Discussion

This investigation describes a human anthrax outbreak in Kween District in June–July 2024 in which six outbreak-associated cases were identified, five of whom were laboratory-confirmed. The cases were all male and predominantly farmers, and multiple exposures involving animals, carcasses, and animal products were reported. Contact with animals that had died or their body fluids, skinning and dressing carcasses, slaughtering animals, and consumption of meat were commonly reported. Together, these findings point to direct interaction with animals and their products as important opportunities for human exposure during the outbreak, although the absence of an unexposed comparison group precluded estimation of associations between individual exposures and illness.

The prominence of carcass-related exposures is consistent with previous anthrax investigations in Uganda. During a 2018 outbreak in Kween District, handling a cow that had died suddenly, including skinning and carrying the carcass, was associated with cutaneous anthrax, while consumption of meat from the affected animal was associated with gastrointestinal anthrax [5]. Similarly, an outbreak in Isingiro District in 2017 was linked to consumption of beef from an animal that had died suddenly [8]. More recently, an investigation in Kanungu District identified handling carcasses and consuming meat from livestock that died suddenly as important exposures [9]. The recurrence of similar exposure patterns across settings suggests that prevention of human anthrax in Uganda depends substantially on preventing the handling, processing, distribution, and consumption of livestock that die suddenly or from unexplained causes [1, 5, 9].

The occurrence of all six cases among men, most of whom were farmers/peasants, may reflect occupational and social roles that increase opportunities for contact with livestock and carcasses. Livestock herding, slaughtering, skinning, carcass transportation, and meat processing can result in direct contact with infected tissues, body fluids, or contaminated animal products [1, 5]. However, because this investigation included only affected persons and did not include a comparison population, neither male sex nor occupation can be interpreted as an independent risk factor for infection. Rather, the findings highlight the importance of directing prevention messages towards persons who routinely undertake high-exposure livestock and carcass-handling activities.

The spatial distribution of cases also needs to be interpreted within the broader ecological and livelihood context of Kween District. Livestock rearing, communal grazing, livestock movement, and proximity of some communities to protected areas create opportunities for interaction at the human-livestock-wildlife-environment interface. Previous animal investigations in Kween have documented anthrax in livestock and implicated practices such as butchering infected carcasses on or near pastureland and inadequate carcass disposal [6]. Environmental studies elsewhere in Uganda have also shown that anthrax occurrence can be shaped by local ecological conditions [2]. However, the present investigation did not include laboratory testing of livestock, wildlife, or environmental samples and therefore cannot establish whether wildlife interaction, environmental contamination, or particular livestock movement routes contributed directly to the 2024 human outbreak. The mapped distribution should consequently be viewed as descriptive rather than evidence of spatial clustering or specific transmission corridors.

These circumstances nevertheless highlight the relevance of a One Health approach to anthrax prevention and control. Human cases may represent downstream consequences of infection and control failures in animal populations, while persistence of Bacillus anthracis spores in the environment makes control difficult through human-health interventions alone [1, 10]. Evidence from African anthrax surveillance also points to persistent gaps arising from fragmented human, animal, wildlife, and environmental surveillance systems [11]. Effective prevention therefore requires coordination between human health, veterinary, wildlife, and environmental sectors. Such coordination is particularly relevant for early notification of sudden livestock deaths, investigation of suspected animal cases, safe carcass disposal, identification of potentially exposed persons, and timely implementation of control measures [1, 11].

The recurrence of anthrax in Kween District suggests a need to move beyond outbreak-specific responses towards sustained prevention. National surveillance data identified 39 human anthrax outbreaks in Uganda during 2017–2024, with Kween recording eight outbreaks, the highest number among affected districts [5]. Historical surveillance data can therefore be used to identify recurrent high-risk areas and prioritize preventive interventions. Livestock vaccination is particularly important because preventing infection in animals reduces the source from which human exposure occurs [1, 5]. Vaccination strategies should prioritize recurrent outbreak areas alongside strengthened veterinary surveillance and rapid investigation of unexplained livestock deaths [1, 4].

Community engagement is equally important because many immediate exposure opportunities occur between the death of an animal and notification of veterinary or public health authorities. Risk communication should extend beyond general awareness of anthrax symptoms to practical decisions following sudden livestock death. Livestock owners, herders, butchers, meat traders, community leaders, and community health workers should be engaged in recognizing and promptly reporting unexplained livestock deaths, avoiding opening or processing suspect carcasses, preventing distribution or consumption of meat from such animals, and facilitating safe carcass disposal [1, 5]. Evidence from recurrently affected communities in Uganda suggests that knowledge alone may not ensure safer practices; economic constraints, the value of livestock and meat, and limited access to vaccination and veterinary services can influence decisions to handle or consume animals that die suddenly [12]. Community engagement and prevention strategies should therefore address both knowledge and the livelihood constraints that shape these practices.

This investigation had some limitations. Only six outbreak-associated human cases were identified, limiting the precision and generalizability of the findings. Exposure information was available only for affected persons. Consequently, associations between reported exposures and illness could not be estimated. Additionally, laboratory confirmation was documented for five of the six cases, while one epidemiologically linked case did not have a documented specimen. Further, the investigation did not include microbiological testing of livestock, wildlife, or environmental samples, limiting our ability to determine the source of infection or establish transmission pathways across the human-livestock-wildlife-environment interface. Finally, the spatial assessment was descriptive and based on a small number of case locations, therefore, proximity to protected areas or other geographic features should not be interpreted as evidence of causation. Despite these limitations, the investigation documents recurring carcass-related exposure patterns in a district with a history of anthrax outbreaks and identifies practical opportunities for strengthening prevention and response.