Gill epithelial cells kinetics in a freshwater teleost, Oncorhynchus mykiss during adaptation to ion-poor water and hormonal treatments

The aim of this work was to determine the kinetics of the dramatic development of the gill chloride cells (CCs) during adaptation of the salmonid Oncorhynchus mykiss to an ion-poor environment.To monitor cell division, the incorporation in the mitotic cell DNA of bromo-deoxyuridine (BrdUrd) was visualized with a monoclonal antibody. The density of labelled nuclei was used as an index of cellular division (proliferation), concomitantly with morphometry of phenotypic changes monitored with SEM.In the filament epithelium, a phase of CC differentiation occurred within 12h after the transfer, followed by a delayed phase of cell proliferation (48h). In the lamellar epithelium, the present study demonstrates the absence of cell proliferation after ion-poor water transfer. The conclusion is that proliferation (mitosis) is important in the primary filament whereas differentiation and migration (from the filament) is the main mechanism for the appearance of CCs on the secondary lamellae.The present study suggests that cortisol promoted differentiation, but not division, of cells. CCs, presumably premature, were stained by anti-cortisol monoclonal antibody indicating the presence of cortisol. No mature CCs were stained.Growth hormone (oGH, ratGH) increased the rate of cell division both in lamellar and filament epithelium.

Transepithelial potential difference of a single gill filament isolated from the crayfish Astacus leptodactylus Esch.: a new method

A new method is described that allows in vitro perfusion and transepithelial electrical potential measurements of a single filament (3-5 mm long; 200 microns in diameter) isolated from the podobranch of the crayfish Astacus leptodactylus. An electrophysiological study was carried out on the preparation to validate this technique. The good physiological quality of the isolated filament preparation has been established and results of continuous measurements of the potential difference under two perfusion conditions are reported. Filaments were perfused with Van Harreveld physiological saline inside and either with Van Harreveld saline or artificial fresh water outside. Large potential differences up to 150 mV between inside and outside of the filament were recorded. When filaments were symmetrically perfused, the behavior of the electrical potential difference allowed two populations of filaments to be distinguished.

Ctenocephalides felis (Siphonaptera, Pulicidae) parasitizing White-eared opossum (Didelphis albiventris) at Southern Brazil - Case report

Didelphis albiventris is a marsupial with synanthropic habits, whose contact with domestic animals and humans is increasing. They are considered potential disseminators of diseases, present as definitive hosts or reservoirs of various pathogenic agents. The present study aim to report, for the first time, the parasitism by Ctenocephalides felis in D. albiventris in Rio Grande, Southern Rio Grande do Sul state, Brazil. An adult female White-eared Opossum (D. albiventris), killed by being run over, was collected on the roads of the city of Rio Grande, Rio Grande do Sul, Brazil and sent to the laboratory for necropsy. During external inspection, a flea was found, which was stored in 70o alcohol until taxonomic identification, being classified as C. felis. This study reports the occurrence of parasitism by C. felis in D. albiventris for the first time in the location studied, demonstrating that these arthropods circulate between the wild and urban environments, and play an important role in the cycle of zoonotic pathogens among wild fauna, companion animals and humans.

First report of parasitism by Eutrichophilus cercolabes (Phthiraptera: Trichodectidae) on Coendou spinosus (Erethizontidae) in Rio Grande do Sul, Brazil - case report

Coendou spinosus is a species of rodent popularly known as porcupine, it has a great ability to adapt to different habitats and is found in tropical forests in countries such as Bolivia, Brazil, Venezuela and Guianas. This mammal has already been identified as a reservoir of several pathogenic agents for humans and other animals and has a variety of ectoparasites, endoparasites and hemoparasites little studied and described. Due to this, the objective was to report the parasitism by Eutrichophilus cercolabes in C. spinosus in the central region of Rio Grande do Sul, southern Brazil. In total, 16 lice were found, one male and 15 females of the species. This is the first report of the parasitism of this Phthiraptera on C. spinosus in Rio Grande do Sul. The scarcity of reports on the taxonomy and biotic characteristics, as well as the vector capacity of pathogens of most species of ectoparasites of wild animals, highlights the need for further studies on the distribution of these arthropods in different regions and host species.

Culicoides' species from a Leishmania transmission hotspot and efficacy of the Captor® suction light trap

Culicoides have medical and veterinary importance, as they play a role as vectors of viruses, protozoa, and nematodes that cause diseases. Despite the relevance to public health, greater attention has been given to other insect vectors. Therefore, the objective of this study was to evaluate the efficiency of the Captor^® light trap in capturing Culicoides that could be examined for the presence of Leishmania DNA. The insects were captured in a rural area of Santa Maria, Rio Grande do Sul, Brazil, where canine and human visceral leishmaniasis have been diagnosed. Adult insects were collected weekly, from 6:00 pm to 6:00 am, for a 12 month period using a Captor^® brand suction light trap. All Culicoides were identified at species level. Pools of Culicoides were tested using the Polymerase Chain Reaction (PCR) technique for the detection of Leishmania DNA. A total of 16,016 specimens were collected (71.54% females and 28.39% males), divided among seven species. In the DNA analysis, none of the pools showed a positive result for Leishmania. The data presented demonstrate that the trap is efficient and can be an alternative for use in entomological research. They also demonstrate that, despite the females having hematophagous habits, similar to other vector insects, they did not have contact with Leishmania in the studied locality.

Absence of Leishmania spp. DNA in road-killed wild mammals in Southern Brazil

Leishmaniasis are neglected diseases transmitted by vectors that affect domestic and wild animals, including humans. Due to its incidence and lethality, this zoonosis is a worrying public health problem, making it essential to identify all links in the transmission chain. Infection of wild mammals by Leishmania spp. remains poorly understood, especially in southern Brazil. Therefore, the objective was to research, using the PCR technique, the presence of Leishmania spp. DNA in road-killed wild mammals in Southern Brazil. Carcasses of 96 animals were collected from highways in the Pelotas microregion, Rio Grande do Sul, southern Brazil and subjected to necropsies. Tissue fragments (spleen, skin, liver, kidney, heart, lung, lymph nodes, bone marrow and blood) were collected and genomic DNA was extracted. PCR protocols targeting the ITS1, kDNA and 18S genes were tested. We found no evidence of Leishmania spp. circulation in the studied population. However, epidemiological studies like this one are of great relevance, as they allow monitoring of the occurrence of pathogens and help identify possible risk areas. As these animals act as epidemiological markers for the presence of the microorganism, studies must be carried out continuously to understand whether there are sources of infection in the region.

Atypical case of recurrent otitis with polyp formation in the ear canal associated with lagochilascariasis in a domestic feline in Brazil

Lagochilascariasis is a neglected zoonosis that affects domestic and wild mammals, including humans, and can form nodules, especially on the neck. Although emerging, it is considered a rare disease in the Americas and, therefore, the objective was to report an atypical case of recurrent otitis with the formation of polyps in the ear canal in a domestic feline associated with lagochilascariasis in Brazil. A cat had a purulent exudate in one of her ears and responded poorly to treatments. During an otoendoscopy procedure, a polyp and nematodes were removed and sent for histopathological and parasitological diagnosis. Nematodes were subjected to DNA extraction, whose amplification of the 18S, cox1 and 12S genes in the Polymerase Chain Reaction (PCR) and genetic sequencing confirmed the presence of Lagochilascaris minor. To our knowledge, this is the first description of recurrent otitis with the formation of polyps in the ear canal associated with lagochilascariasis in domestic cats and the description of this atypical case may contribute to the elucidation of new clinical cases. Additionally, new molecular sequences are provided, contributing to the knowledge of the parasite.

Description of the parasitic fauna of a specimen of Didelphis albiventris at Rio Grande do Sul

Didelphis albiventris is considered the most common marsupial in Rio Grande do Sul. With omnivorous and synanthropic habits, it can serve as a host to various parasites, playing an important role in maintaining their biological cycle. Despite being a widespread and abundant species, it has a relatively little-known parasitic fauna. Therefore, the aim of this study was to report the diversity of parasites in a fecal sample from D. albiventris in Rio Grande do Sul, Southern Brazil. Modified Centrifugal-flotation and Spontaneous sedimentation techniques were used, revealing a high taxonomic diversity of parasites. Eggs of Ancylostoma spp., Toxocara spp., and Anoplocephalidae were reported for the first time in the host in the southern region of the country, along with the first report of pseudoparasitism by Syphacia spp. and Monocystis spp. in this animal species. The presence of different parasites in the feces of D. albiventris is of utmost importance, primarily for public health, but also for understanding the biodiversity of parasites present in wildlife, which has been poorly studied until now. This allows the implementation of effective strategies for controlling, preventing and treating these diseases.

Eustrongylides spp. (Nematoda: Eustrongylidae) in Polypterus endlicheri in central Rio Grande do Sul, Brazil

Abstract The demand for ornamental fish has increased in recent years in Brazil, however, the aquatic environment of artificial breeders facilitates the invasion of pathogens, including parasitic zoonoses, which are a limiting factor for production causing economic losses in creations. Knowledge of the distribution of agents causing parasitic diseases is important so that we can intervene in breeders, therefore, the objective of the present work is to report the occurrence of infection by Eustrongylides spp. (Nematoda: Eustrongylidae) in Polypterus endlicherii (Polypteriformes: Polypteridae) in central Rio Grande do Sul, Brazil. The nematode was identified after being released a cyst in the scales, of a fish of the species P. endlicherii. It can be concluded that this is the first record of the occurrence of Eustrongylides spp. larvae in fish in Rio Grande do Sul, showing that the parasite is present in the central region of the state. Therefore, further studies should be carried out in order to verify the presence of the parasites in fish intended for human consumption. It should also be noted the need to be more careful when feeding fish with oligochaetes, especially those intended for human consumption.

Seroprevalence and factors associated with exposure to Neospora caninum among dairy cattle smallholders in southern Rio Grande do Sul

Neospora caninum is a protozoan parasite that infects several species of animals (domestic and wild) and is one of the most common causes of abortion in cattle worldwide. To better understand the epidemiological chain of neosporosis, update the disease status and propose control measures to improve milk production in Rio Grande do Sul (RS), the present study aimed to evaluate the seroprevalence of N. caninum and its distribution in different municipalities of Rio Grande do Sul, Southern RS, Brazil, and determine the factors associated with exposure to N. caninum in small dairy cattle producers in this region. Cattle from 51 dairy farms located in nine municipalities in the southern region of RS were included in this study. Small dairy farmers were interviewed to collect information about the characteristics of their herds. The association between potential associated factors and seropositivity in cattle was assessed using a logistic regression model with a generalized estimating equation. Seroprevalence in individual animals and between herds was 33.9% (95% CI = 28.1-39.9) (121/309) and 80.4% (95% CI = 67.5-88.9) (41/51), respectively. The high seroprevalence found indicates that cattle are susceptible to exposure by N. caninum in a widespread manner in the Pelotas microregion. Furthermore, the sanitary management of cattle, the adaptation of tools that can improve the milk extraction technique and the technical monitoring of professionals who work on the properties can be effective alternatives for controlling N. caninum.

First record of a rare case of accidental urinary myiasis by Telmatoscopus albipunctata (Diptera: Psychodidae), with morphological description, in a human in Brazil

Telmatoscopus albipunctata is an insect of the Psychodidae family, with a worldwide distribution, particularly in tropical and subtropical countries. Although it does not have hematophagous habits, it has veterinary medical importance due to the mechanical transmission of protozoa and bacteria, many of which cause nosocomial infections. This dipteran has been reported as one of the causative agents of accidental myiasis in humans in several countries, and since it has not been registered in South America, the objective of the present report was to describe a rare case of accidental urinary myiasis caused by T. albipunctata (Diptera: Psychodidae) in humans in Brazil. In the present report, a 25-year-old female patient, resident of the central region of the state of Rio Grande do Sul, Brazil, sought medical attention after finding larvae in her urine. She complained of vaginal itching and skin dermatitis. The larvae were sent to the Veterinary Parasitology Laboratory of the Federal University of Santa Maria, where they were mounted on permanent slides for further taxonomic identification. Morphological characteristics allowed the identification of fourth-stage larvae and pupae of T. albipunctata. Therefore, the present work reports the first record of accidental urinary myiasis caused by T. albipunctata infection in Brazil and South America.

Diagnosis of Giardia spp. in ruminants at Southern Brazil

Giardia spp. is a flagellated protozoan that parasitizes the small intestine of various mammals, birds, and amphibians, being transmitted via the fecal-oral route. Giardiasis is one of the most prevalent parasitic diseases in both developed and developing countries, with a prevalence of 0,1-5% and 20-30%, respectively, and is correlated with poor hygiene practices, such as irregular handwashing, which consequently contaminates food when handled. Cattle and sheep are sources of infection for humans due to the zoonotic potential of the species that affect them, especially calves, which play an important role in the dissemination of the parasite in the environment by excreting 106 cysts per gram of feces, contaminating water sources, which, even when treated, only reduce and do not eliminate the protozoan. This study investigated the prevalence of Giardia spp. in ruminants in the southern region of Rio Grande do Sul, Brazil. Between June 2023 and April 2024, 384 fecal samples from young cattle and sheep were analyzed, collected directly from the rectal ampulla and subjected to coprological tests at the Laboratory, used the zinc sulfate centrifugal flotation technique to visualize protozoan cysts and calculate their prevalence. The results showed that 19,15% of sheep (27/141), 13,99% of cattle (34/243) and 15.88% in both species (61/384) tested positive for Giardia spp. This study revealed a significant prevalence of Giardia spp. in young ruminants in the southern region of Rio Grande do Sul, posing an important zoonotic risk.

First record of Hydatigera taeniaeformis in Geoffroy's cat (Leopardus geoffroyi) in Brazil

Leopardus geoffroyi (Geoffroy's cat) is a neotropical feline considered globally threatened. In Brazil, it occurs exclusively in the Pampa biome. Its predatory habits contribute to the infection, dispersion, and continuation of the life cycle of various pathogens, including helminths, within ecosystems. However, few studies involving cestodes in wild felines are found in the literature, especially in Brazil. Therefore, we aimed to report the first case of parasitism by Hydatigera taeniaeformis in L. geoffroyi. The helminths were found in the small intestine of the necropsied feline. Specimens were analyzed morphometrically and subjected to molecular analyses for taxonomic identification. The molecular phylogeny based on the analysis of the mitochondrial gene (COX1) allowed the identification of these parasites. Thus, this is the first description of H. taeniaeformis parasitizing L. geoffroyi in Brazil. Consequently, the number of known host species parasitized by this helminth in the country and the world is increased. Additionally, a new molecular sequence is being provided, contributing to the knowledge of Hydatigera in South America.

Utilization of machine learning for dengue case screening

Dengue causes approximately 10.000 deaths and 100 million symptomatic infections annually worldwide, making it a significant public health concern. To address this, artificial intelligence tools like machine learning can play a crucial role in developing more effective strategies for control, diagnosis, and treatment. This study identifies relevant variables for the screening of dengue cases through machine learning models and evaluates the accuracy of the models. Data from reported dengue cases in the states of Rio de Janeiro and Minas Gerais for the years 2016 and 2019 were obtained through the National Notifiable Diseases Surveillance System (SINAN). The mutual information technique was used to assess which variables were most related to laboratory-confirmed dengue cases. Next, a random selection of 10,000 confirmed cases and 10,000 discarded cases was performed, and the dataset was divided into training (70%) and testing (30%). Machine learning models were then tested to classify the cases. It was found that the logistic regression model with 10 variables (gender, age, fever, myalgia, headache, vomiting, nausea, back pain, rash, retro-orbital pain) and the Decision Tree and Multilayer Perceptron (MLP) models achieved the best results in decision metrics, with an accuracy of 98%. Therefore, a tree-based model would be suitable for building an application and implementing it on smartphones. This resource would be available to healthcare professionals such as doctors and nurses.

Eustrongylides spp. (Nematoda: Eustrongylidae) em Polypterus endlicheri na região central do Rio Grande do Sul, Brasil

Resumo A criação de peixes para ornamentação teve sua demanda aumentada nos últimos anos no Brasil, no entanto, o ambiente aquático dos criatórios artificiais facilita a invasão por agentes patogênicos, incluindo zoonoses parasitárias, que são um fator limitante para produção causando perdas econômicas nas criações. O conhecimento da distribuição de agentes causadores de enfermidades parasitárias é importante para que se possa intervir nos criatórios, portanto, o objetivo do presente trabalho é relatar a ocorrência da infecção por larva de Eustrongylides sp. (Nematoda: Eustrongylidae) em Polypterus endlicherii (Polypteriformes: Polypteridae) na região central do Rio Grande do Sul, Brasil. O nematódeo foi identificado após ser liberado de um cisto nas escamas, de um peixe da espécie P. endlicherii. Pode-se concluir que este é o primeiro registro da ocorrência de larvas de Eustrongylides sp. em peixes no Rio Grande do Sul, evidenciando que o parasito está presente na região central do estado. Portanto, mais estudos devem ser realizados a fim de verificar a presença dos parasitos em peixes destinados ao consumo humano. Salienta-se ainda, a necessidade de se ter maior cuidado ao alimentar peixes com oligoquetas, principalmente os destinados para alimentação humana.

New species of Polystomoides (Monogenoidea: Polystomatidae) parasitizing the urinary bladder of a freshwater turtle in Brazil

Trachemys dorbigni is the most abundant freshwater turtle species in Rio Grande do Sul, southern Brazil. Chelonians are known to host a wide variety of pathogens, including viruses, bacteria, hemoparasites and helminths. Among these, nine genera of polystomatid flatworms (Monogenoidea; Polystomatidae) infect freshwater turtles: Apaloneotrema, Aussietrema, Fornixtrema, Manotrema, Pleurodirotrema, Polystomoidella, Polystomoides, Uropolystomoides and Uteropolystomoides. However, little is known about the biology of these parasites in the Neotropical Realm. Through investigative cystoscopy, specimens of Polystomatidae were located inside the urinary bladder of the host T. dorbigni. Retrieved specimens were fixed and stained whole mounts prepared for taxonomic identification. In the present paper, a new species of Polystomoides (Monogenoidea: Polystomatidae) parasitizing the urinary bladder of a freshwater turtle of the species T. dorbigni in Brazil is described. Polystomoides santamariensis n. sp. differs from the congeneric species on the length of the genital spines, which are longer. Given the enormous diversity of freshwater turtles around the world, it is likely that a large number of chelonian polystomatids are still unknown.

New records of endoparasites and ectoparasites in free-living road-killed wild animals in the Pampa biome, Southern Brazil

Wild animals host a wide variety of parasites, and the disorders caused by these parasites are among the most prevalent and significant infectious diseases affecting wildlife. The investigation of parasitic fauna is crucial for the conservation of wild animals, domestic populations, and humans. Therefore, the aim of the study was to survey endo- and ectoparasites in free-living wildlife in southern Brazil. Carcasses of road-killed wildlife were collected from highways in the Pelotas microregion, Rio Grande do Sul. All carcasses were necropsied, and endo- and ectoparasites were collected and identified. A total of 82 animals were examined; 87.80% were infected by helminths, 51.21% infested by ectoparasites, and 48.78% were affected by both types of parasites. This study presents the first records of parasitism by Rhipicephalus microplus in Ozotoceros bezoarticus in southern Brazil, and by Ancylostoma caninum in Leopardus geoffroyi worldwide. The study contributes to the knowledge about the parasitic fauna in wild animals of the Pampa biome. The presence of parasites in these threatened species underscores the need for further research into parasitism, which is crucial for their effective management and conservation.