Ch_15___16__Microbial_Mechanisms_of_Pathogenicity__Disease_and_Epidemiology__S_

Microbial Mechanisms of Pathogenicity

The ways in which microorganisms cause disease.

Pathology

The study of disease.

Etiology

The study of the cause of a disease.

Pathogen

Microorganisms that can cause disease.

Pathogenesis

Studies how disease develops.

Infection

The successful colonization of a host by a microorganism.

Disease

An abnormal state in which the body is not functioning normally.

Sign

A change in a body that can be measured or observed as a result of disease.

Symptom

A change in body function that is felt by a patient as a result of disease.

Syndrome

A specific group of signs and symptoms that accompany a disease.

Communicable Diseases

Diseases spread directly or indirectly from one person to another.

Noncommunicable Diseases

Diseases not spread from one person to another.

Infectious Disease

Diseases caused by pathogens.

Noninfectious Disease

Diseases not caused by pathogens.

Incubation Period

The period with no signs or symptoms of disease.

Prodromal Stage

Stage with vague, general/nonspecific symptoms.

Period of Illness

Period in which more severe and specific signs and symptoms occur.

Period of Decline

Period where signs and symptoms decline.

Convalescent Period

Period of recovery from infection.

Acute Disease

Disease that develops rapidly.

Chronic Disease

Disease that develops slowly.

Latent Disease

Disease where the pathogen goes dormant for extended periods.

Koch's Postulates

Set of criteria to establish a causative relationship between a microbe and a disease.

Normal Microbiota

Microorganisms that colonize the body's surfaces without normally causing disease.

Transient Flora

Temporary microorganisms present in the body.

Resident Flora

Microorganisms that permanently reside in the body.

Microbial Antagonism

Normal flora inhibits overgrowth of harmful microbes.

Endogenous Infections

Infections that occur when normal flora is introduced to a previously sterile site.

Primary Pathogens

Pathogens that cause diseases in healthy individuals.

Opportunistic Pathogens

Pathogens that cause diseases in immunocompromised hosts.

Infectious Dose (ID)

Minimum number of microbes required for infection to proceed.

Pathogenicity

The ability of a microorganism to cause disease.

Virulence

Degree of pathogenicity of a microorganism.

Virulence Factors

Traits used by pathogens to invade and establish themselves in the host.

Adhesion

The capability of microbes to attach to host cells.

Invasion

Dissemination of a pathogen throughout local tissues or the body.

Localized Infection

Infection confined to a specific area.

Systemic Infection

Infection spreads throughout the body.

Focal Infection

Infection that originates in one area but affects other areas.

Mixed Infection

Infection caused by multiple microbes.

Portals of Entry

Routes microbes use to enter the body.

Exogenous Agents

Microbes that originate outside the body.

Endogenous Agents

Microbes that originate within the body.

Epidemiology

The study of the distribution and determinants of health problems in populations.

Morbidity

The state of being diseased or unhealthy.

Mortality

Deaths per population.

Incidence

The number of new cases of a disease.

Prevalence

The total number affected by a disease in a population.

Reservoir

Natural habitat of a pathogen.

Carrier

An individual that harbors infections and can spread them to others.

Direct Contact Transmission

Physical contact transmission from person to person.

Droplet Transmission

Transmission via droplet spread over distances of ≤1m.

Indirect Contact Transmission

Transmission via inanimate objects that become contaminated.

Airborne Transmission

Transmission of pathogens on air over distances >1m.

Water-borne Transmission

Transmission through fecal contamination of water.

Food-borne Transmission

Ingestion of food containing pathogens.

Vector

An animal that carries disease from one host to another.

Biological Vector

Vector that participates in a pathogen’s life cycle.

Mechanical Vector

Vector that carries the pathogen without being infected.

Healthcare-associated infections (HAI)

Infections acquired in healthcare settings.

Endemic Disease

Constantly present disease in a population.

Sporadic Disease

Diseases that occur occasionally.

Epidemic Disease

Many people acquire a disease in a short time.

Pandemic Disease

Worldwide epidemic.

Toxins

Substances produced by pathogens that can cause disease.

Exotoxin

Toxins actively secreted by living cells.

Endotoxin

Integral part of the cell wall released when a cell disrupts.

Toxigenicity

Capacity to produce toxins.

Virulence Factors: Antiphagocytic Factors

Factors that help pathogens avoid being engulfed by phagocytes.

Exoenzymes

Enzymes secreted by pathogens that help them invade hosts.

Hyaluronidase

Exoenzyme that degrades hyaluronic acid, promoting the spread of bacteria.

Nucleases

Exoenzymes that degrade DNA, aiding in bacterial spread.

Phospholipases

Exoenzymes that degrade cell membranes, leading to cell lysis.

Proteases

Exoenzymes that degrade proteins, facilitating bacterial spread.

Acute Disease

Sudden onset with rapid progression.

Chronic Disease

Long-term, gradual onset.

Latent Disease

Periods of dormancy without active replication.

Treatment of Infectious Diseases

Can involve antibiotics, antivirals, and vaccines.

Prevention of Infectious Diseases

Focuses on hygiene, vaccination, and public health measures.

Risk Factors for Infectious Diseases

Include age, immunocompromised state, and environment.

Signs of Infection

Fever, chills, fatigue, and localized pain are common.

Symptoms of Infection

Nausea, vomiting, and malaise are typical.

CDC

Centers for Disease Control and Prevention, monitors public health.