title: A census to determine the prevalence and risk factors for caprine arthritis-encephalitis virus and visna/maedi virus in the Swiss goat population.
abstract: In Switzerland, viruses belonging to two different phylogenetic groups of small ruminant lentiviruses (SRLV) are currently circulating: the caprine arthritis-encephalitis virus (CAEV) and visna/maedi virus (VMV). In the past two decades, a mandatory national control program has led to a very low prevalence of seropositivity, while completely eliminating CAE as a clinical manifestation. However, in order to reduce the high costs and effort associated with this program, adjustments based on the most recent epidemiological knowledge are needed. The purpose of this study was to estimate the seroprevalence of CAEV and VMV using the newest diagnostic tools available, and to identify potential risk factors for infection with these viruses in Switzerland. For the prevalence estimation, a census was carried out including 10,696 farms with a total of 85,454 goats. Blood samples were analysed using a 3-step serological testing algorithm consisting of Chekit ELISA, Western Blot and SU5 ELISA. A risk factor analysis was conducted using logistic regression models built with data obtained from a mail questionnaire, and serological results from the census. The apparent herd-level prevalences were 0.38%, 2.77%, and 3.04% for CAEV, VMV and SRLV, respectively. Animal-level prevalences were 0.06% for CAEV, 0.55% for VMV, and 0.61% for SRLV. No statistically significant risk factors associated with CAEV or VMV infection were identified. However, the proportional high number of CAEV seropositive dwarf goats, in relation to their population size, could indicate that these hobby breeds may slip through some of the official controls. For an infection with SRLV, a medium herd size (7-40 goats) was found to be protective, compared with smaller (OR=1.90, p=0.034) and larger herds (OR=1.95, p=0.038). In conclusion, considering that all CAEV positive animals were culled, these results imply that CAEV is no longer actively spreading and has successfully been controlled in Switzerland. However, given the uncertain pathogenic potential of VMV in goats, future surveillance should also be taking into account the not insignificant number of VMV circulating in the Swiss goat population.
authors.affiliation: Veterinary Public Health Institute, Vetsuisse Faculty, University of Bern, Schwarzenburgstrasse 155, 3097 Liebefeld, Switzerland. Electronic address: beat.thomann@vetsuisse.unibe.ch.
authors.forename: B
authors.initials: B
authors.lastname: Thomann
authors.affiliation: Veterinary Public Health Institute, Vetsuisse Faculty, University of Bern, Schwarzenburgstrasse 155, 3097 Liebefeld, Switzerland.
authors.forename: L C
authors.initials: LC
authors.lastname: Falzon
authors.affiliation: Institute of Virology and Immunology, Vetsuisse Faculty, University of Bern, Länggassstrasse 122, 3012 Bern, Switzerland.
authors.forename: G
authors.initials: G
authors.lastname: Bertoni
authors.affiliation: Institute of Veterinary Virology, Vetsuisse Faculty, University of Bern, Länggassstrasse 122, 3012 Bern, Switzerland.
authors.forename: H R
authors.initials: HR
authors.lastname: Vogt
authors.affiliation: Veterinary Public Health Institute, Vetsuisse Faculty, University of Bern, Schwarzenburgstrasse 155, 3097 Liebefeld, Switzerland.
authors.forename: G
authors.initials: G
authors.lastname: Schüpbach-Regula
authors.affiliation: Veterinary Public Health Institute, Vetsuisse Faculty, University of Bern, Schwarzenburgstrasse 155, 3097 Liebefeld, Switzerland.
authors.forename: I
authors.initials: I
authors.lastname: Magouras
mesh_terms: D000818:Animals; D016088:Arthritis-Encephalitis Virus, Caprine; D005260:Female; D015511:Goat Diseases / Q000453:epidemiology* / Q000209:etiology / Q000821:virology; D006041:Goats / Q000821:virology; D016180:Lentivirus Infections / Q000453:epidemiology / Q000209:etiology / Q000662:veterinary*; D008297:Male; D011021:Pneumonia, Progressive Interstitial, of Sheep / Q000453:epidemiology* / Q000209:etiology / Q000821:virology; D015995:Prevalence; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D012756:Sheep; D013557:Switzerland / Q000453:epidemiology; D014790:Visna-maedi virus
keywords: Caprine arthritis-encephalitis virus; Census; Prevalence; Risk factor; Small ruminant lentivirus; Visna/maedi virus