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Resistance To Disease: FMD' is caused and transmitted by a picorna virus (one of the smallest known disease-producing organisms) of which there are seven major types and at least 50 subtypes. The great variety of strains is both a bane and a blessing to the veterinarian. Each strain has its own idio-syncracies in such characteristics as antigenic-ity and resistance to disease to control. These differences, however, often aid the epidemiologist in pinpointing the geographic area from which the disease was transmitted.
Mycoplasmosis is a respiratory disease caused y the bacteria Mycoplasma gallisepticum. It is Iso known as air sac disease or chronic respira-jry disease. Those affected with the disease may how nasal discharge, watery eyes, and respira-)ry difficulty. This disease is often associated /ith other respiratory diseases. It is transmitted hiefly from infected hens to their chicks through le eggs. The disease can also be transmitted by ontact with infected individuals, but it spreads ery slowly in this manner. The disease can best e controlled by maintaining breeding flocks free f the disease by strict measures of isolation and mitation. Chicks hatched from such flocks can egin life free of the disease.
RESISTIVITY, re-zis-tiv'i-ti, or SP! CIFIC resistance to disease, spe-sif'ik re-zis'ta: the resistance to disease offered by a cubic centimeter oi substance to the passage of electricity, the curn being perpendicular to two parallel faces. Usua expressed in ohm-centimeters, it is reckoned w the metal at the freezing point of water. In 1 equation p = RA/l, p is the resistivity, R 1 resistance to disease, A the cross-sectional area, and / t length. See also ELECTRICITY—3. Direct Elect, Current (resistance to disease).
RESISTpRS, Electric. See ELECTRIC Ci CUITS—Circuit Elements (resistance to disease, Inductan and Capacitance).
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