Evidence of intrauterine transmission of Mycobacterium avium subspecies paratuberculosis in pregnant goats.

Abstract

Paratuberculosis (PTBC) is a chronic granulomatous enteritis of ruminants caused by Mycobacterium avium subsp. paratuberculosis (Map). Although PTBC intrauterine transmission has been described in cattle, sheep, and deer, data in dairy goats are limited. The present study investigated intrauterine Map infection in 32 pregnant Saanen goats from a herd with high PTBC prevalence in Jujuy, Argentina. Maternal and fetal tissues were analyzed using a range of methods, including bacteriological culture, IS900 PCR, histopathology, and serology. All goats were positive to the intradermal test, and 75% showed histopathological lesions consistent with PTBC. Map was isolated from 10 of 45 fetuses. Granulomatous lesions were observed in two cases, but no acid-fast bacilli were detected. Furthermore, fetuses from culture-positive dams were 7.8 times more likely to be infected than those from culture-negative ones. This suggests that the maternal bacterial load is a key predictor of fetal infection. These findings represent the first evidence of intrauterine transmission of Map in Saanen goats, even in subclinical cases, indicating that vertical transmission may be more common in this species than previously assumed. This has significant implications for PTBC control programs in small ruminants.