Test 3: Chapter 13

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1.The best descriptive term for the resident biota is
a. commensals
b. parasites
c. pathogens
d. mutualists

a. commensals

2. Resident biota is absent from the
a. pharynix
b. heart
c. intestine
d. hair follicles

b. heart

3. Virulence factors include
a. toxins
b. enzymes
c. capules
d. all of these

d. all of these

6. A short period early in a disease that may manifest with general malaise and achiness is the
a. period of incubation
b. prodrome
c. sequela
d. period of invasion

b. proderome

10. An outbreak caused by a batch of bad potato salad at a picnic is a _________-outbreak.
a. point-source
b. common-source
c. progpagated
d. all of the above

a. point-source

12. Resident microbiota is commonly found in the urethra? T/F

T

14. The general term that describes an increase in the number of the white blood cells is leukopenia

F. The general termt hat describes a decrease in the number of whie blood cells is leukopenia

What is phagocytosis?

Phagocytosis (literally "cell-eating") is a form of endocytosis wherein large particles are enveloped by the cell membrane of a (usually larger) cell and internalized to form a phagosome, or "food vacuole

What are the steps involved with phaogocytosis and destruction of a microbe?

...

List the cell types which are capable of phaogcytosis.

...

A pt's chart shows that eosinophils make up 8
% of his white blood cell count. What does this lead you to suspect?

...

Would your suspicions change if you learned tha thte pt had spent time as an anthropologist living among an African tribe?

...

Sweat glands in the armpits secrete perspiration with a pH close to neutral (7). How does this fact help explain body odor in this area as compared to other parts of the body?

...

Name 5 formites, but make them ones that could potentially be the riskier object for transmitting disease

A fomite is any object that can facilitate horizontal bacteria transmission of bacteria or virus (person to person). Almost every object on earth could theoretically act as a fomite.
(Food - someone sneezed on it and you ate it.)
railings - touch with disease and you touch it. Computers - touched by others & you use it.
Refridgerator doors - Others use and you touch it and rub your eye.

Infectious disease

Any disease caused by a microorganism that enters and mulitiples within tissues at the expense of its host is said to be infectious

Normal Microbiota

* Microbes adapted to the environment of the body, iehter in a symbiotic or synergistic relationship
ie: Bacteria, fungi and protozoa

How is normal microbiota acquired?

birthing process, breast or bottle feeding and exposure to family, health care workers, environments and food

What are the known sites to harbor normal flora

Skin, respiratory tract, digestive tract, outer portion of urethra, external genitalia, vagina

Contamination of infectious disease

is the presence of microbes in or on the body

Infection

is when the microbe evades the body's external defenses, multiplies and becomes established in the body

Disease

results if the invading pathogen alters normal body function

Pathogens

any microbe that causes disease

2 types of pathogens

Opportunistic pathogens
True pathogens

Opportunisitc pathogens

cause disease when the host's immune defenses are compromised or when they become establised in a part of the body that is not natural to them.
ie: Yeast, Staph & E.coli bacteria

True pathogens

are capable of acusing disease in healthy individuals with normal immune defenses.
ie: Salmonella bacteria, influenza virus

Portals of entry

- sites through which pathogens enter the body

What are the 3 major portals of entry pathways?

skin
mucous membrane
placenta

Skin (portal of entry)

- some pathogens can enter through natural openings (hair follicles or sweat glands)
- Some enter through abrasions or cuts
- Some enter through bites or contaminated needles
- Other enter by burrowing into or digesting outer layers of skin

Mucous membranes

lines the body cavities that are open to the environment

What are 3 mucous membranes for portal of entry of pathogens?

1) Respiratory (most common site of entry)
- entry through mouth,nose, or eyes
2) Gastrointestinal tract
- must survive the acidic pH of the stomach
3) urinary and reproductive tracts

What do mucous membranes provide

They provide a moist, warm environment hospitable to pathogens

Placents (portals of entry)

- Typically forms effective barrier to pathogens
- Pathogens may cross the placenta and infect the feus
* Can cause spontaneous abortion, birth defects, premature birth)

What are examples of pathogens that cross the placenta?

* Bacteria causing syphilis and listeriosis
* Viruses causing AIDS and German measles
* Protozoan causeing toxoplasmosis

Size of Inculum for infectius dose of organism

For most organisms, a minimum number (infectious dose) of organisms must enter the body to cause an active infection.
*Infectious dos (ID) can range from
- One organism (rickettsia, TB, Giardia)
- 1,000 for gonorrhea
- 10,000 for anthrax
- 100,000 for salmonella
- 1,000,000 for cholera
- 1,000,000,000 for E. coli

The role of adhesion in Infection

- Process by which microorganisms attach themselves to cells
- Required to successfully establish colonies with in the host

Adhesion factors

* Speicalized structures
- Adhesion disks (protozoa)
- Suckers or hooks (helminths)
* Attachment proteins or ligands (surface glycoproteins or lipoproteins)
- Fimbrae, flagella, glycocalyces (bacteria)
- Capsid or envelope (virus)

Virulence factors of Infectious Agents

Pathogenicity
* Ability of a microorganism to cause disease
Virulence
* Degree of pathogenicity
* Virulence factors contribute to virulence
- Adhesion factors
- Extracellular enzymes
- Toxins (exo-and endotoxins)
- Antiphagocytic factors

Virulence FActors of Infectious Agents

Extracellular enzymes
- Secreted by the pathogen
- Dissolve structural chemicals in the body
- Help pathogen maintain infection, invade,a nd avoid body defenses

Virulence factors of Infectious Agenst (Toxins)

- Chemicals that harm tissues or trigger host immune responses that cause damage
- Toxemia refers to toxins in the bloodstream that are carried beyond the site of infection
- Two types (exotoxins and endotoxins)

Virulence Factors of Infectious Agents: Antiphagocytic factors

- Prevent phagocytosis by host's phagocytic cells
* Bacterial capsule
- Composed of chemicals not recognized
as foreign
- Slippery: difficult for phagocytes to engulf
bacteria
* Antiphagocytic chemicals
- prevent fusion of lysosome and
phagocytic vesicles
- Leukocidins directly destroy phagocytic
white blood cells

The Manifestations of Disease: Symptoms, Signs, and Syndromes
What are symptoms ---

Symptoms:
* Subjective characteristics of disease felt
only by the pt (pain, nausea, headache,
chills, fatique, itching)
Signs:
*Objective manifestations of disease
observed or measured by others (swelling,
rash, vomiting, diarrhea, fever, anemia)
Syndrome:
* Group of symptoms and signs that
characterize a disease or abnormal
condition
Asymptomatic, or subclinical:
* Infections lack symptoms but may still
have signs of infection

Signs

objective manifestations of disease observed or measured by others (swelling, rash, vomiting, diarrhea, fever, anemia)

Syndrome

Group of symptoms and signs that characterized a disease or abnormal condition

Asymptomatic or subclinical

infections lack symptoms but may still have signs of infection

The manifestation of disease: Stages of Infectious disease

-The disease process occurs following infection
- Many infectious diseases have five stages
- Patients could be infectious at all stages
- Length of and intensity depends on virulence of pathogen, infective dose, health of pt, and site of infection.

What are the five stages that many infectious diseases have?

Incubation period
Prodromal period
Illness
Decline
Convaescence

Incubation period

time between infection and first symptom
- has no signs or symptoms

prodromal period

short time of generalized mild symptoms
- vaue, general symptoms

Illness

most severe stage, signs and symptoms most evident
-most severe signs and symptoms

Decline

body begins to return to normal as immune response or medical treatment destroys pathogens, sign and symptoms lessen
- declining signs and symptoms

Convalescence

tissue repair
- no signs or symptoms

patterns of infectious disease: types of infections

Localized
Systemic
Mixed infection
Primary
Secondary

Localized type of infection

microbe remains in area of entrance (fungal skin, infections, warts)

Systemic

microbe spreads to several sites, including blood
- septicemia, bacteremia, viremia, toxemia

Mixed infection (polymicrobial)

infection involves more than one microbe (wound infection, dental caries)

Primary infection

intial infection that is later complicated by additional (secondary) infections

Secondary

an infection that complicates the primary one (HIV-primary, yeast infection of pneumonia-secondary)

Classification of Infectious disease: Terms used to classify infectious disease

Acute
Chronic
Subacute
Latent

Acute disease

diseases that develop rapidly, last short period of time (common cold)

Chronic

diseases develop slowly, are continual or recurrent (HCV)

Subacute

diseases that lie somewhere in between acute and chronic (endocarditis)

Latent

diseases the pathogen remains inactive for a long period of time before becoming active (herpes)

Portals of Exit (movement of Pathogens Out o fHosts)

- sites where pathogens leave host
- many portals of exit are the same as portals of entry
- pathogens often leave hosts in materials the body secretes or excretes
Ear (earwax), Broken skin (blood) Skin (flakes)Anus(feces) Seminal vesicles (semen and lubricatinig secretions
Urethra (urine), Vigina (secretions, blood), Mammary gland - female(milk, secretions), mouth(saliva, sputum), nose(secretions), eyes(tears)

Reservoirs of diseases in humans

Most pathogens cannot survive for long outside of their hosts.
-Reservoirs of infection: sites wehre pathogens are maintained as a source of infection
- Three types of resevoirs
* Animal reservoir
* Huma carriers
* Nonliving reservoir

Animal reservoirs

Zoonoses: Diseases naturally spread from animal host to human
- Acquire zoonoses through various routes
* Direct contact with animal or its waste
* eating animals
*Bloodsucking arthropods
- Humans are usually dead-end host to zoonotic pathogens
Examples: lyme disease, Salmonellosis, Rabies, West Nile virus and tapeworms

Human Carriers

- Infected individuals who are asaymptomatic but infective to others (carriers)
- People with no obvious symptoms before and after illness may also be infective
Examples: tuberculosis, sypilis, herpes, AIDS
(shows picture of Typhoid Mary)

Nonliving Reservoirs

-Soil, water, and food can be reservoirs of infection
*presence of microorganisms often due to contamination by feces or urine
Examples: botulism, tetnus, choler, dysentery, listeriosis

Modes of infectious disease transmission:

-Is from a reservoir or a portal of exit to another host's portal of entry:
- Three groups of transmission
* contact transmission (direct or indirect)
*Vehicle transmission (airborne, waterborne, foodborne
*Vector transmission(biological - or mechanical)

Direct transmission is handshaking. Indirect is by

fomite

What is a biological vector transmission

(mosquito)

What is a mechanical vector transmission of disease?

housefly.

Droplet transmission

sneezing with spit coming out. or just germs

Poorly refrigerated foods can harbor

pathogens

Representative arthropod vectors

tick, flea, lice, tsetse fly, mosquito, true bug

Classification of Infectious Diseases

- Communicable
- Contagious
- Noncommunicable

Copmmunicable

infectious disease can be tranmitted from person to person, flu or herpes

Contagious

Communicable disease that is easily transmissible, chickenpox

Noncommunicable

Not spread from host to host, tetnus

Epidemiology of Infectious Diseases: Nosocomial Infections

- Infections acquired by pts or health care workers while they are int he health care facilities

Types of nosocomial infections

*Exogenous
*Endogenous
*Latrogenic

Exogenous nosocomial infections

pathogen acquired from the health care environment

Endogenous

Pathogen arises from normal microbiota

Latrogenic

Results from modern medical procedures (surgery, catheters)

Control of nosocomial infections

*Precautions designed to redue factors that result in disease
- disinfection, sanitary handling of food, masks, gowns
- Handwashing is the most effective way to reduce nosocomial infections

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