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Biomedical subjects

A B Forbes

Publications and source records attributed to A B Forbes.

At least 37 records · Page 2Linked to original sources
PubMed2002

Sub-clinical parasitism in spring-born, beef suckler calves: epidemiology and impact on growth performance during the first grazing season.

Sub-clinical parasitism in spring-born single suckled beef calves was investigated from the middle of their first grazing season until weaning or housing later the same year. The study was conducted on four beef suckler herds in southern England over a 3-year period and involved a total of 334 spring-born beef suckler calves and their dams. The animals were grazed extensively on pastures naturally infected with nematode larvae. At the start of each period of observation, faecal samples were taken from calves and cows and subjected to routine worm egg counts; calves were re-sampled at the end of the grazing season. In July in each year and at each location the calves were ranked by initial weight within sex, paired according to rank and randomly allocated to either an untreated control group or a group in which the calves were each treated with an ivermectin sustained-release (SR) bolus. The calves in both trial groups, and their dams, were grazed together until weaning or housing. The calves were weighed at the initial allocation and at the end of the study. The adult cows were not treated with any anthelmintic during the study. The faecal nematode egg counts (FECs) conducted in July showed that the suckler cows were excreting worm eggs at low concentrations: range 0-100 eggs per gram (epg), with one individual count of 500epg, 88% of the cows sampled had counts of <50epg. Similarly, the counts from the calf samples were fairly low in July: range 0-250epg, 73% of the calves sampled had counts of <50epg. By the end of the grazing season, the faecal samples from the untreated control calves showed higher values: range 0-650epg, with only 58% having an epg of <50. The average rate of daily liveweight gain in the untreated heifer calves was 0.79kg per day, the corresponding figure for the heifer calves treated with the ivermectin SR bolus in mid-summer was 0.88kg per day; the difference of 90g per day was significantly different (P=0.0118). The average rate of daily liveweight gain in the untreated bull calves was 0.91kg per day, the corresponding figure for the bull calves treated with the ivermectin SR bolus in mid-summer was 1.01kg per day; the difference was significantly different (P=0.0169).

Animals↗
PubMed2002

Case-control studies of sporadic cryptosporidiosis in Melbourne and Adelaide, Australia.

Few studies have assessed risk factors for sporadic cryptosporidiosis in industrialized countries, even though it may be numerically more common than outbreaks of disease. We carried out case-control studies assessing risk factors for sporadic disease in Melbourne and Adelaide, which have water supplies from different ends of the raw water spectrum. In addition to examining drinking water, we assessed several other exposures. 201 cases and 795 controls were recruited for Melbourne and 134 cases and 536 controls were recruited for Adelaide. Risk factors were similar for the two cities, with swimming in public pools and contact with a person with diarrhoea being most important. The consumption of plain tap water was not found to be associated with disease. This study emphasizes the need for regular public health messages to the public and swimming pool managers in an attempt to prevent sporadic cryptosporidiosis, as well as outbreaks of disease.

Adolescent↗
PubMed2001

Assessing the risk of tuberculosis infection among healthcare workers: the Melbourne Mantoux Study. Melbourne Mantoux Study Group.

OBJECTIVE: To determine the potential prevalence of nosocomial infection with Mycobacterium tuberculosis among hospital employees in teaching hospitals in Melbourne. DESIGN: Cross-sectional survey of positive tuberculin skin test (Mantoux) responses among employees in 14 public hospitals in Melbourne, January 1996 to April 1999. PARTICIPANTS: All consenting employees in participating hospitals (4,070 healthcare and 4,298 non-healthcare workers; participation rates, 13%-66%). OUTCOME MEASURES: Prevalence of positive responses to tuberculin skin tests among healthcare and non-healthcare workers and association with employee and hospital characteristics. RESULTS: Healthcare workers were significantly more likely to have a positive tuberculin response than non-healthcare workers (19.3% versus 13.7%; odds ratio, 1.5; 95% CI, 1.3-1.7; P<0.001). Multivariable analysis revealed that age, country of birth (high versus low tuberculosis [TB] prevalence), history of BCG (bacille Calmette-Guérin) vaccination, years since last BCG, occupation (healthcare versus non-healthcare worker) and years of hospital employment were all significantly associated with a positive response. Rates of positive responses among employees varied greatly between hospitals (6%-35%). These differences were not explained by employee characteristics, hospital TB patient load (number of admissions or bed-days) or percentage of hospital patients from countries with high TB prevalence. The hospital with the highest rate of positive responses was notable for its lack of negative-pressure isolation rooms for TB patients. CONCLUSIONS: Positive tuberculin responses are relatively common among hospital employees in Melbourne, with rates varying between hospitals and being higher among healthcare than non-healthcare workers. Employee characteristics, such as age, country of birth and past BCG status, explain little of this variation. More emphasis on TB infection control measures and regular staff screening may be needed.

Adolescent↗
PubMed2001

The relationships between patients' related variables in asthma: iplications for asthma management.

OBJECTIVE: Understanding patients' personal characteristics is essential for better asthma management. This study assessed the relationships between patients' related variables in asthma and identified key associations relevant to asthma management. METHODOLOGY: Subjects were recruited from the Alfred Hospital Asthma and Allergy Clinic (Melbourne, Victoria, Australia) and general practices. Their clinical and demographic characteristics, asthma knowledge, impact of asthma on their quality of life, their self-management skills and attitudes to asthma were assessed. RESULTS: One hundred and sixty-nine subjects participated in the study. Fifty-seven per cent had one or more previous hospital admissions, 94% had either moderate or severe asthma, and 51% reported nocturnal symptoms in the last 6 weeks. Patients who spoke only English, had been admitted to an intensive care unit, had a peak flow meter, and an asthma action plan had significantly better asthma knowledge than those who did not. The impact of asthma was greatest in patients who had a peak flow meter, used oral steroids, had exercise limitation, and developed asthma between the ages of 31-45 years. Female patients had better self-management skills than males. Patients with asthma-related distress were more likely to use oral steroids or theophylline and to have a history of previous hospital admissions. Patient self-confidence was negatively correlated with age. CONCLUSIONS: There are significant relationships between many of patients' variables related to asthma, including their personal clinical, demographic and psychological characteristics. The findings have implications for optimizing asthma management.

Activities of Daily Living↗
PubMed2001

Methods used to maintain a high level of participant involvement in a clinical trial.

OBJECTIVES: To describe the strategies adopted to maintain high level participation throughout a community based clinical trial, and the reasons given by participants for why they participated in the study. DESIGN: Observational study. SETTING: Community based clinical trial in Melbourne, Australia that ran for 68 weeks and involved 2811 community based individuals from 600 families. A high level of commitment was required of the families; each participant completed a Health Diary each week of the 68 week study, as well as answering numerous other questionnaires, and providing faecal and blood samples. MAIN RESULTS: Only 41 of the 600 families withdrew from the study; the majority of these families withdrew because they sold their home and moved from the study area. The completion rate of Health Diaries averaged 90.7% over the 68 weeks of data collection. Of the 559 families who completed the study, 524 (93.7%) completed the Participation Questionnaire. The statement that received the highest rating for why families enrolled in the study was they thought the study was researching an important community issue. The statements that received the highest ratings for why families continued to participate in the study was the family being kept well informed about the study's progress and that the study was well run. CONCLUSIONS: The low numbers of withdrawals and the high level of participation throughout the study suggests the strategies of (a) having a non-aggressive recruitment method, (b) maintaining regular contact with the participants and (c) ensuring participants were kept well informed of the study's progress and constantly encouraged to continue participation were successful. The results also suggest people involve themselves in research because they perceive it to be of value to the community, not simply for personal gain. They indicated that they maintained their participation because it was a well run study and they were kept well informed throughout the study.

Adolescent↗
PubMed2001

Are asthma medications and management related to deaths from asthma?

There is controversy about the role of beta-agonists in asthma mortality, and the impact of asthma management plans remains unclear. We compared blood beta-agonist levels in patients dying from asthma with those in controls, and estimated the risks associated with specific classes of medication and patterns of management. We identified 89 asthma deaths and recruited 322 patients presenting to hospitals with acute asthma. A questionnaire was administered to the next of kin in 51 cases, and to 202 controls. Blood drawn from 35 cases and 229 controls was assayed for salbutamol. Smoking, drinking, and family problems were significantly more likely among the cases of asthma death than among the controls. The two groups were reasonably well matched with regard to markers of chronic asthma severity. Cases of asthma death were significantly less likely than controls to use a peak flow meter. Written action plans were associated with a 70% reduction in the risk of death. Use of nebulized bronchodilators or oral steroids was significantly more likely in cases of asthma death. Mean blood salbutamol concentrations were 2.5 times higher in cases of asthma. The use of oral steroids for an attack of asthma reduced the risk of death by 90%. More widespread adoption of written asthma management plans, with less reliance on beta-agonists and closer medical supervision, should reduce asthma mortality.

Adrenergic beta-Agonists↗
PubMed2001

A randomized, blinded, controlled trial investigating the gastrointestinal health effects of drinking water quality.

A double-blinded, randomized, controlled trial was carried out in in Melbourne, Australia, to determine the contribution of drinking water to gastroenteritis. Melbourne is one of the few major cities in the world that draws drinking water from a protected forest catchment with minimal water treatment (chlorination only). Six hundred families were randomly allocated to receive either real or sham water treatment units (WTUs) installed in their kitchen. Real units were designed to remove viruses, bacteria, and protozoa. Study participants completed a weekly health diary reporting gastrointestinal symptoms during the 68-week observation period. There were 2,669 cases of highly credible gastroenteritis (HCG) during the study (0.80 cases/person/year). The ratio of HCG episode rates for the real WTU group compared to the sham WTU group was 0.99 (95% confidence interval, 0.85-1.15, p = 0.85). We collected 795 fecal specimens from participants with gastroenteritis, and pathogens were not more significantly common in the sham WTU group. We found no evidence of waterborne disease in Melbourne. The application of this methodology to other water supplies will provide a better understanding of the relationship between human health and water quality.

Adult↗
PubMed2000

Patterns of parasitic nematode infection and immunity in dairy heifers treated with ivermectin in a sustained-release bolus formulation either at turnout or in the middle of the grazing season.

Twenty-eight Holstein-Friesian heifers, born the previous year and weighing between 130 and 310 kg, were allocated to one of two treatment groups by restricted randomisation, based on their initial weight. The heifers in group 1 were each treated with ivermectin in a sustained-release bolus formulation at turnout in April, and those in group 2 were each given an ivermectin bolus on July 10, 84 days after turnout. On that day the mean geometric worm egg counts of groups 1 and 2 were 0.4/g and 38.8/g, respectively, and they both had a mean plasma pepsinogen concentration of 0.59 iu/litre; in group 1, two of 14 faecal samples were positive for Dictyocaulus viviparus larvae, and in group 2 all 13 samples were positive; in group 1 eight calves were positive and three inconclusive for the presence of antibodies to D viviparus, and in group 2 the corresponding figures were 10 positive and two inconclusive; the mean liveweights of groups 1 and 2 were 274.4 kg and 262.8 kg, respectively. By December 4,231 days after turnout, the corresponding results were: mean geometric worm egg counts of 2.2/g and 0.5/g; one of 13 and none of 14 faecal samples positive for D viviparus larvae; 12 positive and two inconclusive and none positive and 10 inconclusive for the presence of antibodies to D viviparus; 214 days after turnout their mean liveweights were 361.1 kg and 358.3 kg. Although the patterns of parasitic nematode infection were different in the two groups during the grazing season, by the time they were housed both groups had achieved similar liveweights and showed evidence of an immune response to both D viviparus and gastrointestinal nematodes.

Animals↗
PubMed2000

Evaluation of the effects of nematode parasitism on grazing behaviour, herbage intake and growth in young grazing cattle.

Parasitic nematodes, even in the absence of any clinical disease, can cause a reduction in voluntary feed intake in housed ruminants. This trial examined these effects on young cattle grazing pastures. Twenty dairy heifer calves, born in the previous autumn, were blocked according to liveweight and allocated to one of two groups: either untreated or dosed with an IVOMEC((R)) (ivermectin) SR Bolus 10 days prior to turnout on 1 May 1998. The groups grazed separately on two paddocks on predominately ryegrass swards. Liveweights were recorded every 28 days and faecal samples taken for worm egg counts at the same time. In mid-May and mid-July, for two 14-day periods, animals were paired within treatment groups and transferred to one of 10 replicate paddocks of similar sward height and herbage mass. Grazing behaviour and herbage intake were measured during these periods. In mid-May, 2 weeks after turnout, treated and untreated animals showed no difference in grazing behaviour or daily intake of grass. By mid-July, 10 weeks after turnout, the untreated heifers spent on average 105min less per day in grazing time and their daily herbage intake was 0.78kg dry matter (DM) per day lower than that of the treated animals. Residual sward height, mass and composition in the trial paddocks reflected these differences. There were no clinical signs of gastrointestinal parasitism in the untreated group up to this time; in July, the mean worm egg count in this group was 120 eggs per gram (e.p.g.) of faeces. Faecal samples from several untreated animals were positive for lungworm larvae by July, mild clinical signs of bronchitis were observed in two of these animals in mid-July. Over the period from turnout until mid-July, the untreated heifers showed a reduction in mean daily liveweight gain of 150g, compared to the treated animals.

Animals↗
PubMed2000

The ixodid tick species attaching to domestic dogs and cats in Great Britain and Ireland.

The species of ixodid ticks, attached to dogs and cats presented to veterinary practices in Great Britain and Ireland were identified. Most host animals carried only one tick species with Ixodes ricinus Linné (Acari: Ixodidae) being the most common, identified on 52% of animals, Ixodes hexagonus Leach (Acari: Ixodidae) the second most common (on 39%) and Ixodes canisuga Johnston (Acari: Ixodidae) the third most common (on 11%). A significantly higher proportion of dogs than cats carried I. ricinus, while I. hexagonus was more frequently carried by cats. One animal carried a single specimen of Haemaphysalis punctata Canestrini & Fanzago (Acari: Ixodidae), one carried a Dermacentor reticulatus Fabricius (Acari: Ixodidae) but none carried Rhipicephalus sanguineus Latreille (Acari: Ixodidae). This indicates that the latter two species, vectors of 'exotic' tick-borne diseases, remain at low densities in Great Britain and Ireland. Retrospective information on exposure of the animals to different habitats and geographic regions was collected by questionnaire and subject to contingency table and logistic regression analysis. Woodlands and moorlands were habitats significantly associated with I. ricinus attachment. Exposure to urban parks was significantly associated with I. hexagonus attachment and exposure to boarding kennels and catteries was significantly associated with I. canisuga attachment. Ixodes hexagonus, rather than I. ricinus, was the ixodid tick species most likely to be encountered by urban populations of dogs and cats and, by inference, possibly also humans. The implications of these findings, for the transmission of tick-borne pathogens to dogs, cats and humans are discussed.

Animals↗
PubMed1999

Treatment and prophylaxis of psoroptic mange (sheep scab) using an ivermectin intraruminal controlled-release bolus for sheep.

In an experiment to determine the therapeutic efficacy of an ivermectin intraruminal controlled-release (CR) bolus, 14 mixed breed sheep of one lot were infested with Psoroptes ovis and subsequently divided into two groups of seven. In one of these groups each sheep received one ivermectin CR bolus appropriate to its weight, the other group remained as an untreated control. All mites were eliminated from the group receiving the bolus while the control group remained infested, the disease progressed, and all but one sheep required treatment for psoroptic mange before the end of the experimental period. A second lot of 14 sheep, free from P. ovis, were divided equally into two groups to determine the prophylactic efficacy of the ivermectin CR bolus. In one group, each sheep was given an ivermectin CR bolus according to body weight and the sheep in the other group received no medication and served as untreated controls. Twenty-one days later two sheep infested with psoroptic mange were introduced into each of the groups. These donor sheep were removed 10 days later. The group treated with the ivermectin CR bolus remained mange-free and did not harbour any mites. All of the sheep in the control group developed psoroptic mange and required treatment to control the infestation at the end of the experimental period. Sheep that received the ivermectin CR bolus had greater mean weight gains than the control groups in these experiments. The ivermectin CR bolus releases a minimum dose of 20 microg ivermectin kg/day for 100 days: this prolonged activity should prove a valuable asset for the treatment and control of psoroptic mange in sheep.

Animals↗
PubMed1999

A review of the use of a controlled-release formulation of ivermectin in the treatment and prophylaxis of Psoroptes ovis infestations in sheep.

The options for the treatment and control of sheep scab (psoroptic mange) have been increased in recent years through the introduction of the endectocides ivermectin, doramectin and moxidectin. Whilst therapeutic efficacy is good, the current injectable formulations offer limited protection against re-infestation with Psoroptes ovis. An intraruminal controlled-release formulation of ivermectin has been developed to provide therapeutic and prophylactic activity against a range of sensitive endo- and ecto-parasites of sheep for 100 days after administration. These ivermectin boluses are designed to release ivermectin at 20-40 microg/kg/day over 100 days and were developed for use in sheep of 20-90 kg bodyweight. Several controlled therapeutic and prophylactic trials against sheep scab have been conducted under a variety of protocols with such boluses in Europe and South America. The results of these studies indicate that the bolus provides 100% therapeutic efficacy against established P. ovis infestations and equivalent prophylactic efficacy against challenge infestations administered during the active life of the bolus.

Animals↗
PubMed1997

A survey on resistance to anthelmintics in sheep stud farms of southern Brazil.

A survey to investigate the status of anthelmintic resistance in 29 sheep studs in southern Brazil was conducted from March 1992 to December 1993. Compounds from three drug families (macrocyclic lactone, levamisole and benzimidazole) were evaluated concurrently on 22 of the 29 studs. On seven of these properties, resistance to all three families was declared or suspected; at 15 of the 22 studs, ivermectin was the only compound found to be effective in reducing faecal egg counts. Resistance to levamisole was detected on 22 of the 23 studs where it was evaluated and was suspected in the remaining one. The position of benzimidazoles was similar, resistance being declared or suspected on all 28 studs where they were tested. Results of larval cultures indicated that Trichostrongylus, Ostertagia and Haemonchus were the most prevalent nematode genera in the survey, with Trichostrongylus and Haemonchus being the genera associated with anthelmintic resistance.

Albendazole↗
PubMed1997

Absence of genetic linkage of chromosome 5q31 with asthma and atopy in the general population.

BACKGROUND: Clinical asthma is associated with increased serum total immunoglobulin E (IgE), atopy (skin prick test positivity to common aeroallergens), and bronchial hyperreactivity (BHR) to non-specific stimuli (positive methacholine challenge test). A region on chromosome 5q31-33 has been linked with increased total serum IgE and BHR. A study of the genetic linkage of this region with clinical asthma and atopy was therefore undertaken. METHODS: A polymorphic microsatellite marker in chromosome 5q31 (D5S399) was studied in 119 sibling pairs recruited from the general population who shared asthma, atopy, and/or BHR. Based on our population distribution of 13 different alleles, it was expected that by chance alone sibling pairs would share on average 1.24 alleles and that a significant excess would indicate genetic linkage. RESULTS: No evidence of linkage was found in 45 siblings concordant for asthma (shared alleles = 1.09, p = 0.95), in 103 sibling pairs with atopy (shared alleles = 1.18, p = 0.82), in 51 sibling pairs with BHR (shared alleles = 1.22, p = 0.62), or in 68 sibling pairs who shared atopy in the absence of BHR (shared alleles = 1.22, p = 0.61). A slight non-significant excess of shared alleles (1.44, p = 0.11) was observed in siblings who shared BHR without atopy. CONCLUSIONS: No evidence of genetic linkage of chromosome 5q31 with either clinical asthma or atopy was therefore detected in the population studied. Linkage between chromosome 5q and BHR needs further investigation.

Adult↗
PubMed1995

Linkage of high-affinity IgE receptor gene with bronchial hyperreactivity, even in absence of atopy.

Asthma is a manifestation of bronchial hyperreactivity (BHR) and forms part of the spectrum of atopic disease. Some pedigree studies of atopy have suggested linkage with the high-affinity IgE receptor (Fc epsilon RI beta) gene on chromosome 11q13, but others find no linkage. The molecular genetics of asthma and BHR have not been studied in the general population. We examined the genetic linkage of the Fc epsilon RI beta gene with clinical asthma and the underlying phenotypes of BHR (to methacholine) and atopy (defined by skinprick testing) in 123 affected sibling-pairs recruited from the general population. We found evidence of significant linkage of a highly polymorphic microsatellite marker in the fifth intron of the Fc epsilon RI beta gene to a diagnosis of asthma (18.0% excess of shared alleles, p = 0.002) and to BHR (21.7% excess of shared alleles, p = 0.001). Significant linkage was also observed in siblings sharing BHR when those with atopy were excluded (32.8% excess of shared alleles, p = 0.004). Atopy in the absence of BHR did not show significant linkage to the Fc epsilon RI beta gene (7.2% excess of shared alleles, p = 0.124). These findings suggest that mutations in the Fc epsilon RI beta gene or a closely linked gene influence the BHR underlying asthma, even in the absence of atopy.

Adult↗
PubMed1995

Risk factors for the development of amoxycillin-clavulanic acid associated jaundice.

OBJECTIVES: To identify risk factors for the development of amoxycillin-clavulanic acid associated jaundice. DESIGN: Retrospective case-control study. Cases were selected from those reported to the Adverse Drug Reactions Advisory Committee from the time of introduction of amoxycillin-clavulanic acid to Australia in 1986 until December 1993. SUBJECTS: Thirty-four cases, defined as individuals who developed jaundice within eight weeks of starting amoxycillin-clavulanic acid, with a biochemical picture of cholestasis, normal calibre bile ducts and no other recognised causes of jaundice or recent use of other hepatotoxic drugs, were selected. For each case, four controls who had been prescribed amoxycillin-clavulanic acid without developing jaundice were randomly selected from the patient register of the prescribing doctor. RESULTS: Increasing age was a risk factor for amoxycillin-clavulanic acid associated jaundice; patients over 55 years had an odds ratio of 16.1 (95% confidence interval [CI], 2.9-88.9) compared with patients less than 30 years. Men had an odds ratio of 2.5 (95% CI, 1.1-5.4) compared with women, although the proportion of men in the study group was larger than in the reported cases overall. History of serious medical illness, drug dose, route and duration of therapy, other medications, smoking and previous drug allergies or use of amoxycillin-clavulanic acid were not significantly associated with jaundice. CONCLUSIONS: Because of the higher risk of jaundice with increasing age, the risk-benefit ratio of amoxycillin-clavulanic acid should be carefully considered in older patients. Further assessment is necessary to clarify the association between jaundice and male sex.

Adult↗
PubMed1993

A review of regional and temporal use of avermectins in cattle and horses worldwide.

Ivermectin and abamectin are two members of the group of parasiticides known as the avermectins; ivermectin was first registered as an injectable treatment for cattle in 1981. Since then, abamectin has been registered for cattle and ivermectin for horses. The relative popularity of the avermectins amongst farmers and veterinarians can be attributed to their spectrum of activity, convenience, wide margin of safety and the improved health and performance of stock following their use. Patterns of use in grazing animals apply equally to the avermectins as to other antiparasitics, particularly anthelmintics; these are based on a knowledge of epidemiology integrated with practical management considerations. For cattle, programs are commonly aimed at control of abomasal nematodes of the genera Ostertagia and Haemonchus. Use of avermectins is largely strategic in cattle, treatments being favored at the end of the period of transmission of these parasites; this frequently coincides with housing, entry into a feedlot or movement to another pasture. Simultaneous control of important ectoparasites at this time is an added benefit. Prophylactic use of avermectins at pasture is primarily targeted at the young first season grazing animal. In horses, a bimonthly treatment schedule during the period of risk has proved effective in helping prevent adverse effects of the main target parasites, including large and small strongyles and stomach bots. These patterns of use can be applied to the evaluation of the potential for avermectin residues in feces to have impact on pasture ecology. The evidence presented suggests that any effects are temporally and spatially limited. After more than a decade of practical use, there is no indication that avermectins have had a significant impact on pasture ecology and the environment.

Animals↗