Micro host parasite 2 Flashcards
Consider in conjunction with manifestations of infectious disease and what is happening to the infected individual
Immune system gets working by the illness period
Stages of infectious disease. When is the person infectious?
Incubation, Prodomal, illness , decline , Convalescence . Infectious throughout all of these!
Incubation. Depends on what?
time b/w infection and signs and symptoms; no signs or symptoms; depends on virulence of the agent, infective dose needed, health of the host, nature of pathogen and generation time, site of infection (can really decrease the incubation)
Prodromal
Short, vague, general symptoms: tired, muscles ache
Illness
most severe symptoms, damage is being caused, immune system starts to work
Decline
declining signs and symptoms, immune system and treatments are working, infectious agent is removed unless treatment unsuccessful
Convalescence
no signs or symptoms; depends on level of damage, nature of pathogen, site of infection, health of patience
Difference when you have taken a vaccine?**
Might never reach illness stage because
Exiting the host
usually just like entry and is induced by microbe. Not necessarily out the same way it came in though
Define entry carefully*
Entry is entering the organism. Example, entering the mouth does not equal entering the organism - it has to get inside, to access deeper tissue. It can access mucous membranes but might not cause disease. Just be careful how you describe
Reservoir of infection. Examples
Places where pathogens can survive outside host. Example: animals, humans, nonliving (like water tower)
Carriers
Can be reservoir. Usually asymptomatic
Zoonotic disease
A disease that you get from a living animal. Similarity of hosts increases likelihood of infection. Contact with animals, their waste, of bloodsucking, hard to eradicate
Infectious vs contagious
Some diseases cause infection, but it doesn’t spread.
Human carriers
Large reservoir; can be asymptomatic for a long time (eg AIDS)
Nonliving reservoirs
Food/meat (different from living animal), soil, water with feces with eggs and worms
Modes of disease transmission
Contact: direct or indirect (something someone else touched, sneeze within one meter), Vehicle: airborne (travels more than one meter), waterborne, foodborne, vector: mechanical (on insect’s body), biological
Nosocomial infections
Infection that doesn’t show evidence of incubation when entering hospital; usually caught in health car facility. Difficult to control!
Nosocomial infections types
Exogenous: from healthcare environment; endogenous: arise from normal microbiota due to factors in healthcare setting; iatrogenic: results from modern medical prodecures (eg from catheter)
Factors that lead up to nosocomial infections
Immunocompromised: procedure, age; presence of microorganisms in hospitals: Usually opportunistic or antibiotic resistant; transfer b/w staff and patients and patient to patient.
Why should a hospital rotate the use of antibiotics or disinfectants?
Bacteria adapt to the ones already in place, so we need different ones to keep them clean
Frequency of disease
Occurrence of disease measured by incidence (number of new cases in a period of time) and prevalence (number of total cases in a period of time; often expectation); also geographic distribution
Prevalence vs incidence
Prevalence is expected always greater than incidence
Explain how epidimiology can help when Koch’s postulates cannot be used
Some organisms can’t be cultured, but we can find a probable cause and find a large correlation b/w them and a disease
