Passive surveillance of wild boar showed greater diagnostic sensitivity for African swine fever case detection than active surveillance (PCR: 46.5% vs. 0.48%; antibodies: 7.62% vs. 0.75%).
Observational
Passive surveillance is highly sensitive for detecting African swine fever in wild boar, and the disease has significantly reduced wild boar density in Slovakia over six years.
Absolute Event Rate: 46.5% vs 0.48%
African swine fever (ASF) has reshaped wild boar (Sus scrofa) populations and management across Europe since its reintroduction in 2007. ASF reached Slovakia in August 2019, when wild boar population size and harvest were at six-decade maximums. We analyzed data from six years (2019–2024) of national surveillance and control to quantify spatio-temporal ASF patterns in free-ranging wild boar. Using monthly virological (PCR) and serological (antibody) data from active (hunted) and passive (found dead) surveillance, we (1) estimated temporal variation in the effective reproduction number (Rt); (2) modeled spatio-temporal prevalence in Slovakia and its eastern, central, and western regions; (3) linked these dynamics to management indicators such as wild boar density, harvest, and mortality; and (4) proposed measures to increase surveillance and control effectiveness. Passive surveillance showed greater diagnostic sensitivity than active surveillance for case detection (PCR: 46.5% vs. 0.48%; antibodies: 7.62% vs. 0.75%). Rt peaked at 3.83 in March 2021, then declined but periodically exceeded 1.0 through late 2024. Virological prevalence showed strong late-winter/early-spring seasonality and a persistent east-to-west gradient: peaks occurred first in the east (March 2021, March 2023), with the center surpassing the east in October 2023 and a subsequent rise in the west. Seroprevalence lagged and shifted westward later, peaking in March 2023 and increasing in western Slovakia from mid-2024. Wild boar density decreased by 36.3% from 2019 to 2024 and harvest-based density by 42.8%, returning to post-classical swine fever levels (2009–2013). We recommend prioritizing targeted carcass searches and rapid removal, maintaining low wild boar densities through sustained harvest of adult females, modernizing population monitoring methods, enhancing hunters’ compliance, and strengthening cross-border coordination to improve surveillance and control, thereby slowing ASF spread across Europe.
Smolko et al. (Thu,) conducted a observational in African swine fever. Passive surveillance (found dead) vs. Active surveillance (hunted) was evaluated on Diagnostic sensitivity for case detection (PCR). Passive surveillance of wild boar showed greater diagnostic sensitivity for African swine fever case detection than active surveillance (PCR: 46.5% vs. 0.48%; antibodies: 7.62% vs. 0.75%).