698 research outputs found
Minimal inhibitory and Mutant prevention concentrations of enrofloxacin for Pasteurella multocida from rabbits affected by pasteurellosis
Pasteurella multocida is the agent of one of the most significant diseases in rabbits and it is associated
with a heterogeneous clinical picture. Drugs belonging to the fluoroquinolones class are useful to
control pasteurellosis. Among them, enrofloxacin is one of the most used molecules in rabbit industry
and it is the only one fluoroquinolone registered for this species in Italy.
Enrofloxacin adopted dosages are currently based on Minimum Inhibitory Concentration (MIC).
Nevertheless, MIC is not effective against possible pathogen sub-populations with lower susceptibility
that may be selectively amplified, leading to possible problems of antibiotic resistance. Mutant
Prevention Concentration (MPC) could represent an approach to minimize the risk of resistance
selection in pathogens. The aim of this work was to test the sensitivity to enrofloxacin of P. multocida
strains isolated from rabbits affected by pasteurellosis to evaluate if MPC-based dosages can represent
a valid option.
The study was performed on ten strains of P. multocida isolated from rabbits from two industrial
farms of Puglia, South Italy. The sensitivity to enrofloxacin has been evaluated by MIC tests by
microdilution method and MPC tests performed according to Marcusson et al. (2005) with minor
modifications.
The results of MIC and MPC tests have revealed that MPC dosages are on average 8,4 times higher
than MIC dosages. This data highlight that, although MPC-based dosages are useful to prevent the
selection of potential mutant, they could be higher than MIC-based ones, leading to possible issues
related to their application in field, for example the potential risk of possible toxicity for animals and
residues in meat
Occurrence of pathogenic and faecal Escherichia coli in layer hens
A total of 117 Escherichia coli from colibacillosis affected (APEC) and clinically healthy birds (AFEC) were serotyped and tested for the presence of virulence genes: iss, tsh, cva. A total of 54.5% E. Coli were typeable and 15 different serogroups were identified. The most common serogroups among APEC strains were O78, O2 and O128, whereas O139 was predominant in faecal strains from healthy birds. Iss, tsh e cva were more frequently detected among the septicaemic E. coli strains. The association of virulence genes was observed. Particularly, the pathotype iss-tsh-cva was present in 46.5% of APEC strains. Referring to serogroups, E. coli O78 and O2 originating from colibacillosis affected birds were always isstsh- cva positive but did not share virulence genes when they came from healthy birds
Efficacy of a novel neem oil formulation (RP03™) to control the poultry red mite Dermanyssus gallinae
Dermanyssus gallinae (Mesostigmata: Dermanyssidae) is the most harmful ectoparasite of laying hens, represents an occupational hazard for poultry workers, and a growing threat to medical science per se. There is increasing demand for alternative products, including plant-derived acaricides, with which to control the mite. The present study investigated the efficacy of neem oil against D. gallinae on a heavily infested commercial laying hen farm. A novel formulation of 20% neem oil, diluted from a 2400-p.p.m. azadirachtin-concentrated stock (RP03â ¢), was administered by nebulization three times in 1week. Using corrugated cardboard traps, mite density was monitored before, during and after treatment and results were statistically analysed. Mite populations in the treated block showed 94.65%, 99.64% and 99.80% reductions after the first, second and third product administrations, respectively. The rate of reduction of the mite population was significantly higher in the treated block (P<0.001) compared with the control and buffer blocks. The results suggest the strong bioactivity of neem, and specifically of the patented neem-based formulation RP03â ¢, against D. gallinae. The treatment was most effective in the 10days following the first application and its effects persisted for over 2months. Further studies will aim to overcome observed side effects of treatment represented by an oily layer on equipment and eggs
Avian Pathogenic Escherichia coli in Audouin gulls (Larus audouinii) Could they affect the surviving of the bird colonies
A total of 39 E. coli strains isolated from cloacal swabs and unhatched eggs of Audouin's gulls (Larus audouinii) living the Salento coast (Italy) were serotyped and molecular characterized for the presence of irp2, fyuA, tsh, papC, fimC, iucD, and eae genes described for Avian Pathogenic E. coli (APEC). Eight different serogroups (O1, 06, 08, 015, 075, 0139, 0146, 0147) were distinguished: we recorded a very high rate of untypeable strains. Genotyping by PCR achieved to detect fimC and irp2, described for APEC strains, as most predominant genes circulating in the gulls population, accounting for 94.87% and 97.43% respectively. Nevertheless, a significant co-existance of virulence genes was demonstrated to belong to E.coli of eggs origin. Particularly, fimC/tsh/iucD pathotype, recognized as most responsible of illness in poultry, emerged in 8.69% of E. coli of eggs origin
Efficacy of λ-cyhalothrin, amitraz, and phoxim against the poultry red mite Dermanyssus gallinae De Geer, 1778 (Mesostigmata: Dermanyssidae): an eight-year survey
Dermanyssus gallinae (De Geer, 1778) is a major problem for the poultry industry worldwide, as it negatively affects virtually all kinds of rearing systems. Therefore, the control of infestation has become a routine process, and its economic cost is constantly increasing. Until now, most of the control strategies have relied on the use of synthetic chemical drugs, but their efficacy is often questioned by the emergence and diffusion of resistant mite populations. With this in mind, the efficacy of λ-cyhalothrin, amitraz, and phoxim has been verified by testing them against 86 mite populations collected from the same number of poultry farms in Italy from 2008 to 2015. Assays were performed according to the filter paper method using the recommended, half, quarter, double and quadruple doses. The results showed that phoxim and amitraz were the most effective acaricides (median efficacies 80.35% and 80.83%, respectively), but amitraz exhibited a sharp fall in its efficacy during 2011 and 2012, while phoxim maintained its high effectiveness up to 2015, when it dropped. The overall median efficacy of λ-cyhalothrin was 58.33%. The data also highlighted the importance of the use of the right concentration, as an increase in dosage was not always useful against resistant populations, while its reduction also diminished efficacy, simultaneously increasing the risk for the development of resistance
A Review on the Marek’s Disease Outbreak and Its Virulence-Related meq Genovariation in Asia between 2011 and 2021
Marek’s disease is an infectious disease in poultry that usually appears in neural and visceral tumors. This disease is caused by Gallid alphaherpesvirus 2 infection in lymphocytes, and its meq gene is commonly used in virulent studies for coding the key protein functional in oncogenic transformation of the lymphocytes. Although vaccines have been introduced in many countries to control its spread and are proven to be efficient, recent records show a decline of such efficiency due to viral evolution. In this study, we reviewed the outbreak of Marek’s disease in Asia for the last 10 years, together with associated meq sequences, finding a total of 36 studies recording outbreaks with 132 viral strains in 12 countries. The visceral type is the most common (13 in 16 studies) form of Marek’s disease, but additional unobserved neural changes may exist. MD induces liver lymphoma most frequently (11 in 14 studies), and tumors were also found in spleen, kidney, heart, gizzard, skin, intestine, lung, and sciatic nerve. Twelve viral strains distributed in China have been reported to escape the CVI988 vaccine, reaching a mortality rate of more than 30%. Phylogenetic analyses show the internal connection between the Middle East (Turkey, Iraq, Iran, Saudi Arabia), South Asia (India, Indonesia), and East Asia (China and Japan), while external viral communications might occasionally occur. In 18 strains with both sequential and mortality data, amino acid alignment showed several point substitutions that may be related to its virulence. We suggest more behavioral monitoring in Marek’s disease-endemic regions and further studies on strain virulence, together with its Meq protein structural changes
The Cosmic-Ray Proton and Helium Spectra measured with the CAPRICE98 balloon experiment
A new measurement of the primary cosmic-ray proton and helium fluxes from 3
to 350 GeV was carried out by the balloon-borne CAPRICE experiment in 1998.
This experimental setup combines different detector techniques and has
excellent particle discrimination capabilities allowing clear particle
identification. Our experiment has the capability to determine accurately
detector selection efficiencies and systematic errors associated with them.
Furthermore, it can check for the first time the energy determined by the
magnet spectrometer by using the Cherenkov angle measured by the RICH detector
well above 20 GeV/n. The analysis of the primary proton and helium components
is described here and the results are compared with other recent measurements
using other magnet spectrometers. The observed energy spectra at the top of the
atmosphere can be represented by (1.27+-0.09)x10^4 E^(-2.75+-0.02) particles
(m^2 GeV sr s)^-1, where E is the kinetic energy, for protons between 20 and
350 GeV and (4.8+-0.8)x10^2 E^(-2.67+-0.06) particles (m^2 GeV nucleon^-1 sr
s)^-1, where E is the kinetic energy per nucleon, for helium nuclei between 15
and 150 GeV nucleon^-1.Comment: To be published on Astroparticle Physics (44 pages, 13 figures, 5
tables
Guaranteed and Prospective Galactic TeV Neutrino Sources
Recent observations, particularly from the HESS Collaboration, have revealed
rich Galactic populations of TeV gamma-ray sources, including a collection
unseen in other wavelengths. Many of these gamma-ray spectra are well measured
up to ~10 TeV, where low statistics make observations by air Cerenkov
telescopes difficult. To understand these mysterious sources, especially at
much higher energies--where a cutoff should eventually appear--new techniques
are needed. We point out the following: (1) For a number of sources, it is very
likely that pions, and hence TeV neutrinos, are produced; (2) As a general
point, neutrinos should be a better probe of the highest energies than gamma
rays, due to increasing detector efficiency; and (3) For several specific
sources, the detection prospects for km^3 neutrino telescopes are very good,
about 1-10 events/year, with low atmospheric neutrino background rates above
reasonable energy thresholds. Such signal rates, as small as they may seem,
will allow neutrino telescopes to powerfully discriminate between models for
the Galactic TeV sources, with important consequences for our understanding of
cosmic-ray production.Comment: 12 pages, 5 figures; minor changes to match published versio
Measurement of the flux of atmospheric muons with the CAPRICE94 apparatus
A new measurement of the momentum spectra of both positive and negative muons
as function of atmospheric depth was made by the balloon-borne experiment
CAPRICE94. The data were collected during ground runs in Lynn Lake on the
19-20th of July 1994 and during the balloon flight on the 8-9th of August 1994.
We present results that cover the momentum intervals 0.3-40 GeV/c for negative
muons and 0.3-2 GeV/c for positive muons, for atmospheric depths from 3.3 to
1000 g/cm**2, respectively. Good agreement is found with previous measurements
for high momenta, while at momenta below 1 GeV/c we find latitude dependent
geomagnetic effects. These measurements are important cross-checks for the
simulations carried out to calculate the atmospheric neutrino fluxes and to
understand the observed atmospheric neutrino anomaly.Comment: 28 pages, 13 Postscript figures, uses revtex.sty, to appear in Phys.
Rev.
NEMO: A Project for a km Underwater Detector for Astrophysical Neutrinos in the Mediterranean Sea
The status of the project is described: the activity on long term
characterization of water optical and oceanographic parameters at the Capo
Passero site candidate for the Mediterranean km neutrino telescope; the
feasibility study; the physics performances and underwater technology for the
km; the activity on NEMO Phase 1, a technological demonstrator that has
been deployed at 2000 m depth 25 km offshore Catania; the realization of an
underwater infrastructure at 3500 m depth at the candidate site (NEMO Phase 2).Comment: Proceeding of ISCRA 2006, Erice 20-27 June 200
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