; Dog Diseases - parasitology; Dog Diseases - prevention & control; Dogs; Echinococcosis; Echinococcosis, Hepatic - epidemiology; Echinococcosis, Hepatic - parasitology; Echinococcosis, Hepatic - prevention & control; Echinococcosis, Hepatic - veterinary; Echinococcus granulosus; EG95; enzyme-linked immunosorbent assay; farms; feces; field experimentation; Freshwater; global positioning systems; humans; indigenous peoples; lambs; necropsy; Pilot Projects; polymerase chain reaction; praziquantel; Prevalence; risk; Sheep; Sheep Diseases - epidemiology; Sheep Diseases - parasitology; Sheep Diseases - prevention & control; soil sampling; Spacial analysis; teeth; Vaccination; Vaccines - immunology
• ISSN: 0001-706X; 1873-6254
• DOI: 10.1016/j.actatropica.2013.04.009

A field trial of the EG95 vaccine against cystic echinococcosis was initiated in the Rio Negro province of Argentina. Base-line data are presented for the field trial region as well as preliminary data on the effects of the vaccine's use on Echinococcus granulosus prevalence in sheep. •A field trial of the EG95 vaccine against cystic echinococcosis was initiated in Rio Negro, Argentina.•The prevalence of ovine echinococcosis is 61.3% in old animals at necropsy.•Preliminary assessment identified a reduction in infection in the vaccinated animals. 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