infectious disease and host microbe straight from textbook

opportunistic pathogen

only cause disease when their host is weakened, often through shifts in normal microbiota or weakening of immune system.

true pathogen

does not require a weakened host to cause disease and can infect healthy individuals.

Koch postulate (9.5)

Allow us to identify the causative pathogens of many disease. ORDER: Find the organism in diseased hosts → isolate it in pure culture → cause the same disease in a susceptible healthy host → reisolate the same organism.

direct modes of transmission

host comes into physical contact with the source of pathogen. (touching, kissing, or sexual contact)

indirect mode of transmission

pathogens spread without physical contact with source; airborne (respiratory droplets), vehicle/fomite (contaminated objects), vector transmission (rodents and zoonotic disease)

5 stages of infectious disease how they vary from one pathogen to anothpathogencityer

incubation, prodromal, acute, period of decline, convalscent phase

pathogencity

ability of a microbe to cause disease

virulence

degree or extent of disease that a pathogen causes

virulence factors

mechanism pathogens use to overcome host defenses (adhesion, capsules, toxins, and enzymes)

How host-microbe interactions impact pathogen virulence and transmission

The ability to attach, evade immunity, and damage tissues determines disease severity. Pathogen shedding and symptoms like coughing or diarrhea affect transmission.

5 task pathogens take to infect host

Entry → adherence → invasion and nutrient acquisition → immune evasion → transmission to a new host.

various portal of entry and exit

Respiratory mucosa, otic (ear), ocular, skin, parenteral (bloodstream), GI Mucosa (digestive), transplacental (fetus), urogenital (reproductive)

adhesion roles in establishling infection

allows a pathogen to attach to host cells and resist being washed away

invasion role in establishing infection

allows it to enter cells or tissues, where it can multiply and spread, establishing infection.

mechanisms pathogens use to avoid immune detection and elimiantion

by using capsules to resist phagocytosis, changing surface antigens to avoid recognition, hiding inside host cells, forming protective biofilms, and producing enzymes or proteins that disable immune defenses