Identification of auto-antigens in skin scrapings from scabies-infected pigs.

Sarcoptes scabiei continues to cause major health and economic problems in a large range of animals and humans. Although the inflammatory response to the mite and its antigens is known to cause the main pathology, little work has been carried out on this response at the site of infection. This report presents an initial analysis of the proteins found in skin scrapings and their antigenic responsiveness in pigs. Skin scrapings and mite extracts were isolated from chronically infected sows while infected and uninfected sera were isolated from pigs with confirmed infections or mange-free pigs, respectively. Electrophoresis and sequencing confirmed the main components of both the skin and mite extracts to be serum proteins. Immunoblotting then suggested that transferrin was the major antigen recognised by pooled infected sera in the skin and the mite extracts. Immunoassays confirmed that a majority of infected pigs produced antibodies to transferrin while mange-free pigs did not. A pool of IgG from infected dogs was then used to isolate another antigen from pig skin scrapings which was shown to be haptoglobin. This was also found to induce high titres of antibody in infected pigs as compared with mange-free pigs. The use of albumin as a control antigen showed no reactivity in either group of sera. The finding of two iron-binding molecules as strong auto-antigens in pig scabies has implications for the importance of iron during this infection and may help to explain the persistence and magnitude of the host inflammatory response.

Preventing transmission of sarcoptic mange from sows to their offspring by injection of ivermectin. Effects on swine production.

A blind and controlled field study was conducted on a pig farm in Australia to evaluate the activity of 1% ivermectin solution when injected into pregnant sows that were naturally infested with mites. The study was designed to appreciate the tolerance of the product on sows (litter size, litter birth weights, litter weaning weights, pre-weaning mortality) and to show the effects of sarcoptic mange on the growth performances of their offspring. Twenty sows were selected and ranked on Day-10, prior to the start of the study, on the basis of positive mite counts and parity. Sows were randomly allocated into two groups, A and B. On Day-7, they were injected once with product A (1 ml/33 kg; yielding 300 microg ivermectin/kg BW) or product B (placebo), respectively and then moved to the farrowing unit. Mite counts, ear and body lesions were scored and recorded. The average daily weight gain (ADG) was calculated on piglets from birth to Day-45 (ADG(45)) and birth to Day-70 (ADG(70)). Ivermectin was 100% efficient in preventing the transmission of scabies mites and did not have negative effect on the pregnant sows. Growth performances (ADG(45) and ADG(70)) of piglets from treated sows were significantly higher (452 and 541.5 g per day) than that from untreated sows (433.5 and 518.4 g per day) respectively, confirming that sarcoptic mange is detrimental to the production performances of growing pigs.

Using slaughter inspections to evaluate sarcoptic mange infestation of finishing swine.

Sarcoptic mange is one of the common swine diseases worldwide. Although mange-free populations can be established with caesarean derived stock, by herd repopulation programmes or by eliminating mange with ivermectin, mange remains prevalent in many countries. Field and experimental studies indicate that hypersensitive mange is detrimental to performance of growing pigs. Typically, producers tolerate mange infestation in their herds and control measures are often haphazard. This tolerance to mange infestation is attributable to the covert nature of the losses (reduced growth rate and feed efficiency without mortality) and to the fact that clinical signs of hypersensitive mange (pruritus) are usually viewed as normal. Lack of tools to evaluate mange severity in pigs and to demonstrate its importance has hindered the efforts of veterinarians to control the disease. Traditionally, veterinarians have used slaughter inspections to assess respiratory diseases such as enzootic pneumonia and atrophic rhinitis. Much of the value of slaughter inspections is as a tool with which veterinarians can educate and motivate their clients to improve disease control measures. The potential for evaluating hypersensitive mange by inspecting slaughtered pigs for lesions of papular dermatitis was recognised some time ago, but quantitative evaluation of the reliability of this approach has been lacking. We have conducted several studies in Australia, the USA, Canada, Europe and Latin America to evaluate associations between Sarcoptes infestation and the severity of papular dermatitis at slaughter, using a simple ordinal scale for classifying carcasses. Our initial field and experimental data in Australia indicated the specificity of localised dermatitis to be in the order of 75-80%, but that the generalised dermatitis was highly specific (> 98%) for mange. Subsequent studies in the US Midwest yielded almost identical results, and indicated that the method may also have some utility for surveillance of mange-free herds. Results from other locations invariably have shown significant associations between dermatitis lesions and mange infestation. Relative to other methods such as skin scrapings and monitoring pruritus, this method is simple and relatively objective, and should be considered for routine inclusion in slaughter inspection protocols.

Outbreak of brucellosis at a South-Australian abattoir. 2. Epidemiological investigations.

The outbreak of human brucellosis among employees of a large South Australian abattoir described previously coincided with an increase in the number of cattle showing a positive serological reaction for Brucella abortus being slaughtered. Comparisons showed that two other abattoirs in the area were slaughtering larger numbers of such cattle, but no cases of human brucellosis were diagnosed there. This suggested an additional risk at the abattoir concerned. All infected men had been employed in a particular part of the works. There was a possibility of movement of aerosols, produced on opening the uteri of pregnant cattle, to other parts of the works, putting a larger number of workers at risk of infection. Modifications to the plant greatly reduced the spread of aerosols. No cases of human brucellosis were recorded at this abattoir during the summer of 1980-81.

Outbreak of brucellosis at a South-Australian abattoir. 1. Clinical and serological findings.

During the period October 1979 to May 1980, 22 cases of acute brucellosis occurred at a South Australian abattoir. We obtained blood samples for serological investigations and culture of Brucella abortus, and tested the sera using the standard agglutination test (SAT), dithiothreitol test (DTT), anti-human globulin test (AHG) and complement fixation test (CFT). Patients showed large variations in antibody levels in each of these tests, both on presentation and after treatment. Blood culture was successful in six of 15 patients in whom it was attempted. Using the experience gained during the outbreak, we defined a set of serological criteria for the diagnosis of acute brucellosis, particularly in those who are occupationally exposed.

An abattoir survey of diseases of feral goats.

Caseous lymphadenitis was the most frequently encountered pathological condition in 3,720 feral goats examined during routine meat inspection procedures. Among 9 separate consignments of animals, the prevalence of infection averaged 7.4% (range 0.3% to 18.8%). The majority of lesions were seen in lymph nodes draining superficial body areas although many also occurred in internal nodes and organs. Corynebacterium ovis was isolated from 25 of 32 lesions submitted for bacteriological examination. Other conditions regularly encountered included pneumonia, cysticercosis, sarcosporidiosis and lice infestation, while myonecrosis, pleurisy, pericarditis, nephritis, hepatitis, cirrhosis and mite infestation were only occasionally found. A total of 171 serum samples were collected and tested against 17 antigens. Samples from 57.9% and 51.5% of goats showed positive serological reactions to the antigens for sarcosporidiosis and Q fever respectively.

Haematology of the Australian sea lion, Neophoca cinerea.

The haematology of the Australian sea lion Neophoca cinerea was studied in a breeding colony on Kangaroo Island, South Australia. The methods used to catch and restrain the animals are described and the haematology of 38 animals of varying age and sex groups is recorded. Total values for both erythrocytes and leucocytes were similar to those of other marine mammals and were in the ranges of 4.77 to 6.08 X 10(6) mm3 and 6.3 to 14.6 X 10(3) mm3, respectively. Erythrocytes volumes were very large, measuring from 96 to 112 mm.3 The packed cell volumes ranged from 48.3 to 64.2% and the haemoglobin values from 16.2 to 21 gm percent. The neutrophil lymphocyte ratio varied from 0.5 to 6.2 and in some animals absolute lymphocyte values were less than 1,200 mm.3 In many animals the percentage of eosinophils was greater than 20%, suggesting parasitic disease.

Experimental Sarcoptes scabiei infestation in pigs: (1) pathogenesis.

Animals were experimentally infested with Sarcoptes scabiei var suis at weekly intervals between birth and five weeks of age. Excoriations were observed on the luminal surface of the ear seven days after the initial infestation. Encrusted lesions developed in the ears of all pigs between the third and eighth weeks but spontaneously regressed and disappeared by the 14th week. A generalised pruritus, accompanied by focal erythematous skin lesions developed in a majority of pigs between seven and 11 weeks of age. The presence of pruritus was associated with an eosinophilia and histological changes in the skin which were consistent with an allergic reaction. The results are discussed in relation to their diagnostic significance and their importance in the control and eradication of the disease.

Plasma biochemical values of clinically-normal Australian sea lions (Neophoca cinerea).

Seventeen biochemical constituents were assayed in the blood plasma of clinically-normal Australian sea lions (Neophoca cinerea). The sea lions formed part of a breeding colony which inhabits the southern coast of Kangaroo Island, South Australia. Little variation was found in any of the values obtained from animals of different age and sex. The results were compared with values published for California sea lions (Zalophus californianus), Northern fur seals (Callorhinus ursinus), Harbor seals (Phoca vitulina) and Northern elephant seals (Mirounga angustirostris).

Experimental sarcoptes scabiei infestation in pigs: (2) Effects on production.

A study on the development and effect of experimental Sarcoptes scabiei var suis infestations in growing pigs is described. Pigs were infested at either weekly or fortnightly intervals throughout each experimental and individual growth rates and feed conversion ratios were determined. The animals were fed diets which contained either optimal or sub-optimal levels of protein. They were housed either intensively or extensively. In all experiments the majority of infested animals developed a generalised hypersensitivity to sarcoptes mites and performed significantly less efficiently than non-infested littermates. Mean growth rates were depressed from 9.2 to 12.5 per cent and feed conversion efficiencies by a similar margin. Well fed, intensively housed pigs developed a more severe hypersensitivity reaction than poorly fed, extensively housed pigs.

Viability and ultrastructural changes in group E Streptococci after in vitro phagocytosis by swine macrophages.

The loss of viability and ultrastructural changes were studied in group E Streptococci (GES) after in vitro phagocytosis in immune swine macrophages. There was a 50% reduction in the viability of intracellular GES during the first 60 minutes of incubation and a total loss of viability by 300 minutes as compared to the control tubes where the GES increased. Loss of viability in phagocytized group E Streptococci was associated with the appearance of degenerative changes in the bacterial cytoplasm. This was followed by disruption of the bacterial cell membrane and its separation from the bacterial cell wall. No definite evidence of cell wall degeneration could be found. Unphagocytized organisms incubated for similar periods and fixed in the same manner did not lose viability nor have any degenerative changes.

In vitro studies of group E streptococci in swine leukocytes. I. Phagocytic and bactericidal properties of polymorphonuclear leukocytes from swine.

Serum from both immune and nonimmune ten-week-old swine contained factors which promoted phagocytosis of group E Streptococci (GES). The factors in nonimmune serum, which were heat labile at 70 degrees C for ten minutes, were less efficient than the factors present in immune serum.Bactericidal activity of the polymorphonuclear (PMN) leukocytes against GES was observed with serum from both immune and nonimmune ten-week-old swine, as well as with serum from normal sows and piglets. However, the bactericidal activity of PMN leukocytes in serum from either normal sows or immune ten-week-old swine was greater than the bactericidal activity of PMN leukocytes in either piglet serum or serum from nonimmune ten-week-old swine. When the serum was either heated to 70 degrees C for ten minutes or treated with 2-mercaptoethanol, bactericidal activity of PMN leukocytes against GES was only observed in the presence of immune serum.

In vitro studies of group E streptococci in swine leukocytes. II. Phagocytic and bactericidal properties of macrophages from immune and nonimmune swine.

Macrophages collected from susceptible swine and grown in nonimmune serum phagocytized and digested group E Streptococci (GES). However, macrophages collected from immune swine and grown in nonimmune serum were capable of much higher rates of phagocytosis and intracellular digestion of the organism. The addition of immune serum to cultures of immune macrophages increased the rate of phagocytosis but not the rate of intracellular digestion of GES by the macrophages. These findings are discussed in relation to mechanisms of cellular immunity.

In vitro studies of group E streptococci in swine leukocytes. 3. The migration inhibition test as an indication of delayed hypersensitivity in streptococcic lymphadenitis.

A procedure for conducting tests for leukocyte migration inhibition was developed for swine leukocytes. Leukocytes from normal swine were found to be inhibited by a factor of less than 20% in the presence of the whole cell antigen of group E Streptococci (GES). However, the migration of leukocytes from swine which had been exposed to GES was inhibited by more than 60% in the presence of the antigen. This was considered as significant and an indication for the presence of delayed hypersensitivity to GES in previously exposed swine.