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1.
J Vet Med Educ ; 42(3): 217-31, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26200701

RESUMO

Client or service user perspectives are important when designing curricula for professional programs. In the case of veterinary technology, an emerging profession in the veterinary field in Australasia, client views on desirable graduate attributes, skills, and knowledge have not yet been explored. This study reports on a survey of 441 veterinary clients (with 104 responses) from four veterinary practices in Brisbane, Queensland, conducted between October 2008 and February 2009. The included veterinary practices provided clinical placements for veterinary technology undergraduates and employment for veterinary technology graduates (2003-2007). Client socio-demographic data along with ratings of the importance of a range of technical (veterinary nursing) skills, emotional intelligence, and professional attributes for veterinary technology graduates were collected and analyzed. Overall, the majority of clients viewed technical skills, emotional intelligence, and professional attributes as important in the clinical practice of veterinary technology graduates with whom they interacted in the veterinary practice. Client interviews (n=3) contextualized the survey data and also showed that clients attached importance to graduates demonstrating professional competence. Agglomerative hierarchical cluster analysis revealed four distinct groupings of clients within the data based on their differing perceptions. Using a multivariable proportional-odds regression model, it was also found that some client differences were influenced by demographic factors such as gender, age, and number of visits annually. For example, the odds of female clients valuing emotionality and sociability were greater than males. These findings provide useful data for the design of a professionalizing and market-driven veterinary technology curriculum.


Assuntos
Técnicos em Manejo de Animais , Competência Clínica , Relações Interpessoais , Pacientes , Adulto , Idoso , Idoso de 80 Anos ou mais , Currículo , Educação em Veterinária , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Desenvolvimento de Programas , Queensland , Inquéritos e Questionários
2.
Parasit Vectors ; 16(1): 63, 2023 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-36765417

RESUMO

BACKGROUND: The prevalence of Dirofilaria immitis infection in dogs is increasing globally and spreading into new areas. Prevalence of dirofilariosis in the state of Queensland, Australia, was as high as 90% before the introduction of macrocyclic lactones. Limited research on prevalence of D. immitis infection in dogs in Queensland has been reported in the last 30 years. Antigen testing is the most common method for detection of dirofilariosis but its accuracy is reduced by antigen getting trapped (blocked antigen) in immune complexes (ICs). The objectives of this research were to determine the prevalence of D. immitis infection in dogs from two geographical areas (Brisbane and Townsville) in Queensland, to determine the extent to which blocked antigen affects the validity of antigen testing, and to explore whether this was associated with microfilaraemia, location, age or sex. METHODS: Blood samples from Brisbane (sub-tropical climate) and Townsville (tropical climate) shelter dogs were evaluated for the presence of D. immitis antigen before (conventional antigen testing, CAT) and after dissociation of ICs by heat treatment (antigen testing after heat treatment, ATHT), using a commercially available test. Microfilariae were detected using modified Knott's test (MKT). Test proportions were compared with McNemar's test and the association between antigen test-discordant results (positive for antigen after dissociation of ICs) and microfilaraemia, location, sex and age was modelled using logistic regression. RESULTS: Dirofilaria immitis prevalence in dogs from Townsville (22% by CAT, 32.1% by ATHT and 16.7% by MKT) was significantly higher than in dogs from Brisbane (1.1% by CAT and MKT and 1.7% by ATHT) [Formula: see text]. Dissociation of ICs allowed detection of significantly more D. immitis infected dogs than either conventional antigen testing or microfilariae detection, or the combined antigen and microfilariae detection [Formula: see text]. The odds of dogs being positive for antigen after dissociation of ICs were significantly higher for microfilaraemic, 3-4-year-old female dogs from Townsville. CONCLUSIONS: The high prevalence of infection with D. immitis in dogs from Townsville poses a health risk for local susceptible host species, including humans. Dissociation of ICs increases antigen detection and should be considered in dogs suspected of D. immitis infection but negative on routine testing.


Assuntos
Dirofilaria immitis , Dirofilariose , Doenças do Cão , Feminino , Humanos , Cães , Animais , Pré-Escolar , Queensland/epidemiologia , Prevalência , Doenças do Cão/diagnóstico , Doenças do Cão/epidemiologia , Dirofilariose/diagnóstico , Dirofilariose/epidemiologia , Austrália/epidemiologia , Antígenos de Helmintos , Microfilárias , Complexo Antígeno-Anticorpo
3.
J Vet Med Educ ; 39(3): 263-6, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22951461

RESUMO

Role models incite admiration and provide inspiration, contributing to learning as students aspire to emulate their example. The attributes of physician role models for medical trainees are well documented, but they remain largely unexplored in the context of veterinary medical training. The aim of the current study was to describe the attributes that final-year veterinary students (N=213) at the University of Queensland identified when reflecting on their clinical role models. Clinical role model descriptions provided by students were analyzed using concept-mapping software (Leximancer v. 2.25). The most frequent and highly connected concepts used by students when describing their role model(s) included clients, vet, and animal. Role models were described as good communicators who were skilled at managing relationships with clients, patients, and staff. They had exemplary knowledge, skills, and abilities, and they were methodical and conducted well-structured consultations. They were well respected and, in turn, demonstrated respect for clients, colleagues, staff, and students alike. They were also good teachers and able to tailor explanations to suit both clients and students. Findings from this study may serve to assist with faculty development and as a basis for further research in this area.


Assuntos
Comunicação , Educação em Veterinária , Mentores , Estudantes de Ciências da Saúde , Austrália , Competência Clínica , Humanos
4.
J Vet Med Educ ; 38(3): 251-61, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22023977

RESUMO

The present study evaluated the impact of final-year clinical practice-based training on veterinary students' perceptions of competence in "Day One" abilities by administering a pre- and post-training self-assessment checklist. This study also investigated the influence of student demographics on their perceptions of satisfaction about their own knowledge and skills and preparedness for practice. Perceptions regarding the usefulness of the checklist as a self-audit tool were also sought. Final year students (N=85) were surveyed on commencement and upon completion of the training using a checklist that had been adapted from the list of essential new-graduate abilities that was developed by the Royal College of Veterinary Surgeons and adopted by the Australasian Veterinary Boards Council. Significant improvements in student perceptions of competence were observed for 38 of the 41 abilities. Students' satisfaction with their knowledge and skill base and their perceptions of preparedness for practice were only weakly correlated with overall perceptions of competence for individual ability items and did not vary significantly with student age, gender, background, intended field and location of work, or with their work experience as veterinary nurses-if any-while studying. Two thirds of students believed that access to the self-assessment checklist on commencement of the training helped them identify areas for improvement before graduation. This article concludes that clinical practice-based training results in considerable improvement in senior veterinary students' perceptions of competence in Day One abilities and that a self-assessment checklist may help students guide their learning. Results from the present study may be useful for veterinary schools as they develop or enhance strategies used for outcomes assessment.


Assuntos
Atitude , Competência Clínica , Educação em Veterinária/normas , Avaliação Educacional , Humanos , Queensland , Estudantes de Medicina
5.
J Vet Med Educ ; 36(2): 241-5, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19625675

RESUMO

This article provides a descriptive analysis of the demographics and employment destinations of the first three cohorts (2003-2005) of graduates (N=69) from a program that is unique in Australia: the Bachelor of Applied Science (Veterinary Technology) at the University of Queensland. Data for this study were collected in February 2006 via e-mail, telephone, or personal communication with graduates, and from university records. Ninety-three percent (64/69) of the graduates were female. The mean age was 23 years, and 58% (40/69) had entered university directly from high school. Employment destinations were determined for 96% of the graduates (N=66). Of those, 52% (34/66) were employed in veterinary practices. Government agencies and allied animal industries accounted for 15% (10/66). Another 14% (9/66) had enrolled in further undergraduate study. Three percent (2/66) had enrolled in a research honors year or a doctor of philosophy (PhD) degree program at the School of Veterinary Science. Eight percent (5/66) were employed in wildlife parks, zoos, or universities, and the remaining 9% (6/66) were traveling overseas, seeking employment, or employed outside the field. The study revealed that graduates were employed in diverse veterinary and allied animal health occupations. There appears to be a niche for Australian veterinary technology graduates educated in a university environment that complements the role of the veterinary profession in the twenty-first century. This reflects trends emerging in other countries, most notably the United States and the United Kingdom.


Assuntos
Técnicos em Manejo de Animais/estatística & dados numéricos , Emprego/estatística & dados numéricos , Estudantes de Ciências da Saúde/estatística & dados numéricos , Adulto , Técnicos em Manejo de Animais/educação , Estudos de Coortes , Demografia , Emprego/classificação , Feminino , Humanos , Masculino , Queensland , Universidades , Adulto Jovem
6.
Antimicrob Agents Chemother ; 52(11): 3980-6, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18710918

RESUMO

The anthelmintic pyrantel plays an important role in the control of gastrointestinal helminths of humans and domestic animals. Despite the demonstration of pyrantel resistance in several helminth species over the last 20 years, the resistance mechanism remains unclear. It has been hypothesized that resistance may arise as a consequence of changes to the relative proportions of subpopulations of nicotinic acetylcholine receptors (nAchRs). To test this hypothesis, we examined the responses of two isolates of the canine hookworm Ancylostoma caninum with low-level resistance (isolate NT) and high-level resistance (isolate PR) to pyrantel to nicotinic agonist drugs reported to be selective for three nAchR subtypes. We used larval motility and conformation assays and force transduction experiments with adult worms. Pyrantel and levamisole were less potent against larvae of isolate PR than larvae of isolate NT (up to an 18-fold increase in the 50% inhibitory concentration); on the other hand, bephenium was more potent against larvae of isolate PR than larvae of isolate NT (twofold) and nicotine had the same potency against larvae of both isolates. In adults, pyrantel, levamisole, and nicotine were less potent against isolate PR than isolate NT (two- to threefold), but the potency of bephenium against the two isolates was equivalent. Our data indicate a complex pattern of nAchRs in this species and suggest that the two isolates differ in their relative sensitivities to agonists targeting different nAchRs.


Assuntos
Ancylostoma/efeitos dos fármacos , Antinematódeos/farmacologia , Pirantel/farmacologia , Ancylostoma/isolamento & purificação , Ancylostoma/metabolismo , Ancilostomíase/tratamento farmacológico , Ancilostomíase/parasitologia , Animais , Compostos de Befênio/farmacologia , Cães , Resistência a Medicamentos , Feminino , Humanos , Larva/efeitos dos fármacos , Levamisol/farmacologia , Nicotina/farmacologia , Agonistas Nicotínicos/farmacologia , Fenótipo , Receptores Nicotínicos/classificação , Receptores Nicotínicos/efeitos dos fármacos , Receptores Nicotínicos/metabolismo
7.
Vet Parasitol ; 152(3-4): 284-93, 2008 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-18242867

RESUMO

Resistance of the canine hookworm Ancylostoma caninum to anthelmintic therapy with pyrantel is an emerging problem in canine veterinary practice. Detecting anthelmintic resistance in parasites of pets is problematic because traditional resistance-monitoring techniques used with livestock parasites, such as the faecal egg count reduction test, are often impractical for use in small animals. We used two field-collected isolates of A. caninum in an abbreviated critical trial to test their pyrantel resistance status. The strains showed high-level and low-level resistance, with in vivo pyrantel efficacies of 28% and 71%, respectively. We noted a distinct worm density dependence effect on faecal egg count during the critical trial; egg counts in the dogs containing the low-level resistant isolate were 41% higher 6 days after drug treatment, despite the removal of 71% of the adult worms by the drug treatment. We then assessed four candidate in vitro assays for their ability to detect pyrantel resistance in A. caninum larvae, using these two isolates. The assays included a new format termed the larval arrested morphology assay (LAMA), based on observation of the effects of pyrantel on the body shape adopted by infective stage A. caninum larvae in vitro. Our data suggests that three of these assays, the LAMA, the larval motility assay (LMA), and larval feeding inhibition assay (LFIA) show promise with regards to detection of pyrantel resistance in A. caninum, but the complexity of the LFIA would likely limit its suitability for field studies. In vivo pyrantel efficacies of 28% and 71% in the two A. caninum isolates were associated with a 17-fold shift in the in vitro IC(50) values measured using the LAMA. Further testing with isolates of varying degrees of resistance is required to determine which of these assays is suitable as a rapid in vitro laboratory test for pyrantel resistance in A. caninum. The present study also indicates that potential exists for the novel LAMA or the LMA to be of use in detecting pyrantel resistance in the human hookworms, Necator americanus and Ancylostoma duodenale.


Assuntos
Ancylostoma/efeitos dos fármacos , Ancilostomíase/veterinária , Anti-Helmínticos/farmacologia , Doenças do Cão/tratamento farmacológico , Resistência a Medicamentos , Pirantel/farmacologia , Ancilostomíase/tratamento farmacológico , Animais , Cães , Relação Dose-Resposta a Droga , Fezes/parasitologia , Larva/efeitos dos fármacos , Contagem de Ovos de Parasitas/veterinária , Testes de Sensibilidade Parasitária/veterinária , Resultado do Tratamento
8.
Vet J ; 178(2): 177-84, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17720556

RESUMO

Pyrantel, a tetrahydropyrimidine nicotinic agonist anthelmintic, has been used in companion animal medicine since the 1970s to control two important nematode groups, the hookworms and the roundworms. Given the zoonotic potential of these parasites, pyrantel has served a dual role in helping to protect the health of both companion animals and the public for more than 30 years. This review describes the history and mechanism of action of this drug, and collates evidence that resistance to pyrantel has developed in at least one canine nematode, the hookworm Ancylostoma caninum. The role of in vitro diagnosis tests in managing anthelmintic resistance in companion animal parasites is discussed, as are management practices that may reduce the rate at which resistance develops.


Assuntos
Antinematódeos/uso terapêutico , Doenças do Gato/tratamento farmacológico , Doenças do Gato/parasitologia , Doenças do Cão/tratamento farmacológico , Doenças do Cão/parasitologia , Infecções por Nematoides/veterinária , Pirantel/uso terapêutico , Animais , Gatos , Cães , Nematoides/crescimento & desenvolvimento , Infecções por Nematoides/tratamento farmacológico , Infecções por Nematoides/parasitologia
9.
J Wildl Dis ; 44(2): 295-303, 2008 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18436662

RESUMO

In Australia the brush-tailed rock-wallaby (Petrogale penicillata) is the subject of a national recovery plan, and several sites have been selected for reintroductions. Condition of wild populations and individual animals can be monitored using hematologic and serum biochemistry analytes, and hematologic variables have been correlated with postrelease survival in other species. Prior to such monitoring, reference values for blood variables are required, but these data have not been available for the brush-tailed rock-wallaby. During four trapping periods from November 2004 to August 2005, 116 blood samples were collected from 44 brush-tailed rock-wallabies in a wild colony in southeast Queensland. Some variables varied with sex, age, method of restraint, lactation demands, and trapping period. After partitioning, when required, reference ranges for hematology and serum biochemistry variables were established. This study provides the most comprehensive serum biochemistry reference range for any macropodid marsupial yet published.


Assuntos
Análise Química do Sangue/veterinária , Testes Hematológicos/veterinária , Macropodidae/sangue , Animais , Animais Selvagens/sangue , Feminino , Masculino , Queensland , Valores de Referência
10.
J Wildl Dis ; 44(4): 1036-40, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18957664

RESUMO

This study examined the suitability of immunoblot assays using antigen B from hydatid cyst fluid (HCF) and the recombinant protein EpC1 to estimate the prevalence of hydatid infection in threatened small macropodid populations. When HCF antigen B was used on sera from 29 wild eastern grey kangaroos (Macropus giganteus) examined for the presence of hydatid cysts at necropsy (17 positive and 12 negative), and from five captive-bred macropodids, the sensitivity and specificity were 88% and 41%, respectively. Following optimization, the use of rEpC1 on sera from 51 wild eastern grey kangaroos (48 positive and 3 negative at necropsy), and from 9 captive bred macropodids, resulted in sensitivity and specificity of 48% and 92% respectively.


Assuntos
Equinococose/veterinária , Immunoblotting/veterinária , Macropodidae/parasitologia , Animais , Animais Selvagens/parasitologia , Animais de Zoológico/parasitologia , Equinococose/diagnóstico , Feminino , Immunoblotting/métodos , Masculino , Sensibilidade e Especificidade
11.
Int J Parasitol ; 37(8-9): 943-52, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17362963

RESUMO

The introduced parasite, Echinococcus granulosus, has been reported in numerous macropodid species in various areas of Australia, but no extensive studies investigating the prevalence and risk factors for infection in wild macropodids have been reported. In this study, 2998 macropodid carcasses were examined following commercial culling on 21 properties in southern Queensland. Of the 71 infected animals, all had cysts in the lung tissue, while two also had cysts in the pleural cavity and one animal had a liver cyst. The number of cysts in infected animals ranged from 1 to 17, with the majority of animals (n=64) having one to three cysts. Estimated total cyst volume varied from 0.2 to 1075 cm3. Some animals had a total lung cyst volume likely to have impacted significantly upon respiratory function and cyst degeneration was only seen in approximately one-third of infected animals. Multilevel models were used to investigate putative risk factors at both kangaroo and property levels. At the kangaroo level, females were twice as likely to be infected as males. After adjusting for sex, no property-level risk factors were significantly associated with the presence of hydatid infection. Prevalence varied substantially between properties (range 0-12%) and this high degree of clustering of infection was reflected in a high intra-class correlation co-efficient in the final model (0.333). These results have important implications for both public health and conservation strategies, and suggest that there are important unidentified risk factors for hydatid infection associated with properties. They also demonstrate that spatial clustering should be considered when analysing hydatid infection data in macropodids, particularly when assessing area-level risk factors.


Assuntos
Equinococose/veterinária , Echinococcus granulosus/fisiologia , Macropodidae , Agricultura , Animais , Análise por Conglomerados , Equinococose/epidemiologia , Feminino , Masculino , Prevalência , Queensland/epidemiologia , Fatores de Risco
12.
Int J Parasitol ; 37(12): 1379-89, 2007 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17599844

RESUMO

This study describes the pathological changes associated with an experimental infection of captive wallabies with Echinococcus granulosus. Adult and juvenile tammar wallabies (Macropus eugenii) were infected orally with 0, 1,000, 2,500 or 8,000 E. granulosus eggs. Lung cyst progression was monitored by chest radiography every 4 months until 16 months p.i. Animals were necropsied from 9 to 16 months after infection. Cysts were detected radiographically from 4 months onwards. The number of cysts per animal varied from one to 10 and the majority (36/40) of cysts established in the lungs. Infection rate was low (35.5%), but cyst development was more rapid and onset of fertility much earlier than has been recorded in sheep. Cyst growth resulted in loss of functional lung capacity, up to an estimated 28% within 14 months of infection. Degenerative changes in cysts were less common in tammars than has been reported in sheep, with gross degeneration of cysts identified in only two animals. Complications associated with lung cyst development included fatal anaphylaxis, pneumothorax and atelectasis. Seven of the 11 infected tammars died or were euthanased as a result of infection during the experiment. From the parasite's perspective, infection of this host allows a shortened life cycle and correspondingly greater biotic potential. We believe this is the first published study that demonstrates the susceptibility of tammar wallabies to hydatid disease and confirms their suitability as a laboratory model for studying the disease in macropodids.


Assuntos
Equinococose/patologia , Echinococcus granulosus/parasitologia , Macropodidae/parasitologia , Ovinos/parasitologia , Animais , Austrália , Equinococose/veterinária , Feminino , Masculino , Análise de Regressão
13.
Vet Parasitol ; 143(3-4): 299-304, 2007 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-17011128

RESUMO

While anthelmintic resistance is now a widely recognized issue in the livestock industries, its existence within companion animal medicine has been rarely established conclusively. We undertook a placebo-controlled in vivo trial to measure the efficacy of pyrantel embonate against pooled isolates of the hookworm Ancylostoma caninum from Brisbane, Australia. A statistically significant fall in adult worm burden was observed among dogs in the pyrantel treatment group compared to the control dogs (178.0+/-24.5 versus 239.7+/-14.0; p=0.02), equating to an efficacy of just 25.7% (95% CI, 15.0-35.1%), as based upon reduction in mean worm burden. Analysis of faecal egg count trends through the course of the study revealed that egg counts rose in both control and pyrantel-treated dogs, with a greater rise observed in the latter group (11.6+/-8.3% versus 17.3+/-7.6%; p=0.04), despite the decrease in adult worm numbers in this group. Our results indicate that high-level anthelmintic resistance does occur in companion animal medicine, and highlight the need for greater vigilance and more judicious use of anthelmintics in small animal practice. They further indicate that the faecal egg count reduction test needs to be used with caution with this parasite.


Assuntos
Ancylostoma/efeitos dos fármacos , Ancilostomíase/veterinária , Antinematódeos/uso terapêutico , Doenças do Cão/tratamento farmacológico , Resistência a Medicamentos , Pirantel/uso terapêutico , Ancilostomíase/tratamento farmacológico , Animais , Cães , Fezes/parasitologia , Feminino , Masculino , Contagem de Ovos de Parasitas/veterinária , Testes de Sensibilidade Parasitária/veterinária , Distribuição Aleatória , Resultado do Tratamento
14.
J Vet Med Educ ; 34(5): 542-9, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-18326761

RESUMO

Students in animal science and veterinary science at the University of Queensland (UQ) have similar introductory courses in animal handling in year 1 of their degree programs. Veterinary students take animal-handling instruction in farm and companion animals, whereas animal science students are instructed in handling farm animals, horses, and rodents. Veterinary students are introduced to rodents, and animal science students to dogs and cats, in subsequent years of the curriculum. Both cohorts receive additional training, with clinical emphasis for veterinary students in years 3, 4, and 5 of their five-year curriculum. The introductory course is well received by students; both student cohorts appreciate the opportunity provided and the effort that goes into the animal-handling classes. Undergraduates realize that acquiring animal-handling skills will increase their proficiency in their subsequent careers; veterinary graduates recognize that their handling prowess will give their clients confidence in their abilities. Most clients cannot judge the competence of a veterinarian's diagnosis or treatment but will judge their ability based on their handling skills. Ongoing practice allows students to become competent in animal handling.


Assuntos
Criação de Animais Domésticos/educação , Criação de Animais Domésticos/métodos , Competência Clínica , Educação em Veterinária , Medicina Veterinária/métodos , Animais , Animais Domésticos , Currículo , Humanos , Queensland , Ensino , Universidades
15.
Vet Parasitol ; 211(1-2): 45-53, 2015 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-25983232

RESUMO

There is some evidence that resistance to levamisole and pyrantel in trichostrongylid nematodes is due to changes in the composition of nicotinic acetylcholine receptors (nAChRs) which represent the drug target site. Altered expression patterns of genes coding for nAChR subunits, as well as the presence of truncated versions of several subunits, have been implicated in observed resistances. The studies have mostly compared target sites in worm isolates of very different genetic background, and hence the ability to associate the molecular changes with drug sensitivity alone have been clouded to some extent. The present study aimed to circumvent this issue by following target site gene expression pattern changes as resistance developed in Haemonchus contortus worms under laboratory selection pressure with levamisole. We applied drug selection pressure to early stage larvae in vitro over nine generations, and monitored changes in larval and adult drug sensitivities and target site gene expression patterns. High level resistance developed in larvae, with resistance factors of 94-fold and 1350-fold at the IC50 and IC95, respectively, in larval development assays after nine generations of selection. There was some cross-resistance to bephenium (70-fold increase in IC95). The expression of all the putative subunit components of levamisole-sensitive nAChRs, as well as a number of ancillary protein genes, particularly Hco-unc-29.1 and -ric-3, were significantly decreased (up to 5.5-fold) in the resistant larvae at generation nine compared to the starting population. However, adult worms did not show any resistance to levamisole, and showed an inverse pattern of gene expression changes, with many target site genes showing increased expression compared to the starting population. A comparison of the larval/adult drug sensitivity data with the known relationships for field-derived isolates indicated that the adults of our selected population should have been highly resistant to the drug if the larval/adult sensitivity relationships were in accordance with previous field isolates. Hence, our selected worms showed a life-stage drug sensitivity pattern quite different to that seen in the field. The present study has highlighted an association between drug target site changes and resistance to levamisole in H. contortus larvae. However, it has also highlighted the artificial nature of the larval selection method with levamisole, as the resistance phenotype and the associated molecular changes were only observed in the drug-pressured life stage. The study therefore reinforces the need for caution in extrapolating larval-based laboratory selection outcomes to field resistances.


Assuntos
Antinematódeos/farmacologia , Hemoncose/parasitologia , Haemonchus/efeitos dos fármacos , Larva/efeitos dos fármacos , Levamisol/farmacologia , Doenças dos Ovinos/parasitologia , Animais , Resistência a Medicamentos , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Haemonchus/genética , Proteínas de Helminto/genética , Masculino , Pirantel/farmacologia , Ovinos
16.
Int J Parasitol Drugs Drug Resist ; 4(2): 77-84, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25057457

RESUMO

While there is some evidence that changes in nicotinic acetylcholine receptor (nAChR) subunits confer resistance to levamisole in gastrointestinal helminth parasites, the exact nature of the resistance mechanism(s) is unclear. We utilised the presence of a resistant fraction within the Wallangra 2003 isolate of Haemonchus contortus larvae in order to subdivide the population into three subpopulations of larvae able to survive increasing concentrations of the drug. We then measured gene expression levels in the subpopulations and the larval population as a whole, focusing on genes encoding the subunit components of levamisole-sensitive receptors, genes encoding ancillary proteins involved in receptor assembly, and P-glycoprotein (P-gp) genes. The subpopulation surviving the lowest levamisole concentration showed increases of 1.5- to 3-fold in a number of P-gp genes (Hco-pgp-3, -4, -10, and -14) alongside unchanged receptor genes, compared to the whole Wallangra larval population. On the other hand, the subpopulation surviving the intermediate levamisole concentration showed an increase in only a single P-gp (Hco-pgp-14), alongside decreases in some receptor subunit (Hco-unc-63a) and ancillary protein genes (Hco-unc-50, Hco-ric-3.1 and 3.1). The subpopulation surviving the highest levamisole concentration showed further decreases in receptor subunit genes (Hco-unc-63a and Hco-unc-29 paralogs) as well as genes involved in receptor assembly (Hco-unc-74, Hco-unc-50, Hco-ric-3.1 and 3.1), alongside no increased P-gp gene levels. This suggests a biphasic pattern of drug resistance in the larvae of this worm isolate, in which a non-specific P-gp-mediated mechanism confers low levels of resistance, while higher level resistance is due to altered receptor subunit composition as a result of changes in both subunit composition and in the levels of proteins involved in receptor assembly.

17.
Artigo em Inglês | MEDLINE | ID: mdl-24533293

RESUMO

The mechanism of resistance to the anthelmintic levamisole in parasitic nematodes is poorly understood, although there is some evidence implicating changes in expression of nicotinic acetylcholine receptor (nAChR) subunit genes. Hence, in order to define levamisole resistance mechanisms in some Australian field-derived isolates of Haemonchus contortus we examined gene expression patterns and SNPs in nAChR subunit genes, as well as expression levels for P-glycoprotein (P-gp) and receptor ancillary protein genes, in various life stages of one levamisole-sensitive and three levamisole-resistant isolates of this species. Larvae of two isolates showed high-level resistance to levamisole (resistance ratios at the IC50 > 600) while the third isolate showed a degree of heterogeneity, with a resistance factor of only 1.1-fold at the IC50 alongside the presence of a resistant subpopulation. Transcription patterns for nAChR subunit genes showed a great degree of variability across the different life stages and isolates. The most consistent observation was the down-regulation of Hco-unc-63a in adults of all resistant isolates. Transcription of this gene was also reduced in the L3 stage of the two most resistant isolates, highlighting its potential as a resistance marker in the readily accessible free-living stages. There was down regulation of all four Hco-unc-29 paralogs in adults of one resistant isolate. There were no consistent changes in expression of P-gps or ancillary protein genes across the resistant isolates. The present study has demonstrated a complex pattern of nAChR subunit gene expression in H. contortus, and has highlighted several instances where reduced expression of subunit genes (Hco-unc-63a, Hco-unc-29) may be associated with the observed levamisole resistance. The data also suggests that it will be difficult to detect resistance using gene transcription-based methods on pooled larval samples from isolates containing only a resistant subpopulation due to the averaging of gene expression data across the whole population.

18.
Artigo em Inglês | MEDLINE | ID: mdl-24533269

RESUMO

While the F200Y SNP in the beta-tubulin gene is most commonly associated with benzimidazole resistance in trichostrongylid nematodes, other SNPs as well as drug efflux pathways have been implicated in the resistance. The relative contributions of all these mechanisms are not understood sufficiently to allow expected drug efficacy to be inferred from molecular data. As a component of developing better means to interpret molecular resistance tests, the present study utilised a drug resistant Haemonchus contortus isolate which possesses two of the principal benzimidazole resistance SNPs (E198A and F200Y) in order to assess the relative degree of resistance conferred by the two SNPs. We exposed larvae to a range of thiabendazole concentrations in in vitro development assays, and collected the surviving L3 larvae at each drug concentration to establish sub-populations showing increasing levels of resistance. We then sequenced the isotype 1 beta-tubulin gene in pooled larval samples, and measured allele frequencies at the two SNP positions. The frequency of the resistance allele at the 198 position increased as the thiabendazole concentration increased, while the frequency of the resistance allele at the 200 position decreased. Genotyping of individual larvae showed that the highest drug concentration was associated with the removal of all genotypes except for homozygous resistance at the 198 position alongside homozygous susceptible at the 200 position. This indicates that, at least for larval life stages, the E198A SNP is able to confer higher levels of resistance to benzimidazole drugs than the F200Y SNP, and that the homozygosity at 198 in the highly resistant individuals is mutually exclusive with heterozygosity or resistant homozygosity at the 200 position. This study illustrates the need to understand the relative contributions of different resistance mechanisms in order to maximise the degree to which molecular tests are able to inform on drug resistance phenotype.

19.
Parasit Vectors ; 4: 141, 2011 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-21771313

RESUMO

BACKGROUND: There are few published reports on canine Babesia, Ehrlichia, Anaplasma, Hepatozoon and haemotropic Mycoplasma infections in India and most describe clinical disease in individual dogs, diagnosed by morphological observation of the microorganisms in stained blood smears. This study investigated the occurrence and distribution of canine tick-borne disease (TBD) pathogens using a combination of conventional and molecular diagnostic techniques in four cities in India. RESULTS: On microscopy examination, only Hepatozoon gamonts were observed in twelve out of 525 (2.3%; 95% CI: 1.2, 4) blood smears. Using polymerase chain reaction (PCR), a total of 261 from 525 dogs (49.7%; 95% CI: 45.4, 54.1) in this study were infected with one or more canine tick-borne pathogen. Hepatozoon canis (30%; 95% CI: 26.0, 34.0) was the most common TBD pathogen found infecting dogs in India followed by Ehrlichia canis (20.6%; 95% CI: 17.2, 24.3), Mycoplasma haemocanis (12.2%; 95% CI: 9.5, 15.3), Anaplasma platys (6.5%; 95% CI: 4.5, 8.9), Babesia vogeli (5.5%, 95% CI: 3.7, 7.8) and Babesia gibsoni (0.2%, 95% CI: 0.01, 1.06). Concurrent infection with more than one TBD pathogen occurred in 39% of cases. Potential tick vectors, Rhipicephalus (most commonly) and/or Haemaphysalis ticks were found on 278 (53%) of dogs examined. CONCLUSIONS: At least 6 species of canine tick-borne pathogens are present in India. Hepatozoon canis was the most common pathogen and ticks belonging to the genus Rhipicephalus were encountered most frequently. Polymerase chain reaction was more sensitive in detecting circulating pathogens compared with peripheral blood smear examination. As co-infections with canine TBD pathogens were common, Indian veterinary practitioners should be cognisant that the discovery of one such pathogen raises the potential for multiple infections which may warrant different clinical management strategies.


Assuntos
Infecções Bacterianas/veterinária , Doenças do Cão/epidemiologia , Infecções Protozoárias em Animais/epidemiologia , Doenças Transmitidas por Carrapatos/veterinária , Animais , Infecções Bacterianas/epidemiologia , Sangue/microbiologia , Sangue/parasitologia , Cães , Feminino , Índia/epidemiologia , Masculino , Reação em Cadeia da Polimerase , Doenças Transmitidas por Carrapatos/epidemiologia
20.
Parasit Vectors ; 4: 143, 2011 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-21781294

RESUMO

BACKGROUND: Hippobosca longipennis (the 'dog louse fly') is a blood sucking ectoparasite found on wild carnivores such as cheetahs and lions and domesticated and feral dogs in Africa, the Middle East and Asia, including China. Known as an intermediate host for Acanthocheilonema dracunculoides and a transport host for Cheyletiella yasguri, it has also been suggested that H. longipennis may be a vector for other pathogens, including Acanthocheilonema sp.? nov., which was recently reported to infect up to 48% of dogs in northern India where this species of fly is known to commonly infest dogs. To test this hypothesis, hippoboscid flies feeding on dogs in Ladakh in northern India were collected and subjected to microscopic dissection. RESULTS: A total of 12 infective larvae were found in 10 out of 65 flies dissected; 9 from the head, 2 from the thorax and 1 from the abdomen. The larvae averaged 2, 900 (± 60) µm in length and 34 (± 5) µm in width and possessed morphological features characteristic of the family Onchocercidae. Genetic analysis and comparison of the 18S, ITS-2, 12S and cox-1 genes confirmed the identity of the larvae as the Acanthocheilonema sp.? nov. reported in dogs in Ladakh. CONCLUSION: This study provides evidence for a potential intermediate host-parasite relationship between H. longipennis and the canine Acanthocheilonema sp.? nov. in northern India.


Assuntos
Infecções por Dipetalonema/veterinária , Dipetalonema/isolamento & purificação , Dípteros/parasitologia , Vetores de Doenças , Doenças do Cão/parasitologia , Doenças do Cão/transmissão , Animais , Infecções por Dipetalonema/parasitologia , Infecções por Dipetalonema/transmissão , Cães , Índia , Larva , Microscopia , Parasitologia
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