Volume 24, Number 11—November 2018
Rickettsia rickettsii Co-feeding Transmission among Amblyomma aureolatum Ticks
|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
|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).