Seroprevalence of Lawsonia intracellularis antibody among swine herds in Thailand, December 2021-March 2022

Abstract

The gastrointestinal infectious diseases caused by bacteria have been a major problem in the Thai swine industry. Porcine proliferative enteropathy (PPE), also known as porcine ileitis, is an enteric infectious disease caused by�Lawsonia�intracellularis. Porcine ileitis has been an economic threat to the global pork production system due to various types of diarrheas. Serological diagnosis can be applied for determining pathogen-antibodies seroprevalence and the timing of�L. intracellularis�infection when introduced to the herd. A lack of serological data since 2009, as well as recent antibiotic usage restrictions, may have a negative impact on porcine ileitis seroprevalence in Thailand. Hence, the objective of this present study was to investigate the current serological status and the seroprevalence of antibodies against�L. intracellularis�in large-scale swine herds in Thailand using a commercial blocking enzyme-linked immunosorbent assay (ELISA). A total of 1,234 serums were sampled from 24 non-vaccinated commercial pig farms across Thailand as part of a monitoring program. The herd seroprevalence was obtained in a total of 22�out of 24 herds sampled, and the within-herd seroprevalence was 50.5%�(95% CI: 47.7-53.3%), with higher seropositivity detected in older animals. Furthermore, the most�Lawsonia-antibodies were found in the intensive larger farms in Northern Thailand. There was a significant difference in the within-herd seroprevalence between single-site and multiple-site production systems (P�< 0.001). Here, the finding confirmed that in the absence of the�L. intracellularis�vaccine, PPE seroprevalence in large commercial swine herds in Thailand was prevailing.