Volume 10, Number 8—August 2004
Dispatch
Spotted-Fever Group Rickettsia in Dermacentor variabilis, Maryland
Nicole C. Ammerman*, Katherine I. Swanson*, Jennifer M. Anderson*, Timothy R. Schwartz*, Eric C. Seaberg*, Gregory E. Glass*, and Douglas E. Norris*
Table 1
Characteristics of Dermacentor variabilis collected in Maryland, 2002a
| Characteristic | N | % infection with any Rickettsia organisms (95% CI) | % infection with SFG Rickettsia (%) (95% CI) |
|---|---|---|---|
| All ticks |
392 |
6.1 (4.0–9.0) |
3.8 (2.2–6.3) |
| Sex |
pb = 1.000 |
p = 1.000 |
|
| Male |
185 |
5.9 (3.0–10.4) |
3.8 (1.5–7.6) |
| Female |
207 |
6.3 (3.3–10.5) |
3.9 (1.7–7.4) |
| County of collection |
p = 0.052 |
p = 0.024 |
|
| Anne Arundel |
1 |
0 (0–97.5) |
0 (0–97.5) |
| Baltimore |
342 |
6.1 (3.8–9.2) |
3.5 (1.8–6.0) |
| Calvert |
17 |
0 (0–19.5) |
0 (0–19.5) |
| Charles |
18 |
0 (0–18.5) |
0 (0–18.5) |
| Prince George’s |
1 |
100 (2.5–100) |
100 (2.5–100) |
| Saint Mary’s |
13 |
15.4 (1.9–45.4) |
15.4 (1.9–45.4) |
| Month collected |
p = 0.007 |
p = 0.101 |
|
| April |
146 |
4.8 (1.9–9.6) |
4.8 (1.9–9.6) |
| May |
108 |
4.6 (1.5–10.5) |
1.9 (0.2–6.5) |
| June |
78 |
2.6 (0.3–9.0) |
1.3 (0.03–6.9) |
| July/August |
58 |
17.2 (8.6–29.4) |
8.6 (2.9–19.0) |
| Unknownc | 2 | 0 | 0 |
aCI, confidence interval; SFG, spotted fever group.
bFisher exact p values.
cTicks with unknown month of collection were excluded from the statistical analyses for this characteristic.
