Molecular detection of Rickettsia genus in chigger mites (Trombidiformes: Trombiculidae) collected on small mammals in southeastern brazilian

Abstract

Chiggers are ectoparasites of vertebrates and may cause trombiculiasis or transmit pathogens to their hosts. Specimens collected from rodents and marsupials were morphologically identified as Herpetacarus hertigi, Eutrombicula tinami, Kymocta sp., Quadraseta brasiliensis, Quadraseta falconensis, Quadraseta flochi, Quadraseta mackenziei, Quadraseta pazca, Quadraseta trapezoides, Quadraseta sp., Serratacarus sp., and Trombewingia bakeri. These mites were submitted individually to molecular analyses for the detection of bacteria of the genus Coxiella, Hepatozoon and Rickettsia. Samples were positive to Rickettsia only. Obtained sequences for the gltA (350 pb) and ompA (488 pb) genes were identical to “Candidatus Rickettsia colombianensi”, a species previously detected in ticks. In addition, molecular identification of mites based on 18S rDNA sequences are provided for H. hertigi, Kymocta sp., Q. brasiliensis, Q. pazca, Q. trapezoides, Quadraseta sp., and T. bakeri for the first time. This is the first report of the detection of a Rickettsia sp. in chigger mites collected on rodents in Brazil.

Rickettsia felis and Other Rickettsia Species in Chigger Mites Collected from Wild Rodents in North Carolina, USA

“…In this study, we provide the first evidence of Rickettsia infection in chiggers collected from rodents within North America, a significant extension of recent work finding rickettsial DNA in trombiculid mites from South America and Asia [ 10 , 31 , 32 ]. Nucleotide sequence analyses of Rickettsia -specific 23S-5S IGS, 17 kDa, and gltA gene fragments indicated the amplicons from these chiggers were closely related to those in R. felis , R. conorii , R. typhi , and unidentified Rickettsia species.…”

“…The most frequently detected rickettsial species in our study, Rickettsia felis , is globally distributed and was found in fleas, mosquitoes, ticks, and chigger mites [ 31 ]. There is increasing evidence that chiggers could be vectors of transitional group rickettsiae, because of their discovery in a variety of field-collected chiggers [ 10 , 32 ]. Several other rickettsiae known to infect humans, namely R. japonica , R. akari , R. felis , R. conorii , R. typhi , and other Rickettsia spp.…”

“…[ 9 ]. Recently, Candidatus Rickettsia colombianensi was also detected in chiggers collected from rodents in Brazil [ 10 ]. Despite the public health importance and increasing discovery of chigger-borne human disease outside of the Tsutsugamushi Triangle, the role of chiggers in human infection with rickettsial pathogens in the US is still unknown.…”

Not Only Leptotrombidium spp. an Annotated Checklist of Chigger Mites (Actinotrichida: Trombiculidae) Associated with Bacterial Pathogens

“…Larvae were collected from the colilargo Oligoryzomys sp. Bangs, 1900 (Mammalia: Rodentia) in Brazil [ 76 ].…”

“…Parasite carrying a novel bacterium Candidatus Rickettsia colombianensi. Larvae were collected from the South American water rat Nectomys squamipes (Brants, 1827) (Mammalia: Rodentia) in Brazil [ 76 ].…”