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Volume 24, Number 11—November 2018

Rickettsia rickettsii Co-feeding Transmission among Amblyomma aureolatum Ticks

Jonas Moraes-Filho, Francisco B. Costa, Monize Gerardi, Herbert S. Soares, and Marcelo B. LabrunaComments to Author 
Author affiliations: Universidade Santo Amaro, São Paulo, Brazil (J. Moraes-Filho); University of São Paulo, São Paulo (J. Moraes-Filho, F.B. Costa, M. Gerardi, H.S. Soares, M.B. Labruna); Universidade Estadual do Maranhão, São Luís, Brazil (F.B. Costa).

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Table 2

Rickettsia rickettsii acquisition infestation 2 with Amblyomma aureolatum ticks on 4 guinea pigs 30 days after acquisition infestation 1, Brazil*

Guinea pig
Temperature range, °C
IFA endpoint titer at day 0†
Feeding chamber‡
PCR on ticks after molting, no. infected/no. tested (% infected)
Unfed nymphs
Unfed adults
1 No fever to 38.8 32,768 UL + IN 0/10 (0) 2/2 (100)

0/10 (0)

2 No fever to 38.4 32,768 UL + IN 0/10 (0) 3/3 (100)

0/10 (0)

3 No fever to 39.1 32,768 UL 0/30 (0)

10/30 (33)
3/3 (100)
4 No fever to 39.2 65,536 UL 0/30 (0)
UL + IN 5/30 (17) 3/3 (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 (30 days after acquisition infestation 1) 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).

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Page created: October 17, 2018
Page updated: October 17, 2018
Page reviewed: October 17, 2018
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