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Volume 20, Number 9—September 2014

Feeding Period Required by Amblyomma aureolatum Ticks for Transmission of Rickettsia rickettsii to Vertebrate Hosts

Danilo G. Saraiva, Herbert S. Soares, João Fábio Soares, and Marcelo B. LabrunaComments to Author 
Author affiliations: University of São Paulo, São Paulo, Brazil (D.G. Saraiva, H.S. Soares, J.F. Soares, M.B. Labruna); Bicho do Mato Research Institute, Belo Horizonte, Brazil (D.G. Saraiva)

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Table 2

Fever, seroconversion to Rickettsia rickettsii antigens, and ear and/or scrotal lesions in guinea pigs that were exposed to R. rickettsii–infected Amblyomma aureolatum unfed adult male ticks, Brazil

Guinea pig no. Tick feeding period, h* Fever† Anti-R. rickettsii antibody titers‡ Ear and/or scrotal lesions§
33 2 No <1:64 No
34 2 No <1:64 No
35 4 No <1:64 No
36 4 No <1:64 No
37 6 No <1:64 No
38 6 No <1:64 No
39 8 No <1:64 No
40 8 No <1:64 No
41 10 No <1:64 No
42 10 No <1:64 No
43 12 Yes 4,096 Yes
44 12 Yes 256 No
45 16 Yes 2,048 Yes
46 16 Yes 1,024 Yes
47 20 Yes 512 Yes
48 20 Yes 2,048 Yes
49 24 Yes 2,048 Yes
50 24 Yes Yes
51 36 Yes 2,048 Yes
52 36 Yes 4,096 Yes
53 48 Yes Yes
54 48 Yes 8,192 Yes
55 168 Yes 16,384 Yes
56 168 Yes 16,384 Yes

*Number of hours that an infected male adult tick was allowed to feed on each guinea pig before the tick was manually removed from the host.
Rectal temperature >39.5°C during 21 days after tick infestation.
‡Anti-R. rickettsii IgG endpoint titers determined 21 days after tick infestation.
§Occurrence of ear or scrotal lesions (edema, necrosis) during the febrile period within 21 days after tick infestation.
¶Guinea pig died during the febrile period, before the 21st day after tick infestation; its lung tissue was PCR positive for Rickettsia spp.

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Page created: August 13, 2014
Page updated: August 13, 2014
Page reviewed: August 13, 2014
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