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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).

Main Article

Table 4

Rickettsia rickettsii acquisition infestation 4 with Amblyomma aureolatum ticks on 2 guinea pigs 430 days after acquisition infestation 1, Brazil*

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

2/2 (100)
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).

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