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- 1. 10/19/2023 5th session Introduction to Public Health Presented by Kherailah Khodeda 2nd Class 1st semester 2023-2024 1
- 2. 10/19/2023 Infectious Diseases- Major Killers in Past • Bubonic plague- “Black Death” • Tuberculosis • Smallpox • Cholera • Typhoid fever • Typhus fever • Yellow Fever • Diphtheria • Measles • Influenza The “Conquest” of Infectious Diseases 2
- 3. 10/19/2023 • Immunization • Antibiotics Infectious Agents • Bacteria- tuberculosis, cholera, typhoid, tetanus, diphtheria, dysentery, syphilis, streptococci, staphylococci • Virus- smallpox, poliomyelitis, hepatitis, measles, rabies, AIDS, yellow fever • Parasites- malaria, cryptosporidiosis, giardiasis, roundworms, tapeworms, hookworms, pinworms Infectious Diseases Were “Conquered” by 1960s 3
- 4. 10/19/2023 • Pathogens (infectious agent) • Reservoir • Means of transmission • Susceptible host • Interrupt chain of infection at any link Chain of Infection 4
- 5. 10/19/2023 • Aerosol • Touching contaminated object and putting hands to mouth, nose, or eyes • Contaminated water or food: fecal-oral route • Vectors • Sexual contact Means of Transmission 5
- 6. 10/19/2023 • Kill pathogen with antibiotics • Eliminate reservoir • Prevent transmission o Wash hands o Quarantine o Condom • Increase resistance of host by immunization Interrupting Chain of Infection 6
- 7. 10/19/2023 • Epidemiologic surveillance • Contact tracing • Immunization and treatment of identified patients to prevent further spread • Quarantine if necessary Examples • SARS- controlled by classic public health measures • Rabies o Surveillance of wildlife o Immunization of dogs o Post-exposure prophylaxis Public Health Measures 7
- 8. 10/19/2023 • Possible if no non-human reservoir and a vaccine exists • Smallpox eradicated in 1977 • Polio eradicated from Western Hemisphere o Now only in a few countries o Religious opposition in some countries • Measles is next target ( Now no longer endemic in U.S.) Eradication 8
- 9. 10/19/2023 • Rumors of vaccines causing autism, SIDS • Side effects do exist for some vaccines • Some parents refuse to accept risks • Herd immunity- lost if many people do not get vaccinated • Pharmaceutical companies reluctant to develop vaccines o Low profits o Risk of lawsuits Fear of Vaccines 9
- 10. 10/19/2023 HIV/AIDS • First recognized in U.S. in 1981. Now a world-wide killer • Caused by a retrovirus • Attacks the immune system • Screening test recognizes antibodies • Can measure viruses in the blood • Now many drugs are available, but no cure The Resurgence of Infectious Diseases 10
- 11. 10/19/2023 • Sexual contact o Homosexual- most common in U.S. o Heterosexual- most common around the world • Sharing needles o Intravenous drug use o Medical use of unsterile needles • Mother to infant o Prenatal or during birth o Breast feeding • Blood transfusions o No longer in U.S. HIV/AIDS Transmission 11
- 12. 10/19/2023 • Probable originated in Africa • Cross-species transmission from Monkeys or apes • Spread in human populations due to disruption of traditional lifestyles • Spread to Western countries due to changing patterns of sexual behavior and international travel Where Did HIV Come from? 12
- 13. 10/19/2023 • Ebola • Monkey pox • Hantavirus • Other hemorrhagic fevers • West Nile Virus • SARS Other Emerging Viruses 13
- 14. 10/19/2023 • Human activities that cause ecological damage and close contact with wildlife • Modern agricultural practices • International travel • International distribution of food and exotic animals • Breakdown of social restraints on sexual behavior and intravenous drug use Factors that Lead to Emergence of New Infectious 14
- 15. 10/19/2023 • Virus is constantly mutating • Vaccine must be changed frequently • New, lethal strains appear periodically • Epidemic of 1918-1919 killed 20 million to 40 million worldwide • Concern about bird flu in Asia Influenza 15
- 16. 10/19/2023 • Legionnaire’s Disease • Lyme Disease • Streptococcus A • E.coli O157:H7 in food • Antibiotic resistance o From improper medical care use o Use in agriculture New Bacterial Threats 16
- 17. 10/19/2023 • Leading cause of infectious-disease death worldwide; one third of world population is infected • There was a resurgence in U.S. in early 1990s • Much higher from people with HIV • Transmitted by aerosol • 50 % fatality rate from untreated TB Tuberculosis 17
- 18. 10/19/2023 • Antibiotics are effective, but must be taken for several months • Improper use of antibiotics leads to resistance, including multidrug resistance, when mortality rate can be 50 % • Directly observed therapy works- best approach to preventing antibiotic resistance Tuberculosis, CTD 18
- 19. 10/19/2023 • Creutzfeld-Jacob disease (CJD)- sporadic, in older people • Bovine spongiform encephalopathy (BSE) or ‘mad cow disease’ in Britain • New variant CJD in Britain in younger people, thought to be caused by eating infected beef • Regulations have been tightened on animal feed Prions 19
- 20. 10/19/2023 • Global surveillance • Improve public health capacity • Veterinary surveillance • Reduce inappropriate use of antibiotics • Need for new vaccines • Need for new antimicrobial drugs • Control of vector-borne and animal-borne diseases Public Health Response to Emerging Infections 20
- 21. 10/19/2023 • Approach to bioterrorism is the same as that for natural disease outbreaks • Will probably first be recognized by surveillance • Best defended against by same methods as natural outbreaks Threats of Bioterrorism 21
- 22. Thank you for your attention 10/19/2023 22