NCLEX-PN

Fungi : Present in various environments, including soil, plants, and humans. Most fungi are harmless, but some can cause serious infections in immunocompromised individuals. Fungi have different types of relationships with other organisms, including mutualistic, antagonistic, and commensal relationships. Human fungal infections can be categorized into superficial, cutaneous, subcutaneous, and systemic infections. Systemic infections are especially dangerous, potentially affecting multiple organs. Examples include candidiasis, aspergillosis, and cryptococcosis. Cutaneous infections affect the skin, hair, and nails, like athlete's foot. Superficial infections target the epidermis, such as ringworm. Subcutaneous infections penetrate deeper layers due to traumatic wounds. Parasites: Derive nutrition from their hosts and can cause infections. While most common in tropical regions, parasitic infections can occur globally. Examples of parasites include pinworms, giardia, tapeworms, lice, maggots, and scabies. Prions: Abnormal proteins that affect neural tissue, primarily in the brain. Some prion diseases include "mad cow" disease, Creutzfeldt-Jakob disease, and kuru . Prions aren't living organisms but pose significant health risks, especially in relation to brain function. The ability of microorganisms to cause disease depends on factors like a person's susceptibility, the pathogen's pathogenicity, virulence, and infective dose. ●​ Pathogenicity: The ability to cause disease varies among pathogens. Lower pathogenicity means fewer infections among exposed individuals. ●​ Virulence: This refers to a pathogen's potency in causing severe disease. Some pathogens are more virulent than others. ●​ Infective dose: The amount of microorganisms needed to cause disease varies. Some pathogens require a lower dose than others. The Reservoir and Modes of Transmission Reservoirs: The reservoir is where pathogens live, grow, and reproduce. Reservoirs can be diverse, including humans, animals, water, soil, and insects. Human Reservoirs: Humans can be reservoirs whether they have active infections (symptomatic carriers) or not (asymptomatic carriers). For instance, "Typhoid Mary" was an asymptomatic carrier of typhoid, infecting many. Symptomatic individuals can also spread infections during the incubation or recovery period. Water Reservoirs: Contaminated water can host various infections, such as Legionnaires disease, amebiasis, cryptosporidiosis, schistosomiasis, and giardiasis. Animal Reservoirs: Various animals can serve as reservoirs for specific diseases, like pigs for trichinosis, cows for brucellosis, rodents for plague, and birds for West Nile encephalitis. Diseases like HIV/AIDS and Ebola have transitioned from animal to human reservoirs.

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