What is the term for a disease-causing microorganism?

The term for a disease-causing microorganism is "pathogen." Pathogens include a diverse range of microorganisms such as bacteria, viruses, fungi, and parasites that have the capacity to cause disease in a host. They invade living organisms, disrupt their normal physiological processes, and can lead to a variety of health issues.

It's important to understand the roles of other terms in this context. A vector refers to an organism that transmits pathogens to hosts, such as mosquitoes carrying the malaria parasite. A host is the organism that supports the growth and reproduction of the pathogen. Symptoms are the manifestations of disease, such as fever or lesions, that occur in the host as a result of the pathogenic infection. Recognizing these definitions helps in understanding the complex interactions between pathogens, hosts, and vectors in the study of agriculture and pest control.