Vaccination program in the response to the 2007 equine influenza outbreak in Australia.

At the time of the initial notification of the occurrence of equine influenza (EI) in Australia in August 2007, vaccination was restricted to horses for which it was an import requirement and only with the approval of the state or territory Chief Veterinary Officer. This paper describes the complexities involved in the selection of a vaccine and its distribution. A combination of ring, predictive and blanket vaccination was implemented during the response. The specific vaccination programs, including its use in buffer zones and for movement of horses, the performance of the vaccine, any adverse reactions and the effect on exposure of vaccinated horses to circulating virus, are also described. Vaccination is considered to have made a valuable contribution to the containment and subsequent eradication of EI from Australia and to risk management in the resumption of horse activities in affected areas from December 2007. Movement restrictions and other biosecurity measures were critically important in controlling the spread of EI and contributing to its eventual eradication, and vaccination was an aid to these measures.

Injury caused by self-inoculation with a vaccine of a Freund's complete adjuvant nature (Gudair) used for control of ovine paratuberculosis.

OBJECTIVE: To document the occurrence and consequences of accidental self-inoculation of vaccinators (producers, farm employees, contractors) with the recently registered Gudair vaccine for the control of ovine paratuberculosis in Australia. DESIGN AND PROCEDURE: A survey of the first 50 primary producers permitted to use the vaccine in sheep and a description of six cases of accidental self-inoculation for which medical attention was sought, and which occurred after the vaccine became widely available. RESULTS: The survey recorded that, of 37 respondents vaccinating 155,523 sheep, there were 21 incidents of exposure to the vaccine, an overall rate of one incident per 7406 vaccinations. In five of these incidents there was only superficial skin contact with vaccine; in 16 there was needle penetration without vaccine injection. There were no reports of self-inoculation with vaccine. Six cases of self-inoculation with Gudair vaccine that required medical intervention are described. Of these five were in males and one in a female; four involved injection of vaccine into the leg and single cases involved a foot or hand. Most cases required surgical removal of the injected vaccine to allow wound repair; three required extensive surgery and open drainage. Even with surgery recovery took as long as 9 months. Possible risk factors for self-inoculation and the resulting outcome are discussed. CONCLUSIONS: Gudair ovine paratuberculosis vaccine can cause prolonged granulomatous inflammation if inadvertently injected into human tissue. After.self-inoculation, early surgical debridement of the damaged tissue and drainage to remove the vaccine material are advised to avoid progression to extensive necrosis.

Determinants of dermal exposure relevant for exposure modelling in regulatory risk assessment.

Risk assessment of chemicals requires assessment of the exposure levels of workers. In the absence of adequate specific measured data, models are often used to estimate exposure levels. For dermal exposure only a few models exist, which are not validated externally. In the scope of a large European research programme, an analysis of potential dermal exposure determinants was made based on the available studies and models and on the expert judgement of the authors of this publication. Only a few potential determinants appear to have been studied in depth. Several studies have included clusters of determinants into vaguely defined parameters, such as 'task' or 'cleaning and maintenance of clothing'. Other studies include several highly correlated parameters, such as 'amount of product handled', 'duration of task' and 'area treated', and separation of these parameters to study their individual influence is not possible. However, based on the available information, a number of determinants could clearly be defined as proven or highly plausible determinants of dermal exposure in one or more exposure situation. This information was combined with expert judgement on the scientific plausibility of the influence of parameters that have not been extensively studied and on the possibilities to gather relevant information during a risk assessment process. The result of this effort is a list of determinants relevant for dermal exposure models in the scope of regulatory risk assessment. The determinants have been divided into the major categories 'substance and product characteristics', 'task done by the worker', 'process technique and equipment', 'exposure control measures', 'worker characteristics and habits' and 'area and situation'. To account for the complex nature of the dermal exposure processes, a further subdivision was made into the three major processes 'direct contact', 'surface contact' and 'deposition'.

Use of pooled fecal culture for sensitive and economic detection of mycobacterium avium subsp. paratuberculosis infection in flocks of sheep.

Ovine Johne's disease, or paratuberculosis, occurs in many countries. In Australia, surveillance using serology is used as part of a control program, but the testing regime is costly relative to its sensitivity. For this reason, culturing of Mycobacterium avium subsp. paratuberculosis in fecal samples pooled from a number of sheep was evaluated. Initially, the effect of pooling on the sensitivity of fecal culture was evaluated using samples from 20 sheep with multibacillary paratuberculosis and 20 sheep with paucibacillary paratuberculosis, each confirmed histologically. All multibacillary cases and 50% of paucibacillary cases were detected by culturing of feces at a pooling rate of 1 infected plus 49 uninfected sheep. In a pilot-scale study in 1997, M. avium subsp. paratuberculosis was detected by pooled fecal culture on 93% of 27 infected farms which were identified originally based on history, clinical signs, and one or more rounds of testing using serologic and histopathologic examinations. Pooled fecal culture was compared with serologic examination for submissions from 335 farms where both tests had been conducted on the same sheep and was significantly more sensitive (P<0.001). Computer simulation of random sampling indicated that the testing of 6 pools of 50 sheep would provide 95% confidence in detecting > or =2% prevalence of infection. The estimated laboratory cost of pooled fecal culture when applied as a flock test is approximately 30% that of serologic examination, and sample collection costs are lower. It is recommended that pooled fecal culture replace serologic examination for detection of M. avium subsp. paratuberculosis infection at the flock level.

Comparison of gene probe and conventional methods for the differentiation of ovine footrot isolates of Dichelobacter nodosus.

In a collaborative study that involved four Australian veterinary diagnostic laboratories a gene probe test based on the recombinant plasmids pJIR318, pJIR314B, and pJIR313, which contain genomic vap or vrl regions, was compared with conventional tests used for the differential diagnosis of ovine footrot. A total of 771 clinical dichelobacter nodosus isolates were tested and designated as belonging to one of several gene probe categories. The results showed that 87% of the virulent isolates belonged to gene probe category 1, compared to only 6% of the benign isolates. It was concluded that there was good correlation between the gene probe test and the virulence designation of these isolates as well as the results of elastase, gelatin-gel and protease isoenzyme tests. Furthermore, the gene probe test was converted to a polymerase chain reaction (PCR)-based test. It is suggested that diagnostic laboratories consider carrying out both this PCR test and tests based on the extracellular proteases of D. nodosus.

Assessment of gelatin gel and elastase tests for detection of protease activity of Dichelobacter nodosus isolates from ovine footrot.

Protease tests (the gelatin gel protease thermostability test, the elastase test or both) were performed on 4296 isolates of Dichelobacter nodosus derived from 452 outbreaks of ovine footrot occurring in New South Wales. Both tests showed a high level of repeatability. In the gelatin gel test, culture broths were heated for 16 min at 66.8 degrees C. Heated broths containing thermostable protease digested gelatin (positive gelatin gel test) while those broths containing thermolabile protease failed to digest gelatin (negative gelatin gel test). Gelatin gel positive isolates were unable to be graded into subcategories on the basis of the percentage stability of their protease. In the elastase test, the ability of isolates to digest (positive elastase test) or not digest elastin particles (negative test) was measured up to 28 days incubation. Individual elastase positive isolates yielded a graded result based on the number of days to reach a positive result. There was a very high level of agreement between the gelatin gel and the elastase tests consistent with their separating isolates into two groups based on protease activity (either gelatin gel positive and elastase positive or gelatin gel negative and elastase negative). Either test is suitable for use in footrol control and eradication schemes. The gelatin gel test provides clearcut separation of isolates into positive and negative categories and has the major advantage of yielding a more rapid result than the elastase test. The elastase test should be utilised where a graded assessment of protease activity is desired.

Meningoencephalitis and other conditions associated with Histophilus ovis infection in sheep.

Histophilus ovis was isolated from 29 sheep in 20 flocks and 2 artificial insemination (AI) centres in southern New South Wales from 1984 to 1990. The clinical and pathological findings were consistent with previous reports and included polyarthritis (7 flocks), epididymo-orchitis (5), meningoencephalitis (3), pneumonia (3), septicaemia (2), mastitis (1) and metritis (1). Six sheep had meningoencephalitis, a syndrome not previously associated with H ovis infection in sheep, which was similar pathologically to thromboembolic meningoencephalitis in cattle, caused by the related organism, Haemophilus somnus. H ovis was isolated from the semen of 12-month-old rams in a flock that had polyarthritis due to H ovis, in 4-month-old ram lambs and from the uterus of a ewe in a flock that had sporadic cases of H ovis septicaemia.

Yersinia species isolated from sheep with enterocolitis.

In 40 submissions to the Regional Veterinary Laboratory (RVL) Wagga Wagga from sheep in southern New South Wales from 1981 to 1989, 53 isolates of Yersinia sp were recovered from 45 sheep in 37 flocks. Of 53 isolates, 26 were identified as Y. pseudotuberculosis, 20 as Y. enterocolitica, 5 as Y. intermedia and 2 as Y. frederiksenii. Twelve isolates of Y. pseudotuberculosis tested in the slide agglutination test all belonged to serotype III. The 20 Y. enterocolitica isolates were categorised biochemically as biotype 5 strains and, of 6 isolates serotyped, all belonged to serogroup 2,3. Outbreaks of yersiniosis were most common in late winter and early spring and affected flocks often had experienced a change in husbandry. Infection with Yersinia sp was associated with diarrhoea, illthrift and mortality. At necropsy, congestion and occasionally thickening of the intestinal mucosa were observed in affected sheep. Gastrointestinal nematodiasis and coccidiosis often were concurrent findings. The characteristic histological lesion in sheep infected with Y. pseudotuberculosis was acute segmental suppurative erosive enterocolitis. There were no lesions consistently associated with Y. enterocolitica, Y. intermedia or Y. frederiksenii.

Clostridial myocarditis in lambs.

Five outbreaks of myocarditis were investigated in young sheep. They occurred during late winter and spring when there was lush growth of pasture following a prolonged period of drought. Clinically the disease was characterised by sudden death and pathological findings were dominated by acute multifocal locally extensive necrotising and haemorrhagic myocarditis. A fluorescent antibody technique was used to demonstrate the presence of Clostridium chauvoei in paraffin embedded sections of myocardium from 4 of the outbreaks.

Examination of rams culled during an ovine brucellosis accredited free flock scheme.

During the early stages of an Ovine Brucellosis Accredited Free Flock Scheme in New South Wales 62 rams were examined to determine the status of their flocks of origin with regard to infection with Brucella ovis. Forty rams were selected because they were either single reactors to low titre or one of a small number of reactors in a B. ovis complement fixation test of the whole ram flock. Twenty two rams were selected because they had palpable abnormalities within the scrotum but were negative serologically. After serological, pathological, bacteriological and histological examinations they were classified in the ensuing categories: 7 positive, 7 inconclusive, 26 false positive and 22 with other lesions. The usefulness of this classification, particularly within the accreditation scheme is discussed.

An association between encephalomyocarditis virus infection and reproductive failure in pigs.

An outbreak of reproductive failure, characterised by mummified foetuses and stillbirths, was investigated in an intensive piggery. Six foetuses that died towards the end of gestation had multifocal myocardial necrosis and encephalomyocarditis virus was recovered from 4 of these foetuses but not from 6 mummified foetuses. There was also a significant increase in failure of conception or early embryonic deaths in sows mated at the same time as sows which produced affected litters.

Cryptosporidial infection of piglets.

Cryptosporidia were detected in the brush border of villous epithelium in the small intestine of 4 piglets 2 to 9 weeks old. Although the 4 piglets had been suffering from diarrhoea no specific role could be attributed to the cryptosporidia. Other than damage to the brush border there were no significant histological abnormalities in the small intestine associated with the presence of cryptosporidia.

The New South Wales mastitis control program. 2. Effect upon bacterial infections.

Bacteriological examinations were made on quarter samples from cows in 35 herds over a 3 year period to monitor the response in a mastitis control program. Initially, Staphylococcus aureus predominated in 32 of the herds and the mean herd prevalence was 26%. The control measures halved this rate but there was considerable variation in response between herds. The decline occurred rapidly and there was a significant reduction (P less than 0.01) by 3 months. Streptococcus agalactiae predominated in 3 herds and the overall infection rate was 4.9%. Control measures eliminated the infection completely from most herds but reinfection occurred in 2 herds. The greatest decline occurred in the first 6 months and was significant (P less than 0.05). The measures had little effect upon Str. uberis and Str. dysgalactiae which remained fairly consistently at low levels. Initially, strains of Staph. aureus resistant to penicillin were dominant in most herds. In a minority of herds strains resistant to streptomycin predominated and in these herds there was a concurrent resistance to penicillin. These patterns did not change greatly over the control period. Resistance by Str. agalactiae to streptomycin occurred in most herds at the start of the program.