info@znphi.gov.zm
Abstract
INTRODUCTION: Anthrax is an acute zoonotic disease caused by Bacillus anthracis primarily affecting herbivores, but also carnivores and humans through contaminated meat or environments. On 30 October 2025, a dead hippopotamus from Mosi-oa-Tunya National Park was fed to 36 captive lions, causing morbidities and mortalities prompting an outbreak investigation. The objectives included confirming the outbreak, assessing timeliness of detection, notification, and response, mapping wildlife cases, and evaluating knowledge and practices among at-risk populations.
METHODS: A descriptive case series investigation was conducted from 16-20 November 2025, and characterized the outbreak by time, place, and host (animal/person). Tissue, soil, and water samples were collected and cultured for B. anthracis isolation. Timeliness was assessed using the 7-1-7 metrics, health record reviews, and key informant interviews. Wildlife case distribution was mapped using Quantum Geographic Information System (QGIS 3.44.7). A structured questionnaire was used to assess knowledge and practices, with ≥60% score on Bloom’s taxonomy scale regarded as adequate. Data was cleaned and analyzed in Microsoft Excel and STATA-17.
RESULTS: The anthrax outbreak was confirmed from three animal tissue samples, with one epidemiologically linked human case identified. The outbreak detection occurred 7 days after emergence. Notification was done 6 days after detection while public health responses were initiated 10 days post- notification.16 wildlife cases were identified and a spot map generated. The case fatality rate (CFR) in captive lions was 43.9% (3/7). Among the 25 respondents (80% male; 60% <40 years; 40% livestock farmers, 60% wildlife facility workers), knowledge about anthrax was high with 76%, (19/25) having heard of the disease, 72% (18/25) and 64% (16/25) knew it affects wildlife and livestock respectively. 60% (15/25) were aware of human infection and vaccination as means of livestock protection. However, only 28% (7/25) practiced safe carcass disposal, and 48% (12/25) reported handling or consuming potentially contaminated meat.
CONCLUSION: The outbreak was characterized by delayed notification and response. High-risk community practices were also observed. We recommend launching a multisectoral, coordinated and targeted sensitization and community engagement for safe carcass disposal to prevent meat-borne exposure.