Final answer:
Imperialism harmed the health of colonized peoples predominantly through the spread of infectious diseases, as colonizers introduced new ailments and built infrastructure that facilitated outbreaks.
Step-by-step explanation:
Imperialism adversely affected the health of colonized people through the spread of infectious diseases. Europeans and U.S. visitors brought diseases such as measles, cholera, smallpox, and bubonic plague to regions like Fiji and India, where these diseases were not endemic. For example, the introduction of measles to Fiji in 1875 resulted in a devastating loss of life, with approximately one-quarter of the population dying from the outbreak. Additionally, the creation of infrastructure such as railroads and irrigation canals, while intended to facilitate the extraction of resources, inadvertently contributed to the spread of infectious diseases by increasing human mobility and creating breeding grounds for disease vectors like malaria-bearing mosquitoes.