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Contagious disease
A contagious disease is a subset category of transmissible diseases (can transmit from
person to another), usually infections or some non-infection diseases, which are
transmitted to other persons, either by physical contact (hence the name-origin) with the
person suffering the disease, or by casual contact with their secretions or objects touched
by them or airborne route among other routes.[1]
The non-contagious category of infections usually require a special mode of
transmission between persons or hosts. These include need for intermediate vector
species (mosquitoes that cause malaria) or by non-casual transfer of bodily fluid (such
as transfusions, needle sharing or sexual contact). They can also be inherited from
parents or caused by environmental or behavioral factors.
The boundary between contagious and non-contagious infectious diseases is not
perfectly drawn, as illustrated classically by tuberculosis, which is clearly transmissible
from person to person, but was not classically considered a contagious disease. In the
present day, most sexually transmitted diseases are considered contagious, but only
some of them are subject to medical isolation.
Disease
A disease is a particular abnormal condition, a disorder of a structure or function, that
affects part or all of an organism. The causal study of disease is called pathology.
Disease is often construed as a medical condition associated with
specific symptoms and signs.[1] It may be caused by factors originally from an external
source, such as infectious disease, or it may be caused by internal dysfunctions, such
asautoimmune diseases., "disease" is often used more broadly to refer to any condition
that causes pain, dysfunction, distress,social problems, or death to the person afflicted, or
similar problems for those in contact with the person, it sometimes
includes injuries, disabilities, disorders, syndromes, infections, isolated symptoms,.
Death due to disease is called death by natural causes. There are four main types of
disease: pathogenic disease, deficiency disease, hereditary disease, and physiological
disease
The term disease broadly refers to any condition that impairs the normal
functioning of the body. For this reason, diseases are associated with
dysfunctioning of the body's normal homeostatic process.[4] Commonly, the
term disease is used to refer specifically to infectious diseases, which are clinically
evident diseases that result from the presence of pathogenic microbial agents,
including viruses, bacteria, fungi, protozoa, multicellular organisms, and aberrant
proteins known as prions. An infection that does not and will not produce clinically
evident impairment of normal functioning, such as the presence of the
normal bacteria and yeasts in the gut, or of a passenger virus, is not considered a
disease. By contrast, an infection that is asymptomatic during its incubation period,
but expected to produce symptoms later, is usually considered a disease.Noninfectious diseases are all other diseases, including most forms of cancer, heart
disease, and genetic disease.
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What is Infectious Disease?
An infectious disease or communicable disease is caused by a biological agent such as
by a virus, bacterium or parasite.
Infectious diseases are the invasion of a host organism by a foreign replicator, generally
microorganisms, often called microbes, that are invisible to the naked eye.Microbes that
cause illness are also known as pathogens. The most common pathogens are
various bacteria and viruses, though a number of other microorganisms, including some
kinds of fungi and protozoa, also cause disease. An infectious disease is
termedcontagious if it is easily transmitted from one person to another.
How are infectious diseases diagnosed?Diagnosis is initially by medical
history and physical examination, and imaging (such as X-rays), but
the principal tool in infectious disease is the microbiological culture.
A microbiological culture, or microbial culture, is a method of growing a microbial
organism to determine what it is often used a tool to determine the cause of infectious
disease by letting the agent multiply (reproduce) in predetermined media in laboratory. In
a culture, a growth medium is provided for a particular agent. After inoculation of a
specimen of diseased fluid or tissue onto the medium, it is determined whether bacterial
growth occurs.
What's the difference between infectious and contagious
Infectious diseases are caused by microscopic germs (such as bacteria or viruses) that
get into the body and cause problems. Some — but not all — infectious diseases spread
directly from one person to another. Infectious diseases that spread from person to
person are said to be contagious.
Some infections spread to people from an animal or insect, but are not contagious from
another human. Lyme disease is an example: You can't catch it from someone you're
hanging out with or pass in the street. It comes from the bite of an infected tick.
Contagious diseases (such as the flu, colds, or strep throat) spread from animal to animall
in several ways. One way is through direct physical contact, like touching who has the
infection. Another way is when an infectious microbe travels through the air after
someone nearby sneezes or coughs.
Infection
invasion and multiplication of microorganisms in body tissues, as in an infectious disease.
The infectious process is similar to a circularchain with each link representing one of the f
actors involved in the process. An infectious disease occurs only if each link is present an
d inproper sequence. These links are (1) the causative agent, which must be of sufficient
number and virulence to destroy normal tissue; (2)reservoirs in which the organism can th
rive and reproduce; for example, body tissues and the wastes of humans, animals, and in
sects, andcontaminated food and water; (3) a portal through which the pathogen can leav
e the host, such as the respiratory tract or intestinal tract; (4) amode of transfer, such as t
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he hands, air currents, vectors, fomites, or other means by which the pathogens can be m
oved from one place orperson to another; and (5) a portal of entry through which the path
ogens can enter the body of (6) a susceptible host. Open wounds and therespiratory, inte
stinal, and reproductive tracts are examples of portals of entry. The host must be suscepti
ble to the disease, not having anyimmunity to it, or lacking adequate resistance to overco
me the invasion by the pathogens. The body responds to the invasion of causativeorganis
ms by the formation of ANTIBODIES and by a series of physiologic changes known as INFLA
MMATION.
acute infection
An infection that appears suddenly and may be of brief or prolonged duration.
airborne infection
An infection caused by inhalation of pathogenic organisms in droplet nuclei.
apical infection
An infection located at the tip of the root of a tooth.
bacterial infection
Any disease caused by bacteria. Bacteria exist in a variety of relationships with the huma
n body. They colonize body surfaces and providebenefits, e.g., by limiting the growth of p
athogens and by producing vitamins for absorption (in a symbiotic relationship). Bacteria
can coexistwith the human body without producing harmful or beneficial effects (in a com
mensal relationship). Bacteria may also invade tissues, damagecells, trigger systemic infl
ammatory responses, and release toxins (in a pathogenic or infectious relationship).
See: bacterium for table
blood-borne infection
An infection transmitted through contact with the blood (cells, serum, or plasma) of an infe
cted individual. The contact may occur sexually,through injection, or via a medical or dent
al procedure in which a bloodcontaminated instrument is inadvertently used after inadequatesterilization. Examples of b
lood-borne infections include hepatitis B and C and AIDS.
needle-stick injury;
breakthrough infection
An infection that occurs despite previous vaccination.
chronic infection
An infection having a protracted course.
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morbidity rate
the speed or frequency with which an event or circumstance occurs per unit of time, popul
ation, or other standard of comparison.
., the proportion of persons who are exposed to the disease during the outbreakwho do b
ecome ill.
The proportion of patients with a particular disease during a given year per given unit of p
opulation.
the number of cases of a particular disease occurring in a single year per a specified pop
ulation unit, as x cases per 1000.
Mortality rate
Mortality rate, or death rate,[1] is a measure of the number of deaths (in general, or
due to a specific cause) in a particularpopulation, scaled to the size of that
population, per unit of time. Mortality rate is typically expressed in units of deaths
per 1,000
Prevalence
Prevalence in epidemiology is the proportion of a population found to have a condition
(typically a disease or a risk factor). It is arrived at by comparing the number of animals
found to have the condition with the total number of animals studied, and is usually
expressed as a fraction, as a percentage or as the number of cases per 10,000 or
100,000 people. Point prevalence is the proportion of a population that has the condition
at a specific point in time. Period prevalence is the proportion of a population that has
the condition at some time during a given, and includes people who already have the
condition at the start of the study period as well as those who acquire it during that
period. Lifetime prevalence (LTP) is the proportion of a population that at some point in
their life (up to the time of assessment) have experienced the condition. [1]
.
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