Genotypic profile of benzimidazole resistance associated with SNP F167Y and F200Y beta-tubulin gene in Brazilian populations of Haemonchus contortus of goats.

Benzimidazoles are the most common anthelminthic used for control of gastrointestinal nematodes of goats in the Brazilian semi-arid region. Resistance to these compounds in the nematode Haemonchus contortus has been associated with single nucleotide polymorphisms (SNP) in codons 167 (F167Y) and 200 (F200Y) on the ß-tubulin isotype 1 gene. To determine the resistance profile to benzimidazoles of populations of H. contortus of goats of Brazilian semi-arid region, larvae of 29 populations of these nematodes were individually genotyped by real time PCR using a Taqman assay. The percentage of larvae homozygous (RR) for SNP F200Y was relatively low (18.9%), particularly when compared to SNP F167Y (32.7%), indicating that the latter has more relevance in this region. However, the associations between these two SNP demonstrate percentages of resistance ranging from 34.7% to 100% between populations, being the highest percentages for homozygous individuals resistant for the mutation 167 and susceptible to mutation 200 (RR-F167Y/F200Y-SS: 26.7%), followed by combination of heterozygous for both mutations (F167Y-SR/F200Y-SR: 22.8%). These results indicate high levels of resistance in populations of H. contortus of goats in the Brazilian semi-arid region, and thus ineffective antiparasitic control with the use of benzimidazoles in the region.

Updated canine infection rates for Dirofilaria immitis in areas of Brazil previously identified as having a high incidence of heartworm-infected dogs.

BACKGROUND: Canine heartworm infections were frequently diagnosed in Brazil before the new millennium. After the year 2000, the frequency of diagnosis showed a sharp decline; however, a few years later, new evidence indicated that the parasite was still present and that canine infection rates seemed to be increasing. Therefore, an updated survey of canine heartworm prevalence was conducted in several locations in south, southeast, and northeast Brazil. METHODS: Dogs from 15 locations having previously reported a high prevalence of heartworm infection were included in the survey according to defined criteria, including the absence of treatment with a macrocyclic lactone for at least 1 year. Blood samples from 1531 dogs were evaluated by an in-clinic immunochromatography test kit (Witness® Heartworm, Zoetis, USA) for detection of Dirofilaria immitis antigen. At each location, epidemiologic data, including physical characteristics and clinical signs reported by owners or observed by veterinarians, were recorded on prepared forms for tabulation of results by location, clinical signs, and physical characteristics. RESULTS: The overall prevalence of canine heartworm infection was 23.1%, with evidence of heartworm-infected dogs detected in all 15 locations studied. There was a tendency for higher prevalence rates in environmentally protected areas, despite some locations having less-than-ideal environmental temperatures for survival of vector mosquitoes. Among physical characteristics, it was noted that dogs with predominantly white hair coats and residing in areas with a high (≥20%) prevalence of heartworm were less likely to have heartworm infection detected by a commercial heartworm antigen test kit than were dogs with other coat colors. In general, dogs older than 2 years were more frequently positive for D. immitis antigen than were younger dogs. Clinical signs of heartworm infections were rare or owners were unable to detect them, and could not be used for reliable prediction of the presence of heartworm. CONCLUSIONS: These results indicate that the prevalence of D. immitis has increased in these areas of Brazil over the past few years. Small animal practitioners in these areas should include routine screening tests for heartworm infections in every dog's annual evaluation protocol and make sure to have uninfected dogs on prevention.

[Anthelmintic activity of aqueous extract of Zanthoxylum rhoifolium Lam. leaves (Rutaceae)]. / Atividade anti-helmíntica do extrato aquoso das folhas de Zanthoxylum rhoifolium Lam. (Rutaceae).

The study evaluated the anthelmintic activity of aqueous extract of Zanthoxylum rhoifolium leaves in two experiments. In vitro test, cultures of goat fecal samples were treated with different concentrations of extract (134.5 to 335.0 mg.mL(-1)). In vivo test was composed of 20 sheep: G1: treated with 0.63 g.kg(-1), during four days; G2: same dose, for eight days; G3: ivermectin (200 microg.kg(-1)) and G4 untreated group. In vitro results showed a reduction of Haemonchus spp, Trichostrongylus spp. and Oesophagostomum spp. larvae greater than 95% in the concentrations between 335.0 and 193.7 mg.mL(-1). Faecal egg counting reduction was 51, 56 and 90% in G1, G2 and G3, respectively, while immature stages and adults ranged from 0 to 91% in G1 and from 26 to 94% in G2. Ivermectin effectiveness was 99% for L4 and L5 of H. contortus and 100% for other nematodes species. Clinical and biochemical parameters have remained in the normality and histophatologic analyses did not show alteration suggesting absence of toxicity. Although the great effectiveness of Z. rhoifolium leaves extract in vitro test, it displayed poor efficiency in vivo regarding gastrointestinal nematodes reduction.

Loss of infectivity of Neospora caninum oocysts maintained for a prolonged time.

The purpose of this study was to investigate whether sporulated Neospora caninum oocysts, which had been stored for 46 mo in a 2% sulfuric acid solution at 4 degrees C, remain morphologically viable and infective to gerbils (Meriones unguiculatus). Six gerbils were orally inoculated with doses of 400 or 1,200 oocysts. Two mo after inoculation, the animals did not show any clinical signs, had no histological lesions, and were seronegative for N. caninum at 1: 50 in an immunofluorescent antibody test. PCR using the brain from each gerbil did not reveal N. caninum specific DNA. We conclude that oocysts preserved for 46 mo are not infective, despite being morphologically intact.