Pathogenesis and Infectious Diseases Vocabulary

These vocabulary flashcards cover fundamental terms and concepts related to infection, disease progression, microbial virulence factors, toxins, and relevant medical suffixes from the lecture notes.

Infection

Entry and growth of a microorganism in the body that may cause harm.

Disease

Any change from normal health in which body functions are impaired.

Signs

Objective, measurable indicators of disease such as fever or rash.

Symptoms

Subjective feelings reported by the patient, e.g., pain or fatigue.

Communicable Disease

Illness that can be transmitted from person to person (e.g., flu).

Noncommunicable Disease

Illness that cannot be transferred between people (e.g., tetanus).

Contagious Disease

A communicable disease that spreads very easily, like measles.

Nosocomial Infection

Infection acquired in a hospital setting.

Iatrogenic Infection

Disease caused by medical treatment or procedure.

Incubation Period

Time between pathogen exposure and first symptoms.

Prodromal Period

Early, mild symptoms stage such as headache or tiredness.

Illness Period

Stage when disease is most severe and full symptoms appear.

Decline Period

Phase where symptoms subside as immune response or therapy succeeds.

Convalescence Period

Recovery stage when the body repairs and returns to health.

Acute Disease

Develops quickly and lasts a short time (e.g., common cold).

Chronic Disease

Develops slowly and persists for a long duration (e.g., TB).

Latent Disease

Pathogen remains inactive and can reactivate later (e.g., herpes).

Primary Pathogen

Microbe capable of causing disease in healthy hosts (e.g., S. pyogenes).

Opportunistic Pathogen

Causes disease only when host defenses are compromised.

Koch’s Postulates

Criteria used to link a specific microbe to a specific disease.

Molecular Koch’s Postulates

Modern version focusing on genes responsible for virulence.

ID50 (Infectious Dose 50)

Number of microbes needed to infect 50% of a population.

LD50 (Lethal Dose 50)

Number of microbes required to kill 50% of a population.

Pathogenesis

Process by which a pathogen causes disease: exposure, adhesion, invasion, infection, transmission.

Adhesion

Attachment of pathogens to host cells via pili, fimbriae or proteins.

Adhesins

Specific molecules on pathogens that mediate attachment to host cells.

Invasion

Spread of a pathogen into host tissues using enzymes or other strategies.

Exoenzyme

Enzyme secreted by microbes that breaks down host tissue to aid spread.

Hyaluronidase

Exoenzyme that digests connective tissue hyaluronic acid to promote invasion.

Collagenase

Exoenzyme that breaks down collagen in host tissues.

DNase

Exoenzyme that degrades DNA, reducing pus viscosity and immune trapping.

Toxin

Poisonous substance produced by microbes that damages the host.

Endotoxin

Lipid A portion of Gram-negative LPS; triggers fever, inflammation, shock.

Exotoxin

Potent protein secreted by bacteria causing specific effects (e.g., neurotoxin).

Superantigen

Exotoxin that overstimulates T cells, leading to severe inflammation.

Antigenic Variation

Change of surface proteins by pathogens to evade immunity.

Capsule

Surface polysaccharide layer that inhibits phagocytosis by immune cells.

Plasmid

Small circular DNA in bacteria often carrying virulence or resistance genes.

Virulence Factors

Traits that enable a microbe to cause disease (toxins, enzymes, etc.).

Antigenic Drift

Gradual accumulation of small mutations in viral genes (e.g., annual flu changes).

Antigenic Shift

Sudden major gene reassortment in viruses, producing new strains and potential pandemics.

Fungal Virulence Factors

Include adhesins, enzymes, toxins, and protective capsules (e.g., Cryptococcus).

Protozoan Virulence Factors

Use antigenic variation, adhesins, toxins to infect hosts (e.g., Giardia).

Helminth Evasion Methods

Worms coat themselves in host molecules and suppress immune responses.

Transmission

Final stage of pathogenesis: spread to a new host via cough, contact, etc.

Zoonotic Disease

Illness transmitted from animals to humans (e.g., rabies).

Congenital Disease

Condition present at or before birth due to genetic, environmental, or infectious causes.

Noncommunicable Infectious Disease

Infection not spread person-to-person (e.g., food poisoning from pre-formed toxins).

Fever

Objective sign of infection reflecting immune activation.

Tetanus Toxin

Blocks inhibitory neurons, causing muscle stiffness and spasms.

Endocarditis

Infection of the heart’s inner lining, often from bloodstream bacteria.

Human Immunodeficiency Virus (HIV)

Virus that infects immune cells and causes AIDS; cannot be cultured by classic methods.

Panton-Valentine Leukocidin

Staphylococcus aureus toxin that destroys white blood cells.

Aflatoxin

Carcinogenic liver toxin produced by Aspergillus fungi.

Patulin

Mycotoxin from moldy fruits; toxic but not carcinogenic.

Citrinin

Kidney-damaging mycotoxin produced by Penicillium species.

Ochratoxin

Fungal toxin in cereals, coffee, grapes; linked to kidney injury.

Diphtheria Toxin

Bacterial exotoxin that halts host protein synthesis, killing cells.

Cholera Toxin

Enterotoxin that raises cAMP, causing massive watery diarrhea.

Botulinum Toxin

Blocks acetylcholine release, leading to flaccid paralysis.

Pathogenicity

Ability of a microbe to cause disease (yes/no property).

Virulence

Degree of harm caused by a pathogen once disease occurs.

Vectors

Living carriers like mosquitoes or ticks that transmit pathogens.

-derma

Suffix meaning skin (e.g., dermatitis = skin inflammation).

-itis

Suffix meaning inflammation (e.g., tonsillitis = inflamed tonsils).

-lysis

Suffix meaning breakdown or destruction of cells (e.g., hemolysis).

-osis

Suffix indicating abnormal condition or disease (e.g., cirrhosis).

-oma

Suffix meaning tumor or swelling (e.g., lymphoma).

-emia

Suffix referring to a blood condition (e.g., bacteremia).

Antibody

Protein made by B cells that binds antigens to neutralize pathogens.

CD4 Receptor

Helper T-cell surface protein used by HIV for entry.

Heparan Sulfate

Host cell sugar that some viruses, like herpes simplex, use to attach.

Contagious

Describes diseases that spread very readily between people.

Infectious

Refers to diseases caused by microbes, whether or not easily spread.