Lecture 3 (1) PDF: Epidemiology, Infectious Diseases, and AIDS

Umm Al-Qura University Faculty of Public Health & Health Informatics Health Promotion & Education Department Dr\ Mohamed Osama Nour Associate Professor Health Promotion & Education Department Faculty of Public Health & Health Informatics Umm Al-Qura University Epidemiological Aspects of Commun...

Umm Al-Qura University Faculty of Public Health & Health Informatics Health Promotion & Education Department Dr\ Mohamed Osama Nour Associate Professor Health Promotion & Education Department Faculty of Public Health & Health Informatics Umm Al-Qura University Epidemiological Aspects of Communicable Diseases • Definition: of infection. • Occurrence: 1 Geography, 2 Seasonal variation, 3 Socioeconomic status. • Pre-pathogenic period: 1 Infectious Agent, 2 Source of Infection, 3 Portal of Exit, 4 Mode of Transmission, 5 Portal of Entry, 6 Host Factors: (1 Age, 2 Sex, 3 Habits, 4 Social level, 5 Nutritional status, 6 Immunity). • Pathogenic period: 1 Pathogenesis, 2 Incubation period, 3 Clinical picture, 4 Diagnosis, 5 Period of communicability, 6 Sequel of the disease (1 Complications, 2 Fatality rate, 3 Carrier state). • Prevention (2): General prevention, Specific prevention (Vaccine). • Control (4C): Case, Contact, Carriers, Community. Blood-borne Disease Transmission • Direct blood contact from injured skin or a mucous membrane. • Drug abuse (contaminated syringe). • Sexual contact. • Needle sticks. • Blood transfusion. • Blood product transfusion. • Renal dialysis. • Cuts, scrapes and breaks in skin. • Certain behaviors (shared razors, tattooing, ear piercing, acupuncture). Blood-borne Pathogens • Including viruses, bacteria and other microorganisms causing blood-borne diseases as: Human Immunodeficiency Virus (HIV), Hepatitis B Virus (HBV), Hepatitis C Virus (HCV), Malaria, Syphilis, Brucellosis, Leptospirosis, Mosquitotransmitted diseases, Relapsing fever, Viral hemorrhagic fever. • Blood-borne Pathogens are carried in blood or transmitted by Other Potentially Infectious Materials (body fluids) as: • Plasma and other blood products. • Amniotic fluid, Peritoneal fluid, Cerebrospinal fluid (CSF), Pericardial fluid, Pleural fluid, Synovial fluid, Saliva in dental procedures. • Semen, Vaginal secretions, Breast milk. • Unfixed tissue or organs from a human (living or dead). Blood-borne Pathogens They enter the body through: • Cuts, scrapes and breaks in skin. • Needle sticks. • Mucous Membranes. • Splashes to eyes, nose and mouth. • Lifestyle issues (Intravenous drug use). Acquired Immunodeficiency Syndrome (AIDS) • Definition: • AIDS is a disease that slowly destroys the body's immune system. • It is the advanced stage of HIV infection. • AIDS is a syndrome characterized by presence of opportunistic infections and certain cancers (Kaposi Sarcoma) in a patient without a known cause to explain the immune deficiency. • CDC defined AIDS as proven HIV infection + T-Lymphocytes < 200 /micro liter. • Risk factors (groups): homosexual, heterosexual, multiple sexual partners, having unprotected sex, I.V. drug abuser, having another STIs as Syphilis, Herpes and Gonorrhea, children to infected cases, persons receiving blood and blood products transfusions, hemodialysis, etc. • Occurrence: worldwide (Sub-Saharan Africa is the most affected region). Acquired Immunodeficiency Syndrome (AIDS) • Infectious agent: Human Immunodeficiency Virus (HIV); RNA virus, Retro virus. • HIV targets body immune system, kills T4-helper cells (T-lymphocytes), and weakens defense mechanisms against infections and some types of cancer. • Source of infection: human (cases or carriers). • Portal of exit: body fluids: blood, semen, vaginal secretion, saliva, tear, breast milk. • Mode of transmission: mainly through blood, semen, vaginal secretion. ✓Parenteral: blood transfusion, renal dialysis, shared needles&instruments, shared razors, IV drug abusers, tattooing, ear piercing, acupuncture, and transplacental. ✓Non-parenteral: sexual route, vertical transmission (from mothers to fetus), breast feeding, and saliva. ✓No spread by sneezing, coughing, shaking, insect bite, food or water, sharing drinks, eating utensils ....etc. Acquired Immunodeficiency Syndrome (AIDS) • Portal of entry: blood, skin, mucous membrane, transplacental, vertical transmission (during passage in the birth canal), and lactation. • Incubation period: ranges from 6 months – 6 years. • Symptoms: ✓ Acute stage: fever, headache, malaise, sore throat, rash, nausea, vomiting, diarrhea, lymphadenopathy, and myalgia. ✓ AIDS related complex: chronic fever, oral infection, weight loss, chronic diarrhea, generalized lymphadenopathy, hepatosplenomegaly. ✓ Clinical AIDS: 1Opportunistic infection (toxoplasmosis, herpes simplex, herpes zoster, CMV, TB, E. coli, candidiasis, staph, strept, etc.), 2Opportunistic malignancies (Kaposi’s sarcoma, lymphoma), and 3Neurological diseases (meningitis, encephalitis, peripheral neuritis). Acquired Immunodeficiency Syndrome (AIDS) • Period of communicability: person is infectious from onset of infection throughout life. • Diagnosis: ● Lab: leucopenia, lymphopenia, marked ↓ of T-4 helper (T-lymphocyte). ● Screening test: ELISA test. ● Confirmatory test: Western blot test. • Complication: destruction of the cell mediated immunity. • Fatality rate: high. • Carrier state: usually developed. • Prevention: vaccination under trials, avoid risky behaviors, avoid unprotected sex, no breastfeeding of infected mother, screening of blood, proper infection control practices, avoid professional exposure, sterilization of medical instruments, etc. • All HIV antibody positive individuals should not receive live vaccine. • Use of Antiviral (Anti retroviral) drugs to control the disease. Viral Hepatitis B (Hepatitis B Virus) Discussed in Lecture_2 Viral Hepatitis C (Hepatitis C Virus) Discussed in Lecture_2