Table 5. Transmission infestations on 29 naive guinea pigs infested with Amblyomma aureolatum nymphs derived from larvae that had co-fed with Rickettsia rickettsii–infected nymphs on 6 guinea pigs during acquisition infestations, Brazil*.
| Origin of nymphs |
Transmission infestation |
PCR on unfed adult ticks after molting from engorged nymphs, no. infected ticks/no. tested ticks (% infection) | |||||||
|---|---|---|---|---|---|---|---|---|---|
| AI | Guinea pig† | Feeding chamber† | Guinea pig | Fever onset, dpi | Maximum temperature, °C | Died | IFA endpoint titer‡ | ||
| 1 | 3 | UL | 11 | 6 | 39.6 | No | 65,536 | 2/2 (100) | |
| 4 | UL | 12 | 7 | 40.7 | Yes§ | ND | 8/8 (100) | ||
| 5 | UL | 13 | 7 | 40.4 | No | 65,536 | 7/7 (100) | ||
| 6 | UL | 14 | 7 | 40.7 | No | 65,536 | 14/14 (100) | ||
| 3 | UL + IN | 15 | 6 | 40.9 | No | 65,536 | 6/6 (100) | ||
| 4 | UL + IN | 16 | 6 | 40.3 | Yes§ | ND | 6/6 (100) | ||
|
|
5 |
UL + IN |
|
17 |
7 |
40.6 |
No |
65,536 |
5/5 (100) |
| 2 | 1 | UL | 18 | No fever–38.6 | No | <64 | 0/10 (0) | ||
| 2 | UL | 19 | No fever–39.1 | No | <64 | 0/10 (0) | |||
| 3 | UL | 20 | No fever–39.1 | No | <64 | 0/15 (0) | |||
| 3 | UL | 21 | No fever–38.7 | No | <64 | 0/12 (0) | |||
| 4 | UL | 22 | No fever–38.8 | No | <64 | 0/8 (0) | |||
| 4 | UL | 23 | No fever–39.4 | No | <64 | 0/17 (0) | |||
| 1 | UL + IN | 24 | No fever–38.8 | No | <64 | 0/10 (0) | |||
| 2 | UL + IN | 25 | No fever–39.4 | No | <64 | 0/10 (0) | |||
| 3 | UL + IN | 26 | 8–40.6 | No | 16,384 | 11/12 (92) | |||
| 3 | UL + IN | 27 | 13–40.2 | No | 65,536 | 8/10 (80) | |||
| 4 | UL + IN | 28 | No fever–38.8 | No | <64 | 0/10 (0) | |||
|
|
4 |
UL + IN |
|
29 |
No fever–39.4 |
No |
<64 |
0/10 (0) |
|
| 3 | 1 | UL | 30 | No fever–39.3 | No | <64 | 0/5 (0) | ||
| 2 | UL | 31 | No fever–39.2 | No | <64 | 0/5 (0) | |||
| 3 | UL | 32 | No fever–39.4 | No | <64 | 0/10 (0) | |||
| 4 | UL | 33 | No fever–39.1 | No | <64 | 0/11 (0) | |||
| 1 | UL + IN | 34 | No fever–39.0 | No | <64 | 0/5 (0) | |||
| 2 | UL + IN | 35 | No fever–39.0 | No | <64 | 0/8 (0) | |||
| 3 | UL + IN | 36 | 6–40.9 | No | 32,768 | 7/7 (100) | |||
|
|
4 |
UL + IN |
|
37 |
No fever–38.9 |
No |
<64 |
0/7 (0) |
|
| 4 | 2 | UL | 38 | No fever–38.8 | No | <64 | 0/10 (0) | ||
| 2 | UL + IN | 39 | 10–40.1 | No | 32,768 | 10/10 (100) | |||
*AI, acquisition infestation (see Figure and Tables 1–4); dpi, days postinfestation; IN, infected nymphs; ND, not done; UL, uninfected larvae. †See Figure and Tables 1–4. ‡Blood was collected at 21 days dpi and tested by IFA with R. rickettsii antigens. §This guinea pig died during the febrile period; its spleen was shown by real-time PCR to contain rickettsial DNA.