Micro final review

• Sporadic disease


  Occurs occasionally or infrequently
• Endemic disease


  Steady, low-level frequency at a regular interval
• Epidemic


  Outbreak affecting many people at once
• Pandemic


  Increase in disease within a large population over two countries
• Measuring Infectious Disease Frequency


  • Knowledge of population
  • Exposed people
  • Affected people
• Prevalence


  Total number of people infected at a given time
• Morbidity


  Number of new cases of illness, change in health status over time
• Mortality


  Number of deaths from a disease per number of cases
• Infection disease


  Transmitted by microbe
• Communicable disease


  Person to person
• Common epidemic


  Non communicable, from a common source
• Common epidemic


  • Quick and drops off
• Propagated epidemic


  One infected individual placed into a susceptible population
• Propagated epidemic


  • Allowed, more people get it
• Basic reproduction number R0


  Capacity of an infectious agent to spread
• Basic reproduction number R0


  • Varies on environment and pathogenic density
• Effective reproduction rate Re

  With vaccines in population
• Herd immunity


  Threshold percentage of population having immunity
• Environments with emergence and reemergence of diseases


  • Risk factors
  • Systemic epidemiology: ecological and social factors affecting this
  • Healthcare acquired infections (nosocomial infections)
• Healthcare acquired infections (nosocomial infections)


  UTIs are most common
• Healthcare acquired infections (nosocomial infections)


  • Prolong hospital stays and increases money
  • Proper training in basic infection control would decrease these
• Strategies to reduce or eliminate the source of infection


  • Want to reduce or eliminate the source of infection
  • Water with mosquitos (breeding grounds)
  • Treatment of water
  • Social distancing or isolating carriers
  • Reduce number of susceptibles by raising herd immunity
  • Vaccines and treatments
  • Breaking the chain of infection
• Vaccines


  • Long-term immune response
  • Herd immunity
• Biosafety levels (BSLs)


  • 1: not pathogenic, no extreme safety
  • 2: associated with human disease, potential hazard if opportunity
  • 3: indigenous or exotic agent that can be aerosol transmitted, can cause disease
  • 4: dangerous or letha; agent that pose high risk of life threatening disease, heavy security and not common
• Proper procedures when collecting microbe samples


  • Represent diseased area
  • Sufficient quantity
  • Avoid contamination
  • Proper containment
  • Before antimicrobial treatment
• Tests to identify microbes


  • Rapid biochemical tests
  • API 20E: 20 microtubes with biochemical activity (different metabolites)
  • Microscopy
  • Molecular methods
  • Nucleic acid probing, real-time polymerase chain reaction amplification, dna fingerprinting, whole genome sequencing
  • Ribotyping: identify bacterial genera
  • 16s rRNA
  • Immunological: detection of antigens or antibodies
• Agglutination


  Immune complex is formed from cross-linking cells with antibodies
• Serotyping


  • Finding a distinct variant
  • Agglutination with specific antisera
  • Differentiate cell surface
• Complement fixation


  • Binding of complement system to antigen-antibody complex
  • Finding if antibody to antigen is present
• Enzyme linked immunosorbent assay (ELISA)


  • Most widely used serological tests
  • Direct: detect protein antigens
  • Indirect: detect antibodies
  • Look at presence of antibodies to determine pathogen
• Lateral flow assay


  Look at antibodies through a filter paper
• Human activities that contribute to the emergence and reemergence of diseases


  • Not getting vaccinated
  • Polio coming back
  • Bioterrorism: Using microbes and antigens to scare population and as a weapon
• The Big 3 infectious diseases are TB, HIV, and Malaria
• Modes of transmission for viruses


  • Airborne: coughing, sneezing, or vocalizing
  • Arthropod
  • Direct Contact
  • Food and water
  • Zoonotic
• Airborne viruses


  • Originate from living source
  • Influenza A,B, C
  • Major epidemics
  • Adhere to host respiratory epithelium
  • Viruses propagate and make new versions
• Antigenic drift


  Smaller genetic changes that result in subtle antigen changes
• Antigenic shift


  Large protein sequence change
• Genome exchanges occur when viruses are together
• Chickenpox (varicella) and shingles (herpes zoster)


  • Dormant viral DNA within cranial nerves
  • Shingles= reactivated form (herpes zoster)
• Measles (rubeola)


  • Respiratory tract
  • Koplik's spots: red lesions with bluish white speck in center
  • Very contagious