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Research of tick-borne hemoparasites in small mammals in the states of São Paulo and Mato Grosso do Sul

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Bárbara Conte Weck
Total Authors: 1
Document type: Doctoral Thesis
Press: São Paulo.
Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
Defense date:
Examining board members:
Marcelo Bahia Labruna; Francisco Borges Costa; Felipe da Silva Krawczak; Álvaro Adolfo Faccini Martínez; Hilda Fátima de Jesus Pena
Advisor: Marcelo Bahia Labruna; Sebastián Alejandro Muñoz Leal

Small mammals (rodents and marsupials) are hosts of many species of ticks and also act as reservoirs and/or amplifying hosts of pathogens transmitted by these vectors. In Brazil, studies on wild animals have already been carried out, but the focus on small mammals is still insufficient. This study investigated the occurrence of Hepatozoon, Babesia, Borrelia and Anaplasmataceae agents in small mammals in seven forest fragments in Brazil. Between 2015 and 2021, animals were captured in six forest fragments in the State of São Paulo (Cerrado and Atlantic Rainforest biomes) and one fragment in the State of Mato Grosso do Sul (Pantanal biome). Blood, liver, spleen and lung samples were collected and molecularly screened for Hepatozoon, Babesia, Borrelia and Anaplasmataceae agents. A total of 524 mammals were captured, comprising seven species of marsupials, 14 rodents, two carnivores and one Cingulata. Four new haplotypes (1, 2, 3, 4) of Hepatozoon spp. were detected in small mammals from different biomes and animal species. Despite these distinct geographical and host associations, our phylogenetic analyses indicated that the four Hepatozoon haplotypes belonged to a same clade that contained nearly all haplotypes previously reported on rodents and marsupials, in addition to several reptile-associated haplotypes from different parts of the world. None mammal samples yielded detectable DNA to Babesia spp.. On the other hand, the Anaplasmataceae-targeted PCR assay amplified a sequence 100% identical to the Wolbachia pipientis endosymbiont of the rodent filarid Litomosoides galizai. Lung samples from two Oligoryzomys mattogrossae rodents showed DNA of Lyme group Borrelia. From these samples we performed a molecular characterization of 10 borrelial genes to achieve a robust analysis. The retrieved genetic evidence supports the finding of a novel genospecies of Bbsl that we herein name “Candidatus Borrelia paulista” Rp42. Blood samples from eight Didelphis albiventris showed Borrelia DNA from the Relapsing Fever group. Sequences from flaB and 16s genes showed 100% of identity with a new borrelia specie described in Ornithodoros mimon in Brazil. A molecular characterization was performed with 6 more genes. Further studies are needed to better determine the competence of small mammals in relation to tick-borne agents, as well as to determine they associated vectors. (AU)

FAPESP's process: 17/04249-4 - Survey of tick-borne agents (Anaplasma spp, Babesia spp, Borrelia spp, Ehrlichia spp and Hepatozoon spp) in small mammals and their ticks in endemic and non-endemic areas for Brazilian spotted fever in the state of São Paulo, Brazil.
Grantee:Bárbara Conte Weck
Support Opportunities: Scholarships in Brazil - Doctorate