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Table 2 Results of PCR-RLB hybridization assays or cloning and sequencing of 23S-5S IGS amplicons for identification of Rickettsia species in 17-kDa-positive ticks

From: Prevalence of Rickettsiales in ticks removed from the skin of outdoor workers in North Carolina

 

Year collected

Number (%a) of samples testing positive for eachRickettsiaspecies within each tick species

Rickettsiaspecies

A. americanum[n  = 427]b

A. maculatum[n  = 4]

D. variabilis[n  = 4]

I. scapularis[n=6]

All tick species[n  = 441]f

R. amblyommii c,d

2011

228 (89.8)

2 (28.6)

1 (50.0)

1 (10.0)

232 (85.0)

 

2012

184 (92.5)

-e

-

-

184 (90.2)

 

Total

412 (90.9)

2 (28.6)

1 (20.0)

1 (8.3)

416 (87.2)

R. bellii c

2011

1 (0.4)

1 (14.3)

-

-

2 (0.7)

 

2012

3 (1.5)

-

1 (33.3)

-

4 (1.9)

 

Total

4 (0.9)

1 (14.3)

1 (20.0)

-

6 (1.2)

R. massiliae c

2011

1 (0.4)

-

-

-

1 (0.4)

 

2012

-

-

-

-

-

 

Total

1 (0.2)

-

-

-

1 (0.2)

R. montanensis c,d

2011

-

1 (14.3)

-

1 (10.0)

2 (0.7)

 

2012

-

-

1 (33.3)

-

1 (0.5)

 

Total

-

1 (14.3)

1 (20.0)

1 (8.3)

3 (0.6)

R. parkeri c,d

2011

5 (2.0)

2 (28.6)

-

3 (30.0)

10 (3.7)

 

2012

4 (2.0)

-

-

-

4 (2.0)

 

Total

9 (2.0)

2 (28.6)

-

3 (25.0)

14 (2.9)

R. rickettsii d

2011

-

-

-

-

-

 

2012

1 (0.5)

-

-

-

1 (0.5)

 

Total

1 (0.2)

-

-

-

1 (0.2)

Rickettsia sp. Ac,d

2011

7 (2.8)

-

-

-

7 (2.6)

 

2012

3 (1.5)

-

1 (33.3)

-

4 (2.0)

 

Total

10 (2.2)

-

1 (20.0)

-

11 (2.3)

Rickettsia sp. Bd

2011

-

-

-

-

-

 

2012

2 (1.0)

-

-

-

2 (1.0)

 

Total

2 (0.4)

-

-

-

2 (0.4)

Rickettsia sp. Cd

2011

2 (0.8)

-

-

1 (10.0)

3 (1.1)

 

2012

-

-

-

2 (100)

2 (1.0)

 

Total

2 (0.4)

-

-

3 (27.3)

5 (1.0)

Rickettsia sp. Dc

2011

1 (0.4)

-

-

-

1 (0.4)

 

2012

-

-

-

-

-

 

Total

1 (0.2)

-

-

-

1 (0.2)

Unknown Rickettsiac,d,h

2011

3 (1.2)

1 (14.3)

-

4 (40.0)

8 (3.0)

 

2012

1 (0.5)

-

-

-

1 (0.5)

 

Total

4 (0.9)

1 (14.3)

-

4 (33.3)

9 (1.9)

Unknown SFGc

2011

6 (2.4)

-

1 (50.0)

-

7 (2.6)

 

2012

1 (0.5)

-

-

-

1 (0.5)

 

Total

7 (1.5)

-

1 (20.0)

-

8 (1.7)

Total infections

2011

254

7

2

10

273

 

2012

199

0

3

2

204

 

Total

453

7

5

12

477g

  1. aPercentage in parenthesis was calculated using the total number of infections detected/identified for Rickettsia in each tick species as the denominator.
  2. bNumbers in the brackets represent the total number of 17-kDA–positive samples that were successfully amplified and hybridized in 23S-5S PCR-RLB assay from both years of the study for each tick species.
  3. cRickettsia species identified by reverse line blot hybridization. R. massiliae was identified based on hybridization to the P-MAS/MON and P-MAS/RHIPI probes but not to the P-RHIPI probe.
  4. dRickettsia species identified by cloning and sequencing 23S-5S IGS amplicons.
  5. eThe minus symbol indicates that no positive specimens were found among the tested specimens for this tick species.
  6. fOf 461 23S-5S positive samples,20 samples were not identified by RLB hybridization or through cloning and sequencing. These samples were not included in the table.
  7. gTotal number of infections (n = 477) exceeds the total number of DNA samples (n = 441) because some ticks were infected with more than one Rickettsia species.
  8. hIncludes Rickettsia sp. E shown in the phylogenetic tree constructed of 23S-5S IGS gene sequences (Figure 3).