Rafael Pazinato

Insecticidal and repellent effects of tea tree and andiroba oils on flies associated with livestock

This study aimed to evaluate the insecticidal and repellent effects of tea tree, Melaleuca alternifolia (Myrtales: Myrtaceae), and andiroba, Carapa guianensis (Sapindales: Meliaceae), essential oils on two species of fly. For in vitro studies, free‐living adult flies were captured and reared in the laboratory. To evaluate the insecticidal effects of the oils, adult flies of Haematobia irritans (L.) and Musca domestica L. (both: Diptera: Muscidae) were separated by species in test cages (n = 10 per group), and subsequently tested with oils at concentrations of 1.0% and 5.0% using a negative control to validate the test. Both oils showed insecticidal activity. Tea tree oil at a concentration of 5.0% was able to kill M. domestica with 100.0% efficacy after 12 h of exposure. However, the effectiveness of andiroba oil at a concentration of 5.0% was only 67.0%. The insecticidal efficacy (100.0%) of both oils against H. irritans was observed at both concentrations for up to 4 h. The repellency effects of the oils at concentrations of 5.0% were tested in vivo on Holstein cows naturally infested by H. irritans. Both oils demonstrated repellency at 24 h, when the numbers of flies on cows treated with tea tree and andiroba oil were 61.6% and 57.7%, respectively, lower than the number of flies on control animals. It is possible to conclude that these essential oils have insecticidal and repellent effects against the species of fly used in this study.

Trichostrongylus and Haemonchus anthelmintic resistance in naturally infected sheep from southern Brazil

The anthelmintic resistance in small ruminants is a common problem and concern worldwide. The aim of this study was to verify anthelmintic treatment efficacy in naturally infected sheep. This study was conducted on nine herds that used the same anthelmintic management for over a year. In each farm, the animals were divided into two groups: untreated control group (n = 5) and treated (n = 10) according to the number of eggs per gram of feces (EPG). The treatment effect was checked based on EPG results and larval culture performed before treatment and 10 days after treatment. Significant differences were not observed (P > 0.05) on EPG results between untreated and treated groups. The coproculture showed that the animals were infected primarily by Haemonchus spp., Trichostrongylus spp., Teladorsagia spp., Cooperia spp. and Oesophagostomum spp. In all farms, anthelmintic resistance by genera Haemonchus and Trichostrongylus was found, but this resistance varied greatly between farms. Haemonchus spp. showed resistance to closantel, levamisole, and albendazole. Trichostrongylus spp. was shown to be resistant to closantel, levamisole, and albendazole. The drugs tested showed to be efficient against the genera Teladorsagia, Cooperia, and Oesophagostomum. Based on these results, we conclude that the anthelmintic resistance to the tested drugs is a problem present in the farms evaluated.

Relation between Neospora caninum and abortion in dairy cows: Risk factors and pathogenesis of disease.

Neosporosis is a parasitic disease cause by Neospora caninum, a parasite of great importance in livestock. This study aimed to evaluate the presence of antibody against N. caninum in dairy cattle with history of abortion, as well as to identify associated risk factors for neosporosis. Animals suspected of neosporosis (n = 130) after clinical examination were randomly selected. Sera samples from 29 farms were submitted to indirect immunofluorescence technique (IFA) in order to detect antibodies against N. caninum, and animals were considered positive if ≥ IFA 1:200. An epidemiological questionnaire was used to verify probable risk factors for neosporosis and their cause-effect relation. Serological results showed that 43.8% of the animals were seropositives for N. caninum. The univariate statistical analysis found a significant relation between neoporosis and age. The number of pregnancies and the number of years that the farms had been producing milk were found as associated risk factors for the disease either by univariate or by multivariate analyses. The cause-effect model found a possible relation between reproductive problems and positive serology for neosporosis (P = 0.06). Therefore, it was concluded that approximately 44% of dairy cows with history of abortion were seropositives for N. caninum and that age and the number of years that the farms had been producing milk are risk factors for parasite infection in dairy cattle.

In vitro effect of seven essential oils on the reproduction of the cattle tick Rhipicephalus microplus.

Graphical abstract

Immunological response and markers of cell damage in seropositive horses for Toxoplasma gondii

Toxoplasmosis is an important parasitic disease affecting several species of mammals, but little is known about this disease in horses. This study aimed to investigate the levels of several immunological variables and markers of cell damage in the serum of seropositive horses for Toxoplasma gondii. Sera samples of adult horses from the Santa Catarina State, Brazil used on a previous study were divided into groups according to their antibody levels for T. gondii determined by immunofluorescence assay, i.e. 20 samples from seronegative horses (Group A - control), 20 samples from horses with titers of 1:64 (Group B), 20 samples of horses with titers of 1:256 (Group C), and five samples from horses with titers of 1:1024 (Group D). Positive animals (Groups B, C, and D) had higher levels of immunoglobulins (IgM and IgG), pro-inflammatory cytokines (TNF-α, IFN-γ, IL-1, IL-4, and IL-6) and protein C-reactive protein, as well as lower levels of IL-10 (anti-inflammatory cytokine) when compared to seronegative horses (Group A). The nitric oxide levels were also elevated in seropositive horses. Therefore, we have found humoral and cellular immune responses in seropositive horses, and a correlation between high antibody levels and inflammatory mediators. Markers of cell injury by lipid peroxidation (TBARS) and protein oxidation (AOPP) were elevated in animals seropositives for T. gondii when compared to seronegatives. Therefore, seropositive horses to T. gondii can keep active immune responses against the parasite. As a consequence with chronicity of disease, they show cellular lesions that may lead to tissue damage with the appearance of clinical disease.

Occurrence of gastrointestinal parasites in goats from the Western Santa Catarina, Brazil

This study aims to investigate the occurrence of gastrointestinal parasites in goats from the Western Santa Catarina, Brazil. Twenty four farms were analyzed in 17 different municipalities. Animals (n=217) from different production purposes (milk and meat) and age were randomly chosen. Fecal samples were collected from the rectum stored in plastic bottles and transported to the laboratory in portable coolers at 10 °C. The technique of centrifugal flotation with saturated sugar solution was carried out in order to investigate the presence of eggs, cysts, and oocysts of gastrointestinal parasites. In 88.9% of the investigated animals, it was observed that the presence of nematode eggs which belongs to the Strongylida order, after cultivation and larvae identification were identified as Haemonchus spp., Trichostrongylus spp., Teladorsagia spp., Cooperia spp., and Oesophagostomum spp. Eggs of Thysanosoma, Trichuris, Moniezia, and Neoascaris genus were also observed. Additionally, the presence of oocysts of Eimeria spp. and Cryptosporidium spp. as well as cysts of Giardia spp., and Entamoeba spp. were verified. In all the farms evaluated, the animals showed a single or mixed infection, with the highest occurrence of helminths belonging to the Haemonchus and Trichostrongylus genus, as well as the protozoan Eimeria.

Seroprevalence of Trypanosoma evansi infection in capybaras (Hydrochoerus hydrochaeris) from a nonendemic area in Brazil.

In South America, capybaras (Hydrochoerus hydrochaeris) as well as coatis (Nasua nasua) are the reservoir hosts of Trypanosoma evansi. Capybaras from a T. evansi nonendemic area in the State of São Paulo, southeastern Brazil, were culled because of an ongoing outbreak of Brazilian spotted fever; serum samples from these capybaras were tested for antibodies to T. evansi. Of the 172 sera tested, 17 (9.9%) were seropositive by card agglutination test, with antibody titers of 1:8–1:128; 14 (8.1%) of these 17 seropositive sera were also seropositive by indirect fluorescent antibody test, with antibody titers of 1:16–1:256. Both serologic techniques proved to be efficient, with similar results for detection of antibodies to T. evansi in capybaras from a nonendemic area in Brazil.

The effect of palm oil addition to the diet of dairy sheep on the immune response.

The aim of this study was to evaluate whether a diet based on palm oil has any influence on the immune response and on the number of eggs per gram of faeces (EPG) of gastrointestinal nematodes (GIN) in dairy sheep. To address this issue, 30 ewes in early lactation were confined and divided into three groups (n = 10) receiving a daily isoproteic and isoenergetic diet. Palm oil was added to the feed at different concentrations: 0% (control; group A), 4% (group B) and 6% (group C). The animals were treated with levamisole 10 days before the beginning of the experiment. Faecal samples were collected and analysed for EPG on day zero of the experiment. On days 60 and 120, individual faecal and blood samples were collected, and the FAMACHA(©) score for assessing clinical anaemia was carried out. The groups receiving palm oil showed a significant reduction in EPG in relation to the control group (A) on day 120. Serum immunoglobulin levels (IgG, IgM and IgE) and proinflammatory cytokine levels (TNF-α, IL-1 and IL-6) were significantly increased on days 60 and 120 (p < 0.05) in groups B and C. Therefore, these results suggest that palm oil stimulates the immune response in sheep, thus reducing EPG of GIN. The hypothesis that palm oil has direct anthelmintic activity should be tested in future studies.

Seroprevalence and Risk Factors for Toxoplasma gondii Infection in Goats in Southern Brazil

Background: Toxoplasma gondii is a coccidium, obligate intracellular protozoan, with complex life cycle, affecting virtually all-animal species homoeothermics. Goats are considered susceptible to infection by T. gondii, alterations being reported as pathological fetal death (with subsequent reabsorption), abortion, mummification, and/or the birth of weak goats. Because of these consequences to the animal, the disease is investigated throughout the Brazilian territory. Therefore, the aim of this study was to estimate the seroprevalence of Toxoplasma gondii antibodies and identify risk factors in goats. Materials, Methods & Results: It were collected 654 blood samples from goats distributed on west and mountainous regions of Santa Catarina, Brazil. The number municipalities with the highest numbers of goats were used, with an expected prevalence of 25%, error of 3.2% and confidence level of 95%. All collected samples were tested by indirect immunofluorescence assay (IFA), and 216 (33.02%; 95% CI 29.43-36.77) had antibodies against T. gondii (IFA ≥ 1: 64). Titration 1:64 was observed more frequently (60.2%; 130/216) among seropositive animals. The region with the highest prevalence was the west, i.e., more prone to infections present, with 1.16 more chances than the mountainous region. Animals Boer were more likely to T. gondii infection, being race is a risk factor for disease. When the presence of cats on the property, and these animals had chances of direct contact with cats, the chance of infection increased significantly, being 1.04 times higher went compared with lack of this feature. Regarding age, the animals aged two to five years had higher seropositivity (77.8%). Statistical analysis of effect-cause studies reported a relationship between soropositive animals and neurological problems (P ≤ 0.05), but no relation was found for T. gondii infection and reproductive problems (P > 0.05). Discussion: In the state of Santa Catarina, approximately 33% of the goats were seropositive for T. gondii, according to results of this study. Several other studies has been performed on T. gondii antibodies detection in Brazil, such as Parana which was 44.68%, in Rio Grande do Norte was 17.1%, in Rio de Janeiro was 29.12%, in Maranhao was 36.95%, in Bahia was 17.4%, in Minas Gerais was 21.4%, in Alagoas was 39% and in Rio Grande do Sul was 30%. The type of food and water source given to the animals was not considered a risk factor for T. gondii infection, although some authors mention that cat feces contaminated with oocysts of the parasite can be more easily ingested in the diet with concentrated (cats have access) and natural water sources. This study showed that 53% of the animals studied had contact with cats, and this variable was considered a risk factor for disease. Statistically, unverified relationship between reproductive problems and goats seropositive for T. gondii, although of approximately 24% of the animals studied showed some reproductive problems (abortion, mummified or heat repetition). In the effect-cause analysis, neurological issues were related to infection by T. gondii in goats, the that can easily be explained because the parasitic cysts of T. gondii may persist in the central nervous system for a long period. The results suggest that infection by T. gondii occurs in goats in two regions of Santa Catarina, in addition, and the risk factors related to disease was between both studied regions, race and presence and contact with cats, just as there is a relation between disease and neurological disorders in goats.