| serological, hematologic, and pcr studies of cattle in an area of switzerland in which tick-borne fever (caused by ehrlichia phagocytophila) is endemic. | the purpose of this study was to examine the seasonal variations in seroprevalence to ehrlichia phagocytophila in cattle pastured during the summer months in an area where tick-borne fever is endemic. the study was performed during a 1-year period from april 1996 to march 1997 and involved 34 cows, 22 pregnant heifers, and 14 calves. blood samples, collected from all 70 cattle once a month, were used to determine serum immunoglobulin g titers by indirect immunofluorescence. in addition, blood sm ... | 1998 | 9605986 |