Spotted fever

1966, 4th printing 1967 ; Spotted fever is a disease of wild mammals, man, and other animals. The disease is caused by one of the rickettsiae, Rickettsia rickettsi, and is transmitted by certain species of hard ticks. Rickettsiae are considered an order of bacteria, of which they are among the smallest. Rickettsiae, most of which are obligate intracellular parasites, are unable to reproduce when separated from their host tissues (the rickettsiae causing Q fever are exceptions). The rickettsiae of spotted fever multiply in the endothelial cells of arterioles, venules, and capillaries throughout the body. Infection of spotted fever in man is characterized as an acute febrile illness with sudden onset, a skin rash, high fever, and is one of the most severe of infectious diseases in areas with highly virulent strains. ; Human cases have been reported, in recent years, in 46 of the States of the United States. Spotted fever also occurs in Canada, Mexico, and South America. Human cases have occurred in all months of the year, but are more common in spring and early summer. Sixty-five percent (715 of 1,106) reported cases in the United States during the period 1960-64 occurred in the 10 Appalachian States (Alabama, Georgia, Kentucky, Maryland, North Carolina, Pennsylvania, South Carolina, Tennessee, Virginia, and West Virginia).