Molecular Epidemiology and Risk Factors Analysis of Major Pathogens Causing Neonatal Calf Diarrhea in Muğla, Türkiye

Neonatal calf diarrhea is a widespread and multifactorial condition that poses a significant challenge in cattle farming. The major etiological pathogens include Cryptosporidium parvum, Escherichia coli, bovine group A rotavirus (RVA), and bovine coronavirus (BCoV). Accurate identification of these pathogens is essential for the development of targeted prevention and control strategies. This study aimed to obtain comprehensive molecular epidemiological data on neonatal calf diarrhea by determining the prevalence of major pathogens, evaluating the frequency of mixed infections, and analyzing their association with predisposing factors. Between September 2023 and August 2024, 120 fecal samples were collected monthly from diarrheic neonatal calves across 18 different small-scale cattle farms with similar traditional management practices. Samples were initially screened using polymerase chain reaction (PCR), and positive amplicons were confirmed through sequence analysis. A total of 117 (97.5%) calves were found to be infected with at least one pathogen. Cryptosporidium parvum was the most frequently detected agent, identified in 95 samples (79.1%), followed by E. coli in 61 (50.8%), RVA in 36 (30%), and BCoV in 27 (22.5%). The C. parvum subtype IIaA13G2R1 was identified for the first time in the research area, confirming its dominance as a subtype in calves in Türkiye. Age emerged as the most influential predisposing factor, with E. coli infections occurring most frequently during the first week of life, whereas RVA/BCoV and C. parvum infections peaked during the second week. Seasonal variation also shaped pathogen patterns, with C. parvum occurring at relatively similar rates across seasons, whereas E. coli infections were more frequent in autumn and spring, and RVA/BCoV detections peaked in winter. These findings underscore the importance of early-life monitoring and season-aware management strategies to mitigate neonatal calf diarrhea.

Cite this article as: Sürsal Şimşek, N., Çakmak, I., Özen, D., Cengiz, S., Akgüç Çöl, N. , Çanakoğlu, N., & Şimşek, E. (2026). Molecular epidemiology and risk factors analysis of major pathogens causing neonatal calf diarrhea in Muğla, Türkiye. Acta Veterinaria Eurasia, 52, 0198, doi:10.5152/actavet.2026.25198.