Transcript continued - Human Kinetics

Infectious
Diseases
Objectives
• Define infectious disease.
• Understand the chain of infection.
• Understand the transmission methods of
infectious agents.
• Identify the six major causes of infectious
diseases.
• Understand the difference between
controllable and uncontrollable risk factors.
(continued)
Objectives (continued)
• Understand the components of the external
defenses and immune system of the body.
• Identify common infectious diseases and
their causes, symptoms, and treatments.
• Define acquired immunodeficiency
syndrome (AIDS) and the virus that causes
it.
• Identify ways to protect yourself from
infectious diseases.
What Is an Infectious Disease?
An infectious disease is a disease that can
spread easily from one person to another.
Chain of Infection
• Method by which a pathogen transmits a
disease
• Six distinct links
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Agent
Reservoir
Portal of exit
Mode of transmission
Portal of entry
New host
Links in the Chain of Infection
Agent
• First link in the chain of infection.
• Includes any disease-causing
microorganism.
• Also known as pathogens or germs.
• Can be bacteria, viruses, fungi, protozoa,
parasitic worms, or prions.
• An example is the influenza virus.
Reservoir
• Second link in the chain of infection.
• Optimal environment where an agent can
live, grow, and reproduce.
• Often, the reservoir is the body of an
infected person; other examples of
reservoirs include animals and soil.
• Agents continue to live and grow in the
reservoir before they’re transmitted to
others.
Portal of Exit
• Third link in the chain of infection.
• Route agents take out of the reservoirs on
their way to causing disease in others.
• Main portals of exit are the respiratory,
digestive, urinary, and reproductive
systems, as well as blood.
Mode of Transmission
• Fourth link in the chain of infection.
• Method that agents use to move from
reservoirs through portals of exit into
potential hosts.
• Modes of transmission include direct and
indirect contact, air, and common vehicles.
Portal of Entry
• Fifth link in the chain of infection.
• Three primary portals of entry are the respiratory
system, the digestive system, and breaks in skin.
• Two secondary portals of entry include the genital
tract and the conjunctiva.
• There are three ways for an agent to gain entry to a
potential host:
– Agent can infect cells in one of the portals of entry.
– Agent can enter body through skin that has been broken
through trauma, bite, or infection.
– Infection can be congenital.
New Host
• Sixth link in the chain of infection.
• Includes people who can get sick when they
become exposed to a disease-causing
microorganism.
Methods of Transmission
• Through contact
• Through the air
• By common vehicle and vector
Direct Contact
• Easiest way for pathogens to infect
someone
• Three types
– Person to person (kissing, sharing straws)
– Animal to person (petting a dog, scooping cat litter)
– Mother to unborn child (from placenta to fetus)
Indirect Contact
• Indirect contact is another method of
transmission of pathogens to humans.
• Disease-causing organisms can live on
doorknobs, telephones, and computer
keyboards.
• You can become infected if an infected
person has used the equipment before you.
Airborne
• Droplets and particles are airborne methods
of transmission.
• Tuberculosis and influenza are two types of
infectious diseases that have the ability to
spread both through droplet and particle
transmission.
Common Vehicle and Vector
• Infectious diseases can spread through
insect carriers and even through food.
• Insect carriers are often called vectors.
• Vectors can transmit germs to humans by
landing on or biting them.
• Uncooked meat and unwashed fruits and
vegetables are often carriers for germs, as
is unclean, unpurified water.
Six Major Causes
of Infectious Diseases
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Bacteria
Viruses
Fungi
Protozoa
Parasitic worms
Prions
Bacteria
• Microscopic, single-celled organisms that
can be found practically anywhere.
• Three types, named for shape:
– Cocci (spherical)
– Bacilli (rodlike)
– Spirilla (spiral)
(continued)
Bacteria (continued)
• Many types of bacteria can live in the body
without causing harm.
• Examples include pertussis (Bordetella
pertussis), Lyme disease (Borrelia
burgdorferi), peptic ulcers (Helicobacter
pylori), tuberculosis (Mycobacterium
tuberculosis), and pneumonia
(Mycoplasma).
Viruses
• Infectious parasites made up of a protein shell that
encloses either deoxyribonucleic acid (DNA) or
ribonucleic acid (RNA).
• Can’t reproduce by themselves, so they’re
dependent on other living beings for reproduction.
• Due to their unique makeup, diseases caused by
viruses are among some of the most contagious.
• Examples include the common cold (rhinovirus),
genital warts (human papillomaviruses), influenza
(influenza A and B), chicken pox (varicella zoster),
and genital herpes (herpes simplex 1 and 2).
Fungi
• Single-celled or multicelled plant.
• Replicate by budding or making spores.
• Many fungal infections come from
environmental exposure to the spores.
• Examples include yeast infections (Candida
albicans), athlete’s foot (dermatophyte
fungi), and histoplasmosis (Histoplasma
capsulatum).
Protozoa
• One-celled organisms that usually can live
independently of a host.
• Transmitted by feces or contaminated water
or food.
• Examples include giardiasis (Giardia
lamblia), trichomoniasis (Trichomonas
vaginalis), and amoebic dysentery
(Entamoeba histolytica).
Parasitic Worms
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Also known as helminths.
Largest of the pathogens.
Live on or in a host.
Can infect people who unintentionally consume
worm eggs either in food or water.
• Larvae can break through and burrow into the skin.
• Examples include pinworm infections (Enterobius
vermicularis), hookworm infections (Necator
americanus), and roundworm infections (Ascaris
lumbricoides).
Prions
• Consist solely of protein material but lack
DNA and RNA.
• Responsible for the spread of bovine
spongiform encephalopathy (BSE), or mad
cow disease.
• Diseases caused by prions are usually
characterized by spongelike holes in the
brain, dementia, and weakness.
Controllable and Uncontrollable
Risk Factors
• Acquire and maintain a strong immune system to
avoid diseases.
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Exercise daily.
Eat a well-balanced diet.
Get enough sleep.
Don’t smoke or use illegal drugs; do limit alcohol consumption,
manage stress, and get vaccines.
– Practice good hygiene.
• Some risk factors can’t be avoided.
– Heredity
– Age
– Environment
External Barriers
• First line of defense against invading
pathogens.
• Include both physical and chemical barriers.
• Skin is one of the most important barriers.
• Mucous membranes, hair, and cilia are
other examples of external physical
barriers.
• Saliva and stomach acid are examples of
external chemical barriers.
Innate Immune System
• Component of the immune system that is
present from birth.
• Fast-response system designed to remove
any foreign matter.
• Causes inflammation at the site where a
pathogen breaches the external defenses of
the body.
(continued)
Innate Immune System (continued)
• The inflammation causes redness, pain,
warmth, or swelling.
• Helps the body identify bacteria and
activates cells to clear dead cells.
• Identifies and removes foreign substances
in the organs, tissues, blood, and lymph.
Acquired Immune System
• Component of the immune system that
grows as you are exposed to a variety of
disease-causing pathogens.
• The two parts are active and passive
immunity.
– Active immunity targets specific foreign particles.
Vaccinations are considered part of the active
immune system.
– Passive immunity is from another source, such as
immunity from the mother passed through the
placenta or breast milk.
Common Infectious Diseases
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Common cold
Influenza (flu)
Bacterial meningitis
Pertussis (whooping cough)
Tuberculosis
Mononucleosis (mono)
Pneumonia
West Nile virus
Common Cold
• Also known as acute rhinitis.
• Can be caused by more than 200 types of
rhinoviruses.
• Very contagious viral infection that is
generally spread by person-to-person
contact.
(continued)
Common Cold (continued)
• Early symptoms include runny or stuffy
nose, nasal discharge, mild muscle aches,
and sore throat.
• Ways to alleviate symptoms:
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Drink plenty of fluids.
Get plenty of rest.
Eat well.
Use over-the-counter medications to ease muscle aches.
Gargle with salt water.
Use lozenges.
Influenza
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Caused by the influenza virus.
Infection of the respiratory tract.
Usually transmitted by droplets.
Characterized by headaches, severe muscle
aches, sudden onset fatigue and weakness,
and sudden onset of a high fever, chills,
sore throat, and cough.
• Get plenty of rest, drink lots of fluids, and
use aspirin when needed.
Meningitis
• Meningitis is inflammation of the meninges, the
membranes covering the brain and spinal cord.
• Can be caused by bacteria or viruses.
• Viral meningitis is often mild, but bacterial
meningitis requires immediate attention because it
can be fatal.
• Symptoms of bacterial meningitis include sudden
onset of a high fever, sudden onset of a severe
headache, acute fatigue, nausea, and a stiff neck.
• A vaccine (Menactra) is now available for
meningococcal meningitis and the other three
types of bacterial meningitis.
Pertussis
• Pertussis is an infection of the respiratory
tract also known as whooping cough.
• Symptoms include runny nose, slight fever,
and nasal congestion.
• Distinctive symptom is a dry cough,
resulting in coughing bouts that can last for
several minutes and that end with a
whooping sound.
• Can be treated with antibiotics.
Tuberculosis
• Tuberculosis is a chronic bacterial infection caused
by Mycobacterium tuberculosis.
• Also known as consumption or white death.
• Spreads from person to person through the air
when an infected person coughs, sneezes, or even
speaks.
• Symptoms include fever, weight loss, weakness,
night sweats, chest pain, coughing, and coughing
of blood.
• Can be treated with antibiotics.
Mononucleosis
• Known as kissing disease or mono.
• Caused by Epstein-Barr virus.
• Spread through contact with the saliva of an
infected person.
• Symptoms are sore throat, fever, swollen glands,
headache, chills, nausea, and severe and persistent
fatigue and weakness.
• Requires at least 1 or 2 months of rest.
• Treatment involves getting lots of bed rest, eating a
balanced diet, drinking adequate amounts of fluid,
and using over-the-counter medications such as
aspirin and lozenges.
Pneumonia
• Pneumonia is an infection of the lungs and
lower respiratory tract.
• Caused by bacteria, viruses, or fungi.
• Most common form is bacterial pneumonia.
• Characteristics of pneumonia are high
fever, severe chest pains, shortness of
breath, chills, and a productive cough.
West Nile Virus
• Transmitted by mosquitoes that have bitten
wild birds—usually crows and jays—that
serve as reservoirs for the virus.
• Signs and symptoms include headache,
fever, diarrhea, nausea, vomiting, skin rash,
backache, swollen lymph glands, and lack
of appetite.
• Rarely, the virus can cause encephalitis or
meningoencephalitis.
Sexually Transmitted Infections
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HIV and AIDS
Hepatitis B
Syphilis
Chlamydia
Gonorrhea
Genital herpes
Genital warts
Pelvic inflammatory disease (PID)
HIV and AIDS
• AIDS stands for acquired immunodeficiency
syndrome.
• The virus that causes AIDS is the human
immunodeficiency virus (HIV).
• HIV damages the immune system, making it
difficult for the body to fight off disease-causing
organisms.
• AIDS usually has no signs or symptoms in the early
stage.
• At later stages, signs and symptoms include
swollen lymph nodes, diarrhea, weight loss, fever,
cough, and shortness of breath.
Signs and Symptoms
of Full-Blown AIDS
• Profuse night sweats
• Chills that last for several weeks
• Fever higher than 100 °F (38 °C) that lasts
for several weeks
• Dry cough
• Shortness of breath
• Persistent diarrhea
(continued)
Signs and Symptoms
of Full-Blown AIDS (continued)
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Lesions on the tongue or in the mouth
Headaches
Blurred vision
Chronic fatigue
Swollen lymph nodes
Rapid weight loss
How HIV Is Transmitted
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Sexual transmission
Through infected blood
From mother to child
Through organ transplants
Through the use of unsterilized medical
equipment
Protection From HIV
• Practice safe sex.
• Do not share needles.
• Do not receive blood overseas if you can
help it.
• Get tested for HIV.
Hepatitis B
• Serious liver disease caused by the
hepatitis B virus (HBV).
• Transmitted from one person to another
through sexual contact, through shared use
of needles, and from mother to child during
pregnancy.
• Can also spread through close nonsexual
contact; by exposure to infected blood; and
by contact with mucous membranes.
Symptoms of Hepatitis B
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Nausea
Fever
Chills
Fatigue
Loss of appetite
Dark urine
Abdominal pain
Jaundice
Joint pain
Protection From Hepatitis B
• Get vaccinated.
• Use latex condoms when engaging in
sexual activity.
• Do not share needles or syringes.
• Make sure all needles and syringes are
sterile if you are getting a tattoo or body
piercing.
Syphilis
• Caused by Treponema pallidum bacteria.
• Can be treated with antibiotics.
• Transmitted through direct contact with a
syphilis sore.
Primary Stage of Syphilis
• A chancre sore develops, usually at the site
of the infection.
• In males, the sore is usually near the penis
or scrotum.
• In females, the sore is usually on the cervix
or vaginal wall.
Secondary Stage of Syphilis
• This stage is characterized by white patches
on the skin, lesions on mucous membranes,
hair loss, fever, headache, fatigue, weight
loss, and swollen lymph nodes.
• Lesions can appear 3 weeks to 1 year after
the chancre sore has disappeared.
Tertiary Stage of Syphilis
• The third stage is characterized by damage
to the central nervous system.
• Other effects include blindness, senility,
dementia, and cardiovascular damage.
Chlamydia
• Infection of the urogenital tract caused by
the bacteria Chlamydia trachomatis.
• Transmitted from one infected person to
another through oral, vaginal, or anal sex.
• Infected mothers can also pass the bacteria
to their babies during vaginal childbirth.
Symptoms of Chlamydia
• Approximately 75% of infected women and 50% of
infected men experience no signs or symptoms.
• Women might experience the following:
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Burning sensation when urinating
Abnormal vaginal discharge
Lower back and abdominal pain
Bleeding between menstrual periods
Painful intercourse
• Men might experience the following:
– Penile discharge
– Burning sensation when urinating
– Burning around the opening of the penis
Gonorrhea
• Caused by the bacteria Neisseria
gonorrhoeae.
• Spread by contact through the mouth,
vagina, penis, or anus or from infected
mother to child during delivery.
• Affects the linings of the urethra, genital
tract, pharynx, and rectum.
• Can be treated with antibiotics.
Genital Herpes
• Caused by the herpes simplex virus types 1 (HSV-1)
and 2 (HSV-2).
• Most cases caused by HSV-2.
• Enters the body through tiny breaks in the skin or
mucous membranes through either sexual contact
or skin-to-skin contact.
• Characterized by pain, itching, burning sensation
when urinating, and sores in the genital area, along
with headache, fever, muscle aches, and swollen
lymph nodes in the groin.
• No cure is available.
Genital Warts
• Caused by the human papillomavirus (HPV).
• Can be found in the skin of the penis, vulva, and
anus; in the vagina, cervix, or rectum; or in the
mouth or throat.
• Warts can appear as either flesh-colored bumps or
have a cauliflower-like appearance and are soft,
moist, and pink.
• Can cause itching in the genital area along with
bleeding and pain during intercourse.
• No cure, but warts can be removed using
medications or health care workers can surgically
remove them.
Pelvic Inflammatory Disease
• Infection of the female reproductive organs,
including the uterus and fallopian tubes.
• PID is a frequent and serious complication from
untreated sexually transmitted infections such as
gonorrhea and chlamydia.
• Symptoms include painful intercourse, painful
urination, heavy and odorous vaginal discharge,
pain in the lower back and abdomen, and irregular
menstrual bleeding.
• Can be treated with antibiotics.
Protection From Infectious Diseases:
Immunizations
• Make sure your vaccinations are up to date.
• It’s especially important for college
students to receive the meningitis and HPV
vaccinations.
Protection From Infectious Diseases:
Hand Washing
• Wash your hands often with soap and
water.
• Wash for at least 20 seconds.
Protection From Infectious Diseases:
Safe Sex Practices
• Practice abstinence, if possible.
• Use latex condoms.
• Be in a long-term, mutually monogamous
relationship.
• Avoid sexual activity with any partner whose sexual
history you don’t know.
• Limit excessive use of alcohol or other drugs
because such use can impair judgment, which
could lead to risky sexual practices.