Disease Agents inAmblyomma americanumfrom Northeastern Georgia

Abstract

Amblyomma americanum (lone star tick) is known or suspected to vector several organisms that are implicated as human pathogens, including Ehrlichia chaffeensis, E. ewingii, and Borrelia lonestari. These three agents have also been detected in white-tailed deer (Odocoileus virginianus). Because northeastern Georgia has a high abundance of both lone star ticks and white-tailed deer, and one of these organisms, E. chaffeensis, is already known to be endemic in the area, we assayed individual adult A. americanum, collected during the spring of 2001, 2002, and 2003, for these three organisms. A total of 400 ticks were dissected and tissues assayed by polymerase chain reaction (PCR) using Ehrlichia species-specific and Borrelia genus-wide primers. Of ticks tested, 2.0% (8/398) had evidence of E. chaffeensis, 4.8% (19/398) had evidence of E. ewingii, and 1.0% (4/398) had evidence of B. lonestari. Borrelia sp. spirochetes were also visualized by an indirect fluorescent antibody test, using an anti-flagellin monoclonal antibody (H9724), in a total of 10.7% (32/300) of ticks tested in 2003. These results reconfirm the presence of E. chaffeensis and establish evidence of E. ewingii and B. lonestari in questing adult A. americanum ticks from northeastern Georgia. Detection of at least two of the three organisms in ticks collected each year suggests that people in northeastern Georgia are at risk of infection with these organisms.

Distribution of Antibodies Reactive toBorrelia lonestariandBorrelia burgdorferiin White-Tailed Deer (Odocoileus virginianus) Populations in the Eastern United States

“…Because of this low prevalence, large numbers of WTD need to be tested in individual populations to ensure a proper classification for B. lonestari exposure. Interestingly, the prevalence of both E. chaffeensis and B. lonestari in A. americanum was similar (Varela et al 2004, Mixson et al 2006, Stromdahl et al 2008. Although WTD show a strong immune response to E. chaffeensis (Varela et al , 2005, WTD experimentally inoculated with B. lonestari only develop a low titer, if at all, and for only a short period of time (Moyer et al 2006, Varela-Stokes 2007.…”

“…WTD naturally infected with B. lonestari also have been detected in five populations in the Southeast ); in the current study, antibodies to B. lonestari were detected in three of these four populations for which serum was available for testing. Further, B. lonestari has been detected in A. americanum from many of the southeastern and mid-Atlantic states, including Alabama, Arkansas, Delaware, Florida, Georgia, Kentucky, Maryland, New Jersey, North Carolina, South Carolina, Tennessee, and Virginia (Burkot et al 2001, StegallFaulk et al 2003, Stromdahl et al 2003, Clark 2004, Varela et al 2004, Taft et al 2005, Mixson et al 2006, Schulze et al 2006.…”

Highly Prevalent Coxiella sp. Bacterium in the Tick Vector Amblyomma americanum

“…In parts of New Jersey A. americanum ticks are more commonly encountered than the deer tick Ixodes scapularis (13). While originally considered a nuisance species, A. americanum is now recognized as a vector of Ehrlichia chaffeensis, the agent of human monocytic ehrlichiosis, and E. ewingii, a cause of granulocytic ehrlichiosis in humans and dogs (16). A. americanum is also the vector of Borrelia lonestari (1), an organism that has been implicated but not proven (5,17) as a cause of a tickassociated rash illness in the southern United States (2,9).…”

Retrospective Study of Tick-Borne Pathogens and Observation of <i>Ehrlichia ewingii / Anaplasma phagocytophilum</i> and Hemotropic <i>Mycoplasma</i> spp. in Dogs’ Blood Films

“…These species and may be some other ticks are more important in other countries such as Brazil and Cameroon where E. ewingii has been detected [26,27]. Once ticks are infected by E. ewingii, they remain infected throughout their life (transstadial transmission) [14,55]. A.phagocytophilum can be transmitted by members of the Ixodes persulcatus complex (e.g., I. scapularis, I. pacificus, I. ricinus and I. persulcatus) [3,56].…”