Week 7 - Infection Flashcards
Define infection.
Pathogenic micro-organisms penetrate the host defenses, enter the tissues, and multiply
Define infectious disease.
Pathologic state that occurs due to the disruption of a tissue or organ caused by microbes or their products
Define pathogen.
A microbe whose relationship with its host is parasitic and results in infection and disease
What is the type and severity of infectious disease dependent on?
Pathogenicity of the organism and condition of the host
Define pathogenicity.
The ability of microbial species to produce disease (true and opportunistic pathogens)
Define virulence.
The degree of damage caused by a microbe to its host
Define true pathogen. Give an example.
Causes disease in a healthy person with normal immune defenses
Example: mycobacterium tuberculosis
Define opportunistic pathogen.
Cause disease in immune compromised host and/or cause disease when access to sterile environment
Example: staphylococcus
What are the 6 types of infections?
Primary infection
Reinfection
Superinfection
Secondary infection
Nosocomial infection
Subclinical infection
Define the 6 types of infection.
Primary
Reinfection
Superinfection
Secondary infection
Nosocomial infection
Subclinical infection
Primary infection: initial infection with organism in host
Reinfection: subsequent infection by same organism in a host (after recovery)
Superinfection: infection by same organism in a host before recovery
Secondary infection: when in a host whose resistance is lowered by preexisting infectious disease, a new organism may set up in infection
Nosocomial infection: cross infection occurring in hospital
Subclinical infection: it is one where clinical affects are not apparent
What are 7 details about infectious diseases throughout history?
Infectious agents have probably always caused disease in humans
Smallpox has been described in ancient Egyptian and Chinese writings and may have been responsible for more deaths than all other infectious diseases combined
There is evidence that malaria and poliomyelitis have existed since ancient times
In the 14th Century, the bubonic plague, or Black Death, killed about 20 million people in Europe alone
In the 20th Century, the 1918 influenza may have killed up to 50 million people worldwide
Close to 20 million people have died of AIDS to date
Potato blight (cause of the Irish Potato Famine)
What are the 3 classifications of infectious disease?
Duration, location, and timing
What kinds of diseases are classified by duration?
Acute: develops and runs its course quickly
Example: influenza
Chronic: develops more slowly and is usually less severe, but may persist for a long, indefinite period of time
Example: tuberculosis
Latent: characterized by periods of no symptoms between outbreaks of illness
Example: herpes
What kinds of diseases are classified by location?
Local: confined to a specific area of the body
Systemic: a generalized illness that infects most of the body with pathogens distributed widely in tissues
What kinds of diseases are classified by timing?
Primary: initial infection in a previously healthy person
Secondary: infection that occurs in a person weakened by a primary infection
What are the 6 phases of infectious disease?
- Exposure
- Incubation period: time between infection and appearance of signs and symptoms
- Prodromal period: mild, nonspecific symptoms that signal the onset of some diseases
- Acute stage: person experiences typical signs and symptoms of disease
- Recovery stage: symptoms have disappeared, tissues have healed, and body is slowly recovering strength
- Convalescence: clinical symptoms have actually subsided
What 6 elements are needed for the chain of infection?
- Infectious agent
- Reservoir
- Portal of exit
- Mode of transmission
- Portal of entry
- Susceptible host
What are 3 details about portals of entry for infectious agents that enter the skin? Give examples of diseases that do this.
Nicks, abrasions, and punctures
Intact skin is very tough; few microbes can penetrate
Some create their own passageways using digestive enzymes
Examples:
Staphylococcus aureus
Streptococcus pyogenes
Haemophilus aegyptius
Chalmydia trachomatis
Neisseria gonorrhoeae
What are 2 details about infectious diseases that use the gastrointestinal tract as a portal? Give examples of diseases that do this.
Pathogens contained in food, drink, and other ingested substances
Adapted to survive digestive enzymes and pH changes
Examples:
Salmonella
Shigella
Vibrio
Certain strains of Escherichia coli
Poliovirus
Hepatitis A virus
Echovirus
Rotavirus
Entamoeba hitolytica
Giardia lamblia
What is 1 detail about infectious diseases that use the respiratory portal of entry? Give examples of diseases that use this.
The portal of entry for the greatest number of pathogens
Examples:
Streptococcal sore throat
Meningitis
Diphtheria
Whooping cough
Influenza
Measles
Mumps
Rubella
Chickenpox
Common cold
Bacteria and fungi causing pneumonia
What are 3 details about diseases that use urogenital portals of entry? Gives examples of diseases that do this.
Sexually transmitted diseases (STDs)
Enter skin or mucosa of penis, external genitalia, vagina, cervix, and urethra
Some can penetrate an unbroken surface
Examples
Syphilis (treponema)
Gonorrhea (Nisseria)
Genital warts (Human papilloma virus)
Chlamydiosis (Chlamydia)
What are 2 details about pathogens that infect during pregnancy and birth? Give examples of diseases that do this.
Some microbes can cross the placenta (ex. the syphilis spirochete, rubella)
Other infections occur prenatally when the child is contaminated by the birth canal
Examples:
Toxoplasmosis
Other diseases
Rubella
Cytomegalovirus
Herpes simplex
What are 4 examples of exit portals?
Respiratory and salivary portals: coughing and sneezing, talking and laughing
Fecal Exit
Urogenital Tract
Removal of Blood or Bleeding
What are the 5 methods of transmission of infection? Give examples of diseases for each transmission.
Contact (sexual intercourse):
syphilis, gonorrhea
Inhalation: influenza,
tuberculosis, smallpox, measles,
mumps, etc.
Ingestion: cholera (water), food
poisoning (food) and dysentery
Inoculation: tetanus (infection),
rabies (dog), serum hepatitis, i.e.
Hepatitis B (infection)
Congenital: syphilis, rubella, toxoplasmosis, cytomegaloviruses
What is 1 detail about insects as a method of transmission?
Insects act as mechanical vector (dysentery and typhoid by housefly) or biological vector (malaria) of infectious disease
Define reservoir.
The primary habitat in the natural world from which a pathogen originates
Define a carrier. Give examples.
An individual who inconspicuously shelters a pathogen and spreads it to others without any notice
Examples:
Asymptomatic carriers: “Typhoid Mary”
Incubation carriers
Convalescent carriers
Define a vector and give 2 details.
A live animal that transmits an infectious agent from one host to another
Majority are arthropods
Larger animals can also be vectors
What 5 factors influence microbial growth?
Temperature
pH, or the values used in
chemistry to express the
degrees of acidity or
alkalinity of a substance
Food
Moisture
Oxygen
What are 4 categories of risk factors for infections that someone cannot typically control?
Heredity
Aging
Environmental conditions
Organism virulence and resistance
What are 7 risk factors someone can control?
Stress
Nutrition
Sleep
Drug use
Personal hygiene
High-risk behaviors
Exposure to products and services that increase risk
Define emerging diseases.
Emerging diseases are those that have recently appeared within a population, or whose incidence or geographic range
is increasing rapidly
What 5 things affect disease emergence or re-emergence?
Appearance of a previously unknown agent
Evolution of a new infectious agent
Spread of an infectious agent to a new host
Spread of an infectious agent to new locations
Acquisition of resistance to anti-microbial drugs
What 2 events must occur for a disease to become established?
- The infectious agent must be introduced into a vulnerable population
- The agent must have the ability to spread readily from person to person, cause disease, and sustain itself within the population
What are 5 ways to reduce the spread of infectious diseases?
Vaccines
Antimicrobial drugs
Good personal hygiene and sanitation
Protection against mosquitoes
Quarantine
What are 5 details about vaccines?
The most effective method of stemming the spread of infectious disease is through vaccination
Vaccines consist of weakened or killed microbes, or just components of a pathogen, and stimulate the body’s natural defenses—the
immune system—to combat infections
Vaccination has eliminated smallpox, nearly eradicated poliovirus from much of the world, and drastically reduced
the incidence of childhood infections, such as measles, mumps, and whooping
cough, at least in the developed world
Influenza vaccines are available to reduce the occurrence of seasonal flu, although the shot must be given yearly
due to the extreme variance of the influenza virus from season to season
Vaccines for other infectious diseases, especially HIV, still are being sought
What are 4 details about antimicrobials?
Antibiotics are effective for many types of bacterial infections (although they
are entirely useless against viruses)
But increasingly, bacteria are becoming resistant to the arsenal of antibiotics at our disposal
Very few drugs work well against viruses
Anti-fungal drugs exist, but their use is limited
What are 2 details about protection against mosquitos (and other insect vectors/parasites)?
There are no vaccines against protozoan parasites, and other medications against them are becoming ineffective
Therefore, protection from insect vectors such as mosquitoes and control of mosquito populations are crucial
strategies in containing the spread of insect-borne diseases, such as malaria
What is 1 detail about sanitation?
Good sanitation, water purification, hand washing, and proper cooking and storage of foods all help to reduce the prevalence of infectious disease
What are 2 details about quarantine?
In cases of highly contagious, often fatal diseases, quarantine is employed as a means of preventing the spread of disease through a community
However, regardless of the disease, it is wise to limit contact with other individuals when ill
What are the 3 overarching elements of the CDC’s ID framework?
Element 1: strengthen public health fundamentals, including infectious disease surveillance, laboratory
detection, and epidemiologic
investigation
Element 2: identify and implement high‐impact public health interventions to reduce infectious diseases
Element 3: develop and advance policies to prevent, detect, and control infectious
disease
What are the 4 priorities for Element 1 of the CDC’s ID framework?
Element 1: strengthen public health fundamentals, including infectious disease surveillance, laboratory
detection, and epidemiologic
investigation
Modernize infectious disease surveillance to drive public health action
Expand the role of public health and clinical laboratories in disease control and prevention
Improve capacity for epidemiologic investigations and public health response
Advance workforce development and training to sustain and strengthen public health practice
What are the 2 priorities for Element 3 of the CDC’s ID framework? Give examples of infectious disease issues of special concern.
Element 3: develop and advance policies to prevent, detect, and control infectious
disease
Identify and validate high‐impact tools for disease reduction
Use proven tools and interventions to reduce high‐burden infectious diseases
Examples:
Antimicrobial resistance
Chronic viral hepatitis
Food safety
Healthcare-associated infections
HIV/AIDS
Respiratory infections
Safe water
Vaccine-preventable diseases
Zoonotic and vectorborne diseases
What are the 2 priorities for Element 2 of the CDC’s ID framework?
Element 2: identify and implement high‐impact public health interventions to reduce infectious diseases
Ensure the availability of sound scientific data to support the development of evidence‐based and cost‐effective policies
Activities that help make disease prevention a standardized, routine part of healthcare