Probably airborne respiratory droplets. Highest incidence in young adults; 10% of all their respiratory diseases; 49% attack rate in single-exposure epidemic. Intimate and prolonged contact, eg, intrafamilial, usually necessary for spread
Sx:Malaise (85%), cough (85%), headache (77%), fever (65%), sore throat (44%), sweats (37%), myalgias (41%), arthralgias
Si: Bronchitis; pneumonia (27%); vesicle on tympanic membrane (bullous myringitis), 12% overall, more common age 5-15 yr; rash
Hemolytic anemia with cold agglutinins (Nejm 1977;296:1490); peri- and myocarditis; Guillain-Barré syndrome (Ann IM 1981;94:15)
Lab:Serol:Specific comp-fix antibodies increased. Nonspecific cold agglutinins increased (IgM), 35-75% of patients will be positive after 7 d of illness (Ann IM 1977;86:547); r/o collagen vascular disease, lymphoproliferative disease, mononucleosis
Xray:Chest infiltrates; and/or pleural effusions (in 25%—Nejm 1970;283:790)
Rx:Macrolide drug of choice because effective and also gets pneumococcus, eg, erythromycin, azithromycin, or clarithromycin; tetracycline, but 50% after rx still have nonresistant organisms in respiratory tract (Nejm 1967;277:719), although same may also be true for erythromycin