Correction to "Diversity and eco-epidemiology of ectoparasites and Rickettsia spp. associated with the opossums Didelphis albiventris Lund in livestock farms from Argentinian Pampas region".

Many ectoparasite species serve as vectors for bacteria that are significant to both public and animal health, with wild, domestic and synanthropic mammals acting as reservoirs. However, limited information exists on the circulation and incidence of these vectors in Argentina. We examined the diversity, prevalence and abundance of ectoparasites, along with the presence of Rickettsia spp., of Didelphis albiventris Lund (Didelphimorphia, Didelphidae) within a rural landscape of the Pampas region, Argentina. We also analysed variations in ectoparasite populations concerning seasonality, livestock farm type and farmers' management practices. Seven species of hematophagous ectoparasites were collected, including mites (Mesostigmata, Laelapidae: Laelaps echidninus Berlese); ticks (Ixodida, Ixodidae: Ixodes loricatus Neumann); fleas (Siphonaptera, Rhopalopsyllidae: Polygenis platensis Jordan and Rothschild and Polygenis rimatus Jordan); Stephanocircidae: Craneopsylla minerva wolffhuegeli (Rothschild, Pulicidae: Ctenocephalides felis Bouché); and lice (Phthiraptera, Polyplacidae: Polyplax spinulosa Burmeister). Additionally, two bacteria were detected: Rickettsia felis Bouyer et al. (Rickettsiales, Rickettsiaceae) and Rickettsia sp. (Rickettsiales, Rickettsiaceae) were closely related to Rickettsia bellii Philip et al. (Rickettsiales, Rickettsiaceae). Fleas were the most prevalent and abundant group, with C. felis showing the highest values of mean abundance and prevalence. Parasitological comparisons between dairy farms and feedlots revealed similar results, with comparable densities of D. albiventris in both farm types. Ectoparasite abundance varied seasonally, peaking during the colder season. Regression analysis indicated higher ectoparasite infestation levels on farms with more dogs. The detection of pathogenic bacteria, coupled with the high prevalence and abundance of vectors, such as C. felis, suggests a significant epidemiological risk in the region. The commensal behaviour of D. albiventris facilitates it to thrive in areas modified by anthropogenic activity, positioning this species as a potential nexus between wild and domestic epidemiological cycles of parasites and emerging pathogens. Therefore, our findings suggest that D. albiventris plays a key role in the transmission and maintenance of ectoparasites and ectoparasite-borne bacteria within these ecosystems.

The Pampean plains in South America are well-known for their livestock and agricultural productivity. The peri-urban watershed of El Pescado Creek (Central-Eastern Argentina) has been significantly modified in the last few years due to local land-use changes. This work aims to analyze the dynamics of nutrient content associated with the surface water-groundwater relationship in this watershed and to define the trophic state of the watercourse. Sampling sites were selected for both surface water and groundwater analyses, and field surveys were carried out during the spring and summer of 2017. Handmade shallow groundwater wells were installed along the floodplain of the watercourse. Deep groundwater was analyzed in agricultural and livestock farms. In situ determinations included dissolved oxygen (DO), pH, electrical conductivity (EC), turbidity, transparency, and temperature measurements. Laboratory analyses included NO3--N, total nitrogen (TN), soluble reactive phosphorus (SRP), total phosphorus (TP), and phytobenthonic and phytoplanktonic chlorophyll-a. Results showed an increase in EC and nutrient concentration in the summer samples (both in surface water and shallow groundwater), along with higher turbidity of the surface water. Water flow was dissimilar between samplings (spring: 1.735 m3/s, summer: 0.065 m3/s), showing contrasting hydrological scenarios. Low wash-out conditions enhanced phytobenthonic algae biomass growth, turning most of the sites towards a eutrophic state in summer. Our results showed that the dynamics of nitrogen and phosphorus compounds in the watershed of El Pescado Creek depend on the hydrodynamic processes of the watershed, the different land-uses, and the chemical characteristics of these compounds. In order to develop sustainable management strategies, further understanding of nutrient concentrations effects, and the factors affecting them, must be done in this area of the Pampean region.

Dioctophyme renale (Goeze, 1782) is a parasitic nematode that infects the kidneys of wild and domestic carnivores, including humans. The parasite is highly prevalent in southern Brazil, affecting a wide range of wild and domestic animals. While the high rates of parasitosis in stray and semi-domesticated dogs in the region are well documented, the dynamics of the parasite's life cycle and the intermediate (freshwater invertebrates) and definitive hosts are not completely known. This study aimed to report two new wild hosts for D. renale third-stage larvae in southern Brazil. The study was conducted in Capão do Leão, Rio Grande do Sul, Brazil. Three road-killed mammals, including one Procyon cancrivorus (G. Cuvier, 1798) and two Didelphis albiventris Lund, 1840, were collected and sent to the Federal University of Pelotas for parasitological analysis. The parasites were removed, cleaned, preserved, and identified based on morphological and morphometric characteristics. Third-stage larvae were found encysted in the serosa and gastric submucosa of D. albiventris (one host with 21 larvae and the other with 34 larvae) and in the stomach submucosa, liver parenchyma, and omentum of P. cancrivorus (infected with 3 larvae). This study reports, for the first time, natural infections of P. cancrivorus and D. albiventris by D. renale. Although adult parasites were not detected, the potential of these species to act as definitive or paratenic hosts cannot be dismissed. The findings support previous studies on larval migration involving the stomach and liver before reaching the peritoneal cavity. The study also highlights the relevance of dioctophymosis in the region, where environmental factors, stray dog populations, and interactions between wild and domestic animals may facilitate transmission. Overall, these findings enhance understanding of D. renale’s host range and underscore the need for continued surveillance in wild and urban environments in southern Brazil.

The effects of habitat fragmentation and deforestation are exacerbated by some elements, such as roads and power lines, which may become filters or barriers to wildlife movements. In order to mitigate mortality and restore connectivity, wildlife passages are being constructed as linear corridors. The installation of these mitigation measures must be followed by systematic monitoring, in order to evaluate their use and effectiveness, to assist in their management, and to convince stakeholders of their value. In this paper we present the results of a monitoring study of the use of rope overpasses developed near a protected area in Porto Alegre, southern Brazil. The canopy bridges were installed by the Urban Monkeys Program in places where electric hazards and road-kills of brown howler monkeys (Alouatta guariba clamitans Cabrera, 1940) were recorded. Camera traps were installed at each bridge, and local people were selected and trained to monitor overpass use over 15 months, from August 2008 to October 2009. Three species were recorded using canopy bridges: brown howler monkey (Alouatta guariba clamitans Cabrera, 1940), white-eared opossum (Didelphis albiventris Lund, 1840) and porcupine (Sphiggurus villosus Cuvier, 1823). Rope bridges with the highest number of species recorded had more forest cover and lower urban area around them than overpasses little used. Our results indicate that overpasses, in Porto Alegre, work as a linear corridor between forest remnants, although the outcomes for individual survival, group persistence, population demography or gene flow have not been measured. Furthermore, canopy bridges may be important to mitigate the impact of roads and power lines on wildlife, but electric cables also need to be completely isolated when present, to warrant animals' physical integrity.

Novel Ehrlichia and Hepatozoon genotypes in white-eared opossums (Didelphis albiventris) and associated ticks from Brazil

Opossums are marsupials from the New World of the genus Didelphis and known as synanthropic animals due to their proximity with human beings. To date, 'Candidatus Mycoplasma haemodidelphis' has been solely found infecting the North American opossum (Didelphis virginiana). Accordingly, the aim of this study was to screen eight white-eared opossums (Didelphis albiventris) from a public park in Maringa city, Paraná State, southern Brazil, for hemoplasma infection. Blood samples were taken from caudal venipuncture, and DNA was extracted and further screened by a pan-hemoplasma PCR assay. Seven out of eight (87.50%; CI 95%: 47.35-99.68%) white-eared opossums were positive for Mycoplasma spp. Sequencing of the 16S rRNA fragment showed 98,97% identity with 'Ca. M. haemodidelphis' detected in the USA. Three out of eight (37.50%; CI 95%: 8.52-75.51%) white-eared opossums were infested by Amblyomma dubitatum ticks. This is the first report on detection of a potentially novel hemotropic Mycoplasma sp. infecting opossums from South America.

The white-eared opossum (Didelphis albiventris) is a Neotropical marsupial that occurs in the Brazilian territory. The larynx is an important organ of vocalization in mammals, although, other laryngeal functions are more fundamental for survival of mammals than phonation. The anatomical knowledge of respiratory structures is pivotal for a better understanding of the species. Thus, this study aimed to examine the larynx of the white-eared opossum by gross anatomy, computed tomography and histological description. For this, 10 adult (six females and four males) white-eared opossums (D. albiventris) were used. The white-eared opossum larynx was formed by epiglottis, thyroid, cricoids and arytenoid cartilages and a corniculate process. There is a similarity between the larynx of this marsupial and those reported in other wild mammals, regarding the number of cartilages and their location. Histologically, the epiglottis consisted of elastic cartilage and thyroid, cricoid and arytenoid cartilages were composed of hyaline cartilage. The epiglottis protruded rostrally into the nasal part of the pharynx, above the soft palate, and this is probably a marsupial characteristic as the fact that the thyroid and cricoid cartilages were ventrally fused. The hyoid apparatus was similar to that of other animals, with the same bony constitution, but with a greatly reduced stylohyoid bone. Histologically, the larynx was similar to those of other species such as koala, armadillo, crab-eating foxes and giant anteaters. The knowledge of the larynx morphology is important for the anatomical features of the species and clinical and surgical procedures, such as endotracheal intubation.

Hemoplasmas are epierythrocytic bacteria that infect mammals. 'Candidatus Mycoplasma haemoalbiventris' was detected in white-eared opossums (Didelphis albiventris) from southern and central-western Brazil. The present study aimed at: i) screening opossums for tick-borne (TBP) pathogens (Piroplasmida and Anaplasmataceae) and ii) detecting and characterizing hemoplasma species infecting opossums from Curitiba and Foz do Iguaçu cities in the Paraná State, southern Brazil. Thirty blood samples from white-eared opossums were evaluated by PCR assays. Animals were not infested by ectoparasites. The mammalian endogenous gapdh gene was consistently amplified in all samples. All opossums tested negative for Theileria/Babesia spp. and Ehrlichia/Anaplasma spp. by PCR based on 18S rRNA and 16S rRNA genes, respectively. A genus-specific PCR assay based on the 16S rRNA gene of hemoplasmas showed that three/13 (23.08%; CI 95%: 8.18-50.26%) opossums from Foz do Iguaçu were positive for hemotropic Mycoplasma sp. All opossums from Curitiba tested negative for hemoplasmas. Sequencing of both the 16S and 23S rRNA genes revealed that the animals were infected by 'Ca. M. haemoalbiventris'. Although 'Ca. M. haemoalbiventris' is prevalent in opossums in Brazil, clinical signs associated with its infection and its putative vectors remain unknown.

Editorial- The Role of Complex Agroecosystems in Climate Change Mitigation

Seed dispersal is a process that is fundamental to maintenance of forest ecosystems, enabling plants to successfully germinate in sites that are favorable to their growth, minimizing risks of competition, the action of pathogens and predation by herbivores. Intraspecific and seasonal variations in fruit consumption by Didelphis albiventris, and its contribution to dispersal and germination of endozoochorous seeds were analyzed in a Semideciduous seasonal forest. The study was conducted at Morro do Coco, which is a hilly area in the municipal district of Viamão, RS, Brazil, bordering the shore of Guaíba lake (30º16’15”S, 51º02’54”W), between June 2013 and May 2014, with a total sampling effort of 2992 trap-nights. A total of 18 individuals were captured and 24 fecal samples were collected. Fruits were identified in 96% of the samples, corresponding to 18 plant species, belonging to 10 families. The most common species were Ficus cestrifolia and Syagrus romanzoffiana, which occurred in 66% of the samples, followed by Banara parviflora and Cecropia pachystachya, both with a 25% rate of occurrence. There were no differences between the richness of fruit consumed by males and females (t = 0.083; DF = 32; p = 0.934) and there were no seasonal variations (H = 3.165; p = 0.367). The greatest breadth of dietary niche occurred during the summer, when twice as many fruit species were recorded in the diet than during the autumn, which was the season with the smallest breadth. Both germination percentage and germination velocity of Ficus cestrifolia and Psidium sp. seeds increased after passage through the animals’ digestive tracts (percentage germination increased more than 40% and velocity was up to 7 times highest). Didelphis albiventris can be considered a frugivorous-omnivorous species, since fruit are an important item of its diet, and it contributes to dispersal of a large quantity of small endozoochorous seeds, increasing both germination percentage and germination velocity of some species.

Although the white-eared opossum is frequently observed in both rural and urban environments, there is little anatomical knowledge about this marsupial species. To our knowledge, there are no descriptions of its heart anatomy. Thus, the aim of this study was to describe the anatomy of the heart and its coronary blood supply in the white-eared opossums. Eight adult white-eared opossums (Didelphis albiventris) were used. Heart anatomical features and the coronary blood supply were examined using gross dissection and latex cast preparations. The heart of the white-eared opossum was located between the second and fifth intercostal spaces. Pectinate muscles were observed inside the atria, while papillary muscles and chordae tendineae inside the ventricles. Left and right coronary arteries emerged from the ascending aorta. The main branches of the left coronary artery were the paraconal interventricular and circumflex branches, whereas the subsinuous interventricular branch was the main branch of the right coronary artery. The findings of this study suggest that it is likely that the white-eared opossum presents a balanced pattern without dominance by the coronary arteries, since each coronary artery has an interventricular branch. Furthermore, cardiac morphology in white-eared opossums did not differ from that reported for other domestic and wild mammals.

The white-eared opossum present a higher roadkill number in Brazil, and the vertebral column is often affected when some type of trauma occurs. Thus, this study describes the osteology and radiology of the vertebral column in white-eared opossum to serve as a basis for support in the veterinary clinical care, since the casuistry of care of this marsupial has increased every year. Radiographs of the cervical (C), thoracic (T), lumbar (L), sacral (S) and caudal (Cd) segments of the vertebral column were taken in thirty-five white-eared opossums (Didelphis albiventris). Furthermore, ten opossums without evident vertebral acquired or congenital abnormalities at the radiographic study were selected for anatomical study. Osteology was correlated with the radiographic images. The use of radiographs allowed the identification of congenital and acquired vertebral changes, as well as the identification of anatomical structures, their distribution and morphology and the number of vertebrae. The vertebral formula varied in the white-eared opossum. In 27 of 35 white-eared opossums (77.2%) with normal vertebral morphology, three vertebral formulas were observed: C7/T13/L6/S2 (62.9%), C7/T13/L5/S2 (5.7%) and C7/T13/L7/S2 (8.6%). Most of the specimens presented 27 caudal vertebrae. The anticlinal vertebra was identified as T10 in 77.2% and T11 in 22.8% of opossums. Cervical block vertebra was observed in two animals and sacrocaudal block vertebra in one animal. The haemal arches could be seen from Cd3-Cd4 in 80% and Cd2-Cd3 in 20% of opossums. The white-eared opossum showed a slender vertebral column with a relatively short thoracic region, a relatively long lumbar region and a highly flexible lumbosacral transition, suggesting that this animal is a fast-running and agile opossum. Therefore, these findings may serve as a basis for further research and support the veterinary clinical care, since the casuistry of care for this marsupial has increased every year.

Global human population growth results in increased emissions of chemical pollutants like heavy metals such as cadmium (Cd) and lead (Pb). These two non-essential elements have strong bioavailability and toxicity, causing harmful health effects on humans, and the wider environment. Synanthropic wildlife species like the white-eared opossum may act as sentinels of environmental contamination, since they have a high incidence in urban areas and close contact with humans. The aim of this study was to conduct toxicological and histopathological analyses of white-eared opossums (Didelphis albiventris) that live in the city of Campo Grande, capital of Mato Grosso do Sul state in Brazil. In addition, we surveyed Cd and Pb in soil and water from sites where D. albiventris were captured. A total of 23 animals were captured and, after recording biological parameters, were euthanized and necropsied. Liver and central nervous system (CNS) samples were sent for toxicological analysis of Cd and Pb. Fragments of the liver, brain, kidney, and reproductive system were collected for histopathological evaluation. The presence of Cd and Pb in the liver and CNS was identified, with a high concentration of Pb in the CNS. Additionally, we found higher concentrations of Pb in both soil and water samples than in the animals. In the histopathological analysis, mild to moderate degenerative tissues lesions were found and may be compatible with damage caused by the presence of Cd and Pb. Nevertheless, our statistical analysis indicated that contamination by Cd and Pb did not threaten the health of the sampled animals. This study is the first in Brazil to detect background levels of Cd and Pb in the liver and CNS of D. albiventris, correlating these concentrations with histopathological lesions. The findings further emphasize the importance of understanding the interactions among the environment, humans, wildlife, and domestic animals within the One Health framework.

This study aimed to investigate the presence of microplastics in the gastrointestinal tract and lungs of white-eared opossums (Didelphis albiventris), as well as their effects on these organs and the body condition of sampled animals. We captured 22 opossums from April to December 2023 in six forest fragments of Campo Grande, capital of Mato Grosso do Sul state. Body condition estimates were performed using measurements of weight and head-body length for a total of 22 male and female opossums. Stomach, ileum, and lung fragments were collected during necropsies for histopathological study and detection of microplastics by alkaline digestion with KOH. Digested samples were vacuum filtered using filter paper and dried in an oven. The dried filters were examined under an optical microscope. A total of 270 microplastic specimens were detected in the 22 animals examined. The ileum presented the highest number of microplastics (n = 141), fibers were the most common type (n = 185), and blue was the predominant color (n = 140). Regarding chemical composition, the most frequently detected microplastics were polyvinyl chloride, polyethylene terephthalate, and acrylonitrile butadiene styrene. Although all D. albiventris specimens presented microplastics in their evaluated tissues, no effects on body condition or tissue damage were observed. Since D. albiventris are common animals in Campo Grande and are contaminated by microplastics, these animals can act as sentinels of environmental conditions.

Background : : : : This member of the Didelphidea family, commonly known as opossum, is widely distributed in the American territory, with species found from southern Canada up to northern Argentina. Similarly to all marsupials, they are characterized by a short gestational period, followed by a long development period. Opossums are arboreal, terrestrial slow animals of lonely and nocturnal habits. They are omnivore animals, eating from small rodents, birds, eggs and amphibians to fruits and vegetables. These general characteristics have drawn in the interest and curiosity of the scientific community to this animal, which is now the object of study in several knowledge areas. In order to find morphological information that could assist in discussions from a functional point of view and that could offer support for measures that aim at protecting opossums in their natural environment, the objective of the present study is to divulge the anatomical behavior of their celiac artery and its branches, including its distribution areas, considering the importance of these vessels in the blood supply of several digestive organs. Materials, Methods & Results : In this study, the celiac artery of 24 opossums ( Didelphis albiventris ), of which 17 were females and 7 were males, was systematized. For the purpose, their arterial system was filled with colored latex 603. The abdominal aorta gave off its first visceral collateral branch, the celiac-mesenteric trunk, which originated the celiac artery and the cranial mesenteric artery in 87.5% of the samples, but in 12.5% of the samples, the abdominal aorta gave off these arteries individually. The celiac artery gave off the lienal and hepatic arteries. The lienal artery gave off the left gastric artery to the lesser curvature of the stomach, supplying its parietal and visceral side, also giving off esophageal branches. The lienal artery reached the splenic hilum, giving off several pancreatic branches during its path. Once it reached the splenic hilum, it gave off its own lienal branches and then continued as left gastroepiploic artery towards the greater stomach curvature. The hepatic artery was projected cranially, giving off the gastroduodenal artery and cranial pancreaticoduodenal artery reaching the portal fissure, where hepatic branches arose towards the liver. The gastroduodenal artery gave off the right gastroepiploic artery towards the greater curvature of the stomach, also giving off the right gastric artery towards the lesser curvature of the stomach and then became divided into one branch to the visceral side and one branch to the parietal side, also giving off esophageal and pyloric branches. The cranial pancreaticoduodenal artery branched to the cranial duodenum and right lobe of the pancreas. Discussion : In the majority of opossums (87.5%), the celiac artery had origin in a common trunk with the cranial mesenteric artery, but in 12.5% of the animals, this origin took place separately. In opossums ( Didelphis albiventris) , regardless of its origin, the celiac artery was a single vessel and, essentially, it was divided into the hepatic artery and the lienal artery in 100% of the samples. The left gastric artery arose from the lienal artery, next to the origin of this latter in the celiac artery, similarly to the findings in the collared peccary, swine and equine. Therefore, the celiac artery, through its branches, was the artery responsible for the blood supply of the stomach, pancreas, liver, spleen and first part of the duodenum.