Disease Detectives Division B

Epidemic

The occurrence of more cases of disease, injury, or other health condition than expected in a given area or among a specific group of persons during a particular period. Also known as an outbreak.

Endemic

Constant presence of an agent or health condition within a given geographic area or population.

Pandemic

Epidemic over a wide geographic area and affecting a large proportion of the population.

Vector

a living intermediary that carries an agent from a reservoir to a susceptible host.

Host

A person or other living under natural conditions.

Prevalence

The number or proportion of cases or events or attributes among a given population.

Zoonosis

An infectious disease that is transmissible from animals to humans.

Airborne

Transfer of an agent suspended in the air, considered a type of indirect transmission.

Incidence

A measure of the frequency with which new cases of illness.

Carrier

A person or animal that harbors the infectious agent for a disease and cam transmit it to others, but does not demonstrate signs of the disease.

Surveillance

Monitoring of a person who might have been exposed to an infectious, chemical, radiological, or other potentially causal agent, for the purpose of detecting early symptoms.

Reservoir

The habitat in which an infectious agent normally lives, grows, and multiplies, which can include humans, animals, or the environment.

Transmission

Any mode or mechanism by which an infectious agent is spread to a susceptible host.

Epidemiology

the branch of medicine that deals with the incidence, distribution, and possible control of diseases and other factors relating to health.

Epidemiologist

Someone who studies the distribution and determined of health conditions or events among populations and the application of that study to control health problems.

Plague

A serious, potentially life-threatening infectious disease that is usually transmitted to humans by the bites of rodent fleas. It was one of the scourges of our early history. There are three major forms of the disease: bubonic, septicemic, and pneumonic.

Fomite

A physical object that serves to transmit an infectious agent from person to person. An example of this is lice on a comb. The comb is the fomite and the lice is the agent that can make your hair itch.

Incubation Time

Time in between when a person comes into contact with a pathogen and when they first show symptoms or signs of disease.

Agent

A microbial organism ability of causing disease. ¬Part of the Epidemiological Triad/Triangle.

Epithelial Surface

an open surface that allows infectious materials into the body (not an opening). Ex: skin, internal mucosal surfaces of the respiratory, gastro-intestinal, and urogenital tracts.

Innate Immunity

The early phases of the host response to infection depend on innate immunity in which a variety of innate resistance mechanisms recognize and respond to the presence of a pathogen. Innate immunity is present in all individuals at all times, does not increase with repeated exposure to a given pathogen, and discriminates between a group of related pathogens.

Adaptive Immune Response

The adaptive immune response or adaptive immunity is the response of antigen-specific lymphocytes to antigen, including the development of immunological memory. Adaptive immune responses are generated by clonal selection of lymphocytes. Adaptive immune responses are distinct from innate and nonadaptive phases of immunity, which are not mediated by clonal selection of antigen-specific lymphocytes. Adaptive immune responses are also known as acquired immune responses.

Morbidity

Any departure, subjective or objective, from a state of physiological or psychological health and well being

Bias

A systematic deviation of results or inferences from the truth or processes leading to such systematic deviation

Cluster

an aggregation of cases over a particular period esp. cancer & birth defects closely grouped in time and space regardless of whether the number is more than the expected number

Risk

The probability that an individual will be affected by, or die from, an illness or injury within a stated time or age span. The probability that an event will occur.

Classical Epidemiology

population oriented, studies community origins of health problems related to nutrition, environment, human behavior, and the psychological, social, and spiritual state of a population. The event is more aimed towards this type of epidemiology.

Clinical Epidemiology

studies patients in health care settings in order to improve the diagnosis and treatment of various diseases and the prognosis for patients already affected by a disease. These can be further divided into:

Infectious Disease Epidemiology

heavily dependent on laboratory support

Chronic Disease Epidemiology

dependent on complex sampling and statistical methods

Ecological

comparisons of geographical locations

Cross Sectional

a survey,health questionnaire, "snapshot in time"

Case-Control

compare people with and without disease to find common exposures

Cohort

compare people with and without exposures to see what happens to each

Randomized Controlled Trial

human experiment

Quasi Experiments

research similarities with traditional experimental design or RCT, but lack element of random assignment to treatment/control

Direct Contact

occurs through touching, kissing, and/or sexual intercourse. To prevent direct contact transmission, wear gloves and masks, use condoms, etc.

Indirect Contact

occurs from a reservoir via inanimate objects called fomites. Fomites are basically almost anything an infected individual or reservoir can touch, upon which can be left a residue of contagious pathogen. Exceptions include the various inanimate referred to as vehicles: food, air, and liquids. Typically, it is more difficult to avoid indirect contact transmission than it is to avoid direct contact transmission. A certain degree of organismal durability may be necessary to survive passage on a fomite. The best way to prevent indirect contact transmission is by avoiding contact with fomites, avoiding contact of hands with mucous membranes, especially when handling or potentially handling fomites, the use of barriers when handling fomites, and disinfecting fomites before handling.

Droplet Transmission

consequence of being coughed, sneezed, or spit on. To be considered droplet transmission, mucous droplets must still be traveling with the velocity imparted on it leaving the mouth. As a rule of thumb, this is up to one meter after exiting the mouth. Any further and this is considered airborne transmission. Given interaction within one meter of people is certainly more difficult to avoid droplet transmission than it is to avoid either direct or indirect transmission. Not surprisingly, it is especially respiratory diseases that are transmitted by droplets.

Vehicle Transmission

transmission via a medium such as food, air, and liquid, which are al routinely taken into the body, and thus serve as vehicles into the body.

Airborne Transmission

occurs via droplets (typically mucous droplets) where droplets are liquids that remain airborne whether as aerosols (very small droplets) or associated with dust particles. An example is within airliners where economizing measures reduces the turnover of cabin air and consequently increases air recycling. Organisms which can find their way into the air and remain viable thus have repeated opportunities to infect passengers. It requires greater organismal durability that droplet transmission simply because of the length of time the microorganism is exposed to the air, before infecting a new host, is longer. Increased durability is to the effects of desiccation, exposure to sunlight, etc. This is why breathing does not typically result in the acquisition of disease.

Food-borne Transmission

any number of pathogens are found in food and not killed during processing may be transmitted via food product. Salmonella especially tends to be part of the normal flora of chickens and consequently associated with chicken products.

Water-borne Transmission

fecal contaminated water. Generally, this is via sewage contaminated water supplies. It is especially gastrointestinal pathogens that are present in feces and therefore which rely on this type of transmission.

Vector Transmission

transmission of an infectious agent by an insect, arthropod, or animal

Portals of Entry to the Nervous System

the brain is typically fairly resistant to bacterial infection. There are four common portals of entry to the nervous system. For an organism to take advantage of these routes, they must display increasingly specialized adaptations as read from first to last: parenteral, via the blood, via the lymphatic systems, and up the peripheral nerve axons. Ordering of blood and lymphatic system was arbitrary and not intended to imply that one serves as a significantly more difficult portal to take advantage of than the other