The following terms will be used
in exploring the issues of avian laboratory testing:
Antibody: a specific protein or immunoglobulin
produced in response to an antigenic challenge. The serum
globulins (a protein) can bind to and neutralize bacterial
toxins or band to the surface of bacteria, viruses or parasites.
Antigen: a foreign substance that can
stimulate the production of antibodies.
Bacteria: Single celled member of the
plant family found in all environments and all living multicellular
organisms, some of which may cause disease.
Bactericidal: term used to describe a
drug or chemical agent that kills microorganisms.
Bacteriostatic: term used to describe
a drug or chemical agent that inhibits the growth of an organism
without killing it.
Bursa of Fabricius: a lymphoepithelial
organ found at the junction of the hind gut and cloaca in
birds which is the site of B cell maturation. The site is
the equivalent of bone marrow in humans which produce B cells
to bind with and neutralize antigens (microorganisms)
Chlamydia: a single celled organism that
has been classified as a virus though formerly classified
as a bacteria. Chlamydia psittaci causes pneumonia
and systemic disease in humans. In birds it is called Psittacosis
or Ornithosis.
Closed Aviary: avian environment closely
controlled and maintained to ensure minimal transmission of
disease. Ideally birds do not come into or exit and reenter
the facility without extensive testing for all known pathogens
and lengthy isolation procedures are followed. Visitors are
not allowed and personnel undergo rigorous decontamination
before entering the facility.
Enteric Pathogen: Usually refers to gram
negative bacteria found in the intestines of humans.
False Positive test results: refers to
the detection of a substance or condition that is not there.
False Negative test results: refers to a result that does
not detect a substance or condition that is actually present.
Fungus: a multicellular member of the
plant kingdom which lack roots and stems and are referred
to scientifically as Thallophytes. There are over 50,000
species; of these 50 to 75 are considered pathogens. Fungi
are not usually considered communicable in the usual sense
of person to person or animal to animal transmission, Humans
and animals become an accidental host by inhalation of spores
or through an open wound. The increase that we are seeing
in avian and human infections is in part attributed to suppression
of the immune system.
Overuse or long term use of antibiotics is another
factor contributing to the increased incidence of fungal infections.
Candida and Aspergillus sp. are the most commonly
encountered fungi in avian medicine. Aspergillosis because
of the rapidity of onset and difficulty in treating has become
one of the most frightening diseases of our Parrots.
Nosocomial infection: Term used to describe
infections acquired in a hospital or medical setting. In other
words the patient did not have this infection when admitted
or was seen, but acquired it in the course of being treated.
Non-pathogen: A microorganism usually
isolated from a human or animal source that is considered
part of the normal flora and is not capable of causing disease.
Pathogen: A disease causing microorganism or agent.
Sensitivity of a test: The sensitivity
of a test reflects the level of concentration of a substance
that must be present in order for the methodology to detect
it. A highly sensitive method will detect very small amounts
of a substance. A less sensitive method will require the substance
to be present in greater concentrations for detection.
Specificity of a test: Specificity refers
to how well the method performs in detecting only the desired
substance.
Virus: a subcellular particle lacking
DNA and which cannot reproduce without invading a host and
using the host DNA.
Virulence: The degree of pathogenicity
or ability to cause disease of an organism.
Zoonotic infection or Zoonoses: Infection
caused by organisms that are capable of crossing species barriers.
Recent examples are West Nile virus, the 1997 Hong Kong influenza
virus that was transmitted from chickens to humans and several
species of Chlamydia.
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Definitions
of Terms