Histological Reactions to Bites of Amblyomma variagatum and Rhipicephalus appendiculatus (Acari: Ixodidae) Fed Simultaneously on Naive or Sensitized Rabbits

Abstract

Histopathological studies on attachment sites of nymphs, 48 h after attachment on three groups of rabbits, have revealed differences that were related to the rabbits' previous tick experience. Feeding lesions caused by Amblyomma variegatum (F.) in tick-naive rabbits were extensive and the total number of inflammatory cells was about 10 times greater than that in the feeding lesions caused by Rhipicephalus appendiculatus Neumann fed simultaneously on contralateral ears. Rabbits that were previously sensitized either to A. variegatum or R. appendiculatus by repeated tick infestations showed epidermal vesiculation and significant mobilization of eosinophils at the homologous tick feeding sites, events that did not occur with tick-naive rabbits. The feeding of A. variegatum nymphs on rabbits sensitized to R. appendiculatus produced a similar type of intense reaction, but the cellular responses to R. appendiculatus in the skin of rabbits sensitized to the A. variegatum were negligible.

Stylostome formation in trombiculid mites (Acariformes: Trombiculidae)

“…In the hypothetical absence of stylostome, the larva would be unable to effectively attach to the skin and feed because its quite short mobile digits could fall out of the zone of liquefied and necrotized host tissue. Generally, the cement cone of some ixodid ticks serves the same function (Nelson et al 1975;Balashov 1967Balashov , 1982Latif et al 1990;Banerjee et al 1992;Schumaker et al 1995) producing at the same time a strong antibody reaction in the host skin (Bishop et al 2002). This explains the absence of a stylostome in larvae of the genus Hannemania that encapsulate the soft connective tissue of amphibians with the mouthparts lying closely to the nutritive substrate prepared for ingestion by the lytic action of the salivary secretion (Hyland 1961).…”

Resistance and cross-resistance in rabbits to adults of three species of African ticks (Acari: Ixodidae)

“…In the experiments reported here using adults of the three species, there was no crossresistance in rabbits between the two Amblyomma, but interestingly there was some indication of one-way cross-resistance between R. appendiculatus and A. variegatum; a primary infestation with R. appendiculatus gave some protection against A. variegatum but not vice versa. Latif et al (1990) observed a similar unidirectional resistance between nymphs of the two species based on immuneinduced histological reactions at the bite sites. One-way cross-reactivity of R. appendiculatus and A. variegatum was also noted by Almeida et al (1994); using immunohistochemical techniques, they found that sera from guinea-pigs infested with R. appendiculatus reacted strongly not only with tissues of this species, but also with those of A. variegatum.…”

The effect of inflammatory and hypersensitive reactions, in response to the feeding of the tick Amblyomma variegatum, on the progression of experimental dermatophilosis infections

“…This type of cellular reaction has also been demonstrated by repeated infestations of Amblyomma americanum on bovine hosts (Brown et aL, 1984). However, with A.variegatum feeding on rabbit hosts, the initial cellular reactions are predominantly neutrophil and mononuclear infiltration with eosinophils also infiltrating attachment sites after repeated infestations (Latif et al, 1990).…”