Preventing Infectious Diseases


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  • Preventing Infectious Diseases

    1. 1. Chapter Eleven: Preventing Infectious Diseases
    2. 2. Infectious Disease Transmission <ul><li>Pathogen : A disease-causing agent </li></ul><ul><li>Epidemic : A highly significant increase in the number of cases of an infectious illness existing in a given time period in a given geographical area </li></ul><ul><li>Pandemic : An epidemic that has crossed national boundaries, thus achieving regional or international status </li></ul><ul><ul><li>Example: HIV/AIDS </li></ul></ul>
    3. 3. Pathogens <ul><li>Viruses </li></ul><ul><li>Prions </li></ul><ul><li>Bacteria </li></ul><ul><li>Fungi </li></ul><ul><li>Protozoa </li></ul><ul><li>Rickettsia </li></ul><ul><li>Parasitic worms </li></ul>
    4. 4. Chain of Infection
    5. 5. Chain of Infection <ul><li>Agent: Causal pathogen </li></ul><ul><li>Reservoir: Pathogen’s environment </li></ul><ul><li>Portal of exit </li></ul><ul><li>Mode of transmission </li></ul><ul><ul><li>Direct </li></ul></ul><ul><ul><li>Indirect </li></ul></ul><ul><li>Port of entry </li></ul><ul><li>New host </li></ul>
    6. 6. Stages of Infection <ul><li>Incubation stage </li></ul><ul><li>Prodromal stae </li></ul><ul><li>Clinical stage </li></ul><ul><li>Decline stage </li></ul><ul><li>Recovery stage </li></ul>
    7. 7. Body Defenses <ul><li>Mechanical </li></ul><ul><li>Cellular-chemical (“immune system”) </li></ul>
    8. 8. Divisions of the Immune System <ul><li>Cell-mediated immunity </li></ul><ul><ul><li>T cell-mediated </li></ul></ul><ul><li>Humoral immunity </li></ul><ul><ul><li>B cell-mediated </li></ul></ul><ul><li>Acquired immunity </li></ul><ul><ul><li>Naturally acquired immunity (NAI) </li></ul></ul><ul><ul><ul><li>Response to naturally occurring pathogen </li></ul></ul></ul><ul><ul><li>Artificially acquired immunity (AAI) </li></ul></ul><ul><ul><ul><li>Response to immunization </li></ul></ul></ul><ul><ul><li>Passively acquired immunity (PAI) </li></ul></ul><ul><ul><ul><li>From extrinsic antibodies </li></ul></ul></ul>
    9. 9. Immune Response
    10. 10. Immunizations <ul><li>Vaccinations should be given against the following infectious conditions: </li></ul><ul><ul><li>Diphtheria </li></ul></ul><ul><ul><li>Whooping cough </li></ul></ul><ul><ul><li>Hepatitis B </li></ul></ul><ul><ul><li>Hepatitis A </li></ul></ul><ul><ul><li>Haemophilus influenza type B </li></ul></ul><ul><ul><li>Tetanus </li></ul></ul><ul><ul><li>Rubella (German measles) </li></ul></ul><ul><ul><li>Measles (red measles) </li></ul></ul><ul><ul><li>Polio </li></ul></ul><ul><ul><li>Mumps </li></ul></ul><ul><ul><li>Chicken pox </li></ul></ul><ul><ul><li>Meningococcus </li></ul></ul><ul><ul><li>Pneumococcal infection </li></ul></ul><ul><ul><li>Childhood diarrhea </li></ul></ul><ul><ul><li>Human papillomavirus infections </li></ul></ul><ul><ul><li>Shingles </li></ul></ul>
    11. 11. Nosocomial Infections <ul><li>Infections spread in conjunction with the delivery of health care services </li></ul><ul><li>Over 100,000 deaths/year are attributed to these infections </li></ul>
    12. 12. The Common Cold (Acute Rhinitis) <ul><li>Acute upper-respiratory-tract infection </li></ul><ul><li>Caused by different viruses </li></ul><ul><li>Common symptoms; usually last several days </li></ul><ul><li>Treatments manage symptoms but do not cure the infection </li></ul><ul><li>More severe symptoms may indicate flu, pneumonia, or another infection </li></ul><ul><li>Prevention: Handwashing </li></ul>
    13. 13. Influenza <ul><li>Acute viral infection </li></ul><ul><li>More serious than common cold </li></ul><ul><ul><li>Especially dangerous for young children, pregnant women, older people </li></ul></ul><ul><li>Annual vaccination </li></ul><ul><li>Risk of spread of highly virulent avian influenza </li></ul>
    14. 14. Tuberculosis <ul><li>Bacterial infection of the lungs </li></ul><ul><li>Symptoms </li></ul><ul><ul><li>Chronic coughing </li></ul></ul><ul><ul><li>Weight loss </li></ul></ul><ul><li>Spread through coughing </li></ul><ul><li>Requires long-term treatment with antibiotics </li></ul><ul><li>Antibiotic-resistant strains are a concern </li></ul>
    15. 15. Pneumonia <ul><li>Infectious respiratory conditions </li></ul><ul><ul><li>May be bacterial, viral, fungal, rickettsial, mycoplasmal, or parasitic </li></ul></ul><ul><ul><li>Bacterial is most common, especially among people with other illnesses </li></ul></ul><ul><li>Vaccination for pneumococcal pneumonia for children and older adults </li></ul>
    16. 16. Other Infectious Diseases <ul><li>Mononucleosis (“mono”) </li></ul><ul><ul><li>Viral infection characterized by weakness, fatigue, swollen glands, sore throat, and low-grade fever </li></ul></ul><ul><li>Chronic fatigue syndrome </li></ul><ul><ul><li>Characterized by severe exhaustion, fatigue, aches, and depression </li></ul></ul><ul><li>Bacterial meningitis </li></ul><ul><ul><li>Infection of the thin membranous coverings of the brain </li></ul></ul><ul><ul><li>Higher risk among college students living in residence halls </li></ul></ul><ul><ul><li>Immunization available </li></ul></ul>
    17. 17. Other Infectious Diseases <ul><li>Lyme disease </li></ul><ul><ul><li>Bacterial infection transmitted by deer ticks </li></ul></ul><ul><li>Hantavirus pulmonary syndrome </li></ul><ul><ul><li>Extreme pulmonary distress </li></ul></ul><ul><ul><li>Transmitted from deer mice to humans </li></ul></ul><ul><li>West Nile virus </li></ul><ul><ul><li>Transmitted by mosquitoes </li></ul></ul><ul><ul><li>Flulike symptoms; may involve encephalitis </li></ul></ul><ul><li>Tampon-related toxic shock syndrome </li></ul>
    18. 18. Viral Hepatitis <ul><li>Inflammation of the liver </li></ul><ul><li>Symptoms </li></ul><ul><ul><li>Fever, nausea, abdominal pain, jaundice </li></ul></ul><ul><li>Types: </li></ul><ul><ul><li>Type A – associated with fecal contamination of food due to poor food handling </li></ul></ul><ul><ul><li>Type B – sexual contact, IV drug use, tattooing, piercing </li></ul></ul><ul><ul><li>Type C – similar to type B </li></ul></ul><ul><ul><li>Type D – difficult to treat; found in type B sufferers; contact with bodily fluids </li></ul></ul><ul><ul><li>Type E – water contamination (rare) </li></ul></ul><ul><li>Vaccination available for types A and B </li></ul>
    19. 19. HIV/AIDS <ul><li>Human immunodeficiency virus (HIV) </li></ul><ul><li>Acquired immunodeficiency syndrome (AIDS) </li></ul><ul><li>HIV attacks the helper T cells of the immune system </li></ul><ul><li>Spread </li></ul><ul><ul><li>Direct contact involving the exchange of body fluids (blood, semen, vaginal secretions) </li></ul></ul><ul><ul><li>Sharing of hypodermic needles </li></ul></ul><ul><ul><li>Infected blood products </li></ul></ul><ul><ul><li>Perinatal transmission (mother to fetus or newborn) </li></ul></ul>
    20. 20. HIV/AIDS <ul><li>HIV cannot be transmitted by sweat, saliva, or tears, even though trace amounts of HIV are observed </li></ul><ul><li>Women are at higher risk than men of contracting HIV from an infected partner </li></ul><ul><ul><li>HIV concentration is higher in semen compared with vaginal secretions </li></ul></ul>
    21. 21. Diagnosis of HIV Infection <ul><li>Enzyme linked immunosorbent assay (ELISA) </li></ul><ul><li>Western BLOT test </li></ul>
    22. 22. The Course of HIV Infection <ul><li>Newly infected may experience flu-like symptoms within 1 or 2 months of exposure </li></ul><ul><ul><li>Symptoms disappear quickly </li></ul></ul><ul><li>Immune system is unable to clear HIV from the body </li></ul><ul><li>Asymptomatic stage </li></ul><ul><ul><li>Could last for months to over 12 years </li></ul></ul><ul><ul><li>Length depends on overall health, age, gender, strain of infection </li></ul></ul><ul><li>Immune system worsens </li></ul><ul><ul><li>Level of CD4 helper T cells </li></ul></ul><ul><ul><li>Opportunistic infections </li></ul></ul>
    23. 23. Treatment of HIV Infection <ul><li>No cure at this time </li></ul><ul><li>HAART (highly active antiretroviral therapy) can significantly reduce viral load </li></ul><ul><li>Antiviral drugs, usually taken in combination </li></ul><ul><ul><li>Nucleoside/nucleotide reverse transcriptase inhibitors </li></ul></ul><ul><ul><li>Non-nucleoside reverse transcriptase inhibitors </li></ul></ul><ul><ul><li>Protease inhibitors </li></ul></ul><ul><ul><li>Fusion inhibitors </li></ul></ul><ul><ul><li>CCR5 antagonists </li></ul></ul><ul><li>Drug resistance </li></ul>
    24. 24. HIV/AIDS on the World Stage
    25. 25. Prevention of HIV Infection <ul><li>Learn the sexual history and HIV status of your partner </li></ul><ul><li>Limit the number of sexual partners </li></ul><ul><li>Use condoms correctly and consistently </li></ul><ul><li>Avoid contact with body fluids </li></ul><ul><li>Curtail the use of drugs </li></ul><ul><li>Never share hypodermic needles </li></ul><ul><li>Refrain from sex with known injectable drug users and other high-risk partners </li></ul><ul><li>Get regular tests for STDs </li></ul><ul><li>Do not engage in unprotected anal intercourse </li></ul>
    26. 26. Number of Lifetime Sexual Partners among Adults (Age 20-59)
    27. 27. Sexually Transmitted Diseases <ul><li>HIV/AIDS </li></ul><ul><li>Chlamydia </li></ul><ul><li>Human papillomavirus </li></ul><ul><li>Gonorrhea </li></ul><ul><li>Herpes simplex </li></ul><ul><li>Syphilis </li></ul><ul><li>Pubic lice </li></ul><ul><li>Vaginal infections </li></ul><ul><li>Cystitis and urethritis </li></ul>
    28. 28. Prevalent STDs <ul><li>Chlamydia </li></ul><ul><ul><li>Bacterium Chlamydia trachomatis </li></ul></ul><ul><ul><li>Urethritis </li></ul></ul><ul><ul><li>Left untreated, can cause pelvic inflammatory disease and infertility in women </li></ul></ul><ul><li>Human papillomavirus (HPV) </li></ul><ul><ul><li>Often asymptomatic </li></ul></ul><ul><ul><li>Can cause genital warts, cervical cancer </li></ul></ul><ul><ul><li>Vaccine; not curable </li></ul></ul>
    29. 29. Prevalent STDs <ul><li>Gonorrhea </li></ul><ul><ul><li>Bacterium N. gonorrhoea </li></ul></ul><ul><ul><li>Symptoms: painful urination, discharge </li></ul></ul><ul><ul><li>Treated with antibiotics; some strains are drug-resistant </li></ul></ul><ul><li>Herpes simplex </li></ul><ul><ul><li>HSV 1 (oral) and HSV II (genital) </li></ul></ul><ul><ul><li>Painful blisterlike sores </li></ul></ul><ul><ul><li>Pattern of recurrences </li></ul></ul><ul><ul><li>Persistent; treated with antiviral drugs </li></ul></ul>
    30. 30. Prevalent STDs <ul><li>Syphilis </li></ul><ul><ul><li>Bacterium Treponema pallidum </li></ul></ul><ul><ul><li>Three stages: </li></ul></ul><ul><ul><ul><li>Primary stage: Painless sore called a chancre </li></ul></ul></ul><ul><ul><ul><li>Secondary stage: General symptoms of illness </li></ul></ul></ul><ul><ul><ul><li>Late stage: May recur many years after initial contact; profound damage to many body systems </li></ul></ul></ul><ul><ul><li>Left untreated, can cause death </li></ul></ul><ul><li>Pubic lice (“crabs”) </li></ul><ul><ul><li>Cause intense itching </li></ul></ul><ul><ul><li>Treated with prescription and OTC drugs </li></ul></ul>
    31. 31. Prevalent STDs <ul><li>Vaginal infections </li></ul><ul><ul><li>Yeast infection ( Candida albicans ) </li></ul></ul><ul><ul><li>Bacterial vaginosis (BV) </li></ul></ul><ul><ul><li>Protozoa Trichomonas vaginalis </li></ul></ul><ul><li>Cystitis (infection of bladder) </li></ul><ul><li>Urethritis (infection of urethra) </li></ul><ul><ul><li>Caused by various pathogens </li></ul></ul><ul><ul><li>Treated with antibiotics </li></ul></ul>
    32. 32. Chapter Eleven: Preventing Infectious Diseases
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