Prevalence and regional distribution of scab, lice and blowfly strike in Great Britain

The prevalence of psoroptic mange (sheep scab), louse infestation and blowfly strike in sheep in Great Britain between March 2003 and February 2004 was investigated by means of a retrospective postal survey, stratified by region. Of the 3530 questionnaires sent out, 1067 were returned completed, a response rate of 30.2 per cent. Overall, 9 per cent of the farmers reported at least one outbreak of scab, 10.7 per cent reported an outbreak of lice and 75 per cent reported at least one case of blowfly strike. A mean of 1.4 per cent of ewes were struck by blowfly and 2.8 per cent of lambs. There were strong regional variations in disease prevalence, with scab and lice infestation being highest in Wales, Scotland and the north of England and blowfly strike highest in the south west of England.     

Blowfly strike prevalence in domestic rabbits in southwest England and Wales

The prevalence of blowfly strike in rabbits in southwest England and Wales was investigated using a retrospective postal survey of small animal and mixed veterinary practices. Questionnaires were sent to 474 practices; 219 were returned completed, giving a response rate of 46.2%. The prevalence of blowfly strike was estimated as the percentage of veterinary practices that reporting having treated at least one rabbit for strike between May and September 2005. Overall, 94.5% (+/-2.21) of practices treated at least one case of rabbit strike. Almost half, 49.3% (+/-11.3) of practices reported treating only 1-5 rabbits for blowfly strike in the study period; 32.8% (+/-4.56), 13% (+/-3.27) and 4.8% (+/-2.08) treated 6-10, 11-15 and more than 15 struck rabbits, respectively. In 46.3% (+/-4.84) of the practices most infested rabbits survived. For 40.4% (+/-4.77) of practices, about half the struck rabbits survived. However, for 13.3% (+/-3.30) of practices most struck rabbits were reported to have died. The practices reporting that most animals died were those that saw significantly fewer rabbits and fewer struck rabbits than practices where more animals survived. This suggests that training and experience in the appropriate care of infested rabbits may be critical in ensuring a favorable outcome.     

Prevalence, incidence and geographical distribution of serovars of Salmonella on dairy farms in England and Wales

A study of randomly selected dairy farms in England and Wales was made between October 1999 and February 2001 to estimate the prevalence and incidence of Salmonella serovars. The farms were enrolled through five milk-buying companies, which represented 63 per cent of the dairy farms in England and Wales, and they were sampled on up to four occasions (449 farms at visit 1, 272 farms at visit 2, 251 farms at visit 3 and 243 farms at visit 4). In total, 19,296 samples of pooled faecal pats and slurry were collected. The farm-specific prevalence of all serovars of Salmonella ranged from 12.1 per cent (95 per cent confidence interval [CI] 8.2 to 16.0 per cent) to 24.7 per cent (95 per cent CI 19.4 to 30.1 per cent) at each visit. The most common serovars identified were Salmonella Dublin (3.7 to 6.6 per cent farm-specific prevalence at each visit), Salmonella Agama (1.8 to 7.6 per cent) and Salmonella Typhimurium (2.6 to 4.1 per cent) The prevalence varied by region and month of sampling and increased in late summer. The incidence rate of all serovars of Salmonella was 0.43 (95 per cent CI 0.34 to 0.54) cases per farm-year at risk. There was no significant difference between the incidence rates of the common serovars S Typhimurium (0.07), S Dublin (0.06) and S Agama (0.13). A total of 29 Salmonella serovars were isolated. Few of the isolates were resistant to the 16 antimicrobial agents tested, except the isolates of S Typhimurium dt104, of which 67.9 per cent were resistant to at least five of them.     

Forecasting blowfly strike in Queensland sheep flocks

The occurrence of blowfly strike between 1993 and 1999, derived from the reported use of pesticides for flystrike control, was investigated in 247 sheep flocks in Queensland, Australia using autoregressive techniques. Although there was a small increase (0. 0016 per year) in flystrike incidence during the study period, this long-term linear trend was not significant (p=0.53). The occurrence of flystrike was best described by an autoregressive model that included flystrike in the previous 2 months: flystrike(t)=0.0170+0. 0392 flystrike(t-1)+0.3589 flystrike(t-2). Flystrike was associated with the southern oscillation index (SOI). The SOI is based on barometric pressure readings and is associated with periods of below- (negative SOI) and above-average (positive SOI) rainfall in northern Australia. Flystrike incidence was significantly (p=0.03) greater in months in which the SOI was positive. The strongest correlation (r=0.33) was found between flystrike incidence and the SOI 2 months previously. Using the SOI, the best-fitting autoregressive model describing flystrike was flystrike(t)=0.0238+0. 3033 flystrike(t-2)+0.0009 SOI(t-2). The incidence of flystrike was significantly (p<0.05) correlated with average monthly radiation (r=0.26), but not with average monthly maximum and minimum temperature, total rainfall, evaporation and vapour pressure. The best-fitting autoregressive model describing flystrike occurrence based on these variables was flystrike(t)=-0.0259+0.3610 flystrike(t-2)+0.0022 radiation(t). Results suggest that a useful early-warning system could be developed based on the correlation between flystrike incidence and the SOI up to 2 months previously. Such attempts to forecast flystrike may assist decision-making by wool producers with respect to flystrike control options, leading to more efficient control of blowfly strike in their industry.     

Control of sheep blowfly strike using fly-traps

The use of fly-traps for the control of sheep blowfly strike was examined on 12 commercial sheep farms in south west England in 2003. Two flocks acted as controls, with no prophylactic blowfly strike control. Four flocks of lambs and three flocks of ewes were protected only by blowfly traps, seven of the flocks of ewes and six flocks of lambs were protected by blowfly traps but also had proprietary insecticides applied to them at some stage. There was no difference in the abundance of L. sericata at the various sites. The highest incidence of strike was seen in the two control flocks where 10.9 and 5.8% of the ewes and 10.1 and 9.2% of the lambs were struck. Strike incidence in the flocks that used trapping only and flocks that used trapping plus a chemical preventive was on average five times lower than in the control flocks, but the percentages struck on the sites in the trapping only and trapping plus insecticide groups were not significantly different from each other. The results of this study show that traps can make an effective contribution to blowfly strike control on individual farms.     

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.     

Time-space clustering of reported blowfly strike in Queensland sheep flocks

The reported occurrence of blowfly strike in 57 sheep flocks in Queensland, Australia, was investigated for time-space clustering in an exploratory study using Knox's method. Flystrike occurrence peaked in late spring and early summer, with an additional late-autumn peak in southern-Queensland flocks. A total of 1596 case-pairs was examined. Significant clustering (P = 0.07) was only detected for case-pairs occurring within 3 months and 150 km of each other; 164 case-pairs were declared close compared to an expectation of 151. We suggest that factors common to a district (such as rainfall and temperature) are responsible for clustering of flystrike in Queensland.     

Prevalence of lice on dairy cattle in England and the bordering counties of Wales

A postal questionnaire was used to collect information on the prevalence of lice on cattle on a random sample of dairy farms in England and the bordering counties of Wales. Replies were received from 1040 (52.8 per cent) of the 1970 farms which were mailed. Fifty per cent of farmers reported having ever seen or suspected lice in their herds and 29 per cent reported possible infestations in the winter of 1996/97. Visits were made to 24 farms in the south west of England during February 1998. Twelve of the farmers said that they had seen or suspected lice in their herd since October 1997, and that lice were more frequently observed on the adult cattle. However, examination revealed lice on 18 of the 24 farms, and adult cattle were the least likely group to be infested.     

The effects of oviposition aggregation on the incidence of sheep blowfly strike.

The distribution of a parasite population within its natural host population can have a significant influence on the dynamics of both the host and parasite populations. The majority of parasite species are typically distributed in an aggregated manner within the host population, leaving most hosts lightly infected and a few hosts supporting very large parasite burdens. This paper presents a consideration of the effects of aggregation on the incidence of ovine cutaneous myiasis caused by the sheep blowfly, Lucilia sericata (Meigen). Using simulation analysis, the mechanisms causing larval aggregation are included in the model, allowing the consequences for control to be investigated. By explicitly incorporating host susceptibility, it becomes apparent that early in the season, strategies targeting the blowfly population may prove more effective in suppressing strike levels, whereas later in the season, treatment of the sheep population may be more beneficial. The analysis also shows that the greater the degree of aggregation, the fewer sheep that become struck and, hence, suggests that increasing the heterogeneity in susceptibility amongst a flock of sheep restricts strikes to relatively few sheep. Providing the highly-susceptible sheep could be identified, concentrating strikes on a low number of sheep would allow fewer sheep to be treated, leading to a more efficient means of controlling the blowfly population and suppressing strike.     

The efficacy of ivermectin jetting fluid for control of blowfly strike on sheep under field conditions

SUMMARY Seventeen trials involving 5737 sheep were conducted to test the efficacy of ivermectin jetting fluid (30 ppm in water) for the control of blowfly strike when applied to sheep either by standard hand jetting or through an automatic jetting race. Sheep were observed for up to 14 weeks after treatment and all strikes recorded. The level of fly challenge varied between trials, resulting in strike rates in untreated sheep ranging between 0 and 94%. At 12 weeks after treatment there were 93% fewer strikes in hand jetted sheep and 84% fewer strikes in machine jetted sheep when compared with untreated sheep. At this time point there was a 90%, 86% and 93% reduction in poll, body and breech strikes, respectively, when hand jetting was used, whereas machine jetting reduced poll, body, breech and pizzle strikes by 84%, 81%, 79% and 100%, respectively.     

A postal survey of blowfly strike occurrence in two Queensland shires

OBJECTIVE: To describe the occurrence of blowfly strike in sheep flocks in two shires located in south-eastern Queensland. DESIGN: Postal survey of woolgrowers within Stanthorpe and Inglewood shires. PROCEDURE: Questionnaire posted to woolgrowers in June 1999 seeking information on the monthly occurrence of flystrike and number of sheep at risk. RESULTS: Incidence of body strike and breech strike between August 1998 and May 1999 was 1.1 and 0.5%, respectively. The highest incidence of body strike and breech strike was reported in lambs (6.1%) and weaner sheep (1.5%), respectively. The seasonality of the incidence of body strike was bimodal (November and February), whereas the seasonality of the incidence of breech strike was unimodal (April). Occurrence of body strike within a 3-month period in flocks located within 40 to 50 km of each other was significantly (P < 0.05) clustered. CONCLUSION: Body strike appears to be more common than breech strike in the study area, mainly affects lambs and weaners and high-risk periods occur during late spring and autumn. Study results provide valuable information for planning blowfly strike control programs in the area such as timing of management procedures, use of fly traps), and enable the economic impact of flystrike on the industry in this area to be assessed.     

Prevalence of antibodies to Coxiella burnetii (Q fever) in bulk tank milk in England and Wales.

In the United Kingdom, the infection of people with Coxiella burnetii, the causative agent of Q fever, is of significant public health importance and is associated with contact with dairy cattle. An ELISA was developed for the detection of IgG antibodies against C burnetii in bulk tank milk, and in a survey of randomly selected samples from dairy herds in England and Wales, 21 per cent showed serological evidence of C burnetii infection.     

National intervention study of mastitis control in dairy herds in England and Wales

An intervention study was carried out on 52 dairy farms in England and Wales to determine whether the implementation of a well-specified mastitis control plan in herds with an incidence of clinical mastitis of more than 35 cases per 100 cows per year would reduce the incidence of clinical mastitis, and also reduce the incidence of increases in the somatic cell counts of individual cows. A clearly defined plan for the diagnosis and control of mastitis was developed by two veterinary specialists from the research literature. The herds were randomly allocated to receive the plan either at the start of the study (intervention herds) or after one year (control herds). Data on mastitis management and the farm environment were collected during farm visits. After one year there was a significant 22 per cent reduction in the proportion of cows affected with clinical mastitis on the intervention farms compared with the control farms. There were also significant reductions of approximately 20 per cent in the incidence of clinical mastitis and in the occurrence of increases in the somatic cell counts of individual cows from below, to above 200,000 cells/ml.     

Anthrax in England and Wales 1963-1972.

The records of confirmed anthrax diagnoses held by the bacteriology department of the Central Veterinary Laboratory, Weybridge, for the years 1963 to 1972 inclusive, were analysed. During this decade, 86 per cent of the 2944 deaths recorded were in cattle and 11 per cent in pigs, correlating significantly with the cattle and pig populations in England and Wales during this period. Also, the country could be separated into high and low prevalence counties for cattle anthrax. Norfolk and Somerset had higher than usual cattle deaths per farm ratios and the reasons for this are explored.     

Prevalence of faecal excretion of verocytotoxigenic Escherichia coli O157 in cattle in England and Wales

During the decade to 1999, the incidence of human infections with the zoonotic pathogen verocytotoxin-producing Escherichia coli O157 (VTEC O157) increased in England and Wales. This paper describes the results of a survey of 75 farms to determine the prevalence of faecal excretion of VTEC O157 by cattle, its primary reservoir host, in England and Wales. Faecal samples were collected from 4663 cattle between June and December 1999. The prevalence of excretion by individual cattle was 4.2 per cent (95 per cent confidence interval [CI] 2.0 to 6.4) and 10.3 per cent (95 per cent CI 5.8 to 14.8) among animals in infected herds. The within-herd prevalence on positive farms ranged from 1.1 to 51.4 per cent. At least one positive animal was identified on 29 (38.7 per cent; 95 per cent CI 28.1 to 50.4) of the farms, including dairy, suckler and fattening herds. The prevalence of excretion was least in the calves under two months of age, peaked in the calves aged between two and six months and declined thereafter. The phage types identified most widely were 4, 34 and 2, which were each found on six of the 29 positive farms.     

Epidemiology of Toxocariasis in England and Wales

Toxocara infection occurs through ingestion of parasite eggs excreted by dogs and cats, and can cause severe morbidity. The burden of disease in England and Wales is not well described, and the impact of public health campaigns conducted in the mid‐1990s is uncertain. This paper uses data from two extensive databases to explore the trends in this disease in England and Wales from the 1970s to 2009.     

Prevalence and regional distribution of paratuberculosis in dairy herds in The Netherlands

In the Netherlands a survey was conducted to estimate the prevalence of paratuberculosis in dairy herds. In total 15822 cows of at least 3 years of age, belonging to 378 herds were tested using an absorbed ELISA. Of these herds, 55% (n=207) had one or more serologically positive cows. Of the positive non-vaccinated herds, most had one (n=98) or two (n=49) positive cows. The percentage positive cows per herd was 2.5+/-3.2%.The true prevalences on cow and herd levels, based on a test sensitivity that ranged from 0.3 to 0.4 and a specificity that ranged from 0.985 and 0.995, were estimated at 2. 7-6.9% and 31-71%.Seven herds had been vaccinated against paratuberculosis and these herds had a significantly higher percentage of serologically positive cows (23%) than the non-vaccinated herds (2.5%).In conclusion, a small percentage of the dairy cows and a high percentage of the dairy herds in the Netherlands is serologically positive. The percentages true infected cows and herds are difficult to estimate precisely due to uncertainties in test sensitivity and specificity.     

Prevalence, spread and control of caprine arthritis-encephalitis virus in dairy goat herds in New South Wales

SUMMARY A study of the prevalence, spread and control of caprine arthritis-encephalitis virus (CAEV) in dairy goat herds in New South Wales (NSW) during 1986–1988 found that 56.8% of 1484 goats in 14 dairy herds were infected with CAEV. The prevalence of CAEV infection within most herds not implementing control measures increased during the study. At the end of the study, 59.7% of 1322 goats were infected. The prevalence of CAEV increased with age. Differences between breeds were less apparent. Within seven herds with a high standard of identification of goats, 149 of 812 goats seroconverted in an ELISA. Of these newly infected goats, 142 (95.3%) were > 1 yr of age and 96 (64.4%) were > 2 yr suggesting lateral spread of the virus. Most of the goats > 2 yr of age had been in the milking herd for a minimum of 3 to 6 months. The high seroconversion rate within the milking herd suggested that factors other than the ingestion of infected colostrum and milk before weaning were important for the spread of CAEV. Observations indicated that behaviour of goats, particularly reproductive behaviour among lactating does, and milking herd management practices are important in the spread of CAEV. A high density of livestock, poor livestock control and contamination of feed, water, equipment and personnel were implicated in transmission. Poorly functioning milking machines may also be involved. CAEV was eradicated from 3 herds by the implementation of strict control measures.