Trobicúlidos y trombiculiasis en La Rioja stars

Abstract

Trombiculid mites, also known as chiggers, belong to Family Trombiculidae and are worldwide distributed. Some genera have medical and veterinary importance. In America and Europe they are associated with seasonal pruriginous dermatitis (trombiculiasis). In Southeast Asia and Pacific Islands they are recognized vectors of scrub typhus. The potential role of trombiculid mites in the transmission of other infectious diseases is unknown. The objectives of this study were: 1) Description of the epidemiology of trombiculiasis in La Rioja; 2) Identification of the etiological agent and study of its life cycle; 3) Investigation of the presence of Rickettsia spp., Anaplasma phagocytophilum, Borrelia spp., Coxiella burnetii, Bartonella spp. and Orientia tsutsugamushi in chiggers, and 4) Clinical characterization of trombiculiasis in La Rioja. Our data have shown the coincidence between the seasonality of human and canine cases of trombiculiasis and the presence of larvae over vegetation in well-defined areas from La Rioja. N. inopinata has been described for the first time in Spain. The identification of this trombiculid species in the same season and area where trombiculiasis cases occurred, epidemiologically involves N. inopinata as the etiological agent of this condition. In the studied area, N. inopinata larvae were detected over vegetation since mid-summer to the end of autumn. Furthermore, in spring, adult trombiculid mites belonging to the same species were found in the soil. Trombiculid larvae removed from potentially migratory birds were classified as N. inopinata. In our environment, there is no evidence of Rickettsia spp., A. phagocytophilum, Borrelia spp., C. burnetii, Bartonella spp. or O. tsutsugamushi infection in trombiculid larvae. Nevertheless, their role in human and canine trombiculiasis has to be taken into account as a Public Health concern. People parasitized with trombiculid mites suffer from very disturbing pruriginous dermatitis, whereas massive parasitation in dogs lead to severe clinical pictures reaching sometimes a fatal outcome. To avoid contact with vegetation in periods of time and areas where the presence of trombiculid larvae has been documented is the only effective preventive measure against trombiculiasis. Therefore, preventive strategies to inform the population about the risk of trombiculiasis in La Rioja should be established.