# Epizootiology of African Swine Fever in the Croatian Wild Boar Population and the Estimation of the Surviving Dynamics (2023–2024)

## TL;DR

This study examines the spread and survival dynamics of African swine fever in wild boars in Croatia from 2023 to 2024.

## Contribution

The study provides new insights into the spillover events and infection dynamics of African swine fever virus in wild boar populations.

## Key findings

- ASFV DNA prevalence was highest in Vukovar-Srijem County in 2023 and 2024.
- Older wild boars showed a higher infection rate than younger ones.
- Passive monitoring is highlighted as crucial due to higher virus detection in carcasses.

## Abstract

This study integrates data on the prevalence, infection dynamics and risks associated with African swine fever virus (ASFV) outbreaks in Croatian wild boar during 2023–2024. Although the overall ASFV DNA prevalence in Croatia was 0.24%, the highest prevalence (2.29% in 2023 and 4.69% in 2024) was recorded in Vukovar-Srijem County. Genetic typing identified ASFV genotype II, subgroup 19, consistent with strains isolated from domestic pigs in Croatia and circulating in neighboring countries. Anti-ASFV specific antibodies were detected in 10.34% of wild boar tested in counties with previously reported DNA findings. In Vukovar-Srijem County, 4.60% of wild boar were positive for both, ASFV DNA and antibodies, suggesting ongoing virus infection, whereas the proportion of boar positive only for antibodies was 5.75%, indicating survival of acute infection. Statistical analysis revealed an increase in ASFV DNA detection from 2023 to 2024 (p = 0.043), with a higher prevalence in carcasses than in hunted animals (p = 0.001), highlighting the need for passive monitoring. While gender showed no statistical significance, a higher infection rate was observed in older animals (p = 0.001). The identified course of infection involved spillover events between domestic pigs and wild boar, with a significant anthropogenic influence.