Volume 17, Number 5—May 2011
Research
Experimental Infection of Amblyomma aureolatum Ticks with Rickettsia rickettsii
Marcelo B. Labruna
, Maria Ogrzewalska, João F. Soares, Thiago F. Martins, Herbert S. Soares, Jonas Moraes-Filho, Fernanda A. Nieri-Bastos, Aliny P. Almeida, and Adriano Pinter
, Maria Ogrzewalska, João F. Soares, Thiago F. Martins, Herbert S. Soares, Jonas Moraes-Filho, Fernanda A. Nieri-Bastos, Aliny P. Almeida, and Adriano PinterTable 1
Clinical data of hosts infested by a Rickettsia rickettsii–infected colony of Amblyomma aureolatum ticks, and results of PCR performed on unfed ticks from 4 consecutive generations (F1 to F4)*
| Tick stage and generation | Infested hosts |
PCR of unfed ticks, no. infected/no. tested | ||||||
|---|---|---|---|---|---|---|---|---|
| Host, no. | No. ticks/host | Fever† |
No. deaths | Diagnostic test |
||||
| No. | Onset, dpi | PCR‡ | IFA§ | |||||
| Nymph–F1 | Guinea pig, 2 | 50 | 2 | 6 | 2 | Pos | ND | 45/45¶ |
| Adult–F1 | Dog, 2 | 20 couples | 0 | – | 0 | ND | ND | 10/10 |
| Larva–F2 | Guinea pig, 2 | 1,000–2,000 | 2 | 7–8 | 1 | ND | Pos | – |
| Larva–F2 | Rabbit, 3 | 1,000–2,000 | 3 | 7–9 | 0 | ND | Pos | – |
| Nymph–F2 | Guinea pig, 3 | 80 | 3 | 5 | 2 | Pos | Pos | 30/30 |
| Nymph–F2 | Rabbit, 1 | 200 | 1 | 6 | 0 | ND | Pos | – |
| Adult–F2 | Rabbit, 2 | 7 couples | 2 | 7–8 | 0 | ND | Pos | – |
| Larva–-F3 | Guinea pig, 4 | 1,000–2,000 | 4 | 7–8 | 2 | Pos | Pos | – |
| Nymph–F3 | Rabbit, 1 | 400 | 1 | 6 | 0 | ND | Pos | – |
| Adult–F3 | Dog, 1 | 12 couples | 0 | – | 0 | ND | ND | – |
| Larva–F4 | Guinea pig, 5 | 1,000–3,000 | 5 | 6–7 | 1 | ND | Pos | 100/100 |
| Nymph–F4 | Rabbit, 1 | 500 | 1 | 5 | 0 | ND | Pos | 30/30 |
*dpi, days postinfestation; IFA, immunofluorescence assay; pos, positive; ND, not done; –, data not collected.
†Rectal temperature >40°C.
‡PCR performed on lung-extracted DNA from guinea pigs that died during the febrile period.
§A positive result means seroconversion, namely nonreactive (titer <64) at 0 DPI, and reactive (titer >1,024) at 21 dpi.
Previously reported by Labruna et al. (9).
