The phrase "infective agents" refers to harmful microorganisms like bacteria, viruses, or fungi that can cause diseases or infections in humans, animals, or plants. Full definition
Classic article from 1960: Research on animal and human disease are forcing biologists to consider a hitherto unsuspected class of infective agents (newscientist.com)
As the number of victims accelerated, health officials would be scrambling to figure out what the precise infective agent was, where it came from, how it was transmitted from person to person, and how best to sever the chain. (scientificamerican.com)
Humans may be a temporary host for food - poisoning germs or other infective agents. (sciencenewsforstudents.org)