Prolonged Myocardial Regenerative Capacity in Neonatal Opossum.

BACKGROUND: Early neonates of both large and small mammals are able to regenerate the myocardium through cardiomyocyte proliferation for only a short period after birth. This myocardial regenerative capacity declines in parallel with withdrawal of cardiomyocytes from the cell cycle in the first few postnatal days. No mammalian species examined to date has been found capable of a meaningful regenerative response to myocardial injury later than 1 week after birth. METHODS: We examined cardiomyocyte proliferation in neonates of the marsupial opossum (Monodelphis domestica) by immunostaining at various times after birth. The regenerative capacity of the postnatal opossum myocardium was assessed after either apex resection or induction of myocardial infarction at postnatal day 14 or 29, whereas that of the postnatal mouse myocardium was assessed after myocardial infarction at postnatal day 7. Bioinformatics data analysis, immunofluorescence staining, and pharmacological and genetic intervention were applied to determine the role of AMPK (5'-AMP-activated protein kinase) signaling in regulation of the mammalian cardiomyocyte cell cycle. RESULTS: Opossum neonates were found to manifest cardiomyocyte proliferation for at least 2 weeks after birth at a frequency similar to that apparent in early neonatal mice. Moreover, the opossum heart at postnatal day 14 showed substantial regenerative capacity both after apex resection and after myocardial infarction injury, whereas this capacity had diminished by postnatal day 29. Transcriptomic and immunofluorescence analyses indicated that AMPK signaling is activated in postnatal cardiomyocytes of both opossum and mouse. Pharmacological or genetic inhibition of AMPK signaling was sufficient to extend the postnatal window of cardiomyocyte proliferation in both mouse and opossum neonates as well as of cardiac regeneration in neonatal mice. CONCLUSIONS: The marsupial opossum maintains cardiomyocyte proliferation and a capacity for myocardial regeneration for at least 2 weeks after birth. As far as we are aware, this is the longest postnatal duration of such a capacity among mammals examined to date. AMPK signaling was implicated as an evolutionarily conserved regulator of mammalian postnatal cardiomyocyte proliferation.

Ancestrally Reconstructed von Willebrand Factor Reveals Evidence for Trench Warfare Coevolution between Opossums and Pit Vipers.

Opossums in the tribe Didelphini are resistant to pit viper venoms and are hypothesized to be coevolving with venomous snakes. Specifically, a protein involved in blood clotting (von Willebrand factor [vWF] which is targeted by snake venom C-type lectins [CTLs]) has been found to undergo rapid adaptive evolution in Didelphini. Several unique amino acid changes in vWF could explain their resistance; however, experimental evidence that these changes disrupt binding to venom CTLs was lacking. Furthermore, without explicit testing of ancestral phenotypes to reveal the mode of evolution, the assertion that this system represents an example of coevolution rather than noncoevolutionary adaptation remains unsupported. Using expressed vWF proteins and purified venom CTLs, we quantified binding affinity for vWF proteins from all resistant taxa, their venom-sensitive relatives, and their ancestors. We show that CTL-resistant vWF is present in opossums outside clade Didelphini and likely across a wider swath of opossums (family Didelphidae) than previously thought. Ancestral reconstruction and in vitro testing of vWF phenotypes in a clade of rapidly evolving opossums reveal a pattern consistent with trench warfare coevolution between opossums and their venomous snake prey.

The Role of ATF3 in Neuronal Differentiation and Development of Neuronal Networks in Opossum Postnatal Cortical Cultures.

Activating transcription factor 3 (ATF3), a member of the ATF/cAMP response element-binding (CREB) family, is upregulated by various intracellular and extracellular signals such as injury and signals related to cell proliferation. ATF3 also belongs to the regeneration-associated genes (RAG) group of transcription factors. RAG and ATF/CREB transcription factors that play an important role in embryonic neuronal development and PNS regeneration may also be involved in postnatal neuronal differentiation and development, as well as in the regeneration of the injured CNS. Here we investigated the effect of ATF3 in differentiation, neural outgrowth, network formation, and regeneration after injury using postnatal dissociated cortical neurons derived from neonatal opossums (Monodelphis domestica). Our results show that RAG and ATF genes are differentially expressed in early differentiated neurons versus undifferentiated neurospheres and that many members of those families, ATF3 in particular, are upregulated in cortical cultures obtained from younger animals that have the ability to fully functionally regenerate spinal cord after injury. In addition, we observed different intracellular localization of ATF3 that shifts from nuclear (in neuronal progenitors) to cytoplasmic (in more mature neurons) during neuronal differentiation. The ATF3 inhibition, pharmacological or by specific antibody, reduced the neurite outgrowth and differentiation and caused increased cell death in early differentiating cortical neuronal cultures, suggesting the importance of ATF3 in the CNS development of neonatal opossums. Finally, we investigated the regeneration capacity of primary cortical cultures after mechanical injury using the scratch assay. Remarkably, neonatal opossum-derived cultures retain their capacity to regenerate for up to 1 month in vitro. Inhibition of ATF3 correlates with reduced neurite outgrowth and regeneration after injury. These results indicate that ATF3, and possibly other members of RAG and ATF/CREB family of transcription factors, have an important role both during cortical postnatal development and in response after injury.

Lesions caused by Sarcocystis spp., parasites of opossums (Didelphis aurita), in acute and chronic infections in birds (Melopsittacus undulatus).

Protozoa of the genus Sarcocystis are obligatory heterogenous parasites with both definitive and intermediate hosts. Opossums (Didelphis aurita) can shed multiple species of Sarcocystis with birds as the intermediate host. The pathologies of Sarcocystis species in birds have not been thoroughly elucidated. Therefore, the aim of the present study to determine the main lesions that can occur in acute and chronic infections in intermediate hosts, when they ingest infective sporocysts that are shed in the opossum's feces, using budgerigars as a model. To this end, 12 budgerigars, Melopsittacus undulatus, were divided into two groups that received an inoculum with 60 and 120 sporocysts. Birds that died or were euthanized were necropsied, and the lung, tongue, liver, brain, heart, and skeletal striated muscles were collected and fixed in 10% formalin for histopathological analysis. The infectivity varied according to the sample and infective dose. Acute histopathological lesions were characterized by evidence of slightly degenerated hepatocyte cords that permeated the region of the blood vessel and hepatic sinusoids. Pulmonary tissue lesions were also observed in the parabronchial region with the presence of inflammatory infiltrates associated with areas of edema and atelectasis. In chronic infections, few mature cysts were observed in the chest, and many mature cysts in the thigh and tongue muscles. Thus, it was possible to conclude that lesions are highly characteristic in acute infection and, in chronic infections, cysts were present but without major lesions. In this case, the preferred organs of parasitism were the thigh and the tongue.

Helicobacter monodelphidis sp. nov. and Helicobacter didelphidarum sp. nov., isolated from grey short-tailed opossums (Monodelphis domestica) with endemic cloacal prolapses.

In a search for potential causes of increased prolapse incidence in grey short-tailed opossum colonies, samples from the gastrointestinal tracts of 94 clinically normal opossums with rectal prolapses were screened for Helicobacter species by culture and PCR. Forty strains of two novel Helicobacter species which differed from the established Helicobacter taxa were isolated from opossums with and without prolapses. One of the Helicobacter species was spiral-shaped and urease-negative whereas the other Helicobacter strain had fusiform morphology with periplasmic fibres and was urease-positive. 16S rRNA gene sequence analysis revealed that all the isolates had over 99 % sequence identity with each other, and were most closely related to Helicobacter canadensis. Strains from the two novel Helicobacter species were subjected to gyrB and hsp60 gene and whole genome sequence analyses. These two novel Helicobacter species formed separate phylogenetic clades, divergent from other known Helicobacter species. The bacteria were confirmed as novel Helicobacter species based on digital DNA-DNA hybridization and average nucleotide identity analysis of their genomes, for which we propose the names Helicobacter monodelphidis sp. nov. with the type strain MIT 15-1451T (=LMG 29780T=NCTC 14189T) and Helicobacter didelphidarum sp. nov with type strain MIT 17-337T (=LMG 31024T=NCTC 14188T).

Ticks, fleas and endosymbionts in the ectoparasite fauna of the black-eared opossum Dipelphis aurita in Brazil.

Ticks and fleas are essential vectors of pathogens that affect humans and animals, and among their hosts, synanthropic animals such as the black-eared opossum, Didelphis aurita, play a role in public health due to their ability to move between urban centers and forested areas in Brazil. This study aimed to assess the ectoparasite fauna of D. aurita, as well as the presence of pathogens and endosymbionts in ticks and fleas. Opossums (n = 58) captured in Tomahawk livetraps were examined for ectoparasites, and their blood sampled for further analysis. Additionally, spleen samples were collected in individuals found dead. Samples were PCR screened for Rickettsia spp., Borrelia spp., Anaplasmataceae, and Babesia spp. Two tick species were morphologically identified as Ixodes loricatus 24/58 (41.4%) and Amblyomma sculptum 1/58 (1.7%). For fleas, Ctenocephalides felis was detected in 60.3% (35/58) of the animals, and Xenopsylla cheopis in 5.2% (3/58). PCR analysis detected Anaplasmataceae DNA in 34% (16/47) of pooled samples of C. felis, and in 66.7% (2/3) pooled samples of X. cheopis. Sequence analysis revealed Wolbachia pipientis symbiont in all positive samples. Tick, blood and spleen samples were all negative for the microorganisms assessed. These findings suggest that these arthropods circulate among wildlife and urban environments, which may implicate in their participation in the cycle of zoonotic pathogens among opossums, humans and companion animals.

PHYSIOLOGICAL BASAL PARAMETERS OF FREE-RANGING OPOSSUMS ( DIDELPHIS VIRGINIANA) IN THE YUCATAN PENINSULA, MEXICO.

The aim of the present study is to determine the basal parameters in opossums ( Didelphis virginiana) during physical examination in Yucatan, Mexico. Sixty-six opossums were captured and manually handled for physical examinations. Sex, age, cardiac and respiratory rate, body temperature, pulse, mucous membranes, capillary refill time, hydration, size of superficial lymph nodes, mental status, and body condition were evaluated. Also, comparisons between rectal and auricular temperatures were performed. The means of physiological parameters obtained were: cardiac frequency 146 beats per minute (95% confidence interval [CI]: 138.91-155.24), respiratory frequency 27.33 breaths per minute (95% CI: 25.15-29.64), and body temperature 34.01°C (95% CI: 33.71-34.31). In 54% of animals, a sinus arrhythmia was present. A significant difference was found between rectal and auricular temperature measurements. A variation of -1.64 to 1.14°C was obtained via the auricular thermometer compared with the rectal device.

Prevalence of Trypanosoma cruzi infection in dogs and small mammals in Nuevo León, Mexico.

Chagas disease, caused by the protozoan Trypanosoma cruzi, is an important public health concern in areas extending from South America northward into the southern United States of America. Although this hemoflagellate has many wild and domestic mammalians reported as reservoir hosts, studies on this subject are scarce in Nuevo León state, a region located in northeastern Mexico. This cross-sectional study showed that the general prevalence of T. cruzi infection in Nuevo León state was 14.5% (35/241), this percentage matching the ones determined by PCR and traditional diagnostics. Localities and infected mammals did not significantly differ (χ2=6.098, p=0.192); however the number of infected animals was highly correlated with mammalian species (p=0.009). Striped skunks (Mephitis mephitis) were found to be the most infected overall (11/34, 32.3%), while dogs (Canis familiaris) had the lowest prevalence. In conclusion, although the prevalence of T. cruzi infection in small mammals was lower in Nuevo León than in other states of Mexico, our results provide new locality records, including striped skunks, opossums (Didelphis marsupialis) and dogs, and extend the recorded area to woodrats (Neotoma micropus).

High-Resolution Molecular Typing of Trypanosoma cruzi in 2 Large Outbreaks of Acute Chagas Disease in Colombia.

Oral transmission of Trypanosoma cruzi has gained relevance because of its association with high morbidity and lethality rates. This transmission route is responsible for maintaining the infection of the parasite in sylvatic cycles, and human cases have been associated mainly with the consumption of food contaminated with triatomine feces or didelphid secretions. Several ecological changes allow the intrusion of sylvatic reservoirs and triatomines to the domestic environments with subsequent food contamination. Here, high-resolution molecular tools were used to detect and genotype T. cruzi across humans, reservoirs, and insect vectors in 2 acute outbreaks of presumptive oral transmission in eastern Colombia.

Dogs and Opossums Positive for Vaccinia Virus during Outbreak Affecting Cattle and Humans, São Paulo State, Brazil.

During a vaccinia virus (VACV) outbreak in São Paulo State, Brazil, blood samples were collected from cows, humans, other domestic animals, and wild mammals. Samples from 3 dogs and 3 opossums were positive for VACV by PCR. Results of gene sequencing yielded major questions regarding other mammalian species acting as reservoirs of VACV.

First evidence of gregarious denning in opossums (Didelphimorphia, Didelphidae), with notes on their social behaviour.

The Didelphidae are considered solitary opossums with few social interactions, usually limited to mating-related or mother-pouch young interactions. Anecdotal reports suggest that additional interactions occur, including den sharing by a few individuals, usually siblings. Here, we report novel observations that indicate opossums are more social than previously thought. These include nest sharing by males and females of Marmosa paraguayana, Gracilinanus microtarsus and Marmosops incanus prior to the onset of the breeding season and without signs of sexual activity; this is taken to indicate early pair-bonding matching and cooperative nest building. We also recorded den sharing among recently weaned siblings of Didelphis aurita and Caluromys philander. In addition, we observed 13 individuals of Didelphis albiventris representing three age classes resting without agonistic interactions in a communal den. These are the first reports of gregarious behaviour involving so many individuals, which are either unrelated or represent siblings from at least two litters, already weaned, sharing the same den with three adults. Sociality in opossums is probably more complex than previously established, and field experimental designs combining the use of artificial nests with camera traps or telemetry may help to gauge the frequency and extent of these phenomena.

Detection of macropodid alphaherpesvirus 2 infection and lesions in sudden death of a captive Virginia opossum and a water opossum.

Macropodid alphaherpesvirus 2 (MaAHV2) is best described in macropods and has been implicated in outbreaks among captive marsupial populations in Australia. Natural disease caused by herpesviruses has not been reported previously in opossum species, to our knowledge. One Virginia opossum (Didelphis virginiana) and 1 water opossum (Chironectes minimus) were submitted for postmortem examination from a zoo that housed 6 opossums, all of which died within several weeks. Red kangaroos (Macropus rufus) and red-necked wallabies (Macropus rufogriseus) were also present at the facility. Liver samples from both opossums were submitted for transmission electron microscopy and whole-genome sequencing. Microscopically, both opossums had multifocal necrosis in the liver and lung, with intranuclear inclusion bodies within hepatocytes and pneumocytes. Another significant finding in the Virginia opossum was sepsis, with isolation of Streptococcus didelphis from various organs. Ultrastructural analysis of formalin-fixed liver tissue identified herpesviral replication complexes in both opossums; negative-stain electron microscopy of unfixed liver tissue repeatedly yielded a negative result. The herpesvirus had >99% nucleotide identity with MaAHV2. These 2 cases indicate that both opossum species are susceptible to MaAHV2 infection, and the outbreak has implications for mixed-species facilities that house macropods.

Borrelia puertoricensis in opossums (Didelphis marsupialis) from Colombia.

BACKGROUND: The genus Borrelia comprises pathogenic species of bacteria that pose a significant risk to public health. Borrelia spp. are emerging or reemerging infectious agents worldwide with complex transmission cycles, and many species use rodents as vertebrate reservoir hosts. Spirochetes morphologically compatible with Borrelia have been recurrently observed in opossums; however, there is currently a lack of genetic evidence confirming infection or supporting that these marsupials are hosts of Borrelia spirochetes. METHODS: During 2017, 53 serum samples of Didelphis marsupialis from the municipality of Colosó (department of Sucre, Colombia) were collected and allocated in a serum bank. DNA extracted from the serum samples was submitted to a Borrelia genus-specific real-time PCR targeting the 16S rRNA gene. Positive samples were subsequently derived from semi-nested PCR protocols to obtain large fragments of the 16S rRNA and flaB genes. Obtained amplicons were subjected to Sanger sequencing. One positive sample was randomly selected for next-generation sequencing (NGS). Obtained reads were mapped to genomes of Borrelia spp. and sequences of two genes used in a multilocus sequence typing scheme retrieved for taxonomic assignment and phylogenetic analyses. RESULTS: Overall, 18.8% (10/53) of the samples were positive by qPCR. Of them, 80% (8/10) and 60% (6/10) were positive for the 16S rRNA and flaB genes after semi-nested PCRs, respectively. Bioinformatic analysis of one sample sequenced with NGS yielded 22 reads of genus Borrelia with different sizes. Two housekeeping genes, rplB and pyrG, were recovered. Nucleotide pairwise comparisons and phylogenetic analyses of 16S rRNA, flaB, rplB and pyrG genes showed that the Borrelia sp. found in opossums from Colosó corresponded to Borrelia puertoricensis. CONCLUSIONS: We describe the first molecular evidence to our knowledge of B. puertoricensis in Colombia, specifically in opossums, and the first detection of this spirochete in a vertebrate host since its isolation from Ornithodoros puertoricensis in Panama. This detection is also relevant because of the epidemiological importance of opossums as reservoirs of zoonotic diseases to humans.

Murine Typhus: A Review of a Reemerging Flea-Borne Rickettsiosis with Potential for Neurologic Manifestations and Sequalae.

Murine typhus is an acute febrile illness caused by Rickettsia typhi, an obligately intracellular Gram-negative coccobacillus. Rats (Rattus species) and their fleas (Xenopsylla cheopis) serve as the reservoir and vector of R. typhi, respectively. Humans become infected when R. typhi-infected flea feces are rubbed into flea bite wounds or onto mucous membranes. The disease is endemic throughout much of the world, especially in tropical and subtropical seaboard regions where rats are common. Murine typhus is reemerging as an important cause of febrile illness in Texas and Southern California, where an alternate transmission cycle likely involves opossums (Didelphis virginiana) and cat fleas (Ctenocephalides felis). Although primarily an undifferentiated febrile illness, a range of neurologic manifestations may occur, especially when treatment is delayed. Serology is the mainstay of diagnostic testing, but confirmation usually requires demonstrating seroconversion or a fourfold increase in antibody titer from acute- and convalescent-phase sera (antibodies are seldom detectable in the first week of illness). Thus, early empiric treatment with doxycycline, the drug of choice, is imperative. The purpose of this review is to highlight murine typhus as an important emerging and reemerging infectious disease, review its neurologic manifestations, and discuss areas in need of further study.

First Genomic Evidence of a Henipa-like Virus in Brazil.

The viral genus Henipavirus includes two highly virulent zoonotic viruses of serious public health concern. Hendra henipavirus and Nipah henipavirus outbreaks are restricted to Australia and Southeast Asia, respectively. The Henipavirus genus comprises mostly bat-borne viruses, but exceptions have already been described as novel viruses with rodents and shrews as reservoir animals. In the Americas, scarce evidence supports the circulation of these viruses. In this communication, we report a novel henipa-like virus from opossums (Marmosa demerarae) from a forest fragment area in the Peixe-Boi municipality, Brazil, after which the virus was named the Peixe-Boi virus (PBV). The application of next-generation sequencing and metagenomic approach led us to discover the original evidence of a henipa-like virus genome in Brazil and South America and the original description of a henipa-like virus in marsupial species. These findings emphasize the importance of further studies to characterize PBV and clarify its ecology, impact on public health, and its relationship with didelphid marsupials and henipaviruses.

Sarcocystis neurona Transmission from Opossums to Marine Mammals in the Pacific Northwest.

Increasing reports of marine mammal deaths have been attributed to the parasite Sarcocystis neurona. Infected opossums, the only known definitive hosts, shed S. neurona sporocysts in their feces. Sporocysts can contaminate the marine environment via overland runoff, and subsequent ingestion by marine mammals can lead to fatal encephalitis. Our aim was to determine the prevalence of S. neurona in opossums from coastal areas of Washington State (USA) and to compare genetic markers between S. neurona in opossums and marine mammals. Thirty-two road-kill opossums and tissue samples from 30 stranded marine mammals meeting inclusion criteria were included in analyses. Three opossums (9.4%) and twelve marine mammals (40%) were confirmed positive for S. neurona via DNA amplification at the ITS1 locus. Genetic identity at microsatellites (sn3, sn7, sn9) and the snSAG3 gene of S. neurona was demonstrated among one harbor porpoise and two opossums. Watershed mapping further demonstrated plausible sporocyst transport pathways from one of these opossums to the location where an infected harbor porpoise carcass was recovered. Our results provide the first reported link between S. neurona genotypes on land and sea in the Pacific Northwest, and further demonstrate how terrestrial pathogen pollution can impact the health of marine wildlife.

Establishment of Long-Term Primary Cortical Neuronal Cultures From Neonatal Opossum Monodelphis domestica.

Primary dissociated neuronal cultures have become a standard model for studying central nervous system (CNS) development. Such cultures are predominantly prepared from the hippocampus or cortex of rodents (mice and rats), while other mammals are less used. Here, we describe the establishment and extensive characterization of the primary dissociated neuronal cultures derived from the cortex of the gray South American short-tailed opossums, Monodelphis domestica. Opossums are unique in their ability to fully regenerate their CNS after an injury during their early postnatal development. Thus, we used cortex of postnatal day (P) 3-5 opossum to establish long-surviving and nearly pure neuronal cultures, as well as mixed cultures composed of radial glia cells (RGCs) in which their neurogenic and gliogenic potential was confirmed. Both types of cultures can survive for more than 1 month in vitro. We also prepared neuronal cultures from the P16-18 opossum cortex, which were composed of astrocytes and microglia, in addition to neurons. The long-surviving opossum primary dissociated neuronal cultures represent a novel mammalian in vitro platform particularly useful to study CNS development and regeneration.

Murine Typhus Infection in Pregnancy: Case Series and Literature Review.

Murine typhus is a flea-borne disease of worldwide distribution with a recent reemergence in the United States of America. There are limited data about the presentation, treatment, and outcomes in the pregnant population. We report on two cases of murine typhus during pregnancy and review the literature to compile previously reported cases. A comprehensive search was performed via the PubMed database for published articles between 1990 and 2020. Seven articles met the criteria of symptomatic pregnant murine typhus infection. A total of 37 patients were identified. Patients frequently presented with a prolonged duration of fevers prior to presentation, headache, and elevated hepatic transaminases. The diagnosis was predominantly based on serology. Treatment varied. Overall, the pregnancy outcome was favorable. Murine typhus can mimic other pregnancy-related pathologies. More exclusive and large-scale studies are needed to learn more of murine typhus during pregnancy.

Mesocarnivore landscape use along a gradient of urban, rural, and forest cover.

Mesocarnivores fill a vital role in ecosystems through effects on community health and structure. Anthropogenic-altered landscapes can benefit some species and adversely affect others. For some carnivores, prey availability increases with urbanization, but landscape use can be complicated by interactions among carnivores as well as differing human tolerance of some species. We used camera traps to survey along a gradient of urban, rural, and forest cover to quantify how carnivore landscape use varies among guild members and determine if a species was a human exploiter, adapter, or avoider. Our study was conducted in and around Corvallis, Oregon from April 2018 to February 2019 (11,914 trap nights) using 47 camera trap locations on a gradient from urban to rural. Our focal species were bobcat (Lynx rufus), coyote (Canis latrans), gray fox (Urocyon cinereoargenteus), opossum (Didelphis virginiana), raccoon (Procyon lotor), and striped skunk (Mephitis mephitis). Raccoon and opossum were human exploiters with low use of forest cover and positive association with urban and rural developed areas likely due to human-derived resources as well as some refugia from larger predators. Coyote and gray fox were human adapters with high use of natural habitats while the effects of urbanization ranged from weak to indiscernible. Bobcat and striped skunk appeared to be human avoiders with negative relationship with urban cover and higher landscape use of forest cover. We conducted a diel temporal activity analysis and found mostly nocturnal activity within the guild, but more diurnal activity by larger-bodied predators compared to the smaller species. Although these species coexist as a community in human-dominated landscapes throughout much of North America, the effects of urbanization were not equal across species. Our results, especially for gray fox and striped skunk, are counter to research in other regions, suggesting that mesopredator use of urbanized landscapes can vary depending on the environmental conditions of the study area and management actions are likely to be most effective when decisions are based on locally derived data.

Low occurrence of Bartonella in synanthropic mammals and associated ectoparasites in peri-urban areas from Central-Western and Southern Brazil.

Worldwide, Bartonella species are known to infect a wide range of mammalian and arthropod hosts, including humans. The current study aimed to investigate the prevalence of Bartonella spp. in synanthropic mammals captured in peri-urban areas from Central-Western and Southern Brazil and their ectoparasites. For this aim, 160 mammals belonging to four species, and 218 associated arthropods were sampled. DNA was extracted and subjected to different Bartonella screening assays. Additionally, blood samples from 48 small rodents were submitted to liquid BAPGM culture followed by qPCR assay and solid culture. Two out of 55 Rattus captured in Santa Catarina state were PCR-positive for Bartonella when targeting the nuoG, 16S, and ITS loci. Sequences showed high homology with Bartonella coopersplainsensis. Conversely, all 48 small rodents, 14 capybaras and 43 opossum DNA samples from animals trapped in Mato Grosso do Sul were Bartonella negative in the HRM real time PCR assays targeting the ITS locus and gltA gene. Additionally, all mammal-associated ectoparasites showed negativity results based on HRM real time PCR assays. The present study showed, for the first time, the occurrence of B. coopersplainsensis in Brazil, shedding some light on the distribution of rats-related Bartonella in South America. In addition, the majority of rodents and marsupials were negative for Bartonella spp. Since B. coopersplainsensis reservoirs - Rattus spp. - are widely dispersed around the globe, their zoonotic potential should be further investigated.