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Biomedical subjects

J W Harkness

Publications and source records attributed to J W Harkness.

At least 37 records · Page 2Linked to original sources
PubMed1981

Effect of air filtration on respiratory disease in intensively housed veal calves.

The effect of a recirculating air filter unit on concentrations of airborne bacteria, clinical and subclinical respiratory disease and production performance of veal calves was studied over a period of one year. Six groups of 28 calves in sheds with internally filtered air were paired by age and time of entry with six similar groups in non-filtered sheds; they were also compared with 23 groups, each of 28 calves, in non-filtered sheds present in the unit during the period of study. Mean aerial bacteria concentration in filtered sheds was reduced by 44.9 per cent (P less than 0.0001). A comparison of unfiltered and filtered sheds on a paired basis showed that the number of animals requiring antibiotic treatment for respiratory disease was reduced by 19.3 per cent (P greater than 0.05). The number of repeat courses of treatment was reduced by 28.9 per cent (P less than 0.025) and total antibiotic usage was reduced by 34.8 per cent (P less than 0.025). At slaughter the average area of lung consolidation in calves from filtered sheds was reduced by 38.4 per cent (P less than 0.025. When all the 644 calves in the unit from 23 non-filtered sheds were compared with the 168 calves in the six filtered sheds the reduction in first treatments, repeat courses and total treatments were 19.7 per cent (P less than 0.025), 28.3 per cent (P less than 0.025) and 31.6 per cent (P less than 0.025) respectively. Air filtration was therefore associated with a reduction in both incidence and severity of clinical and subclinical disease in calves. Both treatment for respiratory disease and area of lung consolidation at slaughter were directly related to reductions in daily weight gain. The economic effect of respiratory disease on veal calves is briefly discussed.

Air Microbiology↗
PubMed1981

Human and animal togavirus antibodies in congenitally deformed infants.

The cord bloods of 30 congenitally malformed infants, born consecutively at the Worcester Royal Infirmary, were screened for serological evidence of infection with Border disease and bovine virus diarrhoea viruses as well as for the presence of rubella-, cytomegalovirus-, and measles-specific IgM. Despite Border disease and bovine virus diarrhoea being endemic among sheep and cattle in counties bordering Wales, none of the cord blood samples contained antibodies to Border disease or bovine virus diarrhoea viruses. No rubella-, measles-, or cytomegalovirus-specific IgM was detected. When the total immunoglobulins were estimated, 15 of the malformed infants and elevated levels, but in a control group of 35 infants born in the same unit, none showed significantly elevated immunoglobulin levels.

Antibodies, Viral↗
PubMed1981

Influence of temperature on the growth in cell culture of malignant catarrhal fever virus.

The growth characteristics of malignant catarrhal fever (MCF) virus in bovine thyroid cultures were affected by incubation temperature. The cytopathic effect at 37 degrees C was predominantly syncytial and little or no cell-free virus could be detected. At 32 degrees to 34 degrees C foci of rounded refractile cells were observed, and this was accompanied by an increase in the amount of cell-free virus found in culture fluids. Growth curve studies with one low passage isolate of MCF virus showed that optimum yields of cell-free virus were obtained at 32 degrees to 34 degrees C and survival curves at 32 degrees and 37 degrees C indicated that this was a result of the relatively short half life of the virus at the higher temperature. A number of other benefits resulted from the use of lowered incubation temperature and these are discussed with reference to in vitro work with the virus.

Animals↗
PubMed1980

Bovine virus diarrhoea-mucosal disease virus: pathogenicity for the fetal calf following maternal infection.

Fifteen pregnant, bovine virus diarrhoea-mucosal disease (BVD-MD) antibody-free Jersey heifers were infected experimentally with a mixture of 10 cytopathic strains of BVD-MD virus isolated from cattle in Britain. Each cow was inoculated intramuscularly on gestation day 100 with a high or a low dose of virus grown in primary calf testis tissue cultures. None of the cows showed clinical signs of illness following exposure, but all had seroconverted within six weeks. Six fetuses, including one set of twins, died in utero following infection. Of these five were aborted between days 136 and 154; the sixth one was mummified and still retained at day 300. The remaining 10 fetuses survived to term, but all showed evidence of intrauterine growth retardation with or without gross malformation and/or dysmyelination of the central nervous system. Three were clinically affected with congenital nervous disease. Of the 10 liveborn fetuses, two had specific serum antibodies to BVD-MD. Non-cytopathic BVD-MD virus was recovered from all of the remaining eight. When non-immune cows become infected with BVD-MD virus in mid gestation: transplacental infection of the fetus will probably result; apart from the risk of fetal death, with or without abortion, there is a high probability of fetal mal-development which may not always be clinically obvious; the immunological competence of the fetus may be impaired; congenital infection is likely in a substantial proportion of liveborn calves. About one in 16 bovine fetuses in British herds are estimated to be at risk from BVD-MD virus infection.

Abortion, Veterinary↗
PubMed1980

Epidemiological studies of calf respiratory disease in a large commercial veal unit.

Records of treatments for respiratory disease among 952 calves in a large intensive veal unit were analysed. The frequency of disease was heavily age-dependent in the 34 batches of 28 calves with a peak at five weeks of age and little disease before the fourth or after the eighth week. The effect was evident for all of the three indices of disease examined: the numbers of first treatments, numbers of new courses of treatment and the total number of treatments. Transient synchronisation of outbreaks of disease in separate batches was observed but attempts to correlate the level of disease with climatic events, using data from local meteorological stations, were unsuccessful. Disease was shown to be clustered within crops of calves at one end of the housing or the other, indicating that contact spread may have been important. A variation in the amount of disease on each day of the week may have been attributable to restricted feeding on Sundays.

Age Factors↗
PubMed1979

A field trial with a multicomponent inactivated respiratory viral vaccine.

An inactivated virus vaccine containing strains of parainfluenza type 3 (PI3), bovine adenovirus type 3, reovirus type 1, bovine virus diarrhoea (BVD) and infectious bovine rhinotracheitis (IBR) viruses was tested in a group of 58 calves reared in a semi-intensive management system. Following vaccination, 1/30, 14/30 and 17/30, showed significant rises in antibody titre to reovirus type 1, adenovirus type 3 and IBR respectively. None of the animals showed significant serological response to PI 3 and BVD. In the control group, 2/28, 1/28, 6/28 and 3/28 developed antibody responses to reovirus type 1, BVD, adenovirus type 3 and IBR respectively. Microbiological examination revealed the presence of a wide variety of commensal bacteria and Mycoplasma bovirhinis in both groups. Analysis of the records of clinical examinations indicated that the respiratory tract infections occurred among the calves at between 50 and 80 days after arrival at the farm, and that there was no significant difference between the test and the control groups. A number of animals had maternal antibodies to the various components of the vaccine present before the trial commenced and these antibodies appeared to interfere with the subsequent serological response to the antigen challenge. The vaccination schedule recommended by the manufacturer does not entirely circumvent this problem.

Adenoviridae↗
PubMed1979

Border disease: a sequential study of surviving lambs and an assessment of its effect on profitability.

Pregnant Dorset horn gimmers inoculated with a non-cytopathic strain of the border disease virus produced "hairy shaker" lambs that were individually affected to a varying degree. Surviving lambs were observed for a period of up to 20 weeks when neurological signs were seen to gradually disappear. During this time live virus was isolated from a wide variety of sites in nearly all of the infected lambs. The infected animals grew at a significantly slower rate compared with the controls, particularly during the first 15 weeks. Several morphological defects are described the most consistent being the decreased weight of the central nervous system. By 20 weeks body-weights were about 20 per cent lower and carcase quality scores were reduced. An assessment is made of the economic losses attributable to BD taking into consideration carcase quality at 20 weeks and the perinatal losses.

Animals↗
PubMed1978

Serological evidence of continuing infection of swine in Great Britain with an influenza A virus (H3N2).

Serum samples collected from swine and cattle in Great Britain at various times between July 1971 and July 1977 were examined by haemagglutination-inhibition or single radial haemolysis methods for evidence of infection with influenza A (H3N2) viruses. A small proportion of swine sera collected in each year reacted in the tests but there was no evidence of infection in cattle. The significance of the findings is discussed, with particular reference to the seasonal fluctuations in the prevalence of antibody in swine observed during the period of the study, and their possible relevance to influenzal events in the human population. None of the sera tested had antibody to swine influenza strains (HSw1N1).

Animals↗
PubMed1978

Serological studies of mucosal disease virus in England and Wales.

A survey of the cattle population in England and Wales showed that about 62 per cent of animals had neutralising (SN) antibody to BVD-MD virus in their serum. Fewer seropositive individuals were detected by immunodiffusion (53 per cent), and complement fixation (CF) tests (34 per cent). The prevalence of antibody was not affected by herd size, but some variation was found between various regions of the country, and the proportion of animals seropositive rose markedly with age. The immunodiffusion test was a specific but relatively insensitive method of detecting antibody compared with the SN test. The data suggest that the CF test may detect a different, short-lived antibody. For diagnostic serology, the SN test was superior to the other methods. No antibody to the virus was detected in human or equine sera but about 7.3 per cent of sheep sampled had serum antibody to the virus in the immunodiffusion test.

Animals↗
PubMed1978

The distribution of antibodies to Border disease virus among sheep in England and Wales.

Within a sample of the sheep population of England and Wales, 10.8 per cent of 3506 individuals had immunodiffusion test antibody to bovine viral diarrhoea mucosal disease virus antigen. There were marked differences between various geographical regions in the proportion of sheep with antibody, and Border disease may be more common in some areas than disease records indicate.

Animals↗
PubMed1976

Heterogeneity of infectious bronchitis virus grown in eggs.

Egg-grown infectious bronchitis virus, strain Beaudette, was concentrated and centrifuged on sucrose density gradients to separate the virus into five peaks with densities of 1.144, 1.160, 1.172, 1.191 and 1.218 g/cm3. All peaks retained infectivity, complement fixation activity and were labelled with 3H-uridine. Morphologically the densest peak consisted of very large virus particles and amorphous material, the other peaks consisted of mainly intact particles although small differences in size and pleomorphism were seen. Polyacrylamide gel electrophoresis of material from the density gradient peaks revealed four major polypeptides and at least 10 minor polypeptides. The proportions of the polypeptides were approximately similar for all peaks with the exception of the densest peak in which the major polypeptides were greatly reduced. The four major polypeptides had approximate molecular weights of 1. 52,000, 2. 45,000, 3. 34,000, 4. 32,000. The major polypeptides 1 and 4 were shown to be glycosylated as were two of the minor polypeptides.

Animals↗
PubMed1975

Infectious bursal disease agent: morphology by negative stain electron microscopy.

The virus of infectious bursal disease of chickens was studied by immune electron microscopy. Negatively-stained preparations revealed morphological similarities with both the bluetongue virus group, and the virus of infectious pancreatic necrosis of trout. Results indicated that the small particle found in such preparations is a degradation product of the large particle.

Centrifugation, Density Gradient↗
PubMed1975

Preliminary characterisation of paramyxovirus isolated from a parrot.

A virus, designated 0121, which was isolated from a parrot, was shown to be a paramyxovirus, which was serologically related to the paramyxoviruses Bangor/flinch/N. Ireland/73 (Bangor) and Yucaipa/chicken/California/60(PMY). However, the 0121 virus differed in several properties from both the PMY and the Bangor viruses. The virus was not pathogenic for chickens. I was designated Paramyxovirus: Parrot/England/0121/74.

Animals↗
PubMed1975

The demonstration by interference tests of an infective agent in fetuses from ewes inoculated with Border disease tissue.

Fetuses and placental tissues were taken from pregnant ewes at intervals varying between eight and 21 days after inoculation with tissue suspensions from cases of Border disease. Virus isolation procedures involving the detection of a cytopathic effect in tissue cultures with or without interference tests produced universally negative results but interference tests, using a plaque technique with the NADL strain of bovine virus diarrhoea virus as a challenge virus, detected the presence of an agent in tissues from six out of 10 fetuses. Inoculated ewes allowed to proceed to term showed a serological response characteristic of Border disease infection, as measured by four different tests. Although hairy shaker lambs were not seen, the occurence of abortion and stillbirth due to causes other than bacterial agents, was an indication that the Border disease agent was present. Electron microscopy of fetal fluids failed to detect viral particles.

Abortion, Veterinary↗