Fourth disease
Fourth disease: A disorder characterized by a rash due to a toxin produced by Staphylococcus aureus (Staph aureus bacteria).
Measles and scarlet fever were differentiated from one another in the 17th century. Rubella was accepted as the third distinct pediatric exanthem (rash) in 1881. What were thought to be two distinct forms of rubella were then described and it was proposed that one of these forms of rubella was a separate entity that was called fourth disease. For many years, fourth disease was considered a non-entity, perhaps a mild form of scarlet fever, but certainly not a distinct disease. Now it is clear that fourth disease is caused by exotoxin-producing Staph aureus.
Read Also:
- Fourth stage of labor
Fourth stage of labor: The hour or two after delivery when the tone of the uterus is reestablished as the uterus contracts again, expelling any remaining contents. These contractions are hastened by breastfeeding, which stimulates production of the hormone oxytocin.
- Fourth ventricle
Fourth ventricle: One cavity in a system of four communicating cavities within the brain, which are continuous with the central canal of the spinal cord. The fourth ventricle is the most inferior (lowest) of these. It extends from the aqueduct of the midbrain to the central canal of the upper end of the spinal cord, […]
- Fovea
Fovea: In the eye, a tiny pit located in the macula of the retina that provides the clearest vision of all. Only in the fovea are the layers of the retina spread aside to let light fall directly on the cones, the cells that give the sharpest image. Also called the central fovea or fovea […]
- Fracture
A break in bone or cartilage. Although usually a result of trauma, a fracture can be the result of an acquired disease of bone, such as osteoporosis, or of abnormal formation of bone in a congenital disease of bone, such as osteogenesis imperfecta (‘brittle bone disease’). Fractures are classified according to their character and location […]
- Fraction, ejection
Fraction, ejection: The percentage of blood that is pumped out of a filled ventricle as a result of a heartbeat. The heart does not eject all the blood in the ventricle. Only about two-thirds of the blood is normally pumped out with each beat, and that fraction is referred to as the ejection fraction. The […]