National Center for Biotechnology Information NCBI NLM MEDLINE humans pubmed abstract nih national institutes of health national library of medicine research support non-u.s. gov't u.s. gov't female male aged P.H.S. risk factors 80 and over Respiratory Tract Infections / epidemiology maryland / epidemiology cross infection / epidemiology* prevalence iatrogenic disease / epidemiology* nursing homes / statistics & numerical data* cross infection / diagnosis cross infection / etiology urinary tract infections / epidemiology pmid:1753044 doi:10.1111/j.1532-5415.1991.tb02871.x j magaziner j h tenney j w warren dermatitis / epidemiology fever of unknown origin / epidemiology homes for the aged / statistics & numerical data* skin ulcer / complications vaginitis / epidemiology