Serological survey using ELISA to determine the prevalence of Coxiella burnetii infection (Q fever) in sheep and goats in Great Britain.

A survey of Coxiella burnetii infection (Q fever) in sheep flocks and goat herds in Great Britain was undertaken. A total of 5791 sheep (384 flocks) and 522 goats (145 herds) were examined for C. burnetii antibodies using an ELISA. Overall, 53 sheep (37 flocks), and four goats (four herds), tested positive. Estimates of individual animal, between-flock/-herd and within-flock/-herd crude prevalences were 0·9%, 10·2% and 9·0%, respectively, for sheep, and 0·8%, 3% and 26·3%, respectively, for goats. With sheep, the likelihood of an animal testing positive increased with total flock size (P = 0·002) and number of breeding ewes in the flock (P = 0·021). It also increased with number of goats within a 10 km radius (P = 0·038). There was no evidence for spatial clustering of positive herds above that expected by chance alone. No analysis of risk factors was attempted for goats because of the paucity of positives.

Large outbreak of verocytotoxin-producing Escherichia coli O157 infection in visitors to a petting farm in South East England, 2009.

In the summer of 2009, an outbreak of verocytotoxigenic Escherichia coli O157 (VTEC O157) was identified in visitors to a large petting farm in South East England. The peak attack rate was 6/1000 visitors, and highest in those aged <2 years (16/1000). We conducted a case-control study with associated microbiological investigations, on human, animal and environmental samples. We identified 93 cases; 65 primary, 13 secondary and 15 asymptomatic. Cases were more likely to have visited a specific barn, stayed for prolonged periods and be infrequent farm visitors. The causative organism was identified as VTEC O157 PT21/28 with the same VNTR profile as that isolated in faecal specimens from farm animals and the physical environment, mostly in the same barn. Contact with farm livestock, especially ruminants, should be urgently reviewed at the earliest suspicion of a farm-related VTEC O157 outbreak and appropriate risk management procedures implemented without delay.

Investigation of a spatiotemporal cluster of verotoxin-producing Escherichia coli O157 infections in eastern England in 2007.

An outbreak of verotoxin-producing Escherichia coli O157 (VTEC O157) infections linked to an open farm occurred in eastern England in April and May 2007. This paper describes the investigation and highlights the importance of multidisciplinary collaboration for successful control of such outbreaks. There was a temporal cluster of 12 confirmed symptomatic cases of VTEC O157 and one asymptomatic carrier, from five families. The investigation revealed that four of these cases formed part of an outbreak involving two families who visited an open farm. The phenotypic and genotypic characteristics of the isolates from the two families and the putative farm animal contacts were indistinguishable, indicating that the animals were the source of the primary infections. No epidemiological link could be established between the remaining three families affected and the open farm or people having visited the farm. Control measures included improved hand washing facilities on the farm, information for visitors and staff, restricted access and suspended petting and feeding of animals, and thorough cleaning and disinfection of affected areas.

Verocytotoxigenic Escherichia coli O157 in animals on public amenity premises in England and Wales, 1997 to 2007.

At the request of the public health authorities, 31 public amenity premises in England and Wales containing animals of various species were investigated for the presence of verocytotoxigenic Escherichia coli (VTEC) O157 between 1997 and 2007, because of putative associations with human cases. VTEC O157 was confirmed in one or more species on 19 (61.3 per cent) of the premises. There were significant associations between the presence of VTEC O157 and the number of species sampled, the size of the enterprise, the presence of young cattle and the presence of adult pigs. E coli O157 was isolated from 305 (17.8 per cent) of 1715 samples taken from all the premises, and verocytotoxin genes were detected by PCR in 184 (98.4 per cent) of 187 representative isolates. On positive premises, the highest mean proportion of positive samples (29.0 per cent) was in cattle, followed by sheep (24.4 per cent), donkeys (14.6 per cent), pigs (14.3 per cent), horses (12.3 per cent) and goats (9.9 per cent). A high proportion of positive samples was obtained from camelid species sampled on three of the premises. The main phage types (PT) were 2 and 21/28, which were those most commonly isolated from human cases during the same period. A single PT was detected on 14 of the 19 positive premises, with up to six different species having the same PT.

Ulcerative vulvitis and balanitis in sheep flocks.

Outbreaks of ulcerative vulvitis and balanitis occurred in three commercial sheep flocks in England and Wales. Between 29 and 44 per cent of the ewes were affected; most of the lesions resolved in three weeks. Pathogens such as mycoplasmas, which have previously been associated with these conditions, were not detected despite using improved laboratory techniques. In one of the flocks, ovine herpesvirus type 2 was detected by pcr in the blood of two acutely affected ewes, from the vulval ulcers of one of them, and from the penis of an affected ram.

Cryptosporidium parvum infection in orphan lambs on a farm open to the public.

A longitudinal survey was undertaken on an open farm to investigate the occurrence of Cryptosporidium species infection in orphan lambs obtained from three local flocks. During an initial pilot study, Cryptosporidium oocysts were detected by a fluorescent antibody test (fat) in the faeces of two of 21 lambs aged between one and three weeks derived from one flock (flock A). Pooled pen samples of faeces were collected weekly from lambs derived from each flock; oocysts were detected by fat in 24 (49.0 per cent) of 49 samples from lambs from flock A, 18 (30.5 per cent) of 59 samples from lambs from flock B and 14 (29.8 per cent) of 47 samples from lambs from flock C. Oocyst counts of 1 x 10(3) to more than 2 x 10(6) per gram of faeces were detected in lambs up to 12 weeks old, with the peak counts occurring at six weeks of age in the lambs from flocks A and B and at four weeks of age in those from flock C. The oocysts were confirmed by molecular analysis as Cryptosporidium parvum. Virtually all the infections were subclinical.

Emergence of fasciolosis in cattle in East Anglia.

Liver fluke (Fasciola hepatica) infection caused weight loss, diarrhoea, decreased milk yield and occasionally death in cattle in East Anglia during the winters of 2001 to 2003. The condition had previously been limited mainly to stock imported into this part of Britain from endemically infected areas. In composite faecal samples collected by 16 farm animal veterinary practices in Norfolk, Suffolk and Essex, fluke eggs were found in 15 (28.8 per cent) of 52 previously unaffected suckler herds and 10 (16.7 per cent) of 60 dairy herds. Antibodies to F hepatica were detected by elisa in 32 (53.3 per cent) of the bulk milk samples from these 60 dairy herds, including the 10 in which fluke eggs were found. The emergence of fasciolosis in East Anglia was attributed to recent higher summer rainfall, which favoured the intermediate snail host Lymnaea truncatula and the free-living stages of F hepatica, the increased influx of sheep from endemic fluke areas for seasonal grazing, and the wetter grazing conditions associated with the Environmentally Sensitive Area scheme.

Transmissible gastroenteritis in endemically infected breeding herds of pigs in East Anglia, 1981-85.

Endemic infection was a common sequel to primary outbreaks of transmissible gastroenteritis in large breeding herds of pigs in East Anglia. The main clinical features of the disease were diarrhoea affecting sucking piglets aged about six days or more, diarrhoea among recently weaned pigs and brief episodes of overt clinical recrudescence in part of the herd. Post mortem and bacteriological findings were often more suggestive of colibacillosis than transmissible gastroenteritis. In some herds, endemic infection remained clinically mild or inapparent for long periods. Evidence of endemic transmissible gastroenteritis infection was found in 43 (50.6 per cent) of 85 herds of pigs studied prospectively between 1981 and 1983. There was a significant correlation with herd size; the disease recurred during the 12 months after primary outbreaks in 36 (65.5 per cent) of 55 herds with over 100 sows compared with seven (23.3 per cent) of 30 herds with less than 100 sows (P less than 0.001). In the larger herds it occurred more commonly where finishers were kept (P less than 0.05). Sow morbidity and management factors during the primary outbreak had no statistically significant effect on the incidence of recrudescence. Epidemiological aspects of the findings are discussed with emphasis on the difficulties associated with the diagnosis and control of endemic transmissible gastroenteritis infection.

Observations on clinical aspects of transmissible gastroenteritis of pigs in Norfolk and Suffolk, 1980-81.

Outbreaks of transmissible gastroenteritis in 56 breeding units, six maiden gilt sites and 64 fattening units were investigated during the period December 1980 to October 1981. The disease invariably occurred in classical virulent form, resulting in very high mortality in baby piglets. Reproductive sequelae were sometimes evident. Individual outbreaks continued for longer than in previous years. There was a high rate of recrudescene, particularly in large breeding units, and infection also persisted in many fattening units. The value of control measures and supportive therapy is discussed.

The distribution of Mycoplasma meleagridis in normal turkey carcases and those affected with air sac disease.

Mycoplasma meleagridis was isolated from both normal and diseased air sacs of turkeys examined and graded for air sacculitis on the evisceration line in a processing plant. It was also cultivated from wing bone cavities of turkeys with severe air sac lesions but not from leg bones or from samples of deep muscle. A further investigation, using material taken randomly from the condemned meat container, confirmed that M meleagridis was recoverable from wing bones.

Concurrent maedi-visna virus infection and pulmonary adenomatosis in a commercial breeding flock in East Anglia.

The seroprevalence of maedi-visna virus infection in thin potential cull ewes aged over two years in a flock in East Anglia increased from 3.7 per cent in August 1985 to 39.0 per cent in September 1987 and 93.3 per cent in May 1989. This increase coincided with the first appearance of sheep pulmonary adenomatosis in the flock. Four emaciated ewes which were dyspnoeic were necropsied between 1987 and 1989. Maedi and pulmonary adenomatosis were confirmed histologically in one of these ewes and pulmonary adenomatosis was confirmed in the other three.

Subclinical breakdown with infectious bovine rhinotracheitis virus infection in dairy herd of high health status.

Infectious bovine rhinotracheitis (IBR) virus infection was detected by an antibody ELISA in the bulk milk of a large closed dairy herd of high health status in an area of low cattle density in East Anglia. The herd was managed under high standards of biosecurity and was known to have been serologically free of IBR virus for the previous 13 years. Although over 70 per cent of the cows had seroconverted to IBR virus no clinical signs were observed apart from a slight bilateral watery ocular discharge in a few cows, and their performance and productivity were unaffected. The causal virus, which was isolated after it had been reactivated with corticosteroid, had the DNA profile of a bovine herpesvirus type 1 strain normally associated with clinically severe respiratory disease. In spite of extensive enquiries and seroepidemiological investigations the source of the infection was not determined.

Alopecia in calves associated with milk substitute feeding.

Outbreaks of alopecia with unusually high morbidity occurred among calves reared on milk substitutes on two unrelated farms in Suffolk. On one farm alopecia occurred for three consecutive years; during the winter of 1981-82 there were also clinical signs of muscular dystrophy among the same calves. On the second farm calves with alopecia also showed signs of muscular dystrophy. The apparent relationship between alopecia and milk substitute feeding is discussed together with the possible involvement of vitamin E.

Maedi-visna virus infection in commercial flocks of indigenous sheep in Britain.

The recent identification of maedi-visna virus infection in three commercial flocks of indigenous sheep in Britain is described. In one flock the evidence suggested that overt clinical disease was present. The implications of the findings are discussed.

Severe disease in a dairy herd associated with acute infection with bovine virus diarrhoea virus, Leptospira harjo and Coxiella burnetii.

Between November 1984 and February 1985, a serious outbreak of pyrexia, diarrhoea, agalactia, metritis and severe weight loss affected most of the recently calved cows in a 183-cow dairy herd in Norfolk. Fifteen cows died and 20 were culled. Forty cows aborted during or after the outbreak, and many of them produced mummified fetuses; 18 calves were stillborn and three others died soon after birth. Necropsy of three affected cows revealed ulceration of the gastrointestinal tract similar to that seen in cases of mucosal disease. Bovine virus diarrhoea virus was isolated from the intestines of one cow that died soon after the onset of illness. The virus was also isolated from the blood of four acutely ill cows and seroconversion was demonstrated in three of those that survived. The virus was isolated from three aborted fetuses, a stillborn calf and a live neonatal calf. Body fluids from two aborted fetuses were seropositive for the virus as were sera from all the aborting cows tested. In addition to widespread seroconversion to bovine virus diarrhoea virus during the outbreak, there was serological evidence of recent infection with Leptospira interrogans serovar hardjo and Coxiella burnetii in a high proportion of cows. It was concluded that this was primarily an acute outbreak of bovine virus diarrhoea but its unprecedented clinical severity was probably associated with the concurrent introduction of L hardjo and C burnetii into an immunologically naive herd during the main calving period. Epidemiological analysis suggested that the source of the virus and L hardjo was down-calving heifers returning from communal marsh grazing.

Zinc toxicity, copper deficiency and anaemia in swill-fed pigs.

Zinc toxicity, copper deficiency and an associated anaemia among weaned swill-fed pigs is described. The source of zinc was flaking galvanising from the inside of bins used to store swill before processing. The disease condition readily responded to supplementation of the diet with copper sulphate. The interactions between dietary zinc, copper and calcium are discussed with reference to the swill-feeding industry. It is concluded that supplementary copper should be routinely included in the ration of swill-fed pigs and that the use of galvanised bins for storing swill should be avoided.

Natural scrapie in goats: case histories and clinical signs.

The case histories of the 20 goats affected with natural scrapie which have been examined since 1975 at the Central Veterinary Laboratory, Weybridge, are reviewed. Their ages ranged from two to seven years (median three years, four months) and 85 per cent of them were between two and four years old. The most common clinical signs were hyperaesthesia, ataxia and pruritus. The histories indicated that scrapie can occur in goats which have not been in contact with sheep.

Verocytotoxin-producing Escherichia coli O157 on a farm open to the public: outbreak investigation and longitudinal bacteriological study.

Verocytotoxin-producing Escherichia coli (VTEC) O157 phage type 2 (PT2) was isolated from three calves and two goats on a farm open to the public. Phenotypic and DNA-based typing showed that the strains were identical or very closely related to those obtained from an outbreak of VTEC O157 infection in two separate family groups who visited the farm. No VTEC O157 PT2 was isolated again from the farm during a 12-month longitudinal bacteriological study undertaken after the infected animals had been removed. However, phenotypically and genotypically indistinguishable VTEC O157 PT2/28 strains were detected in two of 474 faecal samples collected at monthly visits from 15 species of animals of various ages. The two isolates were obtained from calves from different sources sampled 146 days apart, suggesting that the infection had persisted on the farm although it was not detected in the other species. The same strain was subsequently isolated from another calf housed in the same pen as one of the infected calves. The longest period during which the organism was excreted was seven days. No VTEC O157 was isolated either from 204 replacement animals (including 138 orphan lambs and 10 calves) brought in from various sources, and sampled while they were kept in isolation for two weeks before being introduced to the farm, or from environmental samples. During the study a visitor became ill with VTEC O157 PT2. However, the isolate was distinct from those recovered from the farm and there was no evidence to suggest that the visit was the source of the infection.

Prevalence of antibodies to bovine virus diarrhoea virus and other viruses in bulk tank milk in England and Wales.

Bulk tank milk samples from 1070 dairy herds in England and Wales were tested by ELISA for antibodies to bovine virus diarrhoea virus (BVDV). A subset of 341 herds was tested by ELISA for antibodies to bovine herpesvirus 1 (BHV-1), bovine respiratory syncytial virus (BRSV) and bovine coronavirus (BCV). None of the herds had less than 40 dairy cows and none had been vaccinated against BVDV. The prevalence of BVDV antibody-positive herds in the national population was estimated at 95 per cent and approximately 65 per cent of the herds had a high level of bulk tank antibody suggestive of recent infection with BVDV. Dairy herds in East Anglia and the south-east of England had a significantly lower risk of being BVDV antibody-positive than herds in the rest of England and Wales. However, these regional differences tended to diminish with increasing herd size. Around 69 per cent of the herds were BHV-1 antibody-positive and all the herds were antibody positive to BRSV and BCV. Comparison with earlier serological surveys revealed that there had been little change in the prevalence and distribution of BVDV antibody-positive herds in England and Wales over the last 20 years, but that there had been an increase in the prevalence of BHV-1 antibody-positive herds.