Prevalence and anticoccidial drug sensitivity of Eimeria tenella isolated from commercial broiler farms in Thailand

Vet World Vol.18 June-2025 Article - 15

Research Article

Veterinary World, 18(6): 1561-1570

https://doi.org/10.14202/vetworld.2025.1561-1570

Suttitas Tongkamsai¹

, Siraprapa Boobphahom²

, Rachan Apphaicha¹

, and Niwat Chansiripornchai³

1. Department of Veterinary Medicine, Faculty of Veterinary Science, Rajamangala University of Technology Tawan-Ok, Chonburi, Thailand.

2. Research Center for Neuroscience, Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand.

3. Avian Health Research Unit, Department of Veterinary Medicine, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand.

Background and Aim: Coccidiosis, a parasitic disease caused by Eimeria species, remains a critical challenge for poultry production worldwide. Eimeria tenella is one of the most pathogenic species, causing intestinal lesions and compromising growth in chickens. This study aimed to estimate the prevalence of Eimeria species and evaluate the anticoccidial drug sensitivity of E. tenella field isolates in commercial broiler farms across Thailand.

Materials and Methods: Four fecal samples were collected from each of the ten broiler farms in seven provinces of eastern and central Thailand. Oocysts were identified through morphological examination and confirmed through species-specific multiplex polymerase chain reaction. E. tenella isolates were propagated and subjected to in vivo anticoccidial sensitivity testing (AST) against four drugs: Nicarbazin (NIC), salinomycin (SAL), monensin (MON), and a combination of MON and NIC. Experimental infection trials were conducted on Ross 308 broiler chicks to assess weight gain, fecal oocyst shedding, lesion scores, and anticoccidial index (ACI) values.

Results: E. tenella and Eimeria praecox were the most prevalent species (40%), followed by Eimeria acervulina, Eimeria brunetti, and Eimeria mitis (20%). Mixed-species infections were detected in 50% of samples. The AST results showed that field isolates were sensitive to NIC, MON, and the MON + NIC combination, with ACI values of 172.51, 175.49, and 174.21, respectively. In contrast, SAL showed an ACI of 158.81, indicating resistance. All treated groups demonstrated reduced oocyst shedding and improved weight gain compared to untreated infected controls, though lesion score differences among treatments were not statistically significant.

Conclusion: This study constitutes the first comprehensive report on anticoccidial drug resistance in E. tenella from broiler farms in Thailand. The findings indicate high efficacy of NIC, MON, and their combination, while revealing emerging resistance to SAL. These results provide crucial insights for revising coccidiosis control strategies and support the need for ongoing monitoring and development of alternative therapeutics to mitigate resistance evolution.

Keywords: anticoccidial sensitivity, broiler chickens, coccidiosis, drug resistance, Eimeria tenella, Thailand.

How to cite this article: Tongkamsai S, Boobphahom S, Apphaicha R, and Chansiripornchai N (2025) Prevalence and anticoccidial drug sensitivity of Eimeria tenella isolated from commercial broiler farms in Thailand, Veterinary World, 18(6): 1561–1570.

Received: 11-01-2025 Accepted: 15-05-2025 Published online: 15-06-2025

Corresponding author: Niwat Chansiripornchai E-mail: niwat.c@chula.ac.th

DOI: 10.14202/vetworld.2025.1561-1570

Copyright: Tongkamsai, et al. This article is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.