Everyone is watched, but not everyone is monitored in the same way. Contagion and the threat of contagion elicits medical surveillance in port cities through monitoring, regulating, quarantining goods and people. In the late nineteenth century, Alexandria, Tripoli, and Tunis were commercial zones where episodic plague and cholera epidemics proliferated causing commercial and mortuary crises. Independent of these outbreaks, constituents such as the International Sanitary Conference (1851) enacted policies to standardize quarantine measures at an international level, which was contested and repackaged in non-Western contexts. How these epidemics were understood and framed was part and parcel of ongoing nationalist and in Mediterranean port cities and beyond. This paper examines the ways that three North African cities—Alexandria, Tripoli, and Tunis—operated as sites of medical surveillance during the late nineteenth century. It does so by showing how indigenous and foreign merchants and medical practitioners defined and regulated goods and people. Starting from the vantage point of the port, the research shows how human and nonhuman entities, whether they were perceived to be infectious or not, were part of a process of globalizing medical surveillance. The port’s physical landscape operates as a case study for understanding how surveillance and sanitation were intimately tied to shifting notions of disease, medicine, and therapeutics in late nineteenth-century North Africa.