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Volume 24, Number 11—November 2018
Research

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).

Main Article

Table 1

Rickettsia rickettsii acquisition infestation 1 with Amblyomma aureolatum ticks on 6 guinea pigs, Brazil*

Guinea pig Fever onset, dpi (maximum temperature, °C) IFA endpoint titer at 21 dpi† Feeding chamber‡ PCR on ticks after molting, no. infected/no. tested (% infected)
Unfed nymphs Unfed adults
1 6 (40.3) 65,536 UL + IN 10/10 (100) 10/10 (100)



UL
10/10 (100)

2 8 (40.0) 65,536 UL + IN 9/9 (100) 10/10 (100)



UL
10/10 (100)

3 8 (40.5) 8,192 UL + IN 15/15 (100) 5/5 (100)



UL
15/15 (100)

4 5 (40.7) 65,536 UL 15/15 (100)



UL + IN
15/15 (100)
8/8 (100)
5 9 (40.0) 16,384 UL 15/15 (100)



UL + IN
15/15 (100)
8/8 (100)
6 7 (40.4) 16,384 UL 15/15 (100)
UL + IN 15/15 (100) 6/6 (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 21 dpi 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).

Main Article

Page created: October 17, 2018
Page updated: October 17, 2018
Page reviewed: October 17, 2018
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
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