Volume 25, Number 5—May 2019
Research Letter
Rickettsiales in Ticks Removed from Outdoor Workers, Southwest Georgia and Northwest Florida, USA
Table
Prevalence of Ehrlichia chaffeensis, PME, and Rickettsia spp. in ticks submitted by outdoor workers, southwestern Georgia and northwestern Florida, USA*
Tick species and stage | Months submitted | No. positive ticks/no. tested (%) |
Rickettsia spp.† | ||
---|---|---|---|---|---|
E. chaffeensis | PME | Rickettsia spp. | |||
Amblyomma americanum, adults | Feb–Sep | 0/11 (0) | 0/11 (0) | 4/11 (36.4) | 2 R. amblyommatis |
A. americanum nymphs‡ | Mar–Sep | 0/43 (0) | 0/43 (0) | 12/43 (27.9) | 9 R. amblyommatis |
A. americanum larvae‡ | Apr and Oct | 0/5 (0) | 0/5 (0) | 1/5 (20.0) | 1 R.amblyommatis |
Amblyomma sp. nymphs | Jun and Oct | 0/3 (0) | 0/3 (0) | 1/3 (33.3) | 1 R. amblyommatis§ |
Amblyomma sp. larvae | Oct | 0/5 (0) | 0/5 (0) | 0/5 (0) | |
A. maculatum adults | May–Oct | 1/83 (1.2) | 2/83 (2.4)¶ | 18/83 (21.7) | 5 R. amblyommatis,§ 4 R. parkeri,§ 1 Rickettsia sp. TR-39/TX125, 2 Candidatus R. andeanae |
A. tuberculatum nymphs‡ | Apr | 0/5 (0) | 0/5 (0) | 1/5 (5.0) | 1 novel SFG Rickettsia sp. |
A. tuberculatum larvae‡ | Feb# | 0/182 (0) | 0/182 (0) | 10/182 (5.5)** | 10 novel SFG Rickettsia sp.** |
Dermacentor variabilis adults | Jun–Aug | 0/10 (0) | 1/10 (10.0) | 2/10 (20.0) | 1 R. amblyommatis§ |
Ixodes scapularis adults | Oct–Mar | NT | 0/15 (0) | 7/15 (46.7) | 4 Rickettsia sp. TR-39, 3 R. buchneri |
*All Rickettsia spp. were identified by sequencing unless otherwise noted. NT, not tested; PME, Panola Mountain Ehrlichia sp., SFG, spotted fever group.
†Rickettsia spp. for whom amplicons did not provide high-quality bidirectional sequences were categorized as unknown Rickettsia spp.
‡Minimum infection prevalence is no. positive tick pools/no. ticks tested.
§The following R. amblyommatis samples were identified by restriction fragment length polymorphism analysis: for 1 D. variabilis adult, 5 A. maculatum adults, and 1 Amblyomma sp. nymph; for A. americanum, 1 adult, 2 nymphs, and 1 larva. Three A. maculatum adults were also identified as containing R. parkeri positive by restriction fragment length polymorphism analysis.
¶Data included in Loftis et al. (5).
#Date was known only for 1 submission of 20 larvae. Dates for others were not provided when submitted.
**Data included in Zemtsova et al. (6).
References
- Allerdice ME, Hecht JA, Karpathy SE, Paddock CD. Evaluation of Gulf Coast ticks (Acari: Ixodidae) for Ehrlichia and Anaplasma species. J Med Entomol. 2017;54:481–4.https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=28031351&dopt=Abstract
1Current affiliation: Hollins University, Roanoke, Virginia, USA.