Volume 20, Number 9—September 2014
Research
Feeding Period Required by Amblyomma aureolatum Ticks for Transmission of Rickettsia rickettsii to Vertebrate Hosts
Table 1
Fever, seroconversion to Rickettsia rickettsii antigens, and ear and/or scrotal lesions in guinea pigs exposed to R. rickettsii-infected Amblyomma aureolatum unfed nymphs through different feeding periods, Brazil
Guinea pig no. | Tick feeding period, h* | Fever† | R. rickettsii antibody titers‡ | Ear and/or scrotal lesions§ |
---|---|---|---|---|
1 | 2 | No | <1:64 | No |
2 | 2 | No | <1:64 | No |
3 | 4 | No | <1:64 | No |
4 | 4 | No | <1:64 | No |
5 | 6 | No | <1:64 | No |
6 | 6 | No | <1:64 | No |
7 | 8 | No | <1:64 | No |
8 | 8 | No | <1:64 | No |
9 | 8 | No | <1:64 | No |
10 | 8 | No | <1:64 | No |
11 | 10 | No | <1:64 | No |
12 | 10 | No | <1:64 | No |
13 | 12 | Yes | ¶ | Yes |
14 | 12 | No | <1:64 | No |
15 | 12 | No | <1:64 | No |
16 | 12 | No | <1:64 | No |
17 | 14 | Yes | 2,048 | Yes |
18 | 14 | No | 256 | No |
19 | 16 | Yes | 512 | No |
20 | 16 | Yes | 512 | No |
21 | 18 | Yes | 8,192 | Yes |
22 | 18 | Yes | 256 | No |
23 | 24 | Yes | 4,096 | Yes |
24 | 24 | Yes | 8,192 | Yes |
25 | 24 | Yes | 4,096 | Yes |
26 | 24 | Yes | 512 | No |
27 | 36 | Yes | 16,384 | Yes |
28 | 36 | Yes | 8,192 | Yes |
29 | 48 | Yes | 4,096 | Yes |
30 | 48 | Yes | 8,192 | Yes |
31 | >96h | Yes | 16,384 | Yes |
32 | >96h | Yes | 16,384 | Yes |
*Number of hours that infected nymphs were allowed to feed on each guinea pig before ticks were manually removed from host.
†Rrectal temperature >39.5°C during 21 d after tick infestation.
‡Anti-R. rickettsii IgG endpoint titers determined 21 d after tick infestation.
§Ear or scrotal lesions (edema, necrosis) during the febrile period within 21 d after tick infestation.
¶Guinea pig died during the febrile period, before the 21st d after tick infestation; its lung was PCR-positive for Rickettsia spp.