Infections of granulocytic ehrlichiae and Borrelia burgdorferi in white-tailed deer in Connecticut

Serum or whole blood samples, obtained from 141 white-tailed deer (Odocoile us virginianus) in Connecticut (USA) during 1980, 1991, and 1996, were anal yzed to detect past or current infections of Ehrlichia phagocytophila genog roup organisms and Borrelia burgdorferi. When the BDS or NCH-1 strains of g ranulocytic ehrlichiae were used separately in indirect fluorescent antibod y (IFA) staining methods, antibody positivity rates varied from 25 to 64% i n 1991 and 1996, respectively. All 50 sera tested from 1980 collections wer e negative. Although percentages of sera with B. burgdorferi antibodies, as detected by an enzyme-linked immunosorbent assay, also differed (23 to 53% ), there were coexisting antibodies to both bacteria in 20 (49%) of 41 sera . In tests on specificity, 19 deer sera with ehrlichial antibodies also wer e tested by IFA staining procedures for Anaplasma marginale antibodies; one serum with a titer of 1: 5,120 to ehrlichial antigen reacted to A. margina le antigen at a serum dilution of 1:320. In parallel analyses of 69 sera, r esults of Western blot analyses for ehrlichial infections in deer were conc ordant (72% agreement) with those of IFA staining methods containing ehrlic hial antigen. All positive immunoblots showed bands to peptides of the NCH- 1 strain of the human granulocytic ehrlichiosis (HGE) agent having molecula r masses of about 44, 105, or 110 kDa. In polymerase chain reaction (PCR) s tudies of blood samples from 63 deer, 11(18%) specimens were positive for 1 6S ribosomal DNA of an Ehrlichia phagocytophila genogroup organism, whereas 23 (37%) samples were positive for the DNA of the 44 kDa gene of the HGE a gent. White-tailed deer are exposed to different tick-borne bacteria in are as where bodes scapularis sticks are abundant and may, in some instances, h ave had concurrent infections.