European Hares in Chile: A Different Lagomorph Reservoir for Mycobacterium avium subsp. paratuberculosis?

Abstract

Ruminants are the principal host for infection by Mycobacterium avium subsp. paratuberculosis (Map), the cause of Johne's disease. Based on studies of a Map-infected population of European rabbits (Oryctolagus cuniculus) in Scotland, lagomorphs as a broad taxonomic order were proposed as potential nonruminant reservoirs for Map. To determine whether a different lagomorph species may serve as a wildlife reservoir, we investigated Map infection in European hares (Lepus europaeus) sharing habitat with known Map-infected dairy cattle in southern Chile. Fecal, mesenteric lymph node, and ileal samples were aseptically collected from 385 wild hares for liquid culture and real-time polymerase chain reaction identification of acid-fast isolates. All tissue samples were also acid-fast stained and examined microscopically. We isolated Map from at least one tissue from 48 hares (12.6%) and fecal samples from 16 hares (4.2%). No Map was found in tissues of eight of the fecal-culture-positive hares. Histologically, all tissues from all hares were within normal limits, and no acid-fast organisms were observed in any sample. Active infection, implying amplification of the organism secondary to resultant disease, was not evident. With this report Map isolations on a population versus incidental detection have now been made from two lagomorph species. However, although the rabbit population studied in Scotland appears to function as a Map reservoir, the hares studied in Chile appear to be a dead-end host, serving only as potential mechanical vectors for the organism.