a disease that develops rapidly and runs its course quickly; examples are measles and the common cold.
an epidemiological study that focuses on establishing a cause-and-effect relationship in the occurrence of diseases in populations; done after the occurrence of the outbreak has been fully described, done to identify specific factors, the risk factors, that result in high frequencies of disease.
the number of cases developing the infection per 100 people exposed.
an infection in which bacteria are transported in the blood but do not multiply in transit; often occurs in cases of injury such as a cut, abrasion, or teeth cleaning.
organisms that can harbor an infectious agent without having any observable clinical signs or symptoms, but can transmit the infection to others.
develops more slowly than an acute disease, is usually less severe, and persists for a long, indeterminate period.
is a study group that has a known exposure to a risk factor; this group is selected and monitored in time; the incidences of disease of those people exposed to the risk factor and of those who were not exposed are then compared.
implies an establishment of microbial growth on or within the host
a symbiotic relationship between two species in which one benefits and the other one neither benefits nor is harmed by the relationship.
Common Source Epidemic
outbreak of disease due to contaminated food, water, or other single source of the infectious agent. An outbreak where there is a rapid rise and fall in the numbers of people who become ill, it is likely they were all exposed to a single common source of the infectious agent.
diseases that can be transmitted from one person to another; example, the common cold or influenza.
done after a disease outbreak to describe the characteristics of the ill persons involved and the place and time of the outbreak
mode of disease transmission requiring person-to-person body contact.
describes a noticeable impairment of body function.
spread of respiratory disease over distances of less than 1 meter through inhalation of large respiratory droplets.
diseases that are constantly present in a given population.
a toxin incorporated in gram-negative bacterial cell walls and released when the bacterium dies (also called lipopolysaccharide).
referring to a disease that has a higher than normal incidence in a population over a relatively short period of time.
a soluble toxin secreted by microbes into their surroundings, including host tissues (proteins).
an infection confined to a specific area from which pathogens can spread to other areas.
a nonliving substance (inanimate object), such as clothing, dishes, or money capable of transmitting disease.
the concept that an entire population is protected from infection by a particular pathogen when 70% of the population is immune to that pathogen (also called group immunity).
diseases that are transmitted by person-to-person contact; examples include hand shaking, kissing, and sexual contact.
the number of new cases of a particular disease per 100,000 population seen in a specific period of time.
the time between infection and the appearance of signs and symptoms.
transmission of disease through fomites or inanimate objects.
number of organisms required to initiate disease.
a disease characterized by periods of inactivity either before symptoms appear or between attacks.
an exotoxin produced by many bacteria, including the streptococci and staphylococci that kill phagocytes.
an infection confined to a specific area of the body.
an infection caused by several species of organisms present at the same time.
the number of persons contracting a specific disease in relation to the total population (cases per 100,000); the number of cases divided by the population at risk.
the number of deaths from a specific disease in relation to the total population; the fraction of people who die from the disease.
a symbiotic relationship in which both partners benefit.
Normal microbial flora
the microorganisms that grow on the external and internal surfaces of the body without producing obvious harmful effects to these tissues.
an infection acquired during a hospitalization.
Opportunists (opportunistic organisms)
an organism that does not ordinarily cause disease but can do so when the host defense mechanisms are impaired.
a worldwide epidemic.
a symbiotic relationship in which one organism, the parasite, benefits from the relationship, whereas the other organism, the host, is harmed by it.
the number of people infected with a particular disease at any one time.
outbreak of contagious disease in which the infectious agent is transmitted to others, resulting in a steady increase in the numbers of persons becoming ill.
a study that looks ahead to see if the identified risk factors can predict a tendency to develop the disease.
a study done following a disease outbreak; looks back to compare the actions of and events surrounding those who developed the disease with those who did not develop the disease (controls).
infection that follows a primary infection.
an infection caused by rapid multiplication of pathogens in the blood (also called blood poisoning).
a disease characteristic that can be observed by examining the patient, such as swelling or redness.
a disease that is intermediate between an acute and a chronic disease.
Subclinical infection or disease
a disease lacking obvious symptoms.
a type of exotoxin that reacts with a part of the T cell receptor not concerned with antigen recognition, thereby stimulating activity nonspecifically in many T cells and leading to illness and sometimes fatal shock.
a secondary infection resulting from the removal of normal microbiota, allowing colonization by pathogenic, and often antibiotic- resistant microbes.
a disease characteristic that can be observed or felt only by the patient, such as pain or nausea.
a combination of signs and symptoms that occur together.
an infection that affects the entire body (also called generalized infection).
an exotoxin inactivated by chemical treatment but which retains its antigenicity and therefore can be used to immunize against the toxin.
Transient microbial flora
microorganisms that inhabit the body only occasionally.
an organism that actively transmits diseases through injecting an infectious agent into another host while taking a blood meal; the pathogen completes part of its life cycle within the organism (examples are mosquitoes, fleas, and ticks).
organisms that transmit diseases passively on their feet and body parts (examples are houseflies.
diseases passed directly from a pregnant woman to the fetus or mother to a newborn.
the relative ability of a pathogen to overcome body defenses and cause disease; properties of microorganisms that assist pathogenicity.
a structural or physiological characteristic that helps a pathogen cause infection and disease.
a disease of animals that can be transmitted to humans.