Chapter 14 Principles of Disease and Epidemiology

Identify four predisposing factors for disease.

-Gender -Inherited traits, such as the sickle cell gene -Climate and weather -Lack of vaccination -Fatigue -Age -Lifestyle -Nutrition Chemotherapy

What are Koch's postulates used for?

-experimental requirements for identifying the agent of an infectious disease.

How does Shigella spread to new cells?

-through the gaps between the inflammation-destroyed junctions between the epithelial cells -by polymerizing actin filaments from the host into a tail-like structure that can propel them

List Koch's postulates in order.

1. The suspected agent must be present in every case of the disease. 2. The pathogen must be isolated from the diseased host and grown in pure culture. 3.The pathogen from the pure culture must cause the disease when it's inoculated into a healthy, susceptible laboratory animal. 4. The pathogen must be isolated from the inoculated animal and must be shown to be the original organism

Describe how the human microbiome is acquired.

A complex ecosystem of microorgamisms (bacteria, fungi, protozoans) living in and on the human body. •Begins to established in utero •More microorganisms acquired from food, people, and pets •Remain throughout life •Distribution and composition of normal microbiota are determined by many factors -Nutrients -Physical and chemical factors -Host defenses Mechanical factors •Vaginal birth -prevalently Lactobacillus and Bacteroides •Cesarean birth -microbiome resembles the human skin -Staphylococcus aureus •Microbial antagonism (competitive exclusion) is a competition between microbes •Normal microbiota protect the host by: -Competing for nutrients -Producing substances harmful to invading microbes -Affecting pH and available oxygen

disease

An abnormal state in which the body is not performing normal functions

human reservoirs

Carriers may have inapparent infections or latent diseases

Collagenase is a virulence factor of _______________.

Clostridium.

Only Gram-positive cells produce endotoxin. T/F

False Gram- produce also

Why is peptidoglycan an antigen that immune cells detect?

It is unique to bacteria, and absent from host cells.

How does Streptococcus pneumoniae avoid destruction by the host immune system?

It produces a capsule, which makes it undetectable by the immune system.

Why does altering surface antigens help pathogens hide from the immune system?

It selects for surface antigens that are not recognized by the immune system

Endotoxin is another name for __________________.

Lipid A

How do A-B toxins function?

The B domain binds to a target cell receptor, while the A domain has a specific function.

What is the role of M cells?

They are the antigen-sampling cells of the intestines.

How do superantigens help a pathogen survive?

They distract the host from eliciting a specific immune response against the pathogen.

How do bacteria such as Listeria escape phagocytosis?

They literally escape from the phagosome

How might Neisseria inactivate host defenses?

They secrete peptidase to destroy IgA AND they use a control molecule mimic to inactivate the complement system.

Why are nosocomial infections a concern for health care workers?

Thousands die each year from nosocomial infections.

animal reservoirs

Zoonoses are diseases transmitted from animals to humans

Describes exotoxins

a bacterial protein that is secreted by a living bacterium into its surroundings, and that can be detrimental to its host

reservoir of infection.

a continual source of infection

noncommunicable disease

a disease that is not spread from one host to another

communicable disease

a disease that is spread from one host to another

syndrome

a specific group of signs and symptoms that accompany a disease

primary infection

acute infection that causes the initial illness

Virulence factors help pathogens establish infection by ___________________________.

allowing them to attach to the host cell. allowing them to penetrate the host tissues. helping them avoid detection and destruction by the immune system.

septicemia

also known as blood poisoning; growth of bacteria in the blood

Human Microbiome Project

analyzes relationships between microbial communities on the body and human health

What are involved in host surveillance of pathogens?

antibodies phagocytes cytotoxic T-cells

Bacteremia

bacteria in the blood

How do staphylokinases help some pathogens penetrate the body's tissues?

by dissolving blood clots that are protecting the skin barrier

latent disease

causative agent is inactive for a time but then activates and produces symptoms; shingles

The function of prostagladins is ________________.

cause fever

Etiology

cause of disease

Signs

changes in a body that can be measured or observed as a result of disease

Symptoms

changes in body function that are felt by a patient as a result of disease

What type of nosocomial infection is most common among newborns?

cutaneous

chronic disease

develops more slowly and the body's reactions may be less severe, but the disease is likely to continue or recur for long periods; TB, hep B

epidemic disease

disease acquired by many people in a given area in a short time

endemic disease

disease constantly present in a population

sporadic disease

disease that occurs only occasionally

Contagious diseases

diseases that are easily and rapidly spread from one host to another

Cytokines are responsible for _________________.

drop of blood pressure AND blood clotting.

What falls under the category of contact transmission?

droplet transmission

When is endotoxin likely to be released?

during cell division during phagocytosis when the bacterium dies

Superantigens are ___________________.

exotoxins that stimulate an excessive immune response.

Inanimate objects that can spread disease are called ___________.

fomites.

What is the most likely source of antibiotic-resistant microbe exposure to a patient?

health care workers

Which of the following are areas of disease that are studied by epidemiology?

how a disease is transmitted

Continual sources of infection

human, animal, nonliving

herd immunity

immunity in most of a population

Systemic (generalized) infection

infection throughout the body

subacute disease

intermediate between acute and chronic

infection

invasion of the body by a pathogenic organism

Hyaluronidase _______________________.

is an enzyme that breaks apart hyaluronic acid.

What is the function of leukocidins?

killing of phagocytes

Which of the following are ways that exotoxins are classified?

location of effect on host structure of the exotoxin how the exotoxin functions

transient microbiota

may be present for days, weeks, or months

Which pathogen would use immune system suppression to evade destruction by the host?

measles

Botulism toxin is an example of which type of exotoxin?

neurotoxin

subclinical disease

no noticeable signs or symptoms (inapparent infection)

Prevalence

number of people who develop a disease at a specified time, regardless of when it first appeared -Takes into account both old and new cases

Incidence

number of people who develop a disease during a particular time period

Acute disease

one that develops rapidly but lasts only a short time; influenza, hep A

secondary infection

opportunistic infection after a primary (predisposing) infection

Local infection

pathogens are limited to a small area of the body

normal microbiota

permanently colonize the host and do not cause disease under normal conditions

What actions can prevent nosocomial infections by health care workers?

proper disinfection and sterilization of equipment proper disposal of infectious material using protective equipment when appropriate

Invasins are _______________________.

proteins that cause the host cell to engulf the Salmonella pathogen.

direct contact transmission

requires close association between infected and susceptible host

The loss of electrolytes and water by intestinal cells results in ___________________________.

secretory diarrhea.

What factors should be considered when selecting needles to minimize the spread of nosocomial infections?

single use disposable sterilized

Where would you likely find an infection caused by an enteric pathogen?

small intestines

nonliving reservoirs

soil and water

indirect contact transmission

spreads to a host by a nonliving object called a fomite

Pathology

study of disease

What is not considered a factor in patient susceptibility to nosocomial infections?

surgical equipment

Mutualism

symbiotic relationship in which both species benefit from the relationship Ex: Oxpecker (a kind of bird) and the rhinoceros or zebra. ... The oxpeckers get food and the beasts get pest control.

Commensalism

symbiotic relationship in which on organism benefits while the other is unaffected Ex: Remora fish have a disk on their heads that makes them able to attach to larger animals, such as sharks, mantas, and whales

Parasitism

symbiotic relationship in which one organism benefits by deriving nutrients at the expense of the other. Ex: Fleas or ticks that live on dogs and cats are parasites. They are living off of the blood of the host animal. Lice are another type of parasite.

focal infection

systemic infection that began as a local infection

The primary goal of a health care professional should be ____________________________.

the health of the patient.

Incidence is _________________.

the number of new cases of a disease over a period of time

contact transmission

the spread of an agent of disease by direct contact indirect contact droplet transmission

What is an example of a passive transfer of a vector disease?

the spread of disease via a fly walking on food

What is the role of epidemiology?

to learn how to treat and prevent the spread of disease

Sepsis

toxic inflammatory condition arising from the spread of microbes, especially bacteria or their toxins, from a focus of infection

Toxemia

toxins in the blood

Congenital transmission

transmission from mother to fetus or newborn at birth

What is the most common type of nosocomial infection?

urinary tract

What is a major category of disease transmission?

vector transmission

Viremia

viruses in the blood

One step that both patients and health care workers can take to limit nosocomial infections is ______________________________.

washing their hands.

When does droplet transmission become aerosol transmission?

when the distance of transfer is greater than 1 meter

pandemic disease

worldwide epidemic

What is the sequence of disease development?

•Incubation period: interval between initial infection and first signs and symptoms •Prodromal period: short period after incubation; early, mild symptoms •Period of illness: disease is most severe •Period of decline: signs and symptoms subside •Period of convalescence: body returns to its prediseased state

Koch's Postulates Exceptions

•Koch's postulates are used to prove the cause of an infectious disease •Exceptions to Koch's postulates -Some pathogens can cause several disease conditions -Some pathogens cause disease only in humans -Some microbes have never been cultured

By employing more stringent aseptic techniques, health care workers can decrease nosocomial infections by how much?

30%

Contrast normal microbiota and transient microbiota with opportunistic microorganisms.

Normal microbiota and transient microbiota can also be opportunist microorganisms when they are in different environments than normal or the host's immune system is suppressed. Opportunistic microorganisms do not have to have a permanent residence in the host.