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Questions and Answers A Guide to Fitness and Wellness 4th Edition

Gary Liguori │ Sandra Carroll-Cobb

©McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior written consent of McGraw-Hill Education.

CHAPTER 12

Infectious Diseases

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COMING UP IN THIS CHAPTER

Discover the major types of infectious organisms and your body’s defenses against disease

Learn about common infections—means of transmission, symptoms, and treatments

Understand common sexually transmitted infections

Take steps to prevent infections and limit their impact

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Infections and Immunity

Infectious diseases: diseases that can be passed to or among people

Colds

Flu

Bronchitis

Mononucleosis

Sexually transmissible infections

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Pathogens, 1

Question: What causes infectious diseases?

Infections are caused by pathogens: disease-causing agents that can be passed among people

The most prevalent type of pathogens are bacteria and viruses

Microbes or microorganisms

Infections can also be caused by larger organisms like lice or parasitic worms

Infestations

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Pathogens, 2

Many microbes live in a healthy human body and are needed to keep the body functioning normally

They can cause illness if they gain entry into a part of the body that is normally microbe-free

Staphylococcus aureus

Thrush

Infection versus disease

Presence of symptoms or asymptomatic

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Pathogens, 3

Question: Why are some infections more serious than others?

Pathogens vary in their virulence—the ability to cause intense or severe symptoms

They affect different parts of the body

i.e., small area of skin versus in the bloodstream

The amount of pathogen initially exposed to can have an influence

The health status of the person is also significant

Strength of the immune system

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FIGURE 12-1 PATHOGENS, EFFECTS, AND ASSOCIATED DISEASES

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The Cycle of Infection, 1

Question: How do you actually catch an infectious disease?

The pathogen must gain entry into the host’s body and start to replicate and cause symptoms

Transmission requires:

A source of pathogens

A susceptible host

A mode of transmission

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The Cycle of Infection, 2

Source of pathogens:

Infectious agents can come from another person, an animal, water, or even soil

Reservoir: the body of an individual already affected

Susceptible host:

People are more susceptible to infection if:

Their immune system is weak

Children, elderly, those with underlying health issues

A natural physical defense is compromised

A cut in the skin

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The Cycle of Infection, 3

Mode of transmission:

Different pathogens have different modes of transmission

Directly, indirectly: cold virus

Airborne: flu

Vector: malaria, Lyme disease

Transmitted through insects or animals

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The Body’s Defenses

Question: How do I get my resistance to disease?

We are each born with a specific capacity to resist certain diseases

There is little consistency from one person to the next

Built-in defenses:

The skin

Mucous membranes in the mouth, nostrils, eyelids, lungs, and genitals

Hair and hairlike cilia

Chemical barriers, including those in the acids, proteins, and enzymes of the digestive tract

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The Immune System, 1

Question: How do I develop my immunity?

The immune system responds and defends the body from disease-causing agents

Immune cells recognize foreign substances

Antigens

Trigger an immune response when recognizing a pathogen

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The Immune System, 2

Some immune cells move to the site of infection and “eat” invading microbes

May cause pain and swelling

If infection persists, the immune system produces antibodies

A low-grade fever (100 degrees Fahrenheit or less) may develop to fight infection

Makes the host less hospitable for the pathogen

Specialized “memory” cells may be produced to provide immunity to that pathogen

Immunity can also be acquired through vaccination

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The Immune System, 3

One sign of the immune response is swollen lymph glands or nodes

Lymphatic system

Network of vessels and organs

Return fluids lost from capillaries to the circulatory system

Plays a key role in defense against invading pathogens

Activates and transports infection-fighting cells

Swollen lymph glands indicate an active response to an infection

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FIGURE 12-2 THE LYMPHATIC SYSTEM

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The Role of Immunizations

Question: Can vaccines weaken my immune system?

Vaccines strengthen the immune system by preparing the body to fight infection

They create immunity against infections you have not previously had

Made from killed, weakened, or incomplete pathogens

No vaccine is completely effective

Boosters may be needed

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Stages and Patterns of Infectious Diseases, 1

Question: Can infections be cured?

Acute infections are most likely to cure on their own or cure quickly with treatment

They are characterized by a short duration and a typical series of stages:

Incubation: the time between infection and symptoms

Prodrome: general appearance of symptoms

Illness: symptoms become more severe

Convalescence: recovery

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Stages and Patterns of Infectious Diseases, 2

Infections can also follow other patterns

Chronic infection

Illness persists or recurs over a long period

Latent infection

Pathogen lies dormant but retains the ability to replicate

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FIGURE 12-3 STAGES AND PATTERNS OF INFECTIONS

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Prevention and Treatment of Infectious Diseases, 1

Question: How can I keep from getting sick?

Keep pathogens out of your body

Wash hands often!

Avoid people who are sneezing and coughing; cover your mouth and nose when sneezing or coughing

Maintain a strong immune system

Eat a healthy diet; get plenty of sleep and exercise

Avoid smoking and excessive drinking

Control stress and maintain mental health

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FIGURE 12-4 HAND-WASHING GUIDELINES

(pug): ©George Doyle/Getty Images RF; (soap and hands): ©Christian Pound/Getty Images RF; (sanitizer): ©Ashok Rodrigues/Getty Images RF.

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FIGURE 12-5 MENTAL HEALTH AND RISK OF INFECTIOUS DISEASE IN COLLEGE STUDENTS

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Prevention and Treatment of Infectious Diseases, 2

Question: I’m confused about antibiotics—when do they really work?

Antibiotics primarily fight bacterial infections but may be prescribed to fight certain fungi and parasites

They do not work against infections caused by viruses

Bacteria can develop resistance to a drug’s effects

The more you take antibiotics, the more you increase the chance of resistance

They can have side effects

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Prevention and Treatment of Infectious Diseases, 3

Question: How are infections treated?

This depends on the type of pathogen, the severity of the infection, and the person’s underlying health status

Some don’t need to be treated

Symptoms can be treated

Over-the-counter medications

Antimicrobials, antibiotics

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Infectious Diseases on Campus: Colds and Influenza, 1

Question: How do you tell if you have a cold or the flu?

Colds and influenza

Caused by viruses and have similar symptoms

Influenza is the more serious disease; colds are more common

Hundreds of viruses can cause the common cold

Transmitted primarily by indirect contact

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Infectious Diseases on Campus: Colds and Influenza, 2

Influenza viruses are more likely to be transmitted through respiratory droplets

Symptoms usually come on quickly and include:

Fever

Body aches

Severe fatigue

Influenza carries a greater risk of serious complications

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TABLE 12-1 IS IT A COLD OR THE FLU?

SYMPTOM	COLD	FLU
FEVER	Rare	Usual; high (100 degrees to 102 degrees Fahrenheit or higher); lasts 3 to 4 days
HEADACHE	Rare	Common
GENERAL ACHES, PAINS	Slight	Usual, often severe
FATIGUE, WEAKNESS	Sometimes	Usual; can last up to 2 to 3 weeks
EXHAUSTION	Never	Usual; typically at the beginning of the illness
STUFFY NOSE	Common	Sometimes
SNEEZING	Usual	Sometimes
SORE THROAT	Common	Sometimes
CHEST DISCOMFORT, COUGH	Mild to moderate	Common; can be severe
COMPLICATIONS	Sinus congestion, middle-ear infection, worsening of asthma symptoms	Bronchitis, pneumonia; worsening of chronic conditions; can be life threatening

©Stockbyte/Getty Images RF

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Infectious Diseases on Campus: Colds and Influenza, 3

Question: Does getting a flu shot really help prevent the flu?

College students benefit from the influenza vaccine

The influenza infection can spread easily in a campus setting

It is important to take a type-specific vaccine

The vaccination is reformulated each year to target the strains most likely to be circulating

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Infectious Diseases on Campus: Infectious Mononucleosis

Question: Does mono only come from kissing?

Mononucleosis (“mono”) is caused by the Epstein-Barr virus (EBV), a member of the herpes family of viruses

Transmitted through saliva: “kissing disease”

Symptoms: fever, sore throat, swollen glands, and fatigue

EBV is a latent infection

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Infectious Diseases on Campus: Meningitis

Question: What is that serious infection that causes a stiff neck?

Meningitis is an inflammation of the membranes that surround the brain and spinal cord

Symptoms: high fever, severe headache, stiff neck, sensitivity to bright light

Two kinds:

Viral: resolves on own in 7 to 10 days

Bacterial: very serious; can cause disability or death

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Infectious Diseases on Campus: Bacterial Skin Infections

Question: What is MRSA?

MRSA is a type of staph bacteria that is resistant to many antibiotics

It is a major agent of skin infections

Risk factors: crowded living conditions; contaminated items and surfaces

Dorms, athletic facilities, military barracks, daycares

Symptoms: red, swollen, painful lumps that look like boils or insect bites

May spread: swollen glands, fever

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TABLE 12-2 COMMON INFECTIONS: SYMPTOMS AND TREATMENTS, 1

ILLNESS (PATHOGEN)	SYMPTOMS	HOME TREATMENT	WHEN TO SEEK MEDICAL CARE
COMMON COLD (over 200 different viruses)	Runny nose, nasal congestion, mild cough, sore throat, low-grade fever, sneezing	Usually resolves on its own; fluids, rest, and over-the- counter medications to treat symptoms; avoid alcohol and tobacco	Worsening symptoms after third day, difficulty breathing, stiff neck
INFLUENZA (influenza A or B virus)	Sudden-onset fever, extreme fatigue, headache, body aches, cough	Usually resolves on its own; same home treatment as for colds; prescription antivirals Available	Difficulty breathing, severe headache or stiff neck, confusion, fever lasting more than 3 days; new, localized pain in ear, chest, sinuses; people at high risk for complications should contact a health care provider if they develop flu symptoms
BRONCHITIS (different viruses or bacteria)	Cough that may start out dry and later produce mucus; sore throat, fever	Usually resolves on its own; same home treatment as for colds	Shortness of breath, high fever, shaking chills (signs of pneumonia); wheezing and cough that last more than 2 weeks; people at high risk for complications should check with a health care provider
MONONUCLEOSIS (Epstein-Barr virus)	High fever, swollen glands, severe sore throat, fatigue; nausea, vomiting, and loss of appetite can occur	Usually resolves on its own; rest, fluids; avoid contact sports until symptoms resolve due to risk of spleen rupture	Fever lasting more than 3 days; symptoms lasting longer than 7 to 10 days; severe abdominal pain (possibly indicating ruptured spleen)
MENINGITIS (several different viruses or bacteria)	High fever, stiff and painful neck, headache; vomiting, sleepiness, confusion, seizures	Requires medical evaluation; if determined to be a viral infection, home treatment to relieve symptoms is appropriate	Immediately; bacterial meningitis requires treatment with antibiotics to avoid serious or deadly complications

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TABLE 12-2 COMMON INFECTIONS: SYMPTOMS AND TREATMENTS, 2

ILLNESS (PATHOGEN)	SYMPTOMS	HOME TREATMENT	WHEN TO SEEK MEDICAL CARE
STREP THROAT (Streptococcus bacteria)	Sudden-onset sore throat and fever; swollen glands; red and white pus on tonsils; absence of cold symptoms	A visit to health care provider is appropriate; saltwater gargles, throat lozenges, over-the-counter medications to treat symptoms	If your strep-related sore throat lasts longer than one to two days, or is accompanied by other symptoms, such as joint pain, difficult breathing, abdominal pain, rash, or fever
BACTERIAL SKIN INFECTION (Staphylococcus aureus or Streptococcus)	Skin sore or rash; red, swollen, warm, and painful areas of skin; if infection spreads, general symptoms of fever, chills, swollen glands	A visit to health care provider is appropriate; warm compresses; keep infected area clean and dry; topical antibiotics if advised by health care provider	If you experience fever or chills, redness on the skin, increased warmth in the affected area, swelling, tenderness, and or drainage from the skin. Other signs or symptoms to seek medical care include, but are not limited to, high fevers or chills, nausea and vomiting, hardening or numbness of the reddened area, and increasing pain, blisters, or pus.
URINARY TRACT INFECTION (different bacteria)	Cloudy, bloody, or strong-smelling urine; frequent urination; pain or burning with urination; low fever; pain in lower abdomen	Requires medical evaluation; drink plenty of water; in women, drinking cranberry juice has been shown to help prevent but not treat urinary tract infections	If you experience blood or pus in the urine, fever, pain in the abdomen region, vomiting, nausea, or symptoms lasting more than 24 hours.

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Sexually Transmitted Infections, 1

Sexually transmitted infections (STIs) are among the most common types of infections in the United States

Spread through person-to-person sexual contact

Half of all new infections are seen in people aged 15 to 24

Some can be treated and cured; others are chronic, incurable, and even life threatening

All are preventable

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Sexually Transmitted Infections, 2

Question: Do women get more STIs than men?

Women are more likely to have STIs and experience complications from them

Women’s cervix is covered with cells that are particularly susceptible

STIs cause more serious problems in women, including infertility

Many STIs are asymptomatic

Anyone who is sexually active can have an STI

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Sexually Transmitted Infections: HPV

Question: What’s the most common sexually transmitted infection?

Human Papillomavirus (HPV)—genital warts

Most common STI in the U.S.; asymptomatic in many

Complications can still develop; and it can still be transmitted to sexual partners

Warts can be treated, but there is no treatment for the underlying viral infection

Primary complication is cervical cancer

Detected through Pap tests

Three vaccines: Cervarix, Gardasil, Gardasil 9

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Sexually Transmitted Infections: Chlamydia

Question: How often should I get checked for chlamydia?

Chlamydia is a bacterial infection transmitted during sex or from an infected mother to the baby during birth

About 70% of infected people have no symptoms

Symptoms: painful urination and abnormal discharge

If untreated, can cause serious infections of the fallopian tubes in women and the urethra and epididymis in men

Those 25 and younger who are sexually active should be checked annually

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Sexually Transmitted Infections: Gonorrhea

Question: Can a person get gonorrhea from oral sex?

Gonorrhea is a bacterial infection that can be spread through contact with the penis, vagina, mouth, or anus

Mostly asymptomatic, although sometimes men have discharge and painful urination

Untreated it can lead to infertility, chronic pelvic pain, and the transmission of dangerous infections to infants in childbirth

Can be cured with antibiotics, but many strains have developed resistance

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Sexually Transmitted Infections: PID

Question: If I have chlamydia, does that mean I also have PID?

Pelvic inflammatory disease (PID)—an infection and inflammation of the uterus, ovaries, fallopian tubes, and reproductive organs in women

Usually the result of chlamydia or gonorrhea

May be asymptomatic or have severe symptoms like fever and pain

Early antibiotic treatment is crucial

Can cause damage to reproductive organs, infertility

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Sexually Transmitted Infections: Syphilis, 1

Question: How many stages of syphilis are there?

Syphilis is a bacterial infection transmitted through infected skin and mucous membranes in the genitals, lips, mouth, and anus

It can be passed from mother to infant during pregnancy: congenital syphilis

Multistage STI

Primary, secondary, latent, tertiary

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Sexually Transmitted Infections: Syphilis, 2

Primary syphilis: painless sore (chancre) that disappears within 3 to 6 weeks

Full of bacteria that can be spread, but can go unnoticed

Secondary syphilis: develops in 2 to 10 weeks

Most common symptom: non-itchy skin rash on palms of hands and soles of feet

Other symptoms include: swollen glands, headache, fatigue, sore throat, and hair loss

Symptoms usually disappear without treatment, but may recur

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Sexually Transmitted Infections: Syphilis, 3

Latent syphilis: develops in untreated cases

Symptoms disappear, but bacteria remains in the body

Can still infect others, but risk fades over time

Tertiary syphilis: develops in a small percentage of cases

Syphilis bacteria cause organ damage, mental illness, heart disease, blindness, and death

Syphilis is curable with antibiotics in all stages

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Sexually Transmitted Infections: Herpes, 1

Question: Does everyone have herpes?

Not everyone has herpes, but it is common

Genital herpes can be caused by:

Herpes simplex virus type 1 (HSV 1)

Generally infects the lips and mouth, producing cold sores; and can cause genital herpes if transmitted through oral sex

Herpes simplex virus type 2 (HSV 2)

Responsible for genital herpes

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Sexually Transmitted Infections: Herpes, 2

Herpes symptoms:

Sores at the site of entry into the body

Herpes is a latent viral infection

There is no treatment or cure for genital herpes

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TABLE 12-4 PREVALENCE OF HERPES SIMPLEX VIRUS TYPE 2 AS MEASURED BY BLOOD TESTS

	PREVALENCE
TOTAL	16.2%
AGE GROUP (YEARS)
14–19	1.4%
20–29	10.5%
30–39	19.6%
40–49	26.1%
REPORTED NUMBER OF LIFETIME SEX PARTNERS
1	3.9%
2–4	14.0%
5–9	16.3%
10	26.7%

*Over 80 percent of those whose blood test was positive for HSV 2 had never received a diagnosis of genital herpes.

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Sexually Transmitted Infections: Viral Hepatitis, 1

Question: Are herpes and HIV the only incurable STIs?

Viral hepatitis: inflammation of the liver caused by infection with one of the hepatitis viruses

Hepatitis A virus: transmitted through food and water

Usually resolves on its own

A vaccine is available

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Sexually Transmitted Infections: Viral Hepatitis, 2

Hepatitis B virus: transmitted through sexual contact, blood, and saliva

Acute symptoms include jaundice

Chronic hepatitis may have no symptoms

It may cause liver damage, cancer

There is a vaccine available

Hepatitis C virus: primarily transmitted through blood

Most new infections are caused by injection drug use

Can become chronic

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Sexually Transmitted Infections: HIV Infection and AIDS, 1

HIV is prevalent in the United States and worldwide

In the U.S., someone is infected with HIV every 10 minutes, and someone dies from HIV/AIDS every 45 minutes

Worldwide, 7,400 people are infected every day, half of them under age 25

HIV is not equally distributed across the U.S. population

Higher rates among men and African Americans

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FIGURE 12-6 ESTIMATED RATES OF DIAGNOSIS OF HIV INFECTION AMONG U.S. ADULTS AND ADOLESCENTS BY SEX AND RACE/ETHNICITY

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Sexually Transmitted Infections: HIV Infection and AIDS, 2

Question: Is there a difference between HIV and AIDS?

The human immunodeficiency virus (HIV) is the infectious agent that causes acquired immune deficiency syndrome (AIDS)

HIV is a pathogen

Destroys CD4+ T cells, which are critical for fighting infection

AIDS is late stage of HIV infection

Diagnosed when an opportunistic infection develops

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Sexually Transmitted Infections: HIV Infection and AIDS, 3

Question: Do condoms help prevent HIV infection?

Condom use does not completely eliminate risk, but it greatly reduces HIV transmission

HIV is spread by:

Unprotected sex

Having multiple sex partners

The presence of other sexually transmitted infections

Sharing needles or other equipment used to prepare illicit drugs or injections

Being born to an infected mother

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FIGURE 12-7 TRANSMISSION ROUTES AMONG U.S. ADULTS AND ADOLESCENTS DIAGNOSED WITH AIDS

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Sexually Transmitted Infections: HIV Infection and AIDS, 4

Question: What are symptoms of HIV and AIDS?

Symptoms during the acute phase may include fever, headache, fatigue, muscle aches, and enlarged lymph nodes

Typically resolve with no treatment and may be attributed to something else

HIV in the acute phase is highly infectious

Following the acute phase, HIV is asymptomatic

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Sexually Transmitted Infections: HIV Infection and AIDS, 5

The late stages of HIV infection are characterized by:

Rapid weight loss

Extreme fatigue

Sores in the mouth or genitals

Neurological disorders

Opportunistic infections of full-blown AIDS include pneumonia, liver disease, cancer, and unusual infections

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Sexually Transmitted Infections: HIV Infection and AIDS, 6

Question: How long do you have to wait to find out if you have HIV?

Blood tests detect antibodies within 2 to 8 weeks of infection

97% of infections can be detected within 3 months

The OraQuick over-the-counter test can yield results in a few minutes

Federal guidelines recommend routine HIV testing for Americans aged 13 to 64

For high risk persons, annual testing is recommended

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Sexually Transmitted Infections: HIV Infection and AIDS, 7

Question: Is HIV still considered life-threatening?

With treatment, people can survive many years or even decades with an HIV infection

Antiviral drugs can suppress the virus

The development of a vaccine is challenging

HIV attacks the immune system, the cells that need to be activated by a vaccine

Microbicides kill microbes or reduce their ability to cause infection

Vaginal application

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TABLE 12-3 STIs IN THE UNITED STATES: A SNAPSHOT

	ESTIMATED ANNUAL INCIDENCE	ESTIMATED PREVALENCE*	OUTLOOK IF DIAGNOSED
HPV INFECTION	14.1 million	20 million	Vaccine-preventable; incurable but often resolves on its own; can cause cancer
CHLAMYDIA	2.8 million	1.9 million	Curable with antibiotics
TRICHOMONIASIS	1.1 million	n/a	Curable with antibiotics
GONORRHEA	820,000	n/a	Curable with antibiotics
GENITAL HERPES	775,000	45 million	Chronic and incurable; treatments can reduce symptoms and outbreaks
SYPHILIS	55,000	n/a	Curable with antibiotics
HIV INFECTION	41,000	1.2 million	Chronic and potentially fatal; treatable but incurable
HEPATITIS B	19,000	1.25 million	Vaccine-preventable; incurable but often resolves on its own; can cause fatal liver disease

*Because viral STIs can be persistent and incurable, the number of currently infected people capable of transmitting the infection (prevalence) greatly exceeds the annual number of new cases (incidence).

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