Banca de DEFESA: TATIANA PÁDUA TAVARES DE FREITAS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : TATIANA PÁDUA TAVARES DE FREITAS
DATE: 16/12/2025
TIME: 13:00
LOCAL: Anfiteatro DPA, sala 14
TITLE:

Occurrence and Genetic Diversity of Babesia and Hepatozoon in Rodents and Marsupials from the States of Rio de Janeiro and Paraná, Brazil

KEY WORDS:

Small mammals, hemoparasites, 18S Ribosomal DNA

PAGES: 85
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUBÁREA: Medicina Veterinária Preventiva
SPECIALTY: Doenças Parasitárias de Animais
SUMMARY:

Apicomplexan protozoa are obligate parasites found in a wide range of vertebrate hosts and hematophagous invertebrates, exhibiting either monoxenous or heteroxenous life cycles depending on the species. Within the suborder Adeleorina, species of the genus Hepatozoon were first recorded infecting small mammals (rodents and marsupials) in Brazil during the last century. In 1915, Hepatozoon muris was detected in the rodent Akodon fuliginosus in São Paulo, and in 1916 another species was reported, described as Haemogregarina didelphydis, in the marsupial Didelphis aurita in the municipality of Rio de Janeiro. More recently, a novel species, Hepatozoon milleri, was described in the rodent Akodon montensis in Botucatu, São Paulo, based on both light microscopy and molecular analyses. In the present study, liver samples and blood smears were collected from 309 non-volant small mammals captured in municipalities of the states of Paraná (Cruz Machado, Lidianópolis, and Ponta Grossa) and Rio de Janeiro (Iguaba Grande and Nova Friburgo), including three species of didelphid marsupials (Didelphis aurita, Monodelphis americana, and Philander quica), 14 species of cricetid rodents, and two species of murid rodents (Mus musculus and Rattus rattus). Blood smears were stained using the Giemsa method, and gamonts were detected by light microscopy in 10% (31/309) of the sampled small mammals (Akodon cursor, Akodon montensis, and Oligoryzomys nigripes). Significant morphometric differences were observed in gamont measurements among Akodon species. Using conventional PCR, 18S rDNA fragments of Hepatozoon spp. were amplified in 23.3% (72/309) of rodents (A. cursor, A. montensis, O. nigripes, Oxymycterus nasutus, Oxymycterus quaestor, Sooretamys angouya, and Mus musculus), whereas no marsupials tested positive for Hepatozoon spp. Phylogenetic analyses showed that sequences obtained from rodents (n = 41) formed a subclade with other sequences from small mammals in Brazil and belonged to four distinct haplotypes. Three long sequences (>1600 bp), representing haplotypes 1, 3, and 4, were subsequently obtained and analyzed. Based on phylogenetic inference, the study reinforces the trophic relationship between rodents and reptiles as a potential transmission route for Hepatozoon in South America. Furthermore, our findings expand the known host range of Hepatozoon spp., reporting Oxymycterus nasutus and Oxymycterus quaestor as new host species and identifying two new haplotypes circulating in rodents from the state of Paraná, where the parasite had not previously been detected in members of this order. Following the qualification examination, the study was expanded to include additional rodent and marsupial samples that also tested positive for Hepatozoon. Additionally, piroplasms were investigated in these populations, with positivity detected in both host groups, significantly enriching the understanding of the parasitic diversity circulating among these mammals.

COMMITTEE MEMBERS:
Presidente - 3103478 - MARISTELA PECKLE PEIXOTO
Interna - 3103528 - CLAUDIA BEZERRA DA SILVA
Interna - 3247559 - BRUNA DE AZEVEDO BAETA
Externa ao Programa - 1299153 - PATRICIA GONZAGA PAULINO - UFRRJExterna à Instituição - KARINA VARELLA ARPON - FIOCRUZ
Externo à Instituição - PAULO SERGIO D'ANDREA
Externa à Instituição - LETÍCIA PEREIRA ÚNGARI - USP