Possible acquired resistance of dogs successively infested by Amblyomma cajennense (Fabricius, 1787) (Acari: Ixodidae) nymphs.
The present study aimed to evaluate the occurrence of immune resistance in dogs successively infested with Amblyomma cajennense nymphs. Five animals were submitted to four consecutive infestations with A. cajennense nymphs, at fourteen-day intervals. For each infestation, 50 nymphs were used per animal and data on the parasitic and non-parasitic periods were recorded. The average recovering rate of engorged nymphs in the successive infestations were 52.0, 29.2, 9.6 and 12.8%, respectively, with a significant reduction (p<0.05) of this parameter from the second infestation onwards. The modal drop-off day of engorged nymphs was Day 4 of parasitism in all infestations. The average mortality rates of nymphs seen on the first, second, third and fourth infestations were 3.6, 3.2, 2.0 and 2.8%, respectively, with no significant differences among them (p<0.05). In addition, no significant differences were seen among the ecdysis rates for specimens recovered from successive parasitic challenges. The study results suggest that the acquired resistance of infested dogs had a negative effect on recovery rate of A. cajennense nymphs; however, it did not affect the other biological parameters evaluated.
de Freitas
Carolina Maria Vianna
CM
Laboratório de Ectoparasitoses, Escola de Veterinária-EV, Universidade Federal de Minas Gerais-UFMG, Av. Antônio Carlos 6627, CEP 30161-970 Belo Horizonte-MG, Brazil.
Leite
Romário Cerqueira
RC
Bastianetto
Eduardo
E
da Cunha
Arildo Pinto
AP
de Paiva Belo
Ana Cristina Passos
AC
D056704:Adaptive Immunity; D000818:Animals; D004283:Dog Diseases / Q000276:immunology*; D004285:Dogs; D026863:Ixodidae; D009758:Nymph; D013984:Tick Infestations / Q000276:immunology / Q000662:veterinary*