Mapping the cross-border pig/carcass food chain between Zambia and the Democratic Republic of Congo: Identifying potential transmission pathways for Taenia solium

Taenia solium is a major foodborne zoonotic parasite highly prevalent in sub-Saharan Africa. A comprehensive farm-to-fork analysis of the pig production and supply systems is essential to identify and mitigate associated risk factors. This study aimed to map the cross-border pig/carcass food chain between Zambia’s Copperbelt and Luapula Provinces (Southern Africa) and Haut-Katanga Province in the Democratic Republic of Congo (Central Africa). A mixed-methods approach was conducted from September 2023 to January 2025, triangulating data from direct observations, stakeholder interviews (96 respondents), border veterinary services records, and counts of pigs crossing the border. This approach mapped food-chain stages and pig/carcass border traffic, evaluated stakeholders' roles and management practices for pigs presumed infected, and identified key operational points targeting potential T. solium exposure risks to improve pork safety management. A cross-border pig/carcass food chain was identified, comprising six stages (supply sources, handling, health inspection, taxes and regulation, transportation, and first and final points of consumption) and ten stakeholder categories (pig shelter managers, pig buyers, sellers, pig slaughterers, handlers, border veterinarians, transporters, slaughterer–retailer pork sellers, veterinary inspectors, and pork sellers at home and in markets, including grilled-pork sellers), extending from supply sources in Zambia and border sites in DRC to several consumption sites in Haut-Katanga Province. Direct field counts recorded 1,696 live pigs and 32 carcasses crossing the border over one week, whereas official registries recorded only 4,799 animals over one year. Market observations documented pork presumed infected, with visible cystic lesions, sold cheaply for human consumption, alongside observed gaps in veterinary pig inspections and non-systematic tongue palpation from supply sources to slaughterhouses. In parallel, survey respondents reported importing pigs presumed infected with cysticercosis and selling suspect pork. Limited regulation and health oversight gaps from border crossings through slaughter to retail delineate critical exposure risk pathways, where the trade of uninspected, suspect pork could serve as a mechanism for human exposure to T. solium along this pig food chain. These findings reveal notable gaps in cross-border surveillance and veterinary inspections, underscoring the critical need for coordinated multi-country control efforts to address potential introduction and transmission pathways for T. solium.