Anthrax outbreak investigation in Kanungu District, Uganda, June–November 2024

Background Anthrax is a recurrent zoonosis in Uganda, with 11 outbreaks reported in 2024. On September 17, 2024, the Ministry of Health received reports of two human deaths in Kanungu District, which were subsequently confirmed as anthrax, marking the district’s first recorded outbreak. We investigated to determine the scope of the outbreak, identify risk factors, and recommend evidence-based control and prevention measures. Methods We defined a suspected cutaneous anthrax case as an acute onset of skin lesions (papule, vesicle, or eschar) with ≥ 2 of skin itching, reddening, lymphadenopathy, fever, or malaise. Suspected gastrointestinal anthrax was the onset of abdominal pain with ≥ 2 of vomiting, diarrhea, fever, or loss of appetite in a resident of Kanungu District, from June 1 to November 4, 2024. Confirmation required PCR detection of Bacillus anthracis . For the case–control study (1:2 unmatched), we enrolled all confirmed and suspected cases, and selected controls from neighbouring households in the two most affected sub-counties, who remained asymptomatic during the same period. Logistic regression was used to identify risk factors for infection. Results We identified 90 cases (86 suspected and 4 confirmed); 80% had cutaneous anthrax, 11% had gastrointestinal anthrax, and 9% had both forms. Males were more affected (attack rate [AR] = 48/100,000) than females (AR = 15/100,000). The case fatality rate was 6.7% (6/90). Overall, 10/27 sub-counties were affected, with Bugongi (AR = 257/100,000) and Katete (AR = 224/100,000) being the most affected. Consuming meat from suddenly dead animals (adjusted odds ratio [aOR] = 5.8, 95% CI: 2.7–12.0), handling their carcasses (aOR = 9.3, 95% CI: 2.5–15.0), and having only primary or no formal education (aOR = 6.2, 95% CI: 2.5–15.0) significantly increased odds of anthrax. Notably, 90% of the case-patients reported buying meat from a single butcher who sourced animals that died suddenly. Conclusion This anthrax outbreak resulted from the consumption and handling of meat from livestock that died suddenly, underscoring gaps in veterinary inspection and carcass management. To prevent future similar outbreaks, we recommend instituting mandatory pre-slaughter veterinary inspections, enforcing hygienic carcass disposal practices, and implementing targeted community education on the risks associated with handling or consuming meat from animals of unknown cause of death. Clinical trial number : Not applicable