A study of outbreaks of Aujeszky's disease in cattle. I. Virological and epidemiological findings.

Twenty-nine outbreaks of Aujeszky’s disease in cattle, involving 54 animals, were studied virologically and epidemiologically. The outbreaks could be divided into two distinct groups, viz., such with pruritus on the anterior (Group I) and such with pruritus on the posterior part of the body (Group II). Though low, the average number of affected animals per outbreak was twice as high in Group I as in Group II. Besides in the tissue of the central nervous system, virus was demonstrated in the oral, pharyngeal, and nasal mucous membranes of eight out of 12 animals from Group I outbreaks, which was thought to be indicative of respiratory infection, and in the vagina of the three animals with perineal pruritus from which such material was examined. It is concluded that the site of pruritus need not be identical with the site of virus entry. The probable routes of infection in the outbreaks examined will be discussed in detail in a subsequent paper.     

The immunogenic properties of Salmonella typhi-murium in sheep

Extract

Salmonellosis of adult sheep due to infection with Salmonella typhi-murium was first recognized and confirmed bacteriologically in New Zealand in March, 1949. Since then, 100 outbreaks have been identified, most of which have occurred in the North Island. These outbreaks have occurred on farms varying in topography and under different conditions of management. With one exception, none of these outbreaks, which occur mainly in late Summer and Autumn, has been associated with transit by truck or rail journeys. In 1950, consideration was given to the possibility of affording protection by prophylactic vaccination, and the purpose of this paper is to record the results of some experiments carried out at Wallaceville and in the field with that object.     

Observations on outbreaks of respiratory disease in calves associated with parainfluenza type 3 virus and respiratory syncytial virus infection.

In four outbreaks of indoor calf pneumonia, dyspnoea was a prominent clinical finding. At necropsy it was associated with pneumonia involving the cranial lobes of the lung and severe pulmonary emphysema. Histological examination of lung tissue revealed bronchiolitis and alveolitis with alveolar epithelial cell hyperplasia and multinucleate syncytium formation. Intraalveolar haemorrhage, intra-alveolar oedema and hyaline membrane formation were also noted. In all cases parainfluenza type 3 (PI3) virus was isolated from the lungs. In each of the four outbreaks there was evidence of PI3 virus and respiratory syncitial virus (RSV) infection.     

Adenovirus infection in lambs. II. Experimental infection of lambs.

Adenovirus strain GY/14 isolated during a natural outbreak was used in experimental infection. Three weeks old lambs responded with temperature rise, respiratory symptoms and diarrhoea to the infection. Infection spread to a contact animal, too. Reisolation of the virus was successful from the nasal discharge and feces from the 3rd to 10th, and the 3rd to 5th day following infection, respectively. In the killed experimental animals the pathological and histological changes observed were similar to those observed in natural cases. On comparing the natural outbreaks with the experimental infection the only difference appeared in the severity of the changes. Following the experimental infection characteristic nuclear inclusions appeared in the nasal and bronchiolar epithelium, in the alveolar septal cells and in the reticular cells of the lymph nodes. Epizootiologic observations and experimental results confirm the assumption that our adenovirus strains isolated from natural cases are pathogenic for lambs.     

P-58 Three cases of pathological dermal deposits associated with internal diseases in dogs (xanthomatosis, calcinosis and amyloidosis)

Intestinal parasites have been anecdotally associated with pruritus in dogs. A relationship was proposed when the elimination of a specific parasite resolved the pruritus, and re-infection with a parasite caused the pruritus to recur. Ascarids, coccidia, hookworms, tapeworms and whipworms have all been incriminated. Recent reports in the human and veterinary literature have suggested that there may be a relationship between Giardia infection and the development of pruritus and other allergic signs. In order to determine if there is an association between infection with Giardia and pruritus in dogs, faecal samples were collected from 71 pruritic dogs and 101 clinically normal dogs. Three faecal samples from each animal were analysed using a zinc-sulphate concentration technique for the presence of Giardia cysts, and one randomly selected faecal sample from each dog was analysed with an ELISA for Giardia -specific antigen. Ten of 101 dogs (9.9%) in the clinically normal group tested positive with the ELISA, and Giardia cysts were detected in the faeces of seven of these antigen-positive dogs. No Giardia cysts were found in the dogs that tested negative with the ELISA. None of the dogs in the pruritic group tested positive for Giardia by either method. The results indicated a negative association between Giardia infection and pruritic skin disease ( P  = 0.006). Cephalexin was commonly used in the pruritic group, but not in the control group, and may therefore be an explanatory variable.
Funding: Ontario Veterinary College Pet Trust.     

The epidemic of foot-and-mouth disease in Saskatchewan, Canada, 1951-1952.

The epidemic of foot-and-mouth disease in Saskatchewan in 1951 and 1952 was studied in order to determine origins of outbreaks and methods of spread. The epidemic was initially considered to be vesicular stomatitis and foot-and-mouth disease was not recognized until February 1952, three months after the initial infection. The reports prepared at that time were reviewed in order to obtain details of the numbers of animals infected and the source and date of infection for the outbreaks. Methods of spread were rated according to their likelihood. The introduction of infection by an immigrant through his clothes as well as by sausage was possible. The sequence of events from the first outbreak to the spread from a feedlot/packing plant and from a dairy farm, which failed to report the disease, were clarified. Methods of spread included movement of animals, animal products and people and the airborne route. Milk delivery and artificial insemination did not result in spread of infection. The quarantine of affected farms reduced spread by animals and deterred visits by people. The original diagnosis of vesicular stomatitis was due to misinterpretation of a lesion in an inoculated horse. Laboratory tests established the presence of foot-and-mouth disease. The limited extent of the epidemic, despite the delay in diagnosis, is attributed to (i) the low density of cattle, (ii) few infected pigs and hence less airborne virus and (iii) absence of waste food feeding and milk collection in addition to the limited quarantine imposed.     

Evaluation of an enzyme-linked immunosorbent assay (ELISA) for detection of Taenia saginata cysticercosis in cattle.

Serum IgG response of cattle with cysticercosis caused by Taenia saginata was studied in an enzyme-linked immunosorbent assay (ELISA) where a T. saginata metacestode surface extract was used as antigen. In experimentally infected calves, a sharp rise in specific antibody levels was found 3-4 weeks after the infection followed by a logical level of detection corresponded to about 25 cysts. The ELISA was employed in cattle herds where cysticercosis outbreaks had occurred and also in supposedly uninfected herds. Significantly increased antibody levels were found in the herds with massive cysticercosis cases. The test was not adapted for individual diagnosis as some animals of the uninfected herds, especially within the older age groups, had elevated antibody values. The ELISA was, however, useful in the investigation of outbreaks to determine the extent and pattern of the infection in the herd. The rate of decline in antibody levels in these herds was studied by follow up sampling. The increased antibody levels in the infected herds were also reflected in colostrum-fed calves. This observation was employed to estimate the time of infection.     

Characterization of Enterococcus hirae outbreaks in broiler flocks demonstrating increased mortality because of septicemia and endocarditis and/or altered production parameters

In Denmark, increased problems associated with streptococci and enterococci have been observed in broilers and broiler parent flocks, resulting in increased mortalities, uneven flocks, and subsequent downgrading and increased condemnations. Postmortem lesions associated with recent outbreaks due to Enterococcus hirae have been accompanied or dominated by septicemia and endocarditis. As a result of infection at an early age and relatively low mortality rates, outbreaks are not always clearly defined and may go unnoticed or may be attributed to poor chick quality. For the same reasons, the pathogenesis and epidemiology of observed outbreaks has only remained speculative. Four separate outbreaks associated with E. hirae infections in broiler flocks occurring between 1998 and 2002 have been investigated. Two of the outbreaks indicated evidence of two separate clones, with 89% and 79% of isolates involved in the individual outbreaks belonging to a single pulsed-field gel electrophoresis (PFGE) profile, respectively. Another outbreak (outbreak 4) demonstrated clear clonality, with all isolates demonstrating affinity to one of two PFGE profiles that differed by only two bands. However, all three outbreaks demonstrated a different clone. The remaining outbreak was nondonal, with isolates distributed between six separate PFGE profiles. One of the outbreaks (outbreak 4) was descended from a parent broiler flock previously associated with an outbreak of Streptococcus gallinaceus; the flock also exhibited septicemia and endocarditis. Initial indications suggested the possibility of vertical transmission of S. gallinaceus to the current broiler flock, causing infection. By extended phenotypic characterization and subsequent genetic characterization, including 16S rRNA sequencing, all strains from the four outbreaks were confirmed as E. hirae. This investigation highlights the problems associated with characterizing enterococci infections in broiler flocks.     

Control of Mycobacterium bovisinfection in two sika deer herds in Ireland

In a number of countries, tuberculosis (due to infection with Mycobacterium bovis) is a significant health problem of captive deer. This paper describes outbreaks of bovine tuberculosis in sika deer (Cervus nippon) on two farms in Ireland and the methods used to control the disease. On Farm A, infection was first detected during 1993. The infection was eradicated using a programme of test and removal, in association with segregation of young animals. A second outbreak (also due to infection with M. bovis, but a different RFLP profile) was detected in 2002. In the latter outbreak, infection was particularly prevalent in two groups of young deer. M. bovis with the same RFLP profile was also isolated in a badger found dead on the farm. Control was achieved by test and removal in association with herd management changes. In Herd B, infection was first detected in 1995, and subsequently eradicated using test and removal alone. In Herd A, re-infection remains an ongoing risk. Control rather than eradication of infection may more realistic in the short-to medium-term.     

A cross-sectional study of risk factors affecting the outcome of rabbit haemorrhagic disease virus releases in New South Wales

OBJECTIVE: To determine what factors governed the extent of outbreaks of rabbit haemorrhagic disease (RHD) following releases in New South Wales. DESIGN: Retrospective cross-sectional study. PROCEDURE: Information from the data set of official releases was subjected to two preliminary analyses. More comprehensive information on a subsample of official RHD releases, sites and animals was gathered by telephone survey of Rural Lands Protection Board staff and farmers. Data were analysed using multivariate techniques to determine which factors were associated with rabbit mortality within one month of RHDV release, within several months of release and in affecting the proportion of the population killed. RESULTS: A strong association was found between the presence of heavy flea infestation (odds ratio 2.7), breeding in rabbits and outbreaks of RHD. For each week following breeding there was an 8% decline in the odds of an outbreak. Low temperatures also promoted outbreaks. Less important effects included the prior presence of RHD at the release site, which reduced the likelihood and severity of outbreaks. The presence of cattle and proximity to the nearest water body were associated with increased severity and likelihood of outbreaks respectively. CONCLUSION: Both breeding of rabbits and associated high flea numbers may act together or independently in promoting outbreaks of RHD. Stresses involved with rabbit reproduction and low environmental temperatures also appear to influence the likelihood of outbreaks. The effects of proximity to cattle and water suggests that both flies and mosquitoes may have a minor role in local transmission.     

The role of pyoderma in pruritus

In the approach to the pruritic patient, it is important to first determine if a pyoderma is present. A thorough investigation of the integument should be undertaken during the physical examination. There are a wide variety of clinical appearances of pyodermas, so the clinician should recognize the lesions that are suggestive of infection (epidermal collarettes, draining tracts, and so on). When infection is present, it is necessary to direct therapy at the pyoderma and then re-evaluate the patient. Any animal that presents with a pruritic pyoderma deserves proper therapy directed at the infection before the clinician can assess the role that the pyoderma is contributing to the pruritus. Rational therapy in these cases requires that one determine the cause of the itch rather than merely masking the symptom of pruritus.     

Chicken Faeces Garden Fertilizer: Possible Source of Human Avian Influenza H5N1 Infection

Avian influenza H5N1 infection in humans is typically associated with close contact with infected poultry or other infected avian species. We report on human cases of H5N1 infection in Indonesia where exposure to H5N1‐infected animals could not be established, but where the investigation found chicken faeces contaminated with viable H5N1 virus in the garden fertilizer. Human cases of avian influenza H5N1 warrant extensive investigations to determine likely sources of illness and to minimize risk to others. Authorities should regulate the sale and transportation of chicken faeces as fertilizer from areas where H5N1 outbreaks are reported.     

Yersinia enterocolitica infection in breeding colonies of ruffed lemurs

Two outbreaks of yersiniosis caused by Yersinia enterocolitica occurred in breeding colonies of red ruffed lemurs (Varecia variegata rubra) and black and white ruffed lemurs (Varecia variegata variegata) housed in outdoor enclosures during the winter breeding season and spring birth season, respectively. Seven of 11 animals at risk in the combined outbreaks became ill, and 3 died of acute to chronic infection. Clinical signs included anorexia, lethargy, diarrhea, abdominal pain, and hyperpyrexia. Necropsy findings included ulcerative enterocolitis and multifocal necrosis and abscess formation in mesenteric lymph nodes, liver, spleen, kidneys, and lungs. Histologically, lesions were characterized by necrotizing inflammation containing masses of basophilic bacteria. Yersinia enterocolitica serotype 0:2 was isolated from lesions. Neomycin sulfate given orally and chloramphenicol given intramuscularly were effective in treatment early in the course of the disease or in mild cases. In severe cases, lemurs did not respond to antibiotic and fluid therapy. Exposure to soil contaminated with infected rodent feces, stress, and behavioral factors in the ruffed lemur species are believed to have precipitated the infection.     

Percloacal infection of chickens with Salmonella typhimurium

The characteristics of Salmonella typhimurium infection in hatchlings and adult poultry given by the intravenous, oral and percloacal routes were compared. Based on LD₅₀ determinations, 1-day-old birds were most susceptible to percloacal infection. It is claimed that this infection technique yields predictable results in terms of mortality and numbers of organisms in the liver, spleen and intestinal tissues. Though older birds do not die when given large doses of organisms by this route, small numbers are sufficient to establish transient infection or carriage in the intestine.Based on quantitative data, the course of the percloacal infection appeared similar to that given by the oral route in hatchlings; however, the number of organisms required to establish infection by the former route was significantly less. It is suggested that the percloacal infection route may be a useful model for studying Salmonella infection-immunity in birds, particularly if resistance mechanisms operating in the intestine are to be taken into account. The possibility that it may be an important infection route in natural circumstances must also be considered.     

Neonatal infections in puppies caused by Escherichia coli serogroups 04 and 025.

Three cases of neonatal E. coli infection in Newfoundland dogs are described. The serological examination showed that the implicated E. coli belonged to sero-group 04 in two outbreaks while sero-group 025 was responsible for one outbreak. In one of the kennels with implication of 04, this 0-group was also isolated from adult dogs with diarrheal conditions.     

Equine coronavirus: An emerging enteric virus of adult horses

Equine coronavirus (ECoV) is an emerging virus associated clinically and epidemiologically with fever, depression, anorexia and less frequently colic and diarrhoea in adult horses. Sporadic cases and outbreaks have been reported with increased frequency since 2010 from Japan, the USA and more recently from Europe. A faeco‐oral transmission route is suspected and clinical or asymptomatic infected horses appear to be responsible for direct and indirect transmission of ECoV. A presumptive clinical diagnosis of ECoV infection may be suggested by clinical presentation, haematological abnormalities such as leucopenia due to lymphopenia and/or neutropenia. Confirmation of ECoV infection is provided by specific ECoV nucleic acid detection in faeces by quantitative PCR (qPCR) or demonstration of coronavirus antigen by immunohistochemistry or electron microscopy in intestinal biopsy material obtained ante or post mortem. The disease is generally self‐limiting and horses typically recover with symptomatic supportive care. Complications associated with disruption of the gastrointestinal barrier have been reported in some infected horses and include endotoxaemia, septicaemia and hyperammonaemia‐associated encephalopathy. Although specific immunoprophylactic measures have been shown to be effective in disease prevention for closely‐related coronaviruses such as bovine coronavirus (BCoV), such strategies have yet not been investigated for horses and disease prevention is limited to basic biosecurity protocols. This article reviews current knowledge concerning the aetiology, epidemiology, clinical signs, diagnosis, pathology, treatment and prevention of ECoV infection in adult horses.     

P‐56 Evaluation of the association between Giardia infection and pruritic skin disease in dogs

Intestinal parasites have been anecdotally associated with pruritus in dogs. A relationship was proposed when the elimination of a specific parasite resolved the pruritus, and re‐infection with a parasite caused the pruritus to recur. Ascarids, coccidia, hookworms, tapeworms and whipworms have all been incriminated. Recent reports in the human and veterinary literature have suggested that there may be a relationship between Giardia infection and the development of pruritus and other allergic signs. In order to determine if there is an association between infection with Giardia and pruritus in dogs, faecal samples were collected from 71 pruritic dogs and 101 clinically normal dogs. Three faecal samples from each animal were analysed using a zinc‐sulphate concentration technique for the presence of Giardia cysts, and one randomly selected faecal sample from each dog was analysed with an ELISA for Giardia‐specific antigen. Ten of 101 dogs (9.9%) in the clinically normal group tested positive with the ELISA, and Giardia cysts were detected in the faeces of seven of these antigen‐positive dogs. No Giardia cysts were found in the dogs that tested negative with the ELISA. None of the dogs in the pruritic group tested positive for Giardia by either method. The results indicated a negative association between Giardia infection and pruritic skin disease (P = 0.006). Cephalexin was commonly used in the pruritic group, but not in the control group, and may therefore be an explanatory variable. Funding: Ontario Veterinary College Pet Trust.     

Modeling the spread and control of foot-and-mouth disease in Pennsylvania following its discovery and options for control

In this paper, we simulate outbreaks of foot-and-mouth disease in the Commonwealth of Pennsylvania, USA - after the introduction of a state-wide movement ban - as they might unfold in the presence of mitigation strategies. We have adapted a model previously used to investigate FMD control policies in the UK to examine the potential for disease spread given an infection seeded in each county in Pennsylvania. The results are highly dependent upon the county of introduction and the spatial scale of transmission. Should the transmission kernel be identical to that for the UK, the epidemic impact is limited to fewer than 20 premises, regardless of the county of introduction. However, for wider kernels where infection can spread further, outbreaks seeded in or near the county with highest density of premises and animals result in large epidemics (>150 premises). Ring culling and vaccination reduce epidemic size, with the optimal radius of the rings being dependent upon the county of introduction. Should the kernel width exceed a given county-dependent threshold, ring culling is unable to control the epidemic. We find that a vaccinate-to-live policy is generally preferred to ring culling (in terms of reducing the overall number of premises culled), indicating that well-targeted control can dramatically reduce the risk of large scale outbreaks of foot-and-mouth disease occurring in Pennsylvania.     

Fatal outbreaks in dogs associated with pantropic canine coronavirus in France and Belgium

Infection with pantropic canine coronavirus was detected during outbreaks in France and Belgium. This was concurrent in most cases with canine parvovirus 2c. One outbreak was a deadly acute systemic disease with a single pantropic canine coronavirus infection. This is the first report of a fatality associated with pantropic canine coronavirus alone outside Italy.     

Susceptibility of adult chickens, with and without prior vaccination, to challenge with Marek's disease virus

Marek's disease (MD) outbreaks can occur in previously healthy adult layer or breeder flocks. However, it is not clear whether such outbreaks are caused by recent challenge with highly virulent (vv and vv+) strains of MD virus (MDV; i. e., new infection hypothesis) or by exacerbation of an earlier MDV infection (i. e., old infection hypothesis). To discriminate between these hypotheses, adult White Leghorn chickens of laboratory strains or commercial crosses with or without prior vaccination or MDV exposure were challenged at 18-102 wk of age with highly virulent MDVs, and lesion responses were measured. Horizontal transmission was studied in one trial. Challenge of adult chickens, which were free from prior MDV vaccination or exposure, with highly virulent MDV strains induced transient paralysis or tumors in 60%-100% of 29 groups (mean = 91%), and horizontal spread of virus was detected. The magnitude of the response was similar to that induced by challenge at 3 wk of age. In contrast, comparable challenge of adult chickens, which had been vaccinated or exposed to MDV early in life, induced transient paralysis or tumors in 0%-6% of 12 groups (mean = 0. 5%), although some birds showed limited virologic evidence of infection and transmission of the virus to contacts. The MD responses were influenced by the virulence of the challenge virus strain, and to a lesser extent by virus dose and route of exposure. Strong inflammatory lesions were induced in the brain and nerves of adult specific pathogen-free (SPF) chickens at 9-15 days after infection. The low susceptibility of previously vaccinated and exposed groups to challenge at > or =18 wk of age suggests that late outbreaks of MD in commercial flocks are not likely a result of recent challenge alone and that additional factors could be involved.