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).