Antimicrobial Use and Veterinary Care among Agro-Pastoralists in Northern Tanzania

Frequent and unregulated use of antimicrobials (AM) in livestock requires public health attention as a likely selection pressure for resistant bacteria. Studies among small-holders, who own a large percentage of the world’s livestock, are vital for understanding how practices involving AM use might influence resistance. We present a cultural-ecological mixed-methods analysis to explore sectors of veterinary care, loosely regulated AM use, and human exposure to AMs through meat and milk consumption across three rural to peri-urban Tanzanian ethnic groups (N = 415 households). Reported use of self-administered AMs varied by ethnic group (Maasai: 74%, Arusha: 21%, Chagga: 1%) as did consultation with professional veterinarians (Maasai: 36%, Arusha: 45%, Chagga: 96%) and observation of withdrawal of meat and milk from consumption during and following AM treatment (Maasai: 7%, Arusha: 72%, Chagga: 96%). The antibiotic oxytetracycline was by far the most common AM in this sample. Within ethnic groups, herd composition differences, particularly size of small-stock and cattle herds, were most strongly associated with differences in lay AM use. Among the Arusha, proxies for urbanization, including owning transportation and reliance on “zero-grazing” herds had the strongest positive associations with veterinarian consultation, while distance to urban centers was negatively associated. For Maasai, consultation was negatively associated with use of traditional healers or veterinary drug-shops. Observation of withdrawal was most strongly associated with owning technology among Maasai while Arusha observance displayed seasonal differences. This “One-Health” analysis suggests that livelihood and cultural niche factors, through their association with practices in smallholder populations, provide insight into the selection pressures that may contribute to the evolution and dissemination of antimicrobial resistance.

畜禽养殖中抗菌药物（antimicrobials, AM）的频繁且无规范使用，作为耐药细菌的潜在选择压力，亟需公共卫生领域的关注。占全球畜禽存栏总量较大比例的小农户群体，其相关研究对于厘清抗菌药物使用行为如何影响耐药性产生至关重要。本研究采用文化生态学混合方法分析框架，针对坦桑尼亚三个分布于乡村至城乡结合部区域的族群（共纳入415户家庭），探究兽医诊疗服务体系、监管宽松的抗菌药物使用现状，以及人类通过肉类与乳制品摄入暴露于抗菌药物的情况。据报告，自行使用抗菌药物的比例因族群而异：马赛族为74%、阿鲁沙族为21%、查加族为1%；咨询专业兽医的比例、以及抗菌药物治疗期间及停药后暂停食用肉奶的休药期依从率，同样存在显著族群差异，其中咨询兽医的比例依次为马赛族36%、阿鲁沙族45%、查加族96%，休药期依从率依次为马赛族7%、阿鲁沙族72%、查加族96%。在本次研究样本中，土霉素是最为常用的抗菌药物。在各族群内部，畜群结构差异——尤其是小型牲畜与牛群的存栏规模——与非专业人员自行使用抗菌药物的情况差异关联最为紧密。对于阿鲁沙族群体而言，拥有交通工具、依赖“零放牧”畜群等城市化表征指标，与咨询专业兽医的行为呈现最强的正向关联；而距城市中心的距离则与该行为呈负相关。而就马赛族群体而言，咨询专业兽医的行为与使用传统医者或兽药店的行为呈负相关。马赛族的休药期依从率与拥有养殖相关技术的关联最为显著，而阿鲁沙族的休药期依从率则存在季节性差异。这项“同一健康（One-Health）”分析表明，生计模式与文化生态位因素通过与小农户群体养殖行为的关联，为理解可能推动抗菌药物耐药性进化与传播的选择压力提供了全新视角。