Volume 20, Number 9—September 2014
Research
Feeding Period Required by Amblyomma aureolatum Ticks for Transmission of Rickettsia rickettsii to Vertebrate Hosts
Table 2
Fever, seroconversion to Rickettsia rickettsii antigens, and ear and/or scrotal lesions in guinea pigs that were exposed to R. rickettsii–infected Amblyomma aureolatum unfed adult male ticks, Brazil
Guinea pig no. | Tick feeding period, h* | Fever† | Anti-R. rickettsii antibody titers‡ | Ear and/or scrotal lesions§ |
---|---|---|---|---|
33 | 2 | No | <1:64 | No |
34 | 2 | No | <1:64 | No |
35 | 4 | No | <1:64 | No |
36 | 4 | No | <1:64 | No |
37 | 6 | No | <1:64 | No |
38 | 6 | No | <1:64 | No |
39 | 8 | No | <1:64 | No |
40 | 8 | No | <1:64 | No |
41 | 10 | No | <1:64 | No |
42 | 10 | No | <1:64 | No |
43 | 12 | Yes | 4,096 | Yes |
44 | 12 | Yes | 256 | No |
45 | 16 | Yes | 2,048 | Yes |
46 | 16 | Yes | 1,024 | Yes |
47 | 20 | Yes | 512 | Yes |
48 | 20 | Yes | 2,048 | Yes |
49 | 24 | Yes | 2,048 | Yes |
50 | 24 | Yes | ¶ | Yes |
51 | 36 | Yes | 2,048 | Yes |
52 | 36 | Yes | 4,096 | Yes |
53 | 48 | Yes | ¶ | Yes |
54 | 48 | Yes | 8,192 | Yes |
55 | 168 | Yes | 16,384 | Yes |
56 | 168 | Yes | 16,384 | Yes |
*Number of hours that an infected male adult tick was allowed to feed on each guinea pig before the tick was manually removed from the host.
†Rectal temperature >39.5°C during 21 days after tick infestation.
‡Anti-R. rickettsii IgG endpoint titers determined 21 days after tick infestation.
§Occurrence of ear or scrotal lesions (edema, necrosis) during the febrile period within 21 days after tick infestation.
¶Guinea pig died during the febrile period, before the 21st day after tick infestation; its lung tissue was PCR positive for Rickettsia spp.