Listeriolysin O-based diagnosis of Listeria monocytogenes infection in experimentally and naturally infected goats

The kinetics of anti-listeriolysin O (ALLO) production in the goats experimentally infected with pathogenic Listeria monocytogenes vis-à-vis isolation of the pathogen was studied. In the experimentally infected goats the pathogen was recovered during days 1–13, 2–14, and 4–5 post-inoculation (PI) in faecal, nasal and haemocultures, respectively. All the animals were culture negative on day 16 PI. Antibodies to LLO appeared by days 10–14 PI, peaked between days 11 and 25 days PI and persisted by end of study (day 80 PI) at a detectable level. Isolation of the pathogen was also attempted from meat and blood of 113 slaughtered goats besides testing of serum samples for ALLO by LLO-based indirect ELISA. L. monocytogenes was isolated from 7.08 and 1.77% of meat (113) and blood (113) samples of goat, respectively. Antibodies against LLO were detected in 21.68% serum samples collected from the slaughtered goats.