Special pathogen
A highly infectious agent that produces severe disease in humans. Special pathogens include the viruses that cause several hemorrhagic fevers, such as Ebola hemorrhagic fever, Lassa fever, and hantavirus pulmonary syndrome, and other recently identified and emerging viral diseases, such as Nipah virus encephalitis. These viruses are RNA-coded (often negative-stranded or ambisense in coding strategy), encased in a lipid envelope, and display a degree of aerosol infectivity in the laboratory. In addition, all of the viruses are vector-borne zoonotic agents (meaning that under normal conditions, these viruses exist in animals); the majority are found in rodents, but some occur in other mammals or arthropods as well. All of these viruses are classified as Biosafety Level 4 (BSL-4) pathogens and as such must be handled in special facilities designed to contain them safely. The coronavirus that causes SARS (severe acute respiratory syndrome) is considered a special pathogen.
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A disorder that selectively affects one area of development, sparing essentially all other areas of development. For example, dysgraphia is one type of specific developmental disorder. In dysgraphia there is inability to write legibly. Problems in dysgraphia may include fine-motor muscle control of the hands and/or processing difficulties. Sometimes occupational therapy is helpful. Most successful […]
- Specific-pathogen free
A term that is applied to animals reared for use in laboratory experiments which indicates that the animals are known to be free of germs that can cause disease. Abbreviated SPF.
- Specificity
1. The quality of being specific as, for example, she showed the use of specificity in her diagnosis. 2. The proportion of persons without a disease who are correctly identified by a test. The specificity is the number of true negative results divided by the sum of the numbers of true negative plus false positive […]
- Speckled iris
Due to little white (or lightly colored) spots that are slightly elevated on the surface of the iris. These spots, arranged in a ring concentric with the pupil, occur in normal children but are far more frequent in Down’s syndrome (trisomy 21). They were described in 1924 by Thomas Brushfield, are called Brushfield’s spots, and […]
- SPECT
An acronym that stands for Single Photon Emission Computed Tomography, a nuclear medicine procedure in which a gamma camera rotates around the patient and takes pictures from many angles, which a computer then uses to form a tomographic (cross-sectional) image. The calculation process in SPECT is similar to that in CT (X-ray computed tomography) and […]