Possible acquired resistance of dogs successively infested by Amblyomma cajennense (Fabricius, 1787) (Acari: Ixodidae) nymphs

Abstract

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.Keywords: Immune resistance, Amblyomma cajennense, Ixodidae, dogs. ResumoO presente trabalho teve por objetivo avaliar a ocorrência de resistência imune em cães, frente a infestações sucessivas por ninfas de Amblyomma cajennense. Para tanto, cinco animais foram submetidos a quatro infestações consecutivas por ninfas de A. cajennense em intervalos de quatorze dias. Foram aplicadas 50 ninfas em cada animal por infestação e os dados referentes aos períodos parasitários e não parasitários, foram registrados. As taxas médias de recuperação de ninfas ingurgitadas, verificadas nas sucessivas infestações foram de 52,0, 29,2, 9,6 e 12,8%, sendo observada uma redução significativa (p < 0,05) nesse parâmetro a partir da segunda infestação. O dia modal de queda das ninfas ingurgitadas em todas as infestações foi o 4º dia de parasitimo. As taxas médias de mortalidade de ninfas observadas no primeiro, segundo, terceiro e quarto desafio parasitário foram de, respectivamente, 3,6, 3,2, 2,0 e 2,8%, não havendo diferença significativa entre elas (p < 0,05). Não observou-se diferença significativa (p < 0,05) entre as taxas de ecdise reportadas para os exemplares recuperados nos sucessivos desafios parasitários. Esses resultados sugerem que a resistência adquirida nos cães parasitados afetou negativamente a taxa de recuperação das ninfas de A. cajennense inoculadas nesses animais, contudo não apresentou nenhum efeito sobre os demais parâmetros biológicos avaliados.Palavras-chave: Resistência imune, Amblyomma cajennense, Ixodidae, cão.

Laboratory evaluation of the efficacy of lotilaner (Credelio™) against Amblyomma cajennense (sensu lato) infestations of dogs

“…ticks is less prevalent in dogs [ 10 ]. In addition, the attachment rate of adult ticks of this species in laboratory dogs is very low, not allowing for the minimum attachment rate of 25% recommended by international guidelines [ 10 , 12 ]. For these reasons, nymphal stages were used for infestation of dogs in this study.…”

“…While dogs are not seen as being a primary host for A. cajennense ( s.l . ), nymphal stages are less host specific than the adult stage and are reported to be aggressive feeders on humans and dogs [ 11 , 12 ]. As such, infestations with A .…”

Tick-host-pathogen systems immunobiology an interactive trio

“…Acquired, immune response based, resistance to tick feeding develops naturally for some tick-host associations, including laboratory animal species, companion animals, horses and cattle (19,29,30,31,32,33). Acquired resistance to tick feeding is expressed as reduced engorgement, disrupted molting, reduced ova production and death of the feeding tick.…”