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caused by or capable of being communicated by infection.
infectious disease one due to organisms ranging in size from viruses to parasitic worms; it may be contagious in origin, result from nosocomial organisms, or be due to endogenous microflora from the nose and throat, skin, or bowel. See also communicable disease.

An emerging infectious disease is one that is endemic in a given population but that has begun increasing in frequency or developing resistance to drug therapy or other treatments.


1. A disease capable of being transmitted from person to person, with or without actual contact.
2. Synonym(s): infective
3. Denoting a disease due to the action of a microorganism.


/in·fec·tious/ (-fek´shus)
1. caused by or capable of being communicated by infection, as an infectious disease.
2. infective (1).


1. Capable of causing infection: an infectious microorganism.
2. Capable of being transmitted by infection: an infectious disease.
3. Capable of transmitting a disease; contagious: Is the patient still infectious?

in·fec′tious·ly adv.
in·fec′tious·ness n.


1 capable of causing an infection.
2 caused by an infection.


1. Referring to an infection.
2. Capable of spreading infection–eg, expulsion of infected aerosol by coughing or sneezing.


1. Capable of being transmitted by infection, with or without actual contact.
2. Caused by infection of the body by pathogenic organisms; not a synonym for contagious.
Synonym(s): contagion.
Synonym(s): infective.


capable of causing or transmitting infection


1. Disease capable of being transmitted from person to person, with or without actual contact.
2. Synonym(s): infective.


adj contagious; communicable; capable of causing infection.


caused by or capable of being communicated by infection.

infectious avian nephritis
caused by a picornavirus this disease of young chickens causes a transient unremarkable disease with lesions appearing in the kidney.
infectious bovine cervicovaginitis
thought to be due to a herpesvirus-4 infection, transmitted by coitus, causing sterility in a high percentage of cows and some bulls. Recorded only in South Africa. Called also epivag.
infectious bovine keratoconjunctivitis
the common infectious keratitis of cattle caused by Moraxella bovis with solar radiation, dust and face flies as contributing factors.. It occurs as outbreaks, characterized by ocular discharge, blepharospasm and pain. Underrunning of the conjunctiva leads to complications in a few cases. Called also pinkeye, blight, New Forest disease.
infectious bovine meningoencephalomyelitis
infectious bovine rhinotracheitis (IBR)
a highly infectious disease of cattle, particularly when crowded together as in feedlots, caused by bovine herpesvirus 1 and characterized by nasal discharge, rhinitis, tracheitis, conjunctivitis, fever and a short course unless complicated by other infections, particularly those leading to pneumonia. Less common forms of the disease include encephalitis in calves and a systemic infection in neonates, manifested by oral erosions and diarrhea. Infectious pustular vulvovaginitis is also caused by this virus. Called also rednose.
infectious bulbar paralysis
infectious caprine keratoconjunctivitis
contagious ophthalmia caused by Mycoplasma conjunctivae.
infectious coryza
see fowl coryza.
infectious equine anemia
see equine infectious anemia.
infectious equine bronchitis
see equine influenza.
infectious equine cough
see equine influenza.
infectious equine encephalomyelitis
see equine viral encephalomyelitis.
infectious hematopoietic necrosis of fish
important rhabdoviral infection of Onchorhyncus spp. especially steelhead (anadromous rainbow trout).
infectious hypodermal and hemopoietic necrosis
parvovirus infection causing high mortalities in juvenile Penaeus stylirostris and runt deformity syndrome in P. vanname.
infectious labial dermatitis
see contagious ecthyma.
infectious laryngotracheitis (ILT)
a highly infectious disease of birds of all ages caused by avian herpesvirus 1 and characterized by a very rapid spread of respiratory distress, the signs including gasping, respiratory gurgling and rattling, and death often from asphyxiation because of massive pseudomembrane formation in the trachea. The mortality rate may be as high as 70%.
infectious necrotic hepatitis
an acute toxemia of cattle, sheep and pigs caused by Clostridium novyi which elaborates a toxin in necrotic infarcts in the liver. These infarcts are caused usually by larvae of Fasciola hepatica. Many affected animals are found dead. Clinical findings include severe depression, hypothermia and muffling of heart sounds. Called also black disease.
infectious pancreatic necrosis of fish
a disease of salmonids caused by a group of related birnaviruses. It is characterized by hemorrhages and anemia, and spiral swimming and abdominal distention in fry.
infectious porcine dermatitis
see contagious porcine pyoderma.
infectious porcine polyarthritis
infectious pustular vulvovaginitis
see infectious pustular vulvovaginitis.
infectious salmon anemia
severe disease of Atlantic salmon, reported only, to date, from Norway; characterized by liver necrosis caused by an unidentified virus.
infectious serositis
a septicemic disease of young ducks caused by Riemerellaanatipestifer and characterized by torticollis, head tremor, loss of balance and a high mortality rate.
infectious sinusitis
a contagious disease of turkeys caused by Mycoplasma gallisepticum. The same infection also causes chronic respiratory disease of chickens. The disease in turkeys is characterized by swelling of the infraorbital sinuses, which are filled with thick exudate. The course is chronic and the death rate low but there is severe loss of condition and damage to the respiratory tract.
infectious stunting syndrome
caused by an enterolike virus this disease causes serious losses in the broiler industry; it is characterized by severe growth depression commencing at 1 week of age or earlier. Called also helicopter disease.
infectious synovitis
see infectious avian synovitis.

Patient discussion about infectious

Q. Is psoriasis infectious? Last week I and my friends from high-school went to the pool. One of my friend has psoriasis on his back, and when the lifeguard noticed it he asked him to leave the pool because he has skin disease that may spread to the other people swimming in the pool. We told him it is psoriasis and not some fungus, but he told us that psoriasis is also infectious. Is that true? Can psoriasis infect people who come in touch with people with psoriasis? Can I go swimming with him or should be more cautious?

A. It is right that psoriasis is not a contagious skin condition. But your friend should take care. However keeping skin humid is better for Psoriasis patients as I recently read these tips at

Q. Is leukemia contagious? A friend of mine got leukemia (blood cancer), can I get it from him if he bleeds and I touch the blood? Like HIV I mean.

A. No, you don't have to be afraid, no chance of that. Your friend will need you to pass this terrible illness. So I recommend learning a bit about leukemia so you understand it better and won't avoid your friend.
You can get information on those 2 sites:

Q. Is psoriasis contagious? My wife got psoriasis and I don’t want to get infected…

A. Psoriasis itself, as was written above, isn't contagious, i.e. if someone has psoriasis he or she can't transmit it to you. However, there is a form of psoriasis called psoriasis guttate that is associated with infection of the throat by a bacterium called streptococcus (which is contagious), so in some way it is contagious.

You may read more here:

More discussions about infectious
References in periodicals archive ?
When scrutinized carefully, we see that the EPA definitions and most state agency definitions for infectious waste actually do fit into the CDC categories.
Infectious waste is "waste which contains pathogens with sufficient virulence and quantity so that exposure to the waste by a susceptible host could result in an infectious disease" (Sell, 1990).
3 Infectious Immunology Test Reagents Pipeline Products By Development Stage
Emphasis on cell-mediated immunity versus humoral immunity changes according to the type of T-helper lymphocytes responding to an infectious threat.
The report found that 17 million people died from infectious diseases in 1995.
But a few bacteria and many viruses, fungi, and protozoa can cause infectious diseases and play a role in cancers, coronary heart disease, diabetes, multiple sclerosis, autism, and chronic lung diseases.
In an attempt to rid the infectious fractions of any prions that might remain, the Yale team treated the samples with a chemical that breaks down proteins not bound to nucleic acids.
WHO: The International Society for Infectious Diseases is the only global membership organization for health professionals committed to improving the care of patients with infectious diseases, the training of clinicians and researchers in infectious diseases and microbiology, and the control of infectious diseases around the world.
Nevertheless, since EM and PCR cannot discriminate between infectious and noninfectious virus particles or nucleic acids, they are not satisfactory when an evaluation of the infectious capacity of viral particles is required.
Developed countries such as the United States have become too complacent about medical science's ability to snuff out whatever novel infectious diseases may flare up, warns a report released last week by the Institute of Medicine, an arm of the U.
OTCBB:CGXP), a biopharmaceutical company focused on infectious disease and dermatology, today announced Michael J.

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