Effect of aqueous extracts of Baccharis trimera on development and hatching of Rhipicephalus microplus (Acaridae) eggs

This study evaluated the effects of aqueous extracts of Baccharis trimera (Less.) DC (Asteraceae), colloquially known as carqueja, on egg production, and hatching rate of larvae of Rhipicephalus microplus. Plant samples were collected in Montes Claros, north of Minas Gerais, Brazil. Adult female ticks were distributed into 24 homogeneous groups of 10. The in vitro test was performed by immersing each group in 10 ml solutions of aqueous extracts at 50, 100, 150, or 200 mg of fresh leaves ml⁻¹. These concentrations were compared with distilled water as negative control and a commercial product as positive control and the tests were repeated four times. The carqueja extract at concentrations of 150 and 200 mg of fresh leaves ml⁻¹ showed 100% efficacy in inhibiting egg hatching and therefore could have potential as an acaricide.     

Efficiency of entomopathogenic fungi in the control of eggs and larvae of the horn fly Haematobia irritans (Diptera: Muscidae)

The present study assessed the pathogenic effect of isolates E9, IBCB425 and IBCB159 of the Metarhizium anisopliae fungus, JAB06, JAB07 and AM09 of Beauveria bassiana, IBCB133 and CB75 of Isaria fumosorosea (=Paecilomyces fumosoroseus) and CG189 and CG195 of Isaria farinosa (=Paecilomyces farinosus) against eggs and larvae of the horn fly Haematobia irritans. Eggs were inoculated with suspensions containing 10⁶, 10⁷ and 10⁸ conidia ml⁻¹ of the fungal isolates and observed after 48 h to determine viability. In the larvae study, eggs were allowed to hatch into fresh bovine feces that had been treated with 10⁸, 10⁷ or 10⁶ conidia mg feces⁻¹. In both studies, 5 days after initial procedures, all formed pupae were transferred to an incubator at 27 ± 0.5 °C until the emergence of the adult flies was complete. The M. anisopliae isolates did not cause the death of H. irritans eggs, but they did promote the death of larvae that hatched from treated eggs, and therefore increased the total mortality. Isolate E9 promoted 100% mortality of treated larvae at a concentration of 10⁸ conidia ml⁻¹. For the B. bassiana isolates, no activity was observed against insect eggs or larvae. Both I. fumosorosea isolates promoted significant mortality (p < 0.05) of eggs at every concentration of conidia. Isolate CG195 of I. farinosa increased the mortality of larvae and pupae that hatched from treated eggs and promoted significant total mortality (p < 0.05) of the insect at every concentration of conidia.     

Assessing the efficacy of Duddingtonia flagrans chlamydospores per gram of faeces to control Haemonchus contortus larvae

The aims were (a) to quantify the number of Duddingtonia flagrans chlamydospores per gram of faeces (CPG) recovered from sheep administered with different oral doses and, (b) to describe the relationship between CPG and eggs per gram of faeces (EPG) on the efficacy to reduce Haemonchus contortus infective larvae. Three doses of chlamydospores per kg BW were orally administered during seven days: (T1) non treated control group, (T2) 1 × 10⁶, (T3) 2.5 × 10⁶ and (T4) 5 × 10⁶. Three lambs, infected with H. contortus, were used per group. Faeces were obtained from the rectum of each lamb during the fungal administration period (days 0–6) and for six days after that period. Four coproculture replicates were made from each animal in days 2, 4, 6, 8 and 10. A higher chlamydospore dose produced higher CPG in faeces (p < 0.05), but a clear dose dependent effect was not found either in the larvae reduction or in the CPG:EPG ratio. When ratios were re-analyzed, independently of the treatment groups of origin, a better efficacy was obtained with a ratio from 5 to 10 CPG:EPG and a higher ratio (>10 per egg) showed a lower reduction efficacy (p < 0.05). The binomial analysis showed that for each unit of increment in CPG:EPG ratio there was a reduction of larvae number until a point (between 5 and 10 CPG:EPG) where no further reduction was detected. The surface response test indicated that the number of larvae was reduced by CPG until possible saturation. The highest CPG:EPG ratios did not necessarily improve efficacy of D. flagrans.     

The efficacy of eprinomectin extended-release injection against Hypoderma spp. (Diptera: Oestridae) in cattle

The efficacy of eprinomectin in an extended-release injection (ERI) formulation was determined in cattle harboring naturally acquired infestations of first- or second- and third-stage larvae of Hypoderma spp. in three studies conducted according to the same protocol in the USA (two studies) and Germany (one study). Thirty cattle sourced from herds with a history of Hypoderma infestation were included in each study. Cattle were formed into replicates of three animals each on the basis of pre-treatment anti-Hypoderma antibody titers. Within replicates each animal was randomly allocated to one of the following treatments: ERI vehicle (control) at 1 mL/50 kg bodyweight, administered once on Day 0; Eprinomectin 5% ERI at 1 mL/50 kg bodyweight (1.0 mg eprinomectin/kg), administered once on Day 0 (when larvae were expected to be first instars); or Eprinomectin 5% ERI at 1 mL/50 kg bodyweight (1.0 mg eprinomectin/kg), administered once when larvae were second or third instars (study dependent, Day 73, 119, or 140). Treatments were administered by subcutaneous injection in front of the shoulder. In all studies, emerging and/or expressed Hypoderma larvae were recovered, speciated, and counted and viability was determined. Eprinomectin LAI treatment was 100% (p < 0.05) efficacious against first- and second- or third-stage larvae of Hypoderma bovis (two studies) and Hypoderma lineatum (one study). All animals accepted the treatment well. No adverse reaction to treatments was observed in any animal in any study.     

Gene markers of generic Escherichia coli associated with colonization and persistence of Escherichia coli O157 in cattle

Enterohemorrhagic Escherichia coli (EHEC) O157 are important foodborne pathogens whose major reservoir are asymptomatic cattle. There is evidence suggesting that nonpathogenic E. coli and bacteriophages in the gastro-intestinal tract can influence the pathogenicity of EHEC O157. The factors contributing to the onset and persistence of shedding EHEC O157 in cattle are not completely elucidated. This study used Bayesian network analysis to identify genetic markers of generic E. coli associated with shedding of EHEC O157 in cattle from data generated during an oral experimental challenge study in 4 groups of 6 steers inoculated with three different EHEC O157 strains. The quantification of these associations was accomplished using mixed effects logistic regression. The results showed that the concurrent presence of generic E. coli carrying the prophage marker R4-N and the virulence marker stx2 increased the odds of the onset of EHEC O157 shedding. The presence of prophage markers z2322 and X011C increased, while C1.N decreased the odds of shedding EHEC O157 two days later. A significant antagonist interaction effect between the presence of the virulence marker stx2 on the day of shedding EHEC O157 and two days before shedding was also found. In terms of the persistence of EHEC O157 shedding, the presence of prophage marker R4-N (OR = 16, and 95% confidence interval (CI): 1.1, 252) was found to increase the odds of stopping EHEC O157 shedding, whereas prophage marker C1.N (OR = 0.16, CI: 0.03, 0.7) and the enterohemolysin gene hly (OR = 0.03, CI: 0.001, 0.8) were found to significantly decrease the odds of stopping EHEC O157 shedding. In conclusion, the study found that the presence of certain genetic markers in the generic E. coli genome can influence the pathogenicity of EHEC O157.     

Evaluation of the in vitro growth-inhibitory effect of epoxomicin on Babesia parasites

Epoxomicin potently and irreversibly inhibits the catalytic activity of proteasomal subunits. Treatment of proliferating cells with epoxomicin results in cell death through accumulation of ubiquinated proteins. Thus, epoxomicin has been proposed as a potential anti-cancer drug. In the present study, the inhibitory effects of epoxomicin on the in vitro growth of bovine and equine Babesia parasites were evaluated. The inhibitory effect of epoxomicin on the in vivo growth of Babesia microti was also assessed. The in vitro growth of five Babesia species that were tested was significantly inhibited (P < 0.05) by nanomolar concentrations of epoxomicin (IC₅₀ values = 21.4 ± 0.2, 4 ± 0.1, 39.5 ± 0.1, 9.7 ± 0.3, and 21.1 ± 0.1 nM for Babesia bovis, Babesia bigemina, Babesia ovata, Babesia caballi, and Babesia equi, respectively). Epoxomicin IC₅₀ values for Babesia parasites were low when compared with diminazene aceturate and tetracycline hydrochloride. Combinations of epoxomicin with diminazene aceturate synergistically potentiated its inhibitory effects in vitro on B. bovis, B. bigemina, and B. caballi. In B. microti-infected mice, epoxomicin caused significant (P < 0.05) inhibition of the growth of B. microti at the non-toxic doses of 0.05 and 0.5 mg/kg BW relative to control groups. Therefore, epoxomicin might be used for treatment of babesiosis.     

Serological survey of Encephalitozoon cuniculi in farm rabbits in Italy

Rabbit sera (n = 1600) from 40 commercial farms were submitted to a serological screening for Encephalitozoon cuniculi by an enzyme-linked immunosorbent assay (ELISA) and a carbon immunoassay (CIA test). Antibodies anti-Encephalitozoon cuniculi were found in 505/1600 (31.6%) sera analysed, and all the farms (100%) resulted positive. Rabbits older than 4 months showed a significantly higher seropositivity for E. cuniculi (chi-squared test: p < 0.0001) than rabbits under 4 months, E. cuniculi sero-prevalence showed an increasing trend in rabbits within the farm along with the increase in the “number of rabbits on the farm”; however, this trend was not significant (Spearman’s correlation: p = 0.073).The findings of the present study confirm that rabbit is the main reservoir of E. cuniculi; they are of epidemiological relevance and immediate public health importance because of the recognized infectivity in humans by the microsporidium.     

Long-term immunogenicity and protection against Mycoplasma agalactiae induced by an oil adjuvant vaccine in sheep

The long-term protective immunity of an inactivated mineral-oil adjuvanted Mycoplasma agalactiae vaccine was evaluated in sheep. The antigen suspension was emulsified with a mixture of three mineral oils (Montanide ISA-563, Marcol-52, Montane-80 at the ratio of 30%, 63%, and 7%, respectively). Twenty-two animals were divided in 2 groups (A and B) and immunised with two doses of the vaccine (group A, n = 14) or used as unvaccinated control (group B, n = 8). Five months after the second vaccination, seven animals of group A and four animals of group B were challenged by nasal route with M. agalactiae. The remaining seven vaccinated and four control animals were challenged intranasally eight months after vaccination. The vaccine was able to induce a full-protective immunity preventing the clinical signs of contagious agalactia and the infection by M. agalactiae in all groups of animals irrespective of the time of challenge after booster administration.     

Evaluation on the pathogenicity of Erysipelothrix tonsillarum for pigs by immunosuppression with cyclophosphamide or dexamethasone

The pathogenicity of Erysipelothrix tonsillarum was evaluated in pigs immunosuppressed with cyclophosphamide (CY) or dexamethasone (DM). Animals were treated with 15 mg/kg CY (n = 8, five injections), 1 mg/kg DM (n = 8, nine injections) or left untreated (n = 8). On the fifth day after the beginning of drug treatments, swine were inoculated with one of two E. tonsillarum serovar 7 strains (approximately 10⁶ CFU per pig). In the CY-treated group, both circulating neutrophil and lymphocyte counts decreased, whereas in the DM-treated group, lymphocyte counts decreased but neutrophil counts increased. During the observation period, none of the CY- or DM-treated pigs developed clinical signs or gross lesions, as well as non-treated pigs. Growth agglutination antibody titres in all pigs remained unchanged. Our findings indicate that E. tonsillarum strains are avirulent for swine, regardless of immune status.     

Prevalence and antibiotic resistance profiles of Enterococcus species in chicken at slaughter level; absence of vanA and vanB genes in E. faecalis and E. faecium

The prevalence of enterococci in neck skin samples of poultry from Ankara region in Turkey was investigated and their antibiotic resistance patterns were determined. In the study, 83 of 106 analyzed neck skin samples were positive for Enterococcus, with E. faecium as the most prevalent species (48%) followed by E. durans (23%) and E. faecalis (19%). Lower numbers were detected for E. gallinarum, E. hirae, E. mundtii and E. casseliflavus. Using the disc diffusion method, it was established that over 90% of E. faecium and E. faecalis isolates were high-level resistant against erythromycin and tetracycline. Four E. faecium isolates were additionally resistant to chloramphenicol, gentamicin and streptomycin, though they were susceptible to penicillin G. The most frequently observed multiple resistance in E. faecium (25%) was against erythromycin, tetracycline, chloramphenicol and streptomycin. Of the E. faecalis isolates, 44% were multiple resistant to erythromycin, tetracycline and streptomycin. Vancomycin resistance could not be demonstrated phenotypically and vanA or vanB genes were not detected by multiplex PCR in any of the isolates. Nevertheless, the observed resistance patterns are of concern for public health.     

Seroprevalence of and risk factors for Toxoplasma gondii in sheep raised in the Jaboticabal microregion, São Paulo State, Brazil

Seroprevalence of and risk factors for toxoplasmosis in sheep from different properties in the Jaboticabal microregion, São Paulo State, Brazil were determined. Antibodies to Toxoplasma gondii were found in sera of 52.0% of 488 sheep tested by indirect fluorescent antibody test (IFAT ? 64). T. gondii seropositivity in sheep was significantly associated with gender of the sheep, pasturing system, contact with cats, and the use of mineral supplements and the type of feed.     

Phenotypic and genotypic characteristics of antimicrobial resistant Escherichia coli isolated from symbovine flies, cattle and sympatric insectivorous house martins from a farm in the Czech Republic (2006-2007)

The prevalence of antimicrobial resistant Escherichia coli was tested in symbovine flies and sympatric house martins (Delichon urbica) at a dairy farm. Antimicrobial resistant E. coli was detected in 89% (n = 147) of isolates from flies within a calf barn. Isolates with the same antimicrobial resistance phenotypes, genes, and pulsotypes were found between both fly and calf E. coli isolates, suggesting that the calves were the initial source of the antimicrobial resistant strains in fly isolates. Symbovine flies were considered as important reservoirs of antimicrobial resistant E. coli strains at a dairy farm, due to their intensive contact with cattle feces and manure. House martin fecal samples from the same farm contained 4.5% (n = 393) of antimicrobial resistant E. coli. House martin isolates displayed different macrorestriction profiles than fly isolates and the significance of house martins as a reservoir and vector of antimicrobial resistant E. coli appears low.     

Rickettsia lusitaniae sp. nov. isolated from the soft tick Ornithodoros erraticus (Acarina: Argasidae)

In this study a novel Rickettsia from the spotted fever group, isolated from Ornithodoros erraticus soft ticks collected from pigpens in the south of Portugal, is described. After initial screening revealed Rickettsia-positive ticks, isolation attempts were then performed. Successful isolates were achieved by shell-vial technique using Vero E6 cells at 28 °C. Molecular characterization of the isolate was performed based on analysis of five rickettsial genes gltA, ompA, ompB, sca1 and htr with their subsequent concatenation along with other rickettsial species resulting in a clustering of the new isolate with Rickettsia felis and Rickettsia hoogstraalii. The degree of nucleotide sequence similarity with other rickettsiae fulfills the criteria for classification of our isolate as a novel species. The name Rickettsia lusitaniae sp. nov. (= CEVDI PoTiRo) is proposed for this new species found in O. erraticus.     

Effect of new ethyl and methyl carbamates on biological parameters and reproduction of the cattle tick Rhipicephalus microplus

The effect of carbamates on engorged female Rhipicephalus microplus ticks and larvae was evaluated using the adult immersion test (AIT) and the larval packet test (LPT), respectively. Seventeen synthetic carbamates different from current commercial acaricides were synthesised at the National Autonomous University of Mexico. None of the carbamates had an effect on the percentage of females laying eggs. Six of the compounds inhibited egg laying up to 65.4% and inhibited egg hatching by up to 100% (p < 0.05). Compared to untreated females, eggs produced by treated females had a dark, dry, opaque appearance and were less adherent. Carbamates LQM 934 and LQM 938 had an effect on larval mortality (p < 0.05). Carbamate LQM 934 showed lethal concentrations (LC) of LC₉₀ = 0.76% and LC₉₉ = 0.87%, while LQM 938 showed concentrations of LC₉₀ = 0.267% and LC₉₉ = 0.305%. The compounds were distributed into three classes of acaricidal activity using the AIT or the LPT. These three classes were as follows: (1) compounds having no apparent effect; (2) compounds that inhibit egg laying and embryo development or (3) compounds that exhibit acaricidal activity to larval ticks.     

Occurrence of weak mutators among avian pathogenic Escherichia coli (APEC) isolates causing salpingitis and peritonitis in broiler breeders

A collection of 46 avian pathogenic Escherichia coli (APEC) isolates was examined for the presence of mutators by determining the rate of mutation to rifampicin resistance. The collection included 34 E. coli isolates obtained in pure culture from chronic lesions of salpingitis and peritonitis in 34 broiler breeders, of which 12 were associated with the development of secondary septicemia. Twelve additional isolates were obtained from a clonal outbreak (ST95) of E. coli peritonitis syndrome (EPS), the lesions of which changed gradually over time into a subacute/chronic form. The hypothesis of the present study was that mutation rates would be higher for chronic infection isolates than for isolates from acute infections/exacerbations. The distribution of mutation rates followed a pattern similar to that found for other clinical isolates of E. coli, with a modal/median value of 1.47 × 10⁻⁸. Of the 46 isolates, 24% (n = 11) were weakly hypermutable (2.00 × 10⁻⁸ ≤ μ < 2.00 × 10⁻⁷), however, no strong mutators were detected (μ ≥ 2.00 × 10⁻⁷). Chronic salpingitis isolates had the highest proportion (45%, P = 0.001) of weak mutators and also, significantly higher mutation rates (P = 0.003) compared to isolates that caused septicemia (4%). In addition, mutation rates were significantly lower among ST95 isolates (P < 0.0005), and among isolates from the same clonal group as ST95 (P = 0.027), when compared to isolates from other groups. Although a clear association with the time phase of infection (as lesions of EPS became more chronic) could not be observed (ρ = 0.523, P = 0.081), a higher frequency of weak mutators among chronic infection isolates suggests that increased mutation rates play a role in adaptation of APEC to long-term persistence in an infected host environment.     

Diversity of Campylobacter jejuni and Campylobacter coli Genotypes from Human and Animal Sources from Rio de Janeiro, Brazil

To compare the genotypes of Campylobacter jejuni and Campylobacter coli isolates of human and animal origin collected in Rio de Janeiro City, 30 C. jejuni and 35 C. coli isolates from animal sources (n = 45) and human patients with gastroenteritis (n = 20) were genotyped by PCR-based techniques, namely random amplified polymorphic DNA (RAPD-PCR) and enterobacterial repetitive intergenic consensus sequence (ERIC-PCR). RAPD-PCR identified 50 types and ERIC-PCR identified 22 genotypes, among the 65 Campylobacter isolates. Both PCR methods discriminated the C. jejuni and C. coli groups of isolates. Combining the results of both methods, no single genotype was shared between isolates from human and animal sources. Two groups of two C. coli isolates each with identical genotypes were found among poultry and pig isolates. A high level of genetic diversity observed among the Campylobacter isolates suggests lack of overlap between isolates from different sources.     

Henneguya corruscans n. sp. (Myxozoa,Myxosporea, Myxobolidae), a parasite of Pseudoplatystoma corruscans (Osteichthyes,Pimelodidae) from the Paraná River,Brazil: A morphological and morphometric study

This paper describes the parasite Henneguya corruscans n. sp. which infects the gills of Pseudoplatystoma corruscans Spix and Agassiz, 1829 found in the Paraná River, Brazil. The parasites belong to the interlamellar-epithelial type as defined by Molnár (2002) [Molnár, K., 2002. Site preference of fish myxosporeans in the gills. Dis. Aquat. Org. 48, 197–207]. The spores examined had thin, smooth walls with symmetric valves; the total length of the spores was 27.6 (25–29) μm. The spore body was ellipsoidal in frontal view and biconvex in lateral view and they measured 14.3 (13–15) μm long by 5 μm wide and 4 μm in thickness. The polar capsules were small and elongated, equally sized, with a rounded posterior extremity and tapering anteriorly, and they corresponded more or less the half the length of the spore body; they were 6.8 (6–7) μm long by 2 μm wide, and the polar filament formed 5–6 coils obliquely to the axis of the polar capsule. The tail was 13.7 (12–15) μm long and bifurcated shortly after the end of the spore body. The importance of the infection for the farming of P. corruscans is discussed.     

Quantitative real-time PCR and culture examination of Mycobacterium avium subsp. paratuberculosis at farm level

Mycobacterium avium subsp. paratuberculosis (MAP) causes Johne's disease in ruminants and may contribute to Crohn's disease in humans. The aim of this study was to determine the occurrence and quantity of MAP in cattle feces and milk in the Iranian context. In addition, we evaluated the effect of cattle age as well as farming system as risk factors contributing to MAP load. For this, a total sample of 373 consisting of 150 cattle feces (CF), 150 individual cow's milk (ICM), as well as 73 bulk-tank milk (BTM) was collected randomly and regardless of the cattle health status. The samples were assayed using F57 quantitative real-time PCR (qPCR) and culture method. According to the results of qPCR which was found ∼10 times more sensitive than culture assay, MAP was detected in 68.66% (103/150) of the CF, 12% (18/150) of the ICM and 52.05% (38/73) of the BTM samples. In contrast to the previous reports, the quantity of MAP in the BTM (2.03–5.97 log cfu/50 ml) was statistically (p < 0.01) higher than the ICM (0.90–1.97 log cfu/50 ml). Data suggested a direct relation (p < 0.01) between the cattle age and the quantity of MAP in the CF samples, while the relation was not statistically significant (p > 0.05) for the ICM. In addition, MAP load in the BTM samples obtained from traditional farms was significantly (p < 0.01) higher than that of the industrial ones, while the differences in CF and ICM was not significant (p > 0.05).     

A longitudinal field trial assesing the impact of feeding waste milk containing antibiotic residues on the prevalence of ESBL-producing Escherichia coli in calves

A longitudinal field trial was carried out on a farm known to harbour cefotaximase (CTX-M)-positive Escherichia coli, in order to assess the impact of feeding waste milk containing antibiotic residues (WM + AR) on the prevalence of these bacteria in the faeces of calves. Fifty calves were alternately assigned to one of two groups at birth and fed either milk replacer (control group) or WM + AR (treatment group). Faecal samples were collected from all calves daily for the first week after enrolment, twice weekly until weaning, then weekly for a further six weeks. Environmental samples from the calf housing were collected weekly. WM + AR and powdered milk samples were examined for antibiotic residues and CTX-M-positive E. coli. Total E. coli and CTX-M-positive E. coli in faecal samples were enumerated using selective media. Regression analyses were performed on the bacterial count data using a population-averaged approach based on generalised estimating equations (GEE) to account for repeated measurements on individual calves over time.     

High seroprevalence of caseous lymphadenitis in Brazilian goat herds revealed by Corynebacterium pseudotuberculosis secreted proteins-based ELISA

We conducted a seroepidemiological survey to determine the prevalence of caseous lymphadenitis (CLA) in goat herds in Minas Gerais state, Brazil. Serum samples were collected from goats (n = 676) from 108 rural properties in 2001, covering most of the sub-regions of this ca. 586,500 square kilometer state. Antibodies against Corynebacterium pseudotuberculosis secreted proteins were detected by an indirect enzyme-linked immunosorbent assay (ELISA). Most of the animals (78.9%) tested positive for CLA; 98% of flocks presented at least one seropositive animal. Goats managed under an extensive production system had a significantly higher seroprevalence of CLA than those in intensive and semi-intensive operations. The age distribution of the animals in the flocks affected the prevalence of this disease; however, goat breed did not. We found seropositivity against C. pseudotuberculosis to be highly prevalent in these Brazilian goat herds; consequently, appropriate management practices for the control of CLA should be implemented.