Volume 24, Number 11—November 2018
Rickettsia rickettsii Co-feeding Transmission among Amblyomma aureolatum Ticks
|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
|2||No fever to 39.2||8,192||UL||0/13 (0)|
|UL + IN
|3||No fever to 38.9||4,096||UL + IN||2/7 (29)||8/8 (100)|
|4||No fever to 38.5||4,096||UL + IN||3/30 (10)||4/4 (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; 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).