Experimental Infection of White-Tailed Deer with Anaplasma phagocytophilum , Etiologic Agent of Human Granulocytic Anaplasmosis

Abstract

Serologic and molecular evidence of Anaplasma phagocytophilum has been demonstrated in white-tailed deer (WTD; Odocoileus virginianus), and deer are an important host for the tick vector Ixodes scapularis. In this study, we describe experimental infection of WTD with A. phagocytophilum. We inoculated four WTD with a human isolate of A. phagocytophilum propagated in tick cells. Two additional deer served as negative controls. All inoculated deer developed antibodies (titers, >64) to A. phagocytophilum, as determined by an indirect fluorescent antibody test, between 14 and 24 days postinfection [p.i.]), and two deer maintained reciprocal titers of >64 through the end of the 66-day study. Although morulae were not observed in granulocytes and A. phagocytophilum was not reisolated via tick cell culture of blood, 16S reverse transcriptase nested PCR (RT-nPCR) results indicated that A. phagocytophilum circulated in peripheral blood of three deer through at least 17 days p.i. and was present in two deer at 38 days p.i. Femoral bone marrow from one deer was RT-nPCR positive for A. phagocytophilum at 66 days p.i. There was no indication of clinical disease. These data confirm that WTD are susceptible to infection with a human isolate of A. phagocytophilum and verify that WTD produce detectable antibodies upon exposure to the organism. Because adults are the predominant life stage of I. scapularis found on deer and because adult I. scapularis ticks do not transmit A. phagocytophilum transovarially, it is unlikely that WTD are a significant source of A. phagocytophilum for immature ticks even though deer have a high probability of natural infection. However, the susceptibility and immunologic response of WTD to A. phagocytophilum render them suitable candidates as natural sentinels for this zoonotic tick-borne organism.

Anaplasma phagocytophilum in central and western Wisconsin: a molecular survey

“…Our study demonstrates that both A. phagocytophilum strains are indeed present in Central and Western Wisconsin, and suggest that two novel variants exist in white-tailed deer that have never been described before. Though recent work by others suggests that the Ap-ha strain can infect white-tailed deer (Tate et al 2005), no evidence of natural infection with this strain has been found in our investigations or those of others (Belongia et al 1997;Massung et al 2002. As both the Ap-ha and Ap-Variant 1 strains were found in naturally infected ticks in both regions of the state, we propose that transmission of both strains is occurring between ticks and wild mammals, and that humans in both places could possibly be at risk for contracting HGA.…”

The Biological Survey of Canada: A Personal History

“…While the white-footed mouse is likely the dominant small-mammal reservoir, infection is usually transient, unlike the chronic infection observed with B. burgdorferi (Goodman 2005). White-tailed deer are important for the maintenance of Ixodes populations, but the role these large mammals play in the life cycle of A. phagocytophilum is unclear (Massung et al 2005;Tate et al 2005;Rainwater et al 2006). White-tailed deer may be seropositive and/or PCR positive for A. phagocytophilum (Bouchard et al 2013).…”

Isolation and Establishment of the RaccoonEhrlichia-Like Agent in Tick Cell Culture

“…of raccoons, Ehrlichia chaffeensis, E. canis, E. ewingii, Anaplasma phagocytophilum, and Borrelia spp. (Little et al 1998, Dugan et al 2005, Tate et al 2005, Moyer et al 2006, and by indirect fluorescent antibody (IFA) testing for antibodies reactive against E. chaffeensis, A. phagocytophilum, and Borrelia spp. as described with modifications (Comer et al 2000, Yabsley et al 2003, Dugan et al 2005, Tate et al 2005, Moyer et al 2006).…”