Microbiology Ch. 14 - Principles of disease and epidemiology

The bacterium Treponema pallidum is known to cause Syphilis but virulent strains have never been cultured on

artificial media

The causative agent of leprosy, Myobacterium Leprae, has never been grown on

artificial media

agents of a local infection enter a blood or lymphatic vessel and spread to other specific parts of the body, where they are confined to a specific areas of the body.

focal infection

these infections can arise from infections in areas such as teeth, tonsils or sinuses

focal infection

Few microorganisms are pathogenic. The presence of some microorganisms can even benefit the

host

principal living reservoir of human disease is the

human body

reservoir of infection can use these sources

human, animal or nonliving

During the period of ______, people can serve as reservoirs of disease and can easily spread infection to other people.

illness

The patients immune response and other defense mechanisms overcome the pathogen and the period of _________ ends. If disease is not successfully overcome, patient dies during this period

illness

people who are _________ to an infectious disease will not be carriers

immune

number of people in a population who develop a disease during a particular time period. Indicator of the spread of the disease

incidence

depends on specific microorganism involved, its virulence, number of infection organisms and the resistance of the host.

incubation period

presence of particular type of microorganism in a part of the body where it is not normally found

infection

Before a women gives birth, _________ in her vagina multiply rapidly

lactobacilli

Newborns first contact with microorganisms/ predominant organisms in the newborns intestine

lactobacilli

A Disease in which the causative agent remains inactive for a time but them becomes active to produce symptoms of the disease - example: shingles caused by varicella virus

latent disease

Both wild and domestic animals are _____ _________ of microorganisms that can cause human diseases.

living reservoirs

normal microbiota can benefit the host by preventing the overgrowth of harmful microorganisms.

microbial antagonism or competitive exclusion

is not spread from one host to another

noncommunicable disease

tetanus: clostridium tetani produces disease only when it is introduced into the body via abrasions or wounds

noncommunicable disease

Two major ______ _________ of infectious disease are soil and water.

nonliving reservoirs

Age, nutritional status, diet, health status, disability, hospitalization, emotional state, stress, climate, geography, personal hygiene, living conditions, occupation and lifestyle. These factors affect:

normal microbiota

ordinarily do not cause disease in their normal habitat in a healthy person by may do so in a different environment.

opportunistic pathogens

An epidemic disease that occurs worldwide, we experience influenzas from time to time or AIDS

pandemic disease

one organism benefits by deriving nutrients at the expense of the other; this relationship is called

parasitism

The manner in which disease develops

pathogenesis

The microorganism injures the host through a process called The extent of the injury depends on the degree to which host cells are damaged

pathogenesis

The patient regains strength and the body returns to its prediseased state. recovery has occurred.

period of convalescence

Makes the body more susceptible to a disease and may alter the course of the disease

predisposing factor

Gender, genetic background, climate and weather, inadequate nutrition, fatigue, age, habits, environment, lifestyle, occupation, preexisting illness, chemotherapy and emotional disturbances.

predisposing factors

number of people in a population who develop a disease a specified time, regardless of when it first appeared. takes into account both old and new cases. indicator of how serious and how long a disease affects a populations.

prevalence

An acute infection that causes the initial illness

primary infection

For a disease to perpetuate itself, there must be a continuous source of the disease organisms, source can be either living or inanimate object that provides the pathogen with adequate conditions for survival and multiplication and an opportunity for transmission

reservoir of infection

Pneumocystis Pneumonia as a consequence of AIDS, Streptococcal bronchopneumonia following influenza - example of a

secondary infection more serious than primary infection

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

sepsis

objective changes the physician can observe and measure

signs

according to Kochs Postulates, a specific infectious disease is caused by a

specific microbe

If a particular disease occurs only occasionally, example is typhoid fever in the US

sporadic disease

A disease that is intermediate between acute and chronic is, example subacute sclerosing panencephalitis - rare brain disease characterized by diminished intellectual function and loss of nervous function

subacute disease

a relationship between two organisms in which at least one organism is dependent on the other.

symbiosis

relationship between normal microbiota and the host

symbiosis

changes in body function such as pain and malaise

symptoms

A specific group of symptoms or signs may always accompany a particular disease

syndrome

human body has ________ more bacterial cells than human cells

ten times

Microorganisms that may be present for several days, weeks, or months and then disappear

transient microbiota

The human body has __________ bacterial cells

1 X 10^14

The typical human body contains ___________body cells

1 x 10^13

thyphoid Mary is a example of a

Carrier

develops more slowly and the body's reactions may be less severe but the disease is likely to continue or recur for long periods of time.

Chronic Disease

evaluation of the signs and symptoms together with the results of lab tests

Diagnosis

occurs when an infection results in any change from a state of health.

Disease

If many people in a given area acquire a certain disease in a relatively short period, example is influenza

Epidemic disease

Cause of disease

Etiology

Many immune people are present in a community

Herd Immunity

Began in 2007, to analyze microbial communities called microbiomes that live in and on the human body

Human Microbiome Project

__________ individuals act as a barrier to the spread if infectious agents

Immune

Rate of which a disease or epidemic spreads is determined in part by

Immunity of the population

The _________ of AIDS in the US in 2007 was 56,300 whereas the _____________ in that same year was estimated to be about 1,185,000

Incidence, Prevalence

Interval between the initial infection and the first appearance of any signs or symptoms. Some diseases this time is the same in others its variable

Incubation period

the invasion or colonization of the body by pathogenic microorganisms

Infection

enables scientists to estimate the range of the diseases occurrence and its tendency to affect some groups of people more than others.

Knowing the incidence and prevalence

1. The same pathogen 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 form the pure culture must cause the disease when it is 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.

Koch's Postulates

one which the invading microorganisms are limited to a relatively small area of the body. EX: boils and abscesses

Local infection

type of symbiosis that benefits both organisms

Mutualism

Microorganisms that establish more or less permanent residence (colonize) but that do not produce disease under normal conditions are members of the body's

Normal microbiota or Normal flora

Scientific study of disease

Pathology

Signs and symptoms subside. Fever decreases and the feeling of malaise diminishes. During this period, the patient is vulnerable to secondary infection

Period of decline

the disease is most severe, the person exhibits overt signs and symptoms of the disease such as fever, chills, muscle pain, sensitivity to light, sore throat, enlargement of lymph nodes and gastrointestinal disturbances.

Period of illness

relatively short period that follows the period of incubation in some disease. Characterized by early, mild symptoms of diseases such as general aches and pains.

Prodromal Period

___ nonliving reservoir pathogens as fungi, which causes mycoses such as ringworm and systemic infections

SOIL

__________ infections of the skin and respiratory tract are common and sometimes more dangerous than the primary infection

Secondary

Caused by an opportunistic pathogen after the primary infection has weakened the body's defenses.

Secondary infection

Septicemia is a common example of

Sepsis

blood poisoning, systemic infection arising form the multiplication of pathogens in the blood

Septicemia

For an infectious disease to occur, there must be a reservoir of infection as a source of pathogens, the pathogen must be transmitted to a susceptible host by direct contact, indirect contact or vectors. Transmission is followed by invasion, microorganisms enter host and multiply, occurrence of the disease depends on the resistance of the host to activities of the pathogen.

Sequence of events during infection

Polio virus and hepatitis A virus can be carried by people who never develop the illnes

Subclinical infection

one that does not cause any noticeable illness

Subclinical or inapparent infection

microorganisms or their products are spread throughout the body by the blood or lymph

Systemic infection or generalized

The presence of bacteria toxins in the blood (tetanus)

Toxemia

provide long lasting and sometimes lifelong protection of an individual against certain diseases

Vaccination

presence of viruses in the blood

Viremia

____ that has been contaminated by feces of humans and animals is a reservoir for several pathogens, usually gastrointestinal disease

WATER

Rabies found in bats, skunks, foxes, dogs and coyotes; Lyme disease found in field mice are examples of

Zoonoses

There are 150 known ______. These can be transmitted to humans via many routes; direct contact with infected animals, direct contact with domestic pet waste, by contamination of food and water, by air from contaminated hides, fur or feathers or by consuming infection animal products or insect vectors.

Zoonoses

diseases that occur primarily in wild and domestic animals and can be transmitted to humans is called

Zoonoses

The state of host resistance also determines the ________ of the infection

extent

Disease that develops rapidly but lasts only a short time, ex: influenza

acute disease

The presence of bacteria in the blood

bacteremia

Human ________ play a role in spread of diseases AIDs, diphtheria, typhoid fever, hepatitis, gonorrhea, amebic dysentery and streptococcal infection

carriers

These people, are important living reservoirs of infection

carriers

Infectious mononucleosis, tuberculosis and hepatitis B are examples of

chronic disease

one of the organisms benefits and the other is unaffected.

commensalism

staphylococcus epidermis, surface of skin, corynebacteria, surface of eye, saprophytic mycobacteriua in the ear and external genitals

commensalism

Any disease that spreads from one hose to another, either by directly or indirectly is said to be a

communicable disease

Chickenpox, measles, genital herpes, typhoid fever and Tuberculosis as examples of

communicable disease

chicken pox and measles are also examples of

contagious diseases

diseases that are easily spread from one person to another

contagious diseases

An infection may exist in the absence of

detectable disease

modifications of Kochs postulates and the use of alternative methods of culturing and detecting certain microbes.

discovery of microorganisms that cannot grow on artificial media

A disease constantly present in a population, example is common cold

endemic disease