Circulating oxidative stress and acute phase protein levels in horses infested with ticks.

Ticks have saliva rich in immunoregulatory molecules that interfere with the host's physiology in order to feed. This study aimed to evaluate the concentration of acute phase proteins and circulating oxidative stress in response to infestation by Amblyomma sculptum and Dermacentor nitens in two breed horses, Mangalarga Marchador and Breton Postier, to define resistance or susceptibility to ticks. Among the oxidative stress markers, we observed lower malondialdehyde and nitric oxide in horses with tick infestation, consequently not altering the antioxidant enzymes. Breton Postier with tick infestation showed a reduction in the ferric reducing ability of plasma (FRAP), which may be due to lower feeding of the host due to the stress caused by the infestation or even to sequestration of components induced by the tick during blood feeding. The alpha-1-antitrypsin, an acute phase protein, showed an increase in Mangalarga Marchador with tick infestation; curiously it is related to a protective action against tissue damage, pathogens and parasites. We could assume that Mangalarga Marchador showed a better response to ticks when compared to Breton Postier. However, it is still early to define the resistance or susceptibility to ticks, as we did not observe significant changes in most of the analyzed variables. Further studies are needed to understand the compounds and mechanisms of action of the tick saliva in the acute phase proteins and the possible relationships of oxidative stress in the host and the tick during blood feeding.

In vitro compatibility and nematicidal activity of Monacrosporium sinense and Pochonia chlamydosporia for biological control of bovine parasitic nematodes.

The use of nematophagous fungi is an alternative for the biological control of nematodes in ruminants. In this study, the compatibility of joint growth of the fungi Monacrosporium sinense and Pochonia chlamydosporia and the joint nematicidal activity of these fungal isolates on bovine infective larvae were evaluated. For that, tests of direct confrontation, the effect of volatile compounds and antibiosis were conducted. In order to carry out the tests, the fungi were inoculated in potato dextrose agar culture medium and, after the incubation period, the growth of the colonies, the formation of an inhibition halo and the effect of volatile metabolites were verified. The compatibility between fungi isolates M. sinense and P. chlamydosporia was confirmed and the nematicidal evaluation proved the best effectiveness was when both were used together, with a 98.90% reduction in the number of bovine nematode infective larvae under in vitro conditions. It was concluded that M. sinense and P. chlamydosporia presented synergistic action, suggesting that the joint application of the fungi increases the effectiveness of biological control of bovine infective larvae.

Didelphis spp. opossums and their parasites in the Americas: A One Health perspective.

Medium sized opossums (Didelphis spp.) are among the most fascinating mammals of the Americas, playing important ecological roles (e.g., dispersal of seeds and control of insect populations) in the environment they inhabit. Nevertheless, as synanthropic animals, they are well adapted to human dwellings, occupying shelters within the cities, peripheral areas, and rural settings. These marsupials can harbor numerous pathogens, which may affect people, pets, and livestock. Among those, some protozoa (e.g., Leishmania infantum, Trypanosoma cruzi, Toxoplasma gondii), helminths (e.g., Ancylostoma caninum, Trichinella spiralis, Alaria marcianae, Paragonimus spp.) and arthropods (e.g., ticks, fleas) present substantial public health and veterinary importance, due to their capacity to cause disease in humans, domestic animals, and wildlife. Here, we reviewed the role played by opossums on the spreading of zoonotic parasites, vectors, and vector-borne pathogens, highlighting the risks of pathogens transmission due to the direct and indirect interaction of humans and domestic animals with Didelphis spp. in the Americas.

Arthrobotrys cladodes and Pochonia chlamydosporia in the biological control of nematodiosis in extensive bovine production system.

Cattle production in extensive systems favours the occurrence of gastrointestinal nematodes, and the use of nematophagous fungi complements the control strategies for these nematodes. The aim of this study was to evaluate the effectiveness of the fungi Arthrobotrys cladodes and Pochonia chlamydosporia in the biological control of gastrointestinal parasitic nematodes in grazing cattle. Twenty-four calves were randomly divided into four groups and allocated to independent paddocks from February 2018 to January 2019. In the first group, the animals received pellets containing P. chlamydosporia. In the second group, the animals received pellets containing A. cladodes. In the third group, the animals received pellets containing a combination of the fungi A. cladodes and P. chlamydosporia. In the control group, the animals received pellets without fungus. The combined use of A. cladodes and P. chlamydosporia showed greater efficacy in the biological control of bovine gastrointestinal parasitic nematodes than the same fungi used separately. The parasite load was lower and weight gain was greater (P ⩽ 0.05) in the groups of cattle treated with nematophagous fungi. Therefore, the use of A. cladodes and P. chlamydosporia is promising in the biological control of nematodiosis in cattle.

Arthrobotrys cladodes and Pochonia chlamydosporia: Nematicidal effects of single and combined use after passage through cattle gastrointestinal tract.

Nematodiosis are responsible for financial losses in cattle production systems due to treatment costs, falling production rates and animal deaths. The incorporation of sodium alginate pellets containing nematophagous fungi in the bovine diet is a method for the control of nematodiosis. The aims of this study were to evaluate the viability of Arthrobotrys cladodes and Pochonia chlamydosporia contained in sodium alginate pellets after passage through the bovine gastrointestinal tract, as well as to evaluate the effects of single and combined use of these fungi against bovine parasitic nematodes. The reduction in parasitic nematode infective larvae of bovines by the combined use of Arthrobotrys cladodes and Pochonia chlamydosporia was more than the reduction in infective larvae by Arthrobotrys cladodes or Pochonia chlamydosporia alone in the collections 12, 24 and 36 h after giving the pellets to the animals. Arthrobotrys cladodes and Pochonia chlamydosporia combined promoted maximum reduction of infective larvae of 86.3%. Therefore, the combination of Arthrobotrys cladodes and Pochonia chlamydosporia may be an effective method to control gastrointestinal nematodiosis affecting grazing cattle.

Germination capacity of the Pochonia chlamydosporia fungus after its passage through the gastrointestinal tract of domestic chickens (Gallus gallus domesticus).

This study evaluated the germination capacity of Pochonia chlamydosporia (VC4) fungus after its passage through the gastrointestinal tract of domestic chickens and its interaction with Ascaridia galli and Heterakis gallinarum eggs. Twenty-two domestic chickens were divided in two groups: control group (G1) received shredded corn substrate without VC4; and treatment group (G2) received a single dose of 29 g corn substrate containing 3.3 × 106 conidia/chlamydospores (VC4). Subsequently, chicken fecal samples were collected at intervals of 0, 6, 8, 10, 12, 18 and 24 h. Petri dishes from fecal samples of the treated group (G2) were subdivided (G2a and G2b), and then replicated in 2% agar-water medium for the microbiological test. After VC4 growth, approximately 200 eggs of A. galli (G2a) and H. gallinarum (G2b) were added to each subgroup to evaluation of ovicidal activity. There was fungal viability after passage through chicken gastrointestinal tract and egg predation of 59.9% and 43.2% for A. galli and H. gallinarum, respectively. The present work demonstrates the ability of the fungus P. chlamydosporia to survive after passing through the gastrointestinal tract of domestic chickens, an extreme environment (low pH, enzymes, microbiota and mechanical action), and still germinate after being excreted with feces.

High prevalence of Ancylostoma caninum infection in black-eared opossums (Didelphis aurita) in an urban environment.

Marsupials of the genus Didelphis, such as black-eared opossums (Didelphis aurita), are common synanthropic animals in urban areas of Brazil. These marsupials are frequently parasitized by numerous helminth species, including ancylostomatid nematodes. This study aimed to report the occurrence of Ancylostoma caninum in black-eared opossums captured in an urban environment of Southeastern Brazil and discuss the potential impact of these findings for public health. From January to June 2019, we collected fecal samples from 49 restrained opossums and evaluated by a simple flotation method; Helminth eggs were observed at different magnifications and identified according to morphological and morphometric features. Genomic DNA was extracted from Ancylostomatidae eggs and screened by duplex PCR for Ancylostoma spp. and Necator americanus using primers that amplify a region of internal transcribed spacer 2 and the 28S ribosomal RNA (ITS2-28S rRNA). Ancylostoma spp. eggs were detected in 65.3% (32/49) of the animals. Sequence analysis revealed 100% homology with A. caninum sequences from GenBank. Our results demonstrate a new host-parasite interaction for A. caninum, suggesting that black-eared opossums may participate in the zoonotic cycle of this parasite in urban areas of Brazil.

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.

In vitro biological control of bovine parasitic nematodes by Arthrobotrys cladodes, Duddingtonia flagrans and Pochonia chlamydosporia under different temperature conditions.

Variations in temperature can affect the development of nematophagous fungi, especially when they are used in the biological control of parasitic nematodes in the pastures where cattle are reared. The aim of this work was to evaluate the effects of temperature on the performance of nematophagous fungi in the biological control of bovine parasitic nematodes. The mycelial growth, chlamydospore production and nematicidal activity of Duddingtonia flagrans, Arthrobotrys cladodes and Pochonia chlamydosporia were evaluated at 15, 20, 25, 30 and 35°C. The fungal strains achieved mycelial growth, chlamydospore production and nematicidal activity on parasitic nematodes under all temperature conditions tested. The fungi showed higher growth at intermediate temperatures (20, 25 and 30°C) than at the extremes of 15 and 35°C. At 25 and 30°C, D. flagrans realized 96.8 and 94.5% nematicidal activity on bovine parasitic nematodes, respectively. Arthrobotrys cladodes effected nematicidal activity of 85.3 and 83.5%, at 20 and 25°C, respectively. At 20 and 30°C, P. chlamydosporia achieved nematicidal activity of 81.3 and 87.4%, respectively. The maximum chlamydospore production was reached at 20, 25 and 30°C for D. flagrans, at 20 and 25°C for A. cladodes and P. chlamydosporia. The results of this study demonstrated that the tested fungal strains of D. flagrans, A. cladodes and P. chlamydosporia, when used in the biological control of bovine parasitic nematodes, were not limited by in vitro temperature variations. Therefore, the use of these strains of fungi as biological control agents of parasitic nematodes is promising.

Association and predatory capacity of fungi Pochonia chlamydosporia and Arthrobotrys cladodes in the biological control of parasitic helminths of bovines.

Nematophagous fungi are used in the biological control of the parasitic helminths of animals and plants. The association of ovicidal and predator nematophagous fungi may present a complementary and increased action on the biological control of helminths. Joint growth compatibility and predation tests were carried out on infective larvae of nematode parasites of bovines with the nematophagous fungus ovicide Pochonia chlamydosporia and the nematophagous fungus predator Arthrobotrys cladodes. The tests of antagonism in direct confrontation, antibiosis and the effect of volatile metabolites between the isolates of P. chlamydosporia and A. cladodes indicated the viability of joint growth of these fungi. The association of the fungi P. chlamydosporia and A. cladodes presented a higher predatory capacity of infective larvae of the parasitic nematodes of bovines when compared to the predation of the fungi used alone. Therefore, under laboratory conditions, the fungi studied presented growth compatibility and the association of these increased the nematicidal activity against parasitic helminths of cattle.

Reduction of bovine strongilides in naturally contaminated pastures in the southeast region of Brazil.

Biological control through the use of nematophagous fungi is a sustainable alternative for combatting helminthes in domestic animals and allows a reduction in the use of anthelmintics. The objective of this research was to evaluate the efficacy of the Arthrobotrys cladodes var macroides fungus in a pelleted formulation, based on sodium alginate and administered twice a week orally, as an alternative for the biological control of nematodes in field-grown young cattle. The experiment was conducted in a farm located in the municipality of Viçosa, MG, where 12 cattle, seven to nine months old, were allocated in two groups (treated group and control group) and distributed in pickets of Brachiaria decumbens, naturally infested with nematode larvae. The animals in the treated group received 1g of sodium alginate matrix pellets for every 10 kg of animal live weight, containing the nematophagous fungus Arthrobotrys cladodes var macroides and administered twice a week in conjunction with commercial feed. In the control group, each animal received 1 g of pellets for every 10 kg of animal live weight, without fungal mycelium added to the feed. Samples of feces and pastures were collected fortnightly for 12 months. The results showed that the most prevalent nematode genera in the coprocultures were Haemonchus sp., Cooperia sp. and Oesophagostomum sp., reflecting the results found in forage. The pasture that contained the animals that received feed with the fungus presented a reduction of 59% and 52% of larvae recovered at distances of 20 cm and 40 cm from the fecal pats, respectively. The mean number of eggs per gram of feces each month and animal body weight did not differ (p > 0.05) between the treated and control groups. Stool and soil samples from both groups were colonized by A. cladodes fungus and other fungi. Administration of Arthrobotrys cladodes var macroides mycelium by means of a sodium alginate matrix twice weekly reduced larval infestation of the surrounding pasture, indicating that this fungus may be a promising biological control of infecting forms of nematodes present in the environment.

Duddingtonia flagrans formulated in rice bran in the control of Oesophagostomum spp. intestinal parasite of swine.

Three experimental assays with Duddingtonia flagrans (isolated AC001) were carried out. The growth of the genus Duddingtonia present in formulation of rice bran, its predatory capability on Oesophagostomum spp. infective larvae (L3) in petri dishes (assay 1), its action in faecal cultures with eggs of that parasite (assay 2) and isolate's capability of predation after passing through gastrointestinal tract of swine (assay 3) was evaluated. At assay 3, feces were collected at time intervals of 12, 24, 36, 48, and 60 h after feed animals with the formulation. Assays 1 and 2 showed a statistical difference (p < 0.01) by the F test when comparing the treated group with the control group. At the both assays, was observed in the treated group a reduction percentage of 74.18% and 88.38%, respectively. In assay 3, there was a statistical difference between the treated group and the control group at all collection times (p < 0.01). Regarding the collection periods, there was no statistical difference over time in the treatment group (p > 0.05). The results demonstrate that the fungal isolate AC001 formulated in rice bran can prey on L3 of Oesophagostomum spp., in vitro and after passing through the gastrointestinal tract, without loss of viability. This isolate may be an alternative in the control of Oesophagostomum spp. in swine.

Using the fungus Arthrobotrys cladodes var. macroides as a sustainable strategy to reduce numbers of infective larvae of bovine gastrointestinal parasitic nematodes.

Research in the area of sanitation in ruminant production has focused on discovery of potential agents for biological control of helminths with nematophagous fungi and has provided evidence of success. The antagonistic potential of the fungus Arthrobotrys cladodes var. macroides on infective larvae of bovine gastrointestinal parasitic nematodes was evaluated by scanning electron microscopy. Additionally, an in vivo test of the resistance to digestive processes and viability of the fungus was carried out using a formulation based on sodium alginate administered orally in cattle. Production of conidia and chlamydospores was high. In in vitro tests, the number of infective nematode larvae was reduced 68.7% by the fungus in the treated group compared to the control group. The interaction between the fungus and the nematodes was confirmed by scanning electron microscopy. Plates containing fecal samples collected after oral administration of 100 g of pellets containing the A. cladodes fungus showed that the fungus survived passage through the gastrointestinal tract of ruminants, grew on agar, formed traps and preyed on L3 larvae of gastrointestinal parasites. The results of the present study provide a new opportunity for alternative, environmentally safe control of ruminant nematodes.

Cananga odorata L., Illicium verum, and Foeniculum vulgare essential oils impair the reproduction of the cattle tick Rhipicephalus microplus (Acari: Ixodidae).

This study aimed to evaluate the acaricidal potential of the essential oils of Cananga odorata L. (ylang-ylang), Illicium verum (star anise), and Foeniculum vulgare (sweet fennel) in Rhipicephalus microplus engorged females. The essential oils were extracted by hydrodistillation, and the females were immersed in each essential oil at concentrations ranging from 10 µL/mL to 50 µL/mL, using 10% dimethyl sulfoxide as a solvent. Tick mortality was evaluated after seven and 14 days, and the following parameters were determined: female weight before oviposition, preoviposition period, egg mass weight, egg production index, incubation period, hatching rate, fecundity, percentage of reduction in oviposition, percentage of reduction in hatching and product efficacy. Lethal concentration (LC50) values were 34.42 µL/mL (28.34-40.86) for C. odorata and 40.60 µL/mL (32.58-58.21) for F. vulgare. This parameter was not calculated for I. verum because there was insufficient mortality at the concentrations evaluated. The greatest efficacy was observed in the group treated with 40 µL/mL F. vulgare essential oil (97.17%), followed by I. verum (91.35%) and C. odorata (86.19%) at the same concentration. Efficacy results were associated with a greater reduction in egg mass weight and lower hatching rates. Although the essential oils caused a slight acaricidal impact, they showed significant effects on the reproductive performance of R. microplus engorged females. Thus, the results of this study indicate that these essential oils can be used in the development of new acaricidal formulations.

Prevalence and seasonal aspects of parasitism by Oestrus ovis (Diptera: Oestridae) in sheep from Mato Grosso State, Brazil.

Oestrus ovis larvae are obligate parasites of vertebrates and cause cavitary myiasis (oestrosis) in sheep and goats. It is also reported as a zoonosis causing ophthalmomyiasis and nasopharyngeal myiasis. Despite being relatively common in Brazil, epidemiological studies on O. ovis are scarce. Considering that the infestation is influenced by the climate and biomes of the studied region, we aimed to investigate the seasonal prevalence of O. ovis among slaughtered sheep in the northern region of the state of Mato Grosso, Brazil. The heads of sheep (n=697) slaughtered at a slaughterhouse in the municipality of Terra Nova do Norte (November 2011 to November 2013) were collected to count, catalog, and identify the larvae found in the upper respiratory tract. Overall, 45.77% (319/697) of the animals were infested with 2,412 recovered larvae, 96.89% (2,337/2,412) of which were identified at the species level as O. ovis. Seasonal variations in prevalence ranged from 41% (spring) to 56% (summer); however, no correlation was observed between prevalence and season, mean humidity, or temperature. In conclusion, parasitism by O. ovis in sheep in the studied area, occurs year-round, considering the occurrence of larvae (L1, L2, and L3) throughout the year, probably because of the area's environmental conditions.

Soft and hard ticks (Parasitiformes: Ixodida) on humans: A review of Brazilian biomes and the impact of environmental change.

Records of accidental parasitism by ticks in humans from Brazil are scarce, with most being reported by researchers who are parasitized during their research and by professionals who work with animals. In order to compile these records, an extensive literature review was carried out. Our revision includes studies published between 1909 and 2022, including nine species of the Argasidae family and 32 species of the Ixodidae family that were reported biting humans in the six biomes of the Brazilian territory. The species with the highest number of records of human parasitism was Amblyomma sculptum, followed by Amblyomma coelebs, Amblyomma cajennense sensu stricto, and Amblyomma brasiliense. The Atlantic Forest was the most frequent biome where human parasitism occurred, probably due to the greater number of inhabitants, universities, and researchers in the region; however, this does not mean that this biome is more conducive to the development of ticks and their parasitism in humans. In addition to Amblyomma ovale, a vector of Rickettsia parkeri in the country, two of the main species that act as vectors of Rickettsia rickettsii, A. sculptum, and Amblyomma aureolatum, have been reported, which is quite worrying considering that the wide distribution of the species and life stages most frequently mentioned in parasitism (i.e., nymphs and adults) are the ones that favour pathogen transmission. This research provides a significant contribution to the knowledge of tick species associated with human parasitism in Brazil; however, due to environmental change potentiated by deforestation and fires, it is expected that there will be a geographic expansion of some tick species and the pathogens that use them as a vector and an increase in human parasitism.

Ixodid diversity and detection of spotted fever group Rickettsia spp. in ticks collected on birds in the Brazilian Atlantic Forest.

The Brazilian Atlantic Forest helds one of the most diverse and unique avifauna in the world. Many vertebrate species are reservoirs of tick-borne pathogens, and birds are an important group among them due to their mobility which facilitates the dispersion of ticks and the infectious agents they carry. This study brings data on the tick diversity parasitizing birds and the molecular detection of Rickettsia spp. in these arthropods. Birds (n = 773) were captured, identified, and banded at Mata do Paraíso Research, Training, and Environmental Education Center located in Viçosa, Minas Gerais, Brazil. Birds were checked for the presence of ticks, which were individually collected, identified, and molecularly processed through Polymerase Chain Reaction (PCR) for the detection of Rickettsia spp. A total of 130 individuals were infested by ticks, and 479 tick specimens were collected, showing a seasonal distribution of the life stages throughout the year. Ticks were identified as Amblyomma longirostre (59/479); Amblyomma calcaratum (20/479); Amblyomma varium (3/479); Amblyomma sculptum (2/479) and Amblyomma spp. larvae (395/479). Seasonal distribution of the life stages of ticks was observed along the year and significant negative correlations were found between temperature and collected ticks and temperature and infested birds. From the evaluated samples of ticks, 25.44% (n = 43/169) scored positive for Rickettsia spp., and sequence analysis indicated high nucleotide identity with Rickettsia rhipicephali, R. massiliae, R. africae and R. honei marmionii. The potential for dispersal of ticks by birds added to the aggressiveness of species of the genus Amblyomma and the zoonotic potential of some species of Rickettsia are quite worrying when we consider that the study area is widely attended by students, researchers, people from the city and neighboring municipalities.

'Candidatus Mycoplasma Haemoalbiventris' and Tick-Borne Pathogens in Black-Eared Opossum (Didelphis aurita) from Southeastern Brazil.

The black-eared opossum (Didelphis aurita) is a South American synanthropic marsupial. The presence of opossums in domestic spaces is relevant in the One-Health context since they are hosts of pathogens and ectoparasites that may affect the health of domestic animals and humans. In this study, we aim to determine the occurrence of hemoplasmas and selected tick-borne pathogens in free-ranging black-eared opossums, along with their molecular characterization, hematological and biochemical evaluation and factors associated with infection, in the municipality of Viçosa, State of Minas Gerais, southeastern Brazil. Thirty black-eared opossums were trapped between March 2021 and June 2022. Ectoparasites were collected. Hematological and biochemical analyses were performed. DNA from EDTA-blood samples were analyzed by PCR and qPCR assays. By molecular analyses, 'Candidatus Mycoplasma haemoalbiventris' was the most prevalent hemoparasite (73.3%), followed by Hepatozoon sp. (22.2%). Significant differences were observed in the number of platelets, and in the concentration of protein and globulins in the animals infected by 'Ca. M. haemoalbiventris' when compared with the negative group. This is the first report of 'Ca. M. haemoalbiventris' infection in D. aurita.

Formulation of the nematophagous fungus Duddingtonia flagrans in the control of equine gastrointestinal parasitic nematodes.

Equine gastrointestinal nematodiosis contributes to the lower productivity of these animals. There are growing reports of the emergence of nematodes resistant to the drugs used for decades in anthelmintic treatments. An alternative to the emergence of resistance may be the use of nematophagous fungi as a complementary method of treatment. Therefore, the objective was to evaluate the effects of the use of the product Bioverm® as a carrier of Duddingtonia flagrans, on pasture contamination level and equine parasitic burden. Sixteen mares were used, divided into two groups, one control and one treated, in which the treated animals received a dose of 1 g of Bioverm®, containing 105 chlamydospores per gram of the commercial product for each 10 kg of body weight, per day, for six months. Efficacy was evaluated by count of eggs per gram of faeces (EPG), coproculture and larval count on pastures and its correlation with climate, as well as weight gain evaluation. During the study, a significant influence of the formulation on weight gain and EPG was observed. The recovery of larvae from coprocultures revealed the predominance of small over large strongyles. There was a significant difference (p < 0.05) between the averages of the number of larvae of small strongyles recovered in the pasture at a distance of 0-20 cm from the faeces of treated and control groups. A correlation was also observed between the number of larvae recovered from the pasture and the average temperature during the experimental period, mainly in August and September. The ingestion of Bioverm® enhances the biological control of gastrointestinal nematodes of pasturing horses.

Oxidative and local histopathological response on skin wound of horses due to Amblyomma sculptum tick parasitism.

Amblyomma sculptum is frequently observed parasitizing horses, responsible for economic losses, damage to the host''s skin and transmission of pathogens. The oxidative stress profile and inflammatory mechanisms involved in this parasitism remain poorly studied. Thus, this study aimed to assess the histopathological changes and oxidative profile responses of horses in the attachment site of A. sculptum to find variations that indicate resistance and susceptibility between the breeds to this tick, based on the hypothesis that resistant animals have a greater inflammatory response and lesser number of attached ticks. We analyzed female horses of two breeds, Mangalarga Marchador and Breton Postier, naturally infested by Amblyomma sculptum. The ticks were counted and full-thickness excisional skin wounds of 10 mm were made on the perineal region on the attachment site of partially engorged females for histological and biochemical analyzes. The occurrence of the tick on the skin caused an increase in cellularity, inflammatory infiltrate, mast cells, pyknotic nuclei, and changes in the fibrous components of the matrix. The negative correlation observed between tick infestation and inflammatory response indicated that animals with greater inflammatory response tend to have less tick infestation. The oxidative stress markers, MDA, PCN and NO not present great variation; however, between the antioxidant enzymes levels, SOD was higher in tick attachment of Breton Postier skin, this may mean that these animals had higher oxidative enzymatic activity and consequently less tissue damage, while the GST dropped in the attachment sites compared to the control, which may indicate that animals were in a state of significant oxidative stress or raises the question of the possibility of enzymatic sequestration by ticks. No significant differences were found in the resistance of the two breeds since most of the analyzes varied due to the presence or absence of the tick attached to the skin. We draw attention to the importance of studying characteristics of the animal's antioxidant responses to the tick and the action of tick saliva on antioxidant enzymes and ROS because these characteristics are interdependent with the inflammatory response.