Caracterização do parasitismo por Ornithodoros brasiliensis (Chelicerata: Argasidae) e da toxicose induzida em humanos e animais

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

2011

RESUMO

Ticks are blood-sucking arthropods distributed worldwide and able to parasitize almost all terrestrial vertebrate animals. Ticks are considered a great hazard for both public health and animal breeding due to their ability to transmit infectious diseases and to induce direct toxic effects leading to clinical disturbances. Ornithodoros brasiliensis, popularly known as mouro tick, is a specie only found in highlands region of Rio Grande do Sul state, Southern Brazil. Since initial reports, O. brasiliensis is considered a potential public health hazard in Rio Grande do Sul state due to the possibility of human parasitism. In addition, few reports indicate that O. brasiliensis bite is able to induce severe local and systemic disturbances in humans and animals. This clinical profile possibly fits in the definition of tick toxicosis syndrome. After more than 50 years without reports about O. brasiliensis, new cases of human and animal parasitism were recently reported in the same region of its original description. This work aimed to describe the characteristics of O. brasiliensis parasitism, as well as the toxicosis observed in bitten hosts. Thus, we performed: (i) an epidemiological study about O. brasiliensis parasitism in farms located in the municipalities of São Francisco de Paula and Jaquirana (endemic region) to determine its prevalence and risk factors, and also, to describe the characteristics of its habitat; (ii) an analysis of retrospective cases of human and animal parasitism; (iii) the report of a clinical case of tick toxicosis in a dog naturally parasitized; (iv) a clinico-pathological characterization of the toxicosis induced in experimentally bitten rats; (v) the evaluation of salivary glands effects on skin wound healing. in vivo and upon endothelial cells. Specimens of O. brasiliensis were collected in 16.7% of sampled farms. Ticks were found near human houses and buried in sand. They were found in a very restricted area and in great density, in a kind of tick ¿nest¿. Risk factor analysis showed that only two of the 17 studied variables (insufficient sanitary conditions and presence of house basement with sand floor) were significantly associated with an increased probability to find O. brasiliensis. Twenty-eight people and eleven bitten dogs were identified by analysis of retrospective cases. This analysis also showed the most common symptoms associated to parasitism (pruritus, erythema, edema, pain and slow healing lesion). Our results indicate that in addition to human and dogs, Conepatus chinga (hog-nosed skunk) and Dasypus hybridus (long nosed armadillo) may serve as potential hosts. The toxicosis syndrome induced by tick bite was characterized registering the clinical progress of a naturally bitten dog, and in experimentally infested rats. The clinical findings both in the dog and in rats were similar, and also were compatible with the symptoms reported by bitten humans. The set of all clinical findings evinced the clinical severity of this syndrome. Finally, it was shown that salivary gland extract inhibit in vivo wound healing, possibly due to inhibition of endothelial cell proliferation and cytotoxicity. This biological activity may explain one of the most common symptoms of O. brasiliensis bite: the induction of a slow healing lesion. The set of all results showed here gives new evidences for the understanding of habitat distribution, biology, ecology and peculiarities of O. brasiliensis, as well as for the clinical signs induced by its parasitism.

ASSUNTO(S)

ornithodoros brasiliensis parasitismo carrapatos

ACESSO AO ARTIGO

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