1. Infectious Diseases

2. 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

3. Microbes that cause infectious diseases
Bacteria
Viruses
Fungi
Protozoa
Helminths
Prions

4. Picture of Health??

5. 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

6. 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.

7. 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

8. Prevention Animal Control Domestic inspections Vaccinations Sanitation
Pre-school
Threshold proportion
Herd immunity

9. 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

10. 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

11. 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

12. Treatment Fungi, protozoans, helminths
Highly toxic because also eukaryotes
Target reproduction, cell membrane, or other necessary functions
Choroquinine - malaria

13. 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

14. The body’s defense mechanisms
First Line of Defense
Skin
Secretions
Non-specific defenses - macrophages
Normal Flora

15. The body’s defense mechanisms
Immune System
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
An inside look at the flu

16. Need for Vaccines Spanish flu killed millions during WWI
Still kills today but generally in the 100s
Endemic – local, normal, baseline disease
Epidemic – widespread and in large numbers at same time
Pandemic – world-wide
Protects individual
Lowering occurrence in population can protect those who can’t get vaccine (herd immunity)
Threshold response - percent of people who need to be vaccinated for herd immunity to work

17. Types of vaccinations Live but weakened disease agents
Good but higher mutations, can cause illness, refrigeration
Inactivated or killed disease agents
Less effective but safer, need boosters
Subunit vaccines – use only subunits of antigens
Toxoid vaccines - against toxins made by bacteria
Conjugate vaccines – helps infants recognize antigens
DNA vaccines
Recombinant vector vaccines

18. Vaccine Production Tested in cells and in animals
Eggs – virus injected into fertilized eggs to reproduce and then protein coats isolated and tested; takes up t0 6 months
Cell Culture – grown in confined cells; cells die and viral coats are isolated and tested, quicker
Pharming - tobacco plant infected with Agrobacterium that has gene for viral coat antigen inserted; virus-like particles of protein then isolated; no DNA so more safety.

19. Issues with Vaccines Public perception Challenges Myths (autism)
Makes me sick or allergies
Government intrusion
Religious freedom
Challenges
Speed of production
Safety and stability
Storage and distribution
Changing pathogen landscape

20. Bioterrorism
Violent acts or acts dangerous to human life that…appear to be intended:
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.

21. 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.

22. 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

23. Bioterrorism External contacts (outside of facility)
Local health department
State Health Department
FBI
CDC
Local police
EMS

24. Bioterrorism Agents Toxins- Botulism and Ricin
Bacterial- Anthrax and Plague
Viral- Small Pox
Toxins- Botulism and Ricin