title: Acquired resistance of horses to Amblyomma cajennense (Fabricius, 1787) ticks.
abstract: Acquired immunity of horses to larvae, nymphs and adults of the Amblyomma cajennense tick was evaluated through three consecutive experimental infestations of tick-bite naïve hosts. Data from these infestations were compared to those from field-sensitized horses and donkeys. It was observed that tick-bite naïve horses developed a low level of resistance after two infestations as shown by a significant decrease in larval yield and a tendency for lower engorged weight of nymphs during third infestation. Ticks fed on field-sensitized horses had a similar biological performance to that observed on the third infestation of tick-bite naïve horses but the mean engorged nymph weight was significantly lower than that of the first infestation from tick-bite naïve horses. Donkeys presented the strongest resistance with significantly lower engorged weights of all instars and of the egg mass compared to the first infestation of tick-bite naïve horses. Donkeys also displayed a significantly higher resistance than field-sensitized horses as demonstrated by significantly lower egg mass weights. Overall these results indicate that donkeys but not horses maintain a strong resistance to A. cajennense ticks. The importance of these findings in relation to vectoring of tick-borne diseases is discussed.
authors.affiliation: Universidade Estadual Paulista, Jaboticabal, SP, Brazil.
authors.forename: Karina C
authors.initials: KC
authors.lastname: Castagnolli
authors.forename: Luciano B
authors.initials: LB
authors.lastname: de Figueiredo
authors.forename: Danilo A
authors.initials: DA
authors.lastname: Santana
authors.forename: Márcio B
authors.initials: MB
authors.lastname: de Castro
authors.forename: Marco A
authors.initials: MA
authors.lastname: Romano
authors.forename: Matias P J
authors.initials: MP
authors.lastname: Szabó
mesh_terms: D000818:Animals; D018397:Equidae / Q000276:immunology* / Q000469:parasitology; D006734:Horse Diseases / Q000276:immunology* / Q000469:parasitology; D006736:Horses; D006790:Host-Parasite Interactions; D007113:Immunity, Innate; D026863:Ixodidae / Q000276:immunology*; D009758:Nymph / Q000254:growth & development / Q000502:physiology; D013984:Tick Infestations / Q000276:immunology / Q000469:parasitology / Q000662:veterinary*