1. Chapter 17
Infectious Diseases and Sexually Transmitted Infections: Risks and Responsibilities

2. Objectives
Explain how your immune system works to protect you, and what you can do to boost its effectiveness.
Discuss actions that you can take to protect yourself from the most common infectious diseases today.
Describe the most common pathogens infecting humans today and the typical diseases caused by each.

3. Objectives (cont.)
Explain the major emerging and resurgent diseases affecting humans nationally and internationally; discuss why they are increasing in incidence and what actions are being taken to reduce risks.
Discuss the various sexually transmitted infections, their means of transmission, and actions that can be taken to prevent their spread.
Discuss human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS), trends in infection and treatment, and their impact on special populations. 3

4. The Process of Infection
Pathogens are disease-causing agents. There are six major types.
Bacteria
Viruses
Protozoans
Parasitic worms
Fungi
Prions
Pathogens must gain entry to the body and begin to grow there before they pose a threat. The skin and internal barriers block most pathogens.

5. The Process of Infection (cont.)
Multifactorial diseases are caused by interactions of several factors.
The host must be susceptible.
Immune system is compromised.
Transmitting agent is present.
Environment must be hospitable to the pathogen.

6. The Body’s Defenses against Disease-Causing Pathogens
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7. Assessing Your Disease Risk
Risk factors you cannot control
Heredity
Aging
Environmental conditions
Organism virulence and resistance
Heredity
Perhaps the single greatest factor influencing disease risk is genetics. Certainly this is true for noninfectious conditions: heart disease, high cholesterol, diabetes. Some believe that we may even inherit immune system quality, meaning that some people are naturally more resistant to disease and infection.
Aging
After age 40, we become more vulnerable to most chronic diseases. As we age, for a variety of reasons, our immune systems appear to be less efficient in handling invading organisms, increasing risks of pathogen entry, and development of disease.
Environmental conditions
Unsanitary conditions and the presence of drugs, chemicals, and hazardous pollutants and wastes in food and water probably have a great effect on our immune systems..
Organism virulence and resistance
Some organisms, such as the foodborne organism that causes botulism (a severe type of food poisoning), are particularly virulent, and even tiny amounts may make the most hardy of us ill.

8. Assessing Your Disease Risk (cont.)
Risk factors you can control
Personal habits
Dosage, virulence, and where agent enters the body
Age at time of infection
Preexisting level of immunity
Health and vigor of immune system
Genetic factors controlling immune response
Nutritional status of host
Comorbidities
Environmental surroundings
Psychological factors
The good news is that we all have some degree of personal control over many risk factors for disease.

9. Routes of Transmission
Direct or indirect contact
Autoinoculation
Airborne contact
Foodborne infection
Animal-borne infection
Interspecies transmission
Waterborne
Insectborne
Perinatally
Try not to give too many examples if you are going to use the activity that follows.
Transmission by direct contact includes between infected persons, such as during sexual relations, kissing, or touching, or by indirect contact, such as by touching an object the infected person has had contact with.
Autoinoculation occurs when you transmit a pathogen from one part of your body to another, via your hands.
Airborne pathogens are those that you inhale from the air.
Foodborne infection occurs if you eat something contaminated by microorganisms.
Pets and other animals are sources of animal-borne pathogens.
Waterborne diseases are transmitted directly from drinking water and indirectly from foods washed or sprayed with contaminated water.
Insectborne diseases arise from pathogens transmitted by mosquitoes, ticks, and other hosts via sucking or biting.
Mothers may transmit diseases perinatally to an infant during birth as the baby passes through the vagina, or they can transmit disease through breast milk.

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11. Activity Break: How Does It Transfer?
In groups of three to five, come up with one example per group of an infection and how it transfers.
Example: Mononucleosis is transferred directly.
No repeats of examples are allowed.
When your group has an example, send one person from the group to the front.
If you have a repeat example, you must return back to your group to think of another example.
Try for 10 groups, even if there are only two students in each group.

12. Your Body’s Response Skin is a physical barrier against pathogens.
Enzymes are complex proteins in sweat that create an inhospitable environment for pathogens.
Mucous membranes trap organisms.
Cilia are hair-like protrusions that sweep trapped organisms toward body openings so they can be expelled.

13. The Immune System
Immunity is the condition of being able to resist a particular disease by counteracting the substance that produces the disease.
Antigen is any substance capable of triggering an immune response.
Antibodies are produced by the body and are matched to specific antigens.
Cell-mediated immunity refers to a grouping of lymphocytes that can attack and destroy a foreign invader.
Other parts of the immune system include the spleen, which makes antibodies and red blood cells and gets rid of old red blood cells; the thymus gland, which manufactures certain white blood cells that chemically recognize specific foreign substances; and the lymph nodes, which are small tissue masses that store protective body cells. Some lymph nodes filter bacteria from lymph vessels as the lymph vessels transport white blood cells

14. The Immune Response
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15. Body Response Fever is a rise in temperature above 98.6°F.
Caused by toxins secreted by pathogens that interfere with the control of body temperature
Pain is an early sign of injury.
Referred pain is pain that is present in one location of the body although the source is at another location.

16. Vaccines
Consist of a killed or attenuated version of a disease-causing microorganism, or an antigen that is similar to but less dangerous than the disease antigen
Acquired immunity
Natural immunity
Active immunity
Passive immunity

17. Recommended Adult Immunization Schedule, by Vaccine and Age Group, 2007
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19. Examples of Four Major Types of Pathogens
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20. Bacteria Single-celled organisms
Three major types: cocci, bacilli, and spirilla
Bacterial toxins cause disease.
Antibiotics
Resistance
Bacteria are simple, one-celled organisms. They are the most abundant pathogens. Good as well as bad types of bacteria exist. Most bacteria can be easily destroyed by antibodies in the human immune system. Bacteria cause infection by releasing cell-digesting enzymes or pathogenic toxins, which cause many deadly diseases.

21. Prevention of Drug-Resistant Pathogens
If someone you know has MRSA, take precautions.
Wash your hands and shower with soap and hot water.
Keep personal items personal.
If you suspect infection
use towels only once.
tell close friends and health care providers.
Keep wounds clean, sterile, and covered.
At the gym, wipe down surfaces you touch with antibiotic washes.

22. ABC News Video: Report on the MRSA Superbug
| Attack of the Superbug: Report on the MRSA Superbug
Discussion Questions
Had you heard of MRSA before watching this clip? What did you know about it?
How do you recognize a MRSA infection?
MRSA is becoming even more resistant to medication. What do you think should be the next step in addressing the overall problem?

23. Other Pathogens
Fungi are hundreds of species of uni- and multicellular plant organisms that cause diseases such as candidiasis, athlete’s foot, and ringworm.
Protozoans are single-celled organisms that cause diseases such as trichomoniasis and giardiasis.
Parasitic worms are the largest of the pathogens; they include pin worms and tape worms.
Prions are self-replicating, protein-based agents.
Fungi are single-celled or multicelled organisms, depending on their specific type. They reproduce by generating spores, which release parasitic enzymes that attack hair-covered areas of the body. These are treated with antifungal drugs.
Protozoans are single-celled organisms that release enzymes that cause cells to decompose and malfunction. Thanks to public health precautions, they’re not a major threat in the United States, but are in nonindustrialized nations. Treatment for protozoan-caused diseases include medicating symptoms, blood and fluid replacement, and drugs designed for specific protozoa.
Parasitic worms get in certain tissues, stealing the nutrients that your tissue should get. The tapeworm is a parasitic worm contracted by eating undercooked beef, pork, or fish that contain tapeworm eggs. Worms are treated with appropriate antibiotics.
Prions are recently discovered pathogens that can affect humans and other animals. A prion is believed to be the underlying cause of spongiform diseases such as Creutzfeldt-Jakob disease, or “mad cow disease.”

24. Viruses
The smallest of the pathogens, viruses have a protein structure that contains RNA or DNA that requires a cell host.
Common cold
Influenza
Infectious mononucleosis
Hepatitis A, B, or C
Mumps
Chicken pox
Measles
Rabies
Viruses are the smallest pathogens, yet the most difficult to get rid of. They are composed of either DNA or RNA (but never both) in a protein coat. Since they can’t reproduce on their own within a host, they need other cells in order to multiply. They are treated with antiviral drugs that work only as quickly as the virus itself; therefore, the earlier a viral infection is treated, the more effective the antiviral drug.

25. Colds and Influenza Colds are endemic, that is, always present.
You can “catch” a cold from the airborne droplets of another’s sneeze or contact.
You cannot catch a cold from a chill.
Five to 20 percent of Americans get the flu each year.
Three major varieties exist of the flu virus, each having many different strains.
Those who should be vaccinated include seniors, pregnant women, those with heart and lung diseases, and those with certain other diseases.

26. Is It a Cold or the Flu?
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27. Streptococcal Infections and Meningitis
Group A streptococci (GAS), or “strep throat”
Necrotizing fasciitis, or “flesh-eating strep”
Group B streptococci can cause illness in newborns and immunocompromised adults
Meningitis
An infection of membranes that surround the brain and spinal cord
Staphylococci are bacteria that usually can be found on our skin or in our body. When they come into contact with a cut, sore, or bruise, they may cause boils, styes, etc.
Staph infections
Bacterial meningitis is a serious, life-threatening, invasive meningococcal disease of membranes surrounding the brain and spinal cord. It can result in hearing loss, kidney failure, and permanent brain damage. Of the 2,400 to 3,000 cases each year, 10 percent are fatal. Vaccines are available for some types of meningitis.

28. Necrotizing Fasciitis
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29. Emerging and Resurgent Diseases
Factors include overpopulation, inadequate health care, drug resistance, and increased international travel.
Mad cow disease
Dengue and dengue hemorrhagic fever
West Nile virus
Ebola hemorrhagic fever
Severe acute respiratory syndrome (SARS)

30. Emerging and Resurgent Diseases (cont.)
Escherichia coli 0157:H7
Cholera
Hantavirus
Listeriosis
Malaria 30

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32. Sexually Transmitted Infections
Each year, the United States sees 15.3 million new cases.
More than 65 million people live with an incurable STI.
Two-thirds of all STIs occur in people 25 years of age or younger.
One in four new STIs occurs in teenagers.
STIs used to be known as venereal disease.
The odds of acquiring an STI during your lifetime are one in four.
It is possible to catch more than one at a time.
Highest rates occur in those 16 to 24 years old.

33. Modes of Transmission Sexual intercourse Oral–genital contact
Hand–genital contact
Anal intercourse

34. Signs or Symptoms of Sexually Transmitted Infections
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35. Chlamydia Often presents no symptoms Affects mostly women
If left untreated, can affect
Men: prostate gland, seminal vesicles
Women: cervix, fallopian tubes
Both: arthritis-like symptoms, damage to heart and blood vessels
Easily treated with antibiotics
Called the “silent disease,” chlamydia is the most widespread bacterial STI.
One in 25 adults is infected.
Infected men may have abnormal discharge or burning sensation when urinating.
When caught early, chlamydia is easily treatable.

36. Gonorrhea More than 700,000 cases per year
Caused by bacterial pathogen Neisseria gonorrhoeae
Primarily infects the linings of the urethra, genital tract, pharynx, and rectum
At highest risk are males age 20 to 24
Treatment with antibiotics
If left untreated, can cause sterility
Also known as the “clap,” males know they have it by the thick, yellow to white pus and burning urination that hurts too much not to see a doctor. Of females, eight out of ten are asymptomatic, but some may experience discharge or a burning sensation.

37. Gonorrhea (cont.)
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38. Pelvic Inflammatory Disease
Pelvic inflammatory disease (PID) describes numerous infections of the uterus, fallopian tubes, and ovaries.
Often results from an untreated STI
Symptoms include abdominal pain, fever, and unusual vaginal discharge.
If left untreated, increases risk for infertility, chronic pelvic pain, and recurrent upper genital infections
PID often occurs as a complication of an STI, usually chlamydia or gonorrhea.
Treatment is with antibiotics.

39. Syphilis Caused by a bacterial organism Progresses in stages
In the primary stage, a chancre develops that disappears in 3 to 6 weeks.
In the secondary stage, 1 to 12 months after the chancre disappears, a rash or white patches on the skin appear and last a few weeks or months.
In the latent stage of infectious lesions, infection can be passed to a fetus (congenital syphilis).
In the late stage, heart damage, central nervous system damage, blindness, paralysis, and dementia occur.
Treatment is with antibiotics.
Syphilis, caused by Treponema pallidum bacterium, is one of the oldest STIs on record. It enters the body through any tiny break in the skin and burrows into the bloodstream.
Treatment is with penicillin or doxycycline.

40. Syphilis: Penis
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41. Syphilis: Hands
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42. Syphilis: Arm
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43. Activity Break: You Be the Judge
Fred and Sally have had a great marriage for 5 years. On a business trip to Seattle, Fred got drunk and ended up having sexual intercourse with a local woman. Fred felt bad afterward but soon forgot about it. A few weeks later, he noticed an open sore on his penis. His doctor said it was syphilis and treated it with penicillin. Fred knew that Sally was infected. He did not want to tell her he had infected her, yet he could not remain silent. Fred and Sally were planning on having their second child in about a year.

44. Activity Break: You Be the Judge (cont.)
What alternatives are open to Fred?
How might Sally react when she finds out?
Is a casual, drunken act in Seattle sufficient to destroy a marriage and a family? 
What would you do if you were Fred?
If you were Sally, how would you react to Fred’s disclosure? 44

45. Herpes
Caused by virus
Genital herpes is caused by herpes simplex virus (HSV).
Two types of HSV
HSV-1
HSV-2
No cure for herpes, although some drugs can ease symptoms

46. Herpes: Genital
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47. Herpes: Mouth
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48. Genital Warts Genital warts are caused by human papillomavirus (HPV).
Affects 6.2 million Americans per year
Two types
Full-blown genital warts
Flat warts
Thirty percent of HPV cases progress to precancerous cells.

49. Genital Warts (cont.)
Treatments for genital warts include podophyllin, cryosurgery, simple excision, laser surgery, creams containing 5-fluorouracil, or interferon injections.
Vaccination
Vaccination
On June 8, 2006, the FDA licensed the first vaccine developed to prevent cervical cancer and other diseases in females caused by certain types of genital HPV.
Gardasil®, protects against two HPV types, which are responsible for 70 percent of cervical cancers and 90 percent of genital warts.
The vaccine is recommended for females age 9 to 26. 49

50. Genital Warts: Male
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51. Genital Warts: Female
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52. ABC News Video: Human Papillomavirus Vaccine Mandatory
Discussion Questions
Do you agree with this proposed law?
How would you explain this vaccine to your 11- or 12-year-old daughter?
What are opponents of the vaccine concerned about? Do you agree or disagree?
Why do you suppose this vaccine is to be mandated and not left as a choice by parents?

53. Candidiasis (Moniliasis)
A yeast-like fungus caused by Candida albicans
Found naturally in the vaginal tract, becomes problematic when normal chemical balance is disturbed
Factors that affect chemical balance
Antibiotics
Changes in hormone levels due to pregnancy, breastfeeding, or menopause
Douches or spermicides
Sexual intercourse
STIs

54. Trichomoniasis Caused by a protozoan
Many carriers experience no symptoms.
Symptoms may include foamy, yellowish, unpleasant-smelling discharge; burning sensation; itching; and painful urination.
Transmitted by sexual contact and spread by toilet seats, wet towels, or other items with discharged fluids on them.
Treatment is with oral metronidazole.

55. Pubic Lice
Small parasites that are usually transmitted during sexual contact
Also known as crabs, they lay eggs at the base of pubic hairs.
Treatment is by washing clothing, furniture, and linens.
Usually takes 2 to 3 weeks to kill all larval forms

56. Pubic Lice (cont.)
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57. General Urinary Tract Infections
Urinary tract infections (UTIs) are caused by various factors.
Invading organisms travel up the urethra and enter the bladder.
Prevention is aided by diligent hand washing.
Treatment depends on the organism.

58. HIV/AIDS
Acquired immunodeficiency syndrome (AIDS) has affected 60 million people worldwide since 1981.
Human immunodeficiency virus (HIV) causes AIDS.
Over 38.6 million people are estimated to be living with HIV or AIDS.
In 2005, 4.1 million new cases were diagnosed worldwide.

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60. Women and AIDS
In 2005, women accounted for over 60 percent of AIDS cases in the United States.
AIDS is the leading cause of death in African American women age 25 to 44.
Women have been underrepresented in clinical trials for HIV treatment and prevention.
Factors for disparities include economic disadvantages, cultural norms, rape, sexual abuse, care-giving burdens, less education, and a passive role in negotiating safe sex.

61. How HIV Is Transmitted HIV enters the host from an infected host.
Mucous membranes of the genitals and anus are easiest route of entry.
Once inside the host, the virus begins to multiply.
Virus begins to destroy helper T cells.
Virus changes the genetic structure of the cells it attacks.
The body begins to produce antibodies.

62. Sources of HIV Infection in Men and Women in the United States
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63. High-Risk Behaviors Exchange of body fluids Injecting drugs
Receiving a blood transfusion prior to 1985
Mother-to-infant (prenatal) transmission

64. Symptoms of HIV Disease
Months or years can pass after initial infection of HIV before symptoms appear.
Immune system changes occur over years.
An infected person may experience a number of opportunistic infections.
Colds, sore throats, fever, tiredness, nausea, and night sweats, generally appear as pre-AIDS symptoms.

65. Testing For HIV Antibodies
ELISA test detects presence of HIV antibodies.
Western blot test is a more expensive confirmatory test.
Positive results do not ensure the infected person will develop AIDS.
Early detection is important so that infected individuals can receive immediate treatment.

66. New Hope and Treatments
New drugs have slowed the progression from HIV to AIDS.
Protease inhibitors block the HIV protease enzyme from cutting protein chains to form new viruses.
Protease inhibitors are difficult to manufacture.
No cure is known.

67. Preventing HIV Infection
Avoid risky behaviors.
Take responsibility for your own health.
Seek information from health educators or other health professionals.

68. Where to Go for Help
Arrange a confidential meeting with a health educator or health professional at your college.
Others can assist with your questions.
Local physicians
Counselors
Professors