Infection and Disease Flashcards
What is a symbiotic relationship?
When you give and you get something from the host
What is a mutualistic relationship?
Both partners benefit and no one is hurt
What is commensal relationship?
Neither host nor microbe is harmed
-neither benefits it just so happens that they are together
What is a parasitic relationship?
One partner benefits and the other is harmed
What are pathogens?
They are diseases caused by microbes that differ in their ability to cause diseases
What is pathogenicity?
Refers to a microbes ability to enter a host and cause disease
What is virulence?
The degree of pathogenicity
What are pathogenicity islands?
Refers to gene clusters responsible for virulence
Is there variance in virulence within the same species?
Yes, some are more virulent than others
Can “passing” through species affect virulence?
Passing through animals of the SAME species can make a pathogen more virulent
Passing though DIFFERENT animals can weaken the pathogen, decreasing virulence
-vaccines do this
What is an Iatrogenic disease?
Diseases that are caused by medical procedures
What is an Idiopathic disease?
Disease that has an unknown cause
What is a Nosocomial infection?
Infections that are contracted in a hospital, doctors office, clinic etc
Why are nosocomial infections bad?
Serious health threats in our health care system
What to nosocomial infections cause?
Health care associated infections (HAI) occur as a result of receiving treatment for another condition
- involves a compromised host
- caused by opportunistic agents
What is the key to reducing nosocomial infections?
Finding the chain of transmission
-standard precautions used by the healthcare team can stop the chain of transmission
What are 2 categories that apply to the infectious disease process?
Communicable diseases are contagious
-transmittable amount hosts in a. population
Noncommunicable diseases are not contagious
-not easily transmitted to another host. acquired directly from the environment
What is the influenza?
Caused by influenza virus transmitted by swine and waterfowl through direct contact
What is rabies?
Caused by lyssavirus transmitted by bats, foxes, dogs and cats through direct contact (bite)
What is the bubonic plague?
Caused by the Yersinia pests transmitted by rodents through flea bites
What is Lyme disease?
Caused by borrelia burgdorferi transmitted by field mice through rick bites
What is Salmonella?
Caused by salmonella species transmitted by poultry, rats, turtles, reptiles by ingestion of contaminated food
What is malaria?
Caused by plasmodium species transmitted by monkeys by mosquito bites
How do pathogens enter the body?
Mouth, nose, general opening, wounds on the skin, eyes, ears
What are vectors?
Agents that may spread disease
-living organisms that act as intermediates
What is herd immunity?
Building up immunity in the population to make contracting the pathogen difficult.
-90% of the population has to have this immunity
What events have to occur for disease to develop in the host?
Exogenous infection-if pathogen breaches the hosts external defences to enter sterile tissue
Endogenous infection- occurs if normal microbiota enter sterile tissue
Opportunisti infections-commensals take advantage of a change in the body environment that favours microbes
Primary infection- occur in healthy bodies
Secondary infection- occur in body weakened by a primary infection
Local disease-restricted to a single area
Systemic disease-disseminate to organs and systems
What are the 5 stages of disease progression?
- Incubation period-between entry of microbe and symptom appearance
- Prodromal phase- time of mild signs or symptoms
- Acme period(climax)- signs and symptoms are most intense
- Decline- signs and symptoms subside
- Convalescence- body returns to normal
What is the difference between sign, symptom and syndrome?
Sign is measurable
Symptom is a feeling
Syndrome is progression
What does pathogen entry into the host depend on?
Cell adhesion and the infectious dose
What is the portal of entry?
The route and exogenous pathogen uses to enter the body -inhalation -fecal-oral -STD Parenteral
What is the infectious dose?
The number of microbes entering the body
What do capsules flagella and pili all have in common?
They are adhesions that allow the pathogen to adhere to a specific tissue
What are the 2 ways in which pathogens can breach barriers?
- invasiveness: ability of a pathogen to penetrate tissues and spread
- Phagocytosis: engulfing another to enter through defences undetected
What successful invasiveness dependant on?
if the pathogen has virulence factors such as
-Enzymes to help pathogens resist body defences and break the glue holding cells together
What is toxigenicity?
The ability of pathogens to produce toxins
What are exotoxins?
proteins produced during bacterial metabolism
What are antitoxins?
Produced by the host body and neutralize toxins
What is toxaemia?
Presence of toxins in the blood
What are toxoids?
Toxins whose toxicity has been destroyed but still elicit an immune response
What are endotoxins?
Released upon disintegration of gram negative cells
-cause blood coagulation and fever. and shock
What is a portal of exit?
Pathogens or toxins leave through a host in order to spread disease
What are direct methods of transmission?
Close personal contact
- kissing
- respiratory droplets
- Mother to child
What are methods of indirect transmission?
Through non-living items
- doorknobs
- aerosols
- mechanical and biological vectors
In many cases the symptoms of a virus infection are more the result of what?
Actions of the immune system
-gfenereally a result of release by white blood cells, of histamines and other factor which promote tissue swelling, fever
Are fungi toxic?
Yes they infect similar ways to bacteria and are toxic and and have various targets
What is an endemic?
Disease continually present in a given areas or population but do not cause major public health problems
What is an epidemic?
Suddenly present in high than normal incidence and ar a public health problem
-can be caused by a change in virulence or the intro of the infectious agent
What is a pandemic?
Disease that are world wide epidemic
What is the difference between epidemiology and etiology?
Epidemiology: study of disease and patterns of the spread of disease
Etiology: Origin of a disease
What is progression of an infectious disease?
The time course of an infection can be categorized into a number of phases
What is a sequelae?
After effects long after apparent recovery
-ex: polio-post polio syndrome can occur decades after polio first contracted
What is the incubation phase?
Course of an infection there will be a short phase where the microbe grows in numbers but little of no ill effect is noted
What is a prodromal phase?
Where there’re the first symptoms of mild unwellness
What is the invasive phase?!
Infection fase is establish and the full signs and symptoms of the disease are found- such as fever and chills or swelling/headache
What is the fulminating phase?
If the signs and symptoms of the invasive phase appear suddenly and severely
What is the decline phase?
Disease declines in severity as the immune system “gets the upper hand” followed by convalescence
What is an outbreak?
More contained epidemic
What is disease emergence and reemergence related to?
- Change in land use or agriculture practices
- Changes in human demographics
- Poor population health
- pathogen evolution
- food source contamination
- International travel
- Climate change
