In microbiology and medicine, microorganisms that cause disease in their host are called what?

Introduction / Context:
In health sciences, it is important to distinguish between different types of microorganisms. Some microbes live harmlessly on or inside the human body, whereas others cause disease. The specific term for disease causing microorganisms appears frequently in questions from microbiology, immunology, and general science, making it a key concept for exams.

Given Data / Assumptions:

• The question asks for the term used for microorganisms that cause disease.
• We assume standard medical and microbiological terminology.
• Options include common words such as pathogens and microbes.
• We only need to identify the correct term, not any examples or subtypes.

Concept / Approach:
The word microbe is a broad term that can refer to bacteria, viruses, fungi, protozoa, or microscopic algae, regardless of whether they are harmful or not. The specific term for microorganisms that cause disease is pathogen. A pathogen is defined as an organism that is capable of causing disease in its host by invading tissues, producing toxins, or triggering harmful immune responses. Other terms like normal flora or commensals are used for microbes that normally live in or on the body without causing disease in healthy individuals.

Step-by-Step Solution:
Step 1: Read the phrase "microorganisms that cause disease" carefully because the property of causing disease is central.Step 2: Recall that the technical term for disease causing agents is pathogen.Step 3: Compare this with option A, which directly uses the word pathogens.Step 4: Note that option B, microbes, is too general because many microbes are harmless or even beneficial.Step 5: Options C, D, and E do not match the specific definition, so the only precise choice is pathogens.

Verification / Alternative check:
Standard definitions in microbiology textbooks describe pathogens as organisms that cause disease, while microflora, normal flora, or commensals refer to microbial communities that typically do not cause harm. Public health discussions on infectious diseases also consistently refer to disease causing viruses or bacteria as pathogens. This widely accepted usage confirms that pathogens is the correct term.

Why Other Options Are Wrong:
Option B, microbes, simply means microorganisms in general and includes both helpful and harmful forms, so it is not specific enough. Option C, infectees, is not a standard term and would refer more logically to infected hosts rather than the organisms that cause infection. Option D, normal flora, describes resident microbes that usually live harmlessly in or on the body. Option E, non infectious commensals, explicitly refers to organisms that do not cause disease, making it the opposite of what the question asks.

Common Pitfalls:
Students often use the word microbe as if it always implied disease, mainly because microbes are frequently mentioned in the context of infections. This leads to confusion between general terms and more precise words. To avoid mistakes, learners should remember that all pathogens are microbes, but not all microbes are pathogens. The exam question is designed to reward that precise understanding.

Final Answer:
The correct term for microorganisms that cause disease in their host is Pathogens.