Transcript Slide 1
Infectious Diseases
Nature of infectious diseases
Pathogens
Infection
Disease
In order to cause disease, pathogens must be able
to
enter, adhere, invade, colonize, and inflict
damage
Growth of pathogens or the production of
toxins/enzymes cause disease
Microbes that cause infectious diseases
Bacteria
Viruses
Fungi
Protozoa
Helminths
Prions
Occurrence of infectious diseases
Epidemiology –study of the occurrence of disease in
populations
Disease reservoirs-where the infectious agent
survives (humans, rodents) Example = yersinia
pestis (plague)
Modes of transmission
ingestion, inhalation, casual contact, intimate
contact, bites/animals
History
Emerging infectious diseases Have not occurred in humans before,
Have occurred previously but affected only small
numbers,
Or have occurred throughout human history, but
only recently recognized as disease due to
infectious agent
Re-emerging infectious diseases
Once were major health problems globally or in
a particular country, then declined dramatically,
but are again becoming health problems for a
significant proportion of the population.
The body’s defense mechanisms
First Line of Defense
Skin
Secretions
Non-specific defenses macrophages
Normal Flora
The body’s defense mechanisms
Immune System
http://www.learner.org/channel/co
urses/biology/archive/animations
/hires/a_hiv1_h.html
Humoral (antibody) response –
B-cells
B-cell, plasma cell, antibodies,
memory B-cells
Cell-mediated response – T-cells
helper T-cells, killer T-cells,
memory T-cells
Vaccination produces immunity
Prevention
Safewater
Purification methods
Testing against contamination
Sewage Treatment
Waste water plants separate components of sewage and
treat them
Chlorination
Food Safety
Inspections
Pasteurization
Regulations
Prevention
Animal Control
Domestic inspections
Vaccinations
Sanitation
Vaccinations
Pre-school
Threshold proportion
Herd immunity
Public Health Organizations
NIH – supports health-related research
CDC – investigates disease outbreaks, informs the
public
FDA – monitors safety of foods and medicines
WHO – coordinates health/vaccine programs
internationally
Treatment
Bacteria (prokaryotes)
Antibiotics “destroyer of life”
Inhibit cell wall, protein, lipid, or RNA synthesis
Penicillin was the first – interfers with cell wall
Chloramphenicol, tetracycline – protein synthesis
Rifampicin – prevents RNA from being made
Treatment
Viruses
Non-living; uses cell materials to replicate
Highly toxic to host cells
Target virus-specific enzymes involved in making DNA/RNA
Acyclovir – herpes
Amantadine – influenza
AZT - AIDS
Treatment
Fungi, protozoans, helminths
Highly toxic because also eukaryotes
Target reproduction, cell membrane, or other necessary
functions
Choroquinine - malaria
Resistance
Resistance
the ability of the pathogen to survive treatment by a particular
drug
Growing problem
Mechanism
change in genes that allows them to evade the action of the drug
Stuctural changes in proteins, receptors
Transfer of anti-microbial genes
Don’t mutate but acquire it from others
Transformation – taking up free-floating DNA plasmids
Transduction – virus carries resistant gene to other bacteria
Transposons – small “rogue” sections of DNA
Mutations and genetic exchange is rare; but bacterial growth is
high
Bioterrorism
Violent acts or acts dangerous to human life
that…appear to be intended:
1.
2.
3.
To intimidate or coerce a civilian population;
To influence the policy of a government by intimidation or
coercion; or
To affect the conduct of a government by assassination or
kidnapping.
Bioterrorism
Biological weapons used in bioterrorism are living
microorganisms such as bacteria, viruses, fungi,
that can kill or incapacitate.
Health care facilities may be the initial site of
recognition and response to bioterrorism activity.
Because of this, the names and telephone numbers
for internal and external departments or agencies
that need to be contacted should be kept by each
facility in its bioterrorism readiness plan.
Bioterrorism
Response to bioterrorism agents:
Internal reporting requirements (within a facility):
Infection control personnel
Epidemiologist (local and state)
Administration (health care facility and health department)
Office of public affairs in the health facility
Bioterrorism
External contacts (outside of facility)
Local health department
State Health Department
FBI
CDC
Local police
EMS
Bioterrorism
Agents
Bacterial- Anthrax and Plague
Viral- Small Pox
Toxins- Botulism and Ricin