Volume 24, Number 11—November 2018
Research
Rickettsia rickettsii Co-feeding Transmission among Amblyomma aureolatum Ticks
Jonas Moraes-Filho, Francisco B. Costa, Monize Gerardi, Herbert S. Soares, and Marcelo B. Labruna
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.
Page created: October 17, 2018
Page updated: October 17, 2018
Page reviewed: October 17, 2018
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.