Abstract The objective of this study was to determine the prevalence of Babesia bigemina infection and associated risk factors in Crioula Lageana cattle, a Brazilian native breed known for its tick resistance. Blood samples were collected from 311 registered cattle (62 males, 249 females) from conservation nucleus properties in Santa Catarina State, Brazil. Samples underwent DNA extraction and nested PCR targeting the rap-1a gene for B. bigemina detection. Animals were categorized by sex, age class, and tick presence during sampling. An epidemiological questionnaire assessed potential risk factors. The overall B. bigemina prevalence was 60% (186/311; 95% CI: 56,95%-62,67%). Males showed significantly higher infection rates (79%; 49/62) compared to females (55%; 137/249; OR=3.36, p<0.001). Bulls (81%; 26/32) and calves (78%; 56/72) exhibited higher infection rates than cows (50%; 70/141) and heifers (52%; 34/66; p<0.001). Tick presence during sampling increased infection probability (OR=2.00, p=0.006). Contact with other animal species (OR=1.57, p=0.037) and regular veterinary care (OR=6.77, p=0.009) were identified as significant risk factors. Results indicate enzootic instability in the studied population, with distinct sex-based susceptibility patterns. These findings provide baseline data for developing targeted control strategies for B. bigemina in Crioula Lageana breeding programs.

Abstract Leishmaniasis is a parasitic disease caused by Leishmania spp., transmitted to hosts through the bite of female phlebotomine sandflies, with domestic dogs serving as reservoirs for the disease. Understanding the entomofauna is crucial for effective control of vector-borne diseases, such as leishmaniasis, because various environmental and climatic factors can influence sandfly presence and distribution. This study aimed to conduct a quantitative and qualitative survey of the entomofauna in urban and peri-urban areas of Lages, Santa Catarina, Brazil, and to analyze documented cases of canine leishmaniasis in the city, in response to the rising number of non-autochthonous cases in dogs. The lack of prior studies on this fauna in the municipality raises concerns for public health services. Nine areas were monitored over the course of one year, and clinical and epidemiological records of canine leishmaniasis in the city were analyzed. A total of 10,638 insects were collected, with no phlebotomine sandflies identified. All evaluated cases of canine leishmaniasis were classified as non-autochthonous based on the movement history of these animals and the absence of the disease vector in the municipality. This information may guide further control and prevention measures for leishmaniasis in the region, aligned with a One Health perspective.

Abstract Rhipicephalus microplus is an ectoparasite responsible for causing economic losses in livestock farming totalling approximately $3.24 billion dollars per year. The main control method involves the use of chemical acaricides. However, the incorrect and intensive use of these chemicals has led to an increasing number of reports of resistance to acaricides. Therefore, the objective of this study was to develop and evaluate a laser prototype with a voltage of 5 V and power of 1000 mW to reduce the development of R. microplus. The methodology evaluated did not result in a high mortality rate; therefore, it was necessary to carry out a larval migration test. To carry out the test, 3 treatments were evaluated in triplicate (negative controls H20, 60% ethanol and positive control), with 20 larvae were evaluated for each replicate of the treatments, which resulted in an increase in the percentage of migration from 2.5% and 3.2% to above 94.9% and 93.5% in the negative controls, while in the positive control group there was no showed a significant change in migration, reaching close to 100%. This study demonstrated that physical control caused damage to ectoparasite locomotor structures and could affect the parasite's life cycle.

Abstract Opossums are synanthropic animals that participate in the zoonotic transmission cycles. Chagas disease, a neglected tropical disease caused by Trypanosoma cruzi, affects many domestic and wild animals and humans worldwide. This study aimed to determine the occurrence of T. cruzi in free-ranging opossums in Canoinhas, Santa Catarina, Brazil. Fifty opossums (Didelphis albiventris) (33 captured and 17 road-killed) were evaluated using Nested-PCR assay. All tissue samples were negative (0/17). Eight of the 33 (24.24%; 95% CI:11.94–40,89%) blood samples were positive for T. cruzi. No significant associations were found between the sex (male/ female, p = 0.423), the trap area (rural/urban, p = 0.163), and positivity for T. cruzi in opossum blood samples. All samples showed 100% identity with T. cruzi (KF788250) isolated from Panstrongylus megistus in São Paulo, Brazil. The phylogenetic analysis model allocated all sequences obtained from D. albiventris to the large TcI clade of T. cruzi. This study provides the first record of T. cruzi in white-eared opossums in Canoinhas, Santa Catarina, southern Brazil.

Abstract Aplectana comprises species of gastrointestinal helminths commonly found parasitizing amphibians and reptiles worldwide. However, most species of the genus are described based only on morphological traits. During helminthological surveys, we found nematodes identified as Aplectana pella parasitizing the hylid frog Osteocephalus cabrerai from the same locality as the original description. We provided the first nucleotide sequence of ribosomal gene 18S rDNA for Aplectana pella and established the species' phylogenetic position between representatives of Cosmocercidae. A pairwise genetic comparison between A. pella and its congeners revealed a low genetic divergence. We found that our sequences clustered with species of Cosmocerca, reinforcing the hypothesis that representatives of the genus Aplectana do not form a monophyletic group.

Abstract Bovine trypanosomiasis, caused by infection with the protozoan Trypanosoma vivax, is harmful to livestock worldwide. Knowing its epidemiology is relevant to evaluate the susceptibility, resistance, and tolerance of animals. The objective of this study was to determine the prevalence of T. vivax in Crioula Lageana cattle and relate them to clinical, hematological, and biochemical findings to elucidate the breed’s health and disease tolerance characteristics. Venous blood samples from 310 bovines considered healthy during the clinical examination were used to perform polymerase chain reaction (PCR) analysis, Immunofluorescence Antibody Test (IFAT) assays, hemogram tests, and serum biochemistry. The collected data were subjected to statistical analyses to compare seropositive and negative groups. IFAT indicated that the seroprevalence for T. vivax was 8% (24/310); however, all tested animals were negative in the conventional PCR (0%, 0/310). Higher amounts of platelets and less cholesterol were detected in seropositive animals but were within the reference values. Ruminal hypomotility and mild tachycardia were observed in all sampled animals. Considering the non-specific clinical signs and the absence of hematological alterations in infected animals, the seropositivity found indicates previous exposure to the protozoan, and the absence of clinically affected animals may result from characteristics inherent to this breed.

Abstract This study evaluated dynamics of antibodies in dogs treated for canine visceral leishmaniasis (CVL). Twenty-one dogs naturally infected by Leishmania spp. were grouped based on the treatment protocol: G1 (n=4) received allopurinol; G2 (n=10) allopurinol with miltefosine; and G3 (n=7) allopurinol, miltefosine and Leish-Tec® vaccine. The dogs were monitored monthly for a period of one year. To verify serum antibody titers, an indirect immunofluorescence reaction was performed. We found that dogs from G1 and G2 had lower clinical scores and antibody titers, when compared to the parameters evaluated in pre-treatment; however, clinical relapses were observed in three animals. In G3, clinical scores were lower than pre-treatment; however, they presented relatively stable antibody titers and no clinical relapse was observed. All animals submitted to the evaluated treatment protocols showed relative improvement in clinical signs. Furthermore, the immune response of animals must be considered, given the challenges of parasitic loads in infections. Therefore, it is necessary to complement the methods of clinical and therapeutic monitoring of dogs with CVL in order to establish the risk of transmissibility of the agent in infected and treated dogs.

Abstract This study investigated infection by Leishmania spp., Leptospira spp., Toxoplasma gondii, and Trypanosoma cruzi in six-banded armadillos (Euphractus sexcinctus) from the semiarid region of northeastern Brazil. Twenty specimens of E. sexcinctus were captured alive by wildlife veterinarians from their natural habitats in different locations. The animals were euthanized following induction of anesthesia, and different biological samples were collected. Infection with four pathogens was subsequently evaluated: Leishmania infection was investigated by spleen and liver Polymerase Chain Reaction (PCR); Leptospira spp. infection was evaluated by kidney PCR and serologically by microscopic agglutination test; T. gondii infection was assessed by PCR of the heart, lung, and spleen; and T. cruzi infection was investigated by heart and whole blood PCR and hemoculture. All tests presented negative results apart from whole blood PCR to detect T. cruzi, which was positive in one of the 20 animals tested and confirmed by genetic sequencing. It is important to highlight that this is the first study comprising a molecular investigation of different zoonotic pathogens in six-banded armadillos, and the findings reported here bring new and important knowledge regarding zoonotic diseases in this species.

Abstract A complex interaction of gastrointestinal parasites with sheep hosts may involve bacteria communities, parasite genera, parasitic genes, and biological pathways. Haemonchus contortus presents a global challenge for ruminants, and the bacterial community can influence sheep's resistance and susceptibility to these parasites. Thus, a better understanding of this complex interaction could contribute to the development of a new approach to parasite control. This study evaluated the bacterial community of Corriedale sheep naturally infected with H. contortus based on the fecal egg counts over ten months and then classified as having low (LC), intermediate (IC), or high (HC). Stool samples were collected monthly for egg counts (EPG), and 16S rRNA gene sequencing was performed on five animals from each group. The average EPG was 2,635 ± 105 for HC, 845 ± 129 for IC, and 110 ± 70 for LC, with a significant difference (p = 0.0001). Firmicutes, Proteobacteria, and Spirochaetes were more abundant in the HC group. 102 bacterial genera showed significant differences between the LC and HC groups. Beta diversity was statistically different (p<0.005) for HC compared with the other two groups; also, different communities were found between LC and HC. Sediminispirochaeta, Oribacterium, Alloprevotella, Prevotellaceae_UCG-001, Prevotellaceae_UCG-003, Ruminiclostridium_6 and Ruminococcus_1were significant more abundant in LC, and IC group. Acetobacter and Methanocorpusculum had a significant reduction in the LC group. Thus, bacterial genera related to low methane emission and food efficiency were significantly present in the LC group. Therefore, a better understanding of the role of host-bacterial community-parasite interaction could contribute to improving parasite control management.

Abstract Non-human primates are potential hosts for helminths of various phyla, and the presence of these parasites can cause changes in organ morphology and functionality. In this study, we present the alterations induced by the presence of acanthocephalan parasites in the small intestine of a snub-nosed monkey that died in the Bosque Rodrigues Alves, municipality of Belém, Pará state, Brazil. Ten specimens of Saimiri sciureus had their intestines analyzed and the parasites recovered were cleaned, quantified, fixed and observed using light microscopy and scanning electron microscopy, and fragments of the intestine were separated for histological analysis to identify the alterations. All the animals were parasitized, and a total of 50 specimens representing the Acanthocephala Phylum were recovered, which morphologically showed characteristics compatible with Prosthenorchis elegans (Diesing, 1851). Light microscopy revealed the presence of parasites attached to the mucosal layer, passing through the underlying layers until they reached the muscular layer. Scanning electron microscopy showed the tissue lesions caused by the proboscis hooks and the flattening of the intestinal villi in the presence of the parasite. The presence of the parasites in the intestine changed the morphology of the organ, possibly causing loss of functionality at the site of attachment and adjacent tissue.