HEA 201 Chapter 8, Fall 2007

Infectious Diseases 1. Agents of infection  Viruses - Can modify their shape to escape recognition by IS (flu, HIV) - Can remain in the body & flare up periodically (herpes) - Are not affected by antibiotics  Bacteria - Some are friendly (e.g. intestinal  produce vitamins) - Can be killed by antibiotics - Inadequate AB treatment  selection of AB-resistant bacteria  Parasites, e.g. worms (Taenia): killed by anti-parasitic drugs  Fungi: killed by anti-fungal drugs 2. Vectors  Animals/insects: pets, mosquitoes, ticks…  Person-to-person: coughing/sneezing, kissing/touching, sharing dishes  Food: contaminated food (under/inadequately cooked, improperly canned)  Water: contaminated water (e.g. polluted by sewage) 3. Process of Infection  Incubation period: time between infection & appearance of 1st symptoms  Illness period: duration of symptoms, most contagious  Recovery: disappearance of symptoms: body beats germs and heals itself 4. Immunity  External barriers - Skin (rigid) & its secretions (sweat, sebum) - Mucous membranes (fragile), their secretions (saliva, mucus, acid) & cilia  Cells and organs - Cells: white blood cells - Organs: include bone marrow, spleen, lymph nodes  Non-specific response (inflammation) - Immediate - Involves macrophages same cells for all pathogens eat up intruders & destroy them - Eliminate or keep germs under control until specific response is made  Specific immune response - Requires several days - Involves B and T lymphocytes B lymphocytes: produce specific antibodies (neutralize germs) T lymphocytes CD8 T cells (killers): can kill infected cells CD4 T cells (helpers): activate other immune cells - Is specific: different T and B cells for different pathogens - Improves with successive encounters with germ (memory) 5. Ways to boost immunity  Balanced diet - Many nutrients necessary for immunity (vitamins, minerals, proteins) - Avoid fatty foods: low-fat diets increase immune cells activity  Sleep  Exercise  No smoking  Limiting alcohol intake  Managing stress 6. High-risk populations  Infants  Elderly  Immuno-deficient people (e.g. AIDS patients)  Smokers & people with respiratory problems  People in close contact with someone sick  Residents or workers in poorly ventilated buildings  Pregnant and lactating women: risk for baby 7. Examples of infectious diseases 1. Cold (virus)  Many different viruses  Spread by cough, sneeze & touch  Symptoms: stuffy nose, headache, runny eyes, sore throat, cough/sneezing  Treatment - Time, rest & warmth (allow the immune system to eliminate the virus) - Drinking plenty of fluids (to replace lost fluids, liquefy mucus) - Medications to relieve symptoms 2. Influenza (virus)  Spread by cough, sneeze, touch & even normal conversation  Symptoms - More severe than cold & last longer - Aches, fever, exhaustion, cough, complications (pneumonia, bronchitis)  Treatment - Same as cold: time, rest, fluids… - Medications to relieve symptoms, sometimes anti-viral drugs  Vaccine available, new one needed every year (virus is constantly changing) 3. Mononucleosis = Kissing disease (virus)  Spread by kissing & any form of close contact  Symptoms include: sore throat, fever, prolonged weakness, skin rash…  Treatment: none specific: time, rest … 4. Hepatitis (virus, including A & B)  Inflammation of the liver B: can cause cirrhosis and cancer  potentially fatal infected people might carry the virus for years, even life A: less serious disease  Spreading B: blood (needles, transfusions) and sexual secretions A: poor sanitation: fecal contamination of food or water  Symptoms include: jaundice, fever, vomiting/diarrhea…  Treatment - Time, rest … - High-protein diet - Avoidance of alcohol - Medication: including antiviral drugs  Vaccine available 5. Vaginal infections (fungi, bacteria)  Overgrowth of microorganisms normally present in vagina, but held in check  Unbalance can have several causes: stress, malnutrition, antibiotics…  Symptoms: burning, itching & whitish, smelly discharge  Treatment: specific medications (pills or gels) 6. Urinary tract infections (mostly bacteria)  More frequent in women  Favoring factors include - Pregnancy (irritation/swelling of urethra/bladder) - Irritants (bubble bath) - Urinary stones - Prostate enlargement - Sexual intercourse  Symptoms include: burning, painful urination, blood in urine, fever  Treatment: antibiotics  Prevention - Wiping from front to back (prevents stool germs from reaching vagina) - Drinking plenty of water - Not using chemical irritants (bubble bath…) - Urinating immediately after intercourse 7. STDs  Sexually Transmitted (“venereal”) Diseases - Strike both sexes at all ages - One person can have/catch more than 1 STD at a time - May not cause any symptom => people unaware they have them - Can be fatal  STDs can - Cause infertility, pregnancy & fetal problems - Spread to other organs through blood and cause damage/death  Prevention - Abstinence is the only guarantee of sexual safety - For sexually active people mutually faithful relationship with a healthy partner (safest option) condoms and spermicides ( risk, although protection not guaranteed)  Examples a) Chlamydial infection and Gonorrhea (bacteria) - Symptoms (more severe for gonorrhea than for chlamydial infection) sometimes none (especially in women) or burning during urination, discharge - Treatment: antibiotics b) Herpes (virus) - Symptoms blisters on skin or mucous membranes sometimes none (individuals without symptoms still shed the virus) - Course virus never goes away, remains for life in nerves near the spinal cord sores return generally after body change/stress (periods, heat, stress) attacks generally  in frequency & severity over time - Transmission by contact with mucous membranes or skin (esp. sores) - Treatment antiviral drugs relief of discomfort (cold compresses, anesthetic cream) c) Syphilis (bacteria) - Includes many stages (may extend over 20 years) - Symptoms Outer lesions (contagious) first: chancre: lesion at the point of bacteria entry later: possible recurrent large lesions around mouth/genitals Organ damage progressive heart & brain damage can lead to disability or death - Transmission through contact with lesions (intercourse, kissing…)  as disease progresses, no transmission after 2-4 years - Treatment: antibiotics d) Pubic lice and scabies - Generally found in pubic hair, can migrate to other hairy body areas - Symptoms: irritation, itching  scratching  sores - Transmission: by contact - Treatment: repeated shampoo treatment + washing clothes & bedding e) HIV (virus) - Fragile virus: only survives in blood, sexual secretions & milk - Invades & destroys CD4 T lymphocytes (helpers) Means of transmission - Blood & products: transfusion, organ transplants, needles, razors - Sexual secretions (vaginal secretions & semen): intercourse (higher risk from ♂ to ♀) - From mother to baby: during pregnancy, delivery or breastfeeding Safe practices/body fluids: touching/kissing, saliva, tears… Course of the disease/symptoms - Primary infection: no symptoms or flu-like symptoms for few days - Asymptomatic phase: no signs, lasts many years, CD4  progressively - AIDS: CD4  below a certain level  opportunistic diseases develop: cancer dangerous infections generally death within 2 years Routine test: detection of antibodies anti-HIV (feasible after few weeks: time to make antibodies) Treatment - Treatment of opportunistic infections - Antiviral drugs Vaccine: still under trial 8. Vaccination  Principle - Based on specific immune response characteristics: specificity, memory - Vaccine = dead/inactivated germ (or part of it)  does not cause disease - Vaccination induces a 1st specific immune response - Encounter with real germ  stronger & faster response  no/mild disease - Specific => different vaccines for different germs  Important vaccines for college students - Tetanus: booster every 10 years - Mumps (وبأ بعك), Measles (ةبصح), Rubella (ةبصح ةيناملأ), Varicella (chick. pox, يردج): if one hasn’t been properly vaccinated & did not have the disease - Hepatitis B