Maria João Caldeira, Marta Ruíz de Arcaute, João Jacob-Ferreira, Tifany Pereira, Carina Rodrigues, João R Mesquita, David Guallar, Pablo Quilez, Aurora Ortín, Diana Marteles-Aragüés, Sergio Villanueva-Saz, Hélder Quintas, Delia Lacasta
The high seroprevalence indicates substantial C. burnetii circulation in the study region. Management characteristics, particularly confinement and herd structure, were associated with seropositivity, although these associations should not be interpreted causally given the cross-sectional design. These findings support risk-based surveillance and targeted biosecurity measures within a One Health framework to reduce zoonotic risk.
BACKGROUND: Q fever, caused by Coxiella burnetii, is a globally distributed zoonosis associated with small ruminants. In Mediterranean regions, where extensive farming systems prevail, understanding environmental and management drivers of infection is essential for public health. This study estimated the seroprevalence and identified multilevel factors associated with C. burnetii exposure among small ruminants in Trás-os-Montes, Portugal.
METHODS: A cross-sectional study was conducted across 105 farms (n = 1827 animals; 1596 sheep and 231 goats). Serum samples were analysed using a commercial ELISA. Animal-, herd-, and management-level variables were evaluated using multivariable logistic regression to identify factors associated with seropositivity.
RESULTS: Overall apparent seroprevalence was 40.7% (95% CI: 38.5-43.0), with apparent spatial heterogeneity in seroprevalence estimates across municipalities. Older age (≥18 months; aOR = 2.02), larger herd size (≥100 animals; aOR = 1.35), mixed ovine-caprine rearing (aOR = 1.58), and permanent confinement (aOR = 3.88) were associated with higher odds of seropositivity. Furthermore, the introduction of animals without prior health screening (aOR = 5.64; 95% CI: 1.40-51.4) and sharing of drinking troughs (aOR = 1.31) were associated with higher odds of seropositivity, whereas the absence of a maternity pen (aOR = 0.57) and participation in livestock competitions (aOR = 0.71) were associated with lower odds of seropositivity.
CONCLUSION: The high seroprevalence indicates substantial C. burnetii circulation in the study region. Management characteristics, particularly confinement and herd structure, were associated with seropositivity, although these associations should not be interpreted causally given the cross-sectional design. These findings support risk-based surveillance and targeted biosecurity measures within a One Health framework to reduce zoonotic risk.