Volume 24, Number 11—November 2018
Research
Rickettsia rickettsii Co-feeding Transmission among Amblyomma aureolatum Ticks
Table 3
Rickettsia rickettsii acquisition infestation 3 with Amblyomma aureolatum ticks on 4 guinea pigs 120 days after acquisition infestation 1, Brazil*
| Guinea pig | Temperature range, °C | IFA endpoint titer† | Feeding chamber‡ | PCR on ticks after molting, no. infected/no. tested (% infected) | |
|---|---|---|---|---|---|
| Unfed nymphs | Unfed adults | ||||
| 1 | No fever to 38.9 | 16,384 | UL | 0/13 (0) | |
| UL + IN |
0/13 (0) |
5/5 (100) |
|||
| 2 | No fever to 39.2 | 8,192 | UL | 0/13 (0) | |
| UL + IN |
0/13 (0) |
7/7 (100) |
|||
| 3 | No fever to 38.9 | 4,096 | UL + IN | 2/7 (29) | 8/8 (100) |
| UL |
3/25 (12) |
||||
| 4 | No fever to 38.5 | 4,096 | UL + IN | 3/30 (10) | 4/4 (100) |
| UL | 5/30 (17) | ||||
*Each guinea pig was infested on day 0 with R. rickettsii IN and on day 3 with UL. Recovered engorged larvae and nymphs were allowed to molt to nymphs and adult ticks, respectively, which were tested by real-time PCR for presence of rickettsial DNA. dpi, days postinfestation; IFA, immunofluorescence assay; IN, infected nymphs; UL, uninfected larvae.
†Blood was collected at day 0 (120 and 90 days after acquisition infestations 1 and 2, respectively) and tested by IFA with R. rickettsii antigens.
‡Tick infestations were performed on 2 feeding chambers glued to the shaved back of each guinea pig; 1 chamber receiving IN and UL, the other receiving only UL (Figure).