Epidemiology

Flashcards covering key vocabulary terms related to infection, infectious diseases, and epidemiology, based on lecture notes.

Symbiosis

The relationship between normal microbiota and the host.

Commensalism

A symbiotic relationship where one organism benefits, and the other is unaffected.

Mutualism

A symbiotic relationship where both organisms benefit.

Parasitism

A symbiotic relationship where one organism benefits at the expense of the other.

Opportunistic Pathogens

Normal microbiota that can cause disease under certain circumstances.

Normal Microbiota

Microorganisms that permanently colonize the host but do not produce disease under normal circumstances.

Pathogenesis

Development of disease

Pathogenicity

Ability to cause disease

Transient Microbiota

Microorganisms that are present but only temporarily.

Axenic

Development in the womb free of microorganisms.

Reservoirs of Infection

Sites where pathogens are maintained as a source of infection, including animal, human, and nonliving sources.

Animal reservoir

Diseases naturally spread from animal hosts to humans. (Zoonoses)

Human Carriers reservoir

Infected individuals who are asymptomatic but infective to others, often with latent diseases. (AIDS, gonorrhea)

Nonliving Reservoirs

Soil, water, and food that can maintain pathogens and serve as sources of infection due to contamination.(botulism, tetanus, cholera)

Contamination

The mere presence of microbes in or on the body.

Portals of Entry

Different areas of the body through which pathogens can enter, such as skin, mucous membranes, placenta, and the parenteral route.

Mucus membrane entry

Can cause conjunctiva, and STD

Skin entry

Hookworm larvae bore infection

Placenta entry

Can cause abortion, birth defects and premature birth

Parenteral Route

Deposition of microorganisms directly into the tissues beneath the skin or mucous membranes, typically through punctures, injections, bites, or wounds.

LD50 (Lethal Dose 50%)

The lethal dose of a toxin for 50% of the test population.

ID50 (Infectious Dose 50%)

The infectious dose for 50% of the test population.

Receptors (host cells)

Host cell's surface molecules to which pathogens attach.

Adhesins/Ligands (pathogen)

Pathogen's surface molecules that bind to host cell receptors.

Virulence Factors

Components or characteristics of pathogens that contribute to their ability to cause disease, such as adhesion factors, enzymes, and toxins.

Extracellular Enzymes (Exoenzymes)

Enzymes produced by bacteria and ejected from the cell that aid in virulence.

Leukocidins

Extracellular enzymes that destroy neutrophils and leukocytes, impairing phagocytosis.

Hemolysins

Extracellular enzymes that cause lysis of erythrocytes (red blood cells).

Streptolysins

Hemolysins produced by streptococci.

Coagulase

An enzyme that coagulates fibrinogen, potentially protecting bacteria from phagocytosis by forming clots.

Kinases

Enzymes that digest fibrin and break down clots, aiding in the spread of bacteria.

Hyaluronidase

helping microorganisms spread from the initial site of infection.

Collagenase

produced by Clostridium and involved in gas gangrene.

Lecithinase

An enzyme that destroys plasma membranes.

Protease

An enzyme that breaks down proteins, such as in muscle tissue.

Cytotoxins

Exotoxins that kill host cells or affect their function.

Enterotoxins

Exotoxins that affect cells in the gastrointestinal tract.

Septic Shock

A life-threatening loss of blood pressure caused by a Gram-negative organism's endotoxins.

Pyrogenic Response

The fever-inducing response triggered by endotoxins stimulating macrophages to release cytokines that affect the hypothalamus.

Antiphagocytic Factors

Factors that prevent phagocytosis by the host's phagocytic cells, such as bacterial capsules and certain chemicals.

Lysogenic Phages

Bacteriophages incorporated into the bacterial cell's chromosome, which can alter cell characteristics through lysogenic conversion.

Lysogenic Conversion

Changes in the characteristics of a bacterial cell due to the integration of a lysogenic phage, often leading to increased virulence.

Cytopathic Effects

Damage caused to cells by viruses, including damage to plasma membranes or inhibition of DNA, RNA, or protein synthesis.

Inclusion Bodies

Granules sometimes produced in virus-infected cells.

Antigenic Variation

A mechanism used by some protozoa and other pathogens to avoid host defenses by changing their surface antigens.

Paralytic Shellfish Poisoning

A type of poisoning caused by harmful algal blooms, specifically dinoflagellates producing saxitoxin.

What are the 5 stages of infectious disease

Incubation period, prodromal period, illness, decline, convalescence

Incubation Period

The time between infection and the appearance of the first symptoms or signs of disease.

Prodromal Period

A short period of mild, vague symptoms following the incubation period and preceding the main illness.

Illness

Exhibits overt signs and symptoms

Decline

The stage where signs and symptoms diminish, and the patient becomes susceptible to secondary infections.

Convalescence

The final stage where the patient regains strength and returns to a pre-diseased state.

3 ways to transmit disease

Contact, vehicle, vector

Indirect Contact Transmission

Transmission of disease via inanimate objects called fomites.

Fomites

Inanimate objects that can harbor and transmit pathogens, facilitating indirect contact transmission.

Droplet Transmission

Transmission of disease via airborne droplets, typically over short distances.

Vehicle Transmission

Transmission of disease by an inanimate reservoir such as food, water, or air.

Vector Transmission

Transmission of disease by animals (vectors) that carry pathogens from one host to another.

Mechanical Vector

An arthropod that carries a pathogen on its feet or other body parts without the pathogen reproducing inside it.

Biological Vector

A vector (e.g., mosquito) in which the pathogen reproduces or completes part of its life cycle.

Acute disease

Symptoms develop rapidly but last short time

Chronic disease

Disease develops slowly, less severe but can be recurrent

Latent disease

Disease with a period of no symptoms when causative agent is inactive.

Communicable Disease

A disease that is spread from one host to another.

Incidence (of disease)

The fraction of a population that contracts a disease during a specific time period.

Prevalence (of disease)

The fraction of a population having a specific disease at a given time.

Sporadic Disease

A disease that occurs occasionally and irregularly.

Endemic Disease

A disease that is constantly present in a given area or population.

Epidemic Disease

A disease acquired by many hosts in a given area in a short time.

Emerging Infectious Diseases

New or changing diseases showing an increased incidence in the recent past or a potential to increase in the near future.

Local Infection

An infection where pathogens are limited to a small area of the body.

Systemic Infection

An infection throughout the body.

Septicemia

The growth and reproduction of bacteria in the blood.

Focal Infection

A systemic infection that began as a local infection.

Primary Infection

The acute infection that causes the initial illness.

Secondary Infection

An opportunistic infection that occurs after a primary (predisposing) infection.

Subclinical Disease

An infection with no noticeable signs or symptoms (inapparent infection).

Predisposing Factors

Factors that make the body more susceptible to disease, such as age, lifestyle, or inherited traits.

Nosocomial Infections

Infections acquired during a hospital stay or while receiving medical treatment.

Exogenous Infection (Nosocomial)

Pathogen acquired from the health care environment.

Endogenous Infection (Nosocomial)

Pathogen arises from normal microbiota due to factors within the health care setting.

Iatrogenic Infection (nosocomial)

A type of nosocomial infection that results from modern medical procedures.

What are 3 Nosocomial prevention

Preventative procedures, aseptic technique, isolation.

How do we develop normal microbiota

During the birthing process in the womb free of microorganisms

What are exceptions regarding Koch’s postulates

Some pathogens can’t be cultured in the lab, disease caused by a combination of pathogens and other cofactors, some only cause disease in humans