Volume 24, Number 11—November 2018
Research
Rickettsia rickettsii Co-feeding Transmission among Amblyomma aureolatum Ticks
Table 4
Rickettsia rickettsii acquisition infestation 4 with Amblyomma aureolatum ticks on 2 guinea pigs 430 days after acquisition infestation 1, Brazil*
| Guinea pig | Temperature range, °C | IFA endpoint titer† | Feeding chambers‡ | PCR on ticks after molting, no. infected/no. tested (%) |
|
|---|---|---|---|---|---|
| Unfed nymphs | Unfed adults | ||||
| 1 | No fever to 38.7 | 4,096 | UL | ND | |
| UL + IN |
ND |
2/2 (100) |
|||
| 2 | No fever to 38.7 | 512 | UL | 2/16 (13) | |
| UL + IN | 1/12 (8) | 5/5 (100) | |||
*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; ND, not done because very few engorged larvae were recovered from the animal; UL, uninfected larvae.
†Blood was collected at day 0 (430, 400, and 310 days after acquisition infestations 1, 2, and 3, 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).