Animal listeriosis in Türkiye: A descriptive and comparative study of a One Health relevant disease

Listeriosis is a significant zoonotic disease affecting ruminants and causing substantial economic losses in livestock production. Although numerous regional studies have been conducted in Türkiye, a comprehensive synthesis of available data has been lacking. The current study aimed to evaluate the epidemiology, clinical forms, diagnostic approaches, and regional distribution of animal listeriosis in Türkiye. Studies reporting clinical listeriosis in animals in Türkiye between 1980 and 2024 were included. Due to methodological heterogeneity, a descriptive-analytic approach was adopted. A total of 26 studies were included. Most studies were conducted in Eastern and Central Anatolia, regions with intensive ruminant farming and widespread silage use. Sample sizes ranged from 18 to 3,760 animals. The most frequently investigated species were sheep (n=13 studies) and cattle (n=9 studies), followed by goats, dogs, and horses. Molecular and culture-based studies generally reported low positivity rates (0–7.29%), whereas serological studies showed a substantially wider range (17–86.69%), suggesting past exposure rather than active infection. An exceptionally high culture positivity rate (66.6%) was reported in a small-scale investigation of an encephalitic outbreak, whereas 100% seropositivity was observed in limited farm-based screenings of horses and dogs. Both findings likely reflect context-specific findings from small samples rather than population-level prevalence. Clinically, encephalitic and abortive forms were predominant in small ruminants, whereas subclinical infections were frequently reported in cattle through serological surveillance. The available evidence indicates that contaminated silage is a major epidemiological risk factor, particularly in regions with prolonged winter feeding. Notably, national surveillance data remain scarce, and most studies were cross-sectional or case-based. In conclusion, animal listeriosis remains a significant health concern in Türkiye, particularly in ruminant-dense regions. Strengthening surveillance and expanding molecular diagnostics in primary animal production farms, along with integration within a One Health framework, are essential to better define the disease burden and reduce zoonotic risk.