Swine Brucellosis Research Articles

FLUORESCENCE POLARIZATION ASSAY FOR THE DIAGNOSIS OF BRUCELLOSIS: A REVIEW

Fluorescence polarization assay (FPA) is based on the rotational differences between a small soluble antigen molecule in solution (labelled with a fluorochrome) and the antigen molecule complexed with its antibody. A small molecule will rotate randomly at a rapid rate, resulting in rapid depolarization of light, while a larger complex molecule will rotate slower and depolarize light at a reduced rate. The rate change in depolarization can be measured. The FPA is a homogeneous assay which does not require removal of unreacted reagents and can, therefore, be performed very quickly and, given portable equipment, in the laboratory and in the field. The latter obviates the need for shipping samples and eliminates waiting for results, as well as reducing test costs. The FPA technology has been developed and validated for the serological diagnosis of brucellosis in cattle, swine, sheep, goats, bison, and cervids. Sufficient cross reactivity of the common epitopes of Brucella abortus, B. melitensis and B. suis O-polysaccharide (OPS) allowed for the use of a single antigen for all species of smooth Brucella and animals. The OPS prepared from B. abortus S1119.3 was conjugated with fluorscein isothiocyanate (FITC). The FPA was initially developed for testing serum; however, the technology has been extended to testing whole blood and milk from individual animals or bulk tank samples pooled from 2000 or fewer animals. The accuracy of the FPA equalled or exceeded those obtained using other serological tests such as the buffered antigen plate agglutination test (BPAT), the milk ring test (MRT), the complement fixation test (CFT), the indirect enzyme immunoassay (IELISA), and the competitive enzyme immunoassay (CELISA).

Evaluation of primary binding assays for presumptive serodiagnosis of swine brucellosis in Argentina.

An indirect enzyme-linked immunosorbent assay (IELISA), a competitive ELISA (CELISA), and a fluorescence polarization assay (FPA) for the presumptive serological diagnosis of swine brucellosis were evaluated using two populations of swine sera: sera from brucellosis-free Canadian herds and sera from Argentina selected based on positive reactions in the buffered antigen plate agglutination test (BPAT) and the 2-mercaptoethanol (2-ME) test. In addition, sera from adult swine from which Brucella suis was isolated at least once for each farm of origin were evaluated. The IELISA, CELISA, and FPA specificity values were 99.9, 99.5, and 98. 3%, respectively, and the IELISA, CELISA, and FPA sensitivity values relative to the BPAT and the 2-ME test were 98.9, 96.6, and 93.8%, respectively. Actual sensitivity was assessed by using 37 sera from individual pigs from which B. suis was cultured, and the values obtained were as follows: BPAT, 86.5%; 2-ME test, 81.1%; IELISA, 86.5%; CELISA, 78.5%; and FPA, 80.0%.

Log-linear and logistic modeling of dependence among diagnostic tests

We developed log-linear and logistic-modeling approaches to investigate dependence among diagnostic tests. To illustrate the approaches, we used published data for swine toxoplasmosis, bovine paratuberculosis, and swine brucellosis. These diseases were selected because each animal’s true disease status was known, at least five tests were used, and the serologic tests had been previously shown to have moderate-to-high pairwise dependence in test sensitivities (and sometimes in test specificities). Log-linear and logistic modeling yielded similar results for swine toxoplasmosis and swine brucellosis. However, logistic modeling could not be used to investigate test dependence for bovine paratuberculosis because of quasi-separation in the data attributable to two fecal-based tests having specificities of 100%. Findings from our modeling indicated that 3 (modified agglutination, enzyme-linked immunosorbent assay (ELISA), latex agglutination) of 5 serologic tests for toxoplasmosis and 2 (rivanol and particle concentration fluorescence immunoassay) of 6 serologic tests for brucellosis were adequate for diagnosis. For bovine paratuberculosis, both fecal-based tests (Herrold’s egg-yolk culture and radiometric culture) and 1 (ELISA) of 3 serologic tests were necessary in serial and parallel testing schemes.

Conditional dependence between tests affects the diagnosis and surveillance of animal diseases

Dependence between the sensitivities or specificities of pairs of tests affects the sensitivity and specificity of tests when used in combination. Compared with values expected if tests are conditionally independent, a positive dependence in test sensitivity reduces the sensitivity of parallel test interpretation and a positive dependence in test specificity reduces the specificity of serial interpretation. We calculate conditional covariances as a measure of dependence between binary tests and show their relationship to kappa (a chance-corrected measure of test agreement). We use published data for toxoplasmosis and brucellosis in swine, and Johne’s disease in cattle to illustrate calculation methods and to indicate the likely magnitude of the dependence between serologic tests used for diagnosis and surveillance of animal diseases.

Venezuelan field trials of vaccines against brucellosis in swine

Abstract Objective To evaluate live attenuated Brucella abortus RB51, killed B suis cells, O-polysaccharide (OPS) from B abortus 1119-3 and OPS from B suis 1330, for protection of swine against B suis challenge exposure under farm conditions. Animals 10 infected boars, 160 unvaccinated control sows and their 1,040 progeny, and 610 vaccinated sows and their 6,600 progeny. Procedure Gilts (45 to 65 days or 4 to 6 months old) were vaccinated or not vaccinated. For the latter gilts, additional variables studied were dose, number of doses, and delivery route. Mature gilts were mated with 4 infected boars, then serologic reaction to Brucella spp, results of bacteriologic culture of vaginal secretions, presence of abortion, and litter size were assessed. Various tissues obtained from aborted fetuses were obtained for culture of Brucella spp. Results About 40% of unvaccinated control gilts seroconverted to Brucella spp, 27% were positive for OPS precipitation by use of agar gel immunodiffusion, 23% aborted their fetuses, and the remaining gilts had litters of 5 to 8 pigs. Killed B suis cells provided the following protection: 25% of vaccinates were seropositive, 5% had positive results of agar gel immunodiffusion, 5% aborted, and the remaining gilts had litters of 7 to 8 pigs. Gilts that received live RB51 or OPS vaccine were protected. Serologic reactions were always negative, abortion did not occur (ie, 100% were protected), and litter size was 10 to 12 pigs. Conclusions Live attenuated B abortus RB51 or purified OPS was effective in protecting gilts against B suis infections. Dose (106 to 109 cells, 100 to 500 μg, respectively), number of doses (1 or 3), or route (IM or PO) made little difference. Further research is required to determine why these 2 vaccine candidates are similar in protection effectiveness and whether they can be used after infection as a treatment. (Am J Vet Res 1998;59:546–551)

Serological and bacteriological study of swine brucellosis.

A serological and bacteriological study was performed with sera taken from 2,228 swine from six states in Venezuela. None of the animals were vaccinated against brucellosis, and the prevalence of the disease varied from 5 to 89% on farms located in these states. Our studies indicated that the animals could be categorized into four groups depending on the degree of reactivity in serological tests. Brucella suis biovar 1 was isolated from the lymph nodes, spleens, and semen samples of seropositive animals and identified by oxidative metabolic techniques. B. suis could not be isolated from tissues of seronegative swine even from farms with cases of the disease (detected by serology). Results suggest that, although the immunodiffusion assay using Brucella melitensis B115 polysaccharide B or B. abortus 1119-3 O-polysaccharide could be useful in the detection of active infections, it is perhaps not as sensitive as some of the other standard serological tests used in this study for the detection of swine brucellosis.

Comparison of serologic tests and bacteriologic culture for detection of brucellosis in swine from naturally infected herds

Objective— To compare results of 6 serologic tests with results of bacteriologic culture for Brucella suis in swine. Design— Prospective study. Animals— Two hundred twenty-one swine from 39 naturally infected herds. Procedure— Blood samples and lymph nodes were collected at slaughter. Serologic tests conducted were the particle concentration fluorescence immunoassay, the automated complement fixation assay, the card test, the buffered acidified plate antigen assay, the standard tube test, and the rivanol test. Lymph nodes were plated on Farrell's medium and serum-enriched agar for bacteriologic culture. Results— Sensitivities ranged from 57 (automated complement fixation assay) to 83% (standard tube test). Specificities ranged from 62 (standard tube test) to 95% (rivanol test). Brucella suis was isolated from 46 of the 221 (21%) pigs. For 8 of the 46 culture-positive pigs, results of all 6 tests were negative. Clinical Implications— Data illustrate the difficulty of eliminating brucellosis by means of a test-and-removal program and support the policy of slaughtering infected herds.

Outbreak of Brucellosis at a United States Pork Packing Plant

In 1992, the North Carolina Department of Environment, Health, and Natural Resources received 18 case reports of brucellosis from a county health department. All patients had potential exposure to the kill floor of one pork processing plant. A subsequent National Institute for Occupational Safety and Health health hazard evaluation surveyed 154 (99%) of 156 kill floor workers of this plant and found that 30 (19%) had evidence of recent (or persistent) brucellosis. These data show that significant exposure to Brucella is occurring among packing plant workers in North Carolina and suggest that some of the approximately 38,000 production workers in pork processing plants in the United States are at risk of contracting swine brucellosis. Additional measures may need to be taken to prevent occupational exposure to Brucella.

A Serologic Survey of Selected Viral and Bacterial Diseases of European Wild Hogs, Great Smoky Mountains National Park, USA

Blood samples were collected from 108 wild hogs (Sus scrofa) from the Great Smoky Mountains National Park (GSMNP), USA, February to July 1990. We found no antibodies for swine brucellosis, pseudorabies, bovine virus diarrhea virus or porcine rotavirus infection. Antibody titers to porcine parvovirus were found in 15 (14%) samples and antibody to one or more leptospiral serovars was found in 48 (44%) samples. Thirty-nine (89%) of the 44 positive samples reacted to all five leptospiral serovars tested.

Serological reactions to Brucella species in British pigs

Until and including 1987 diagnostically significant serological titres to swine brucellosis had occurred in the serum agglutination test (SAT) or the complement fixation test (CFT), ie, > or = 100 iu or > or = 20 icftu, respectively, almost every year since reliable records began, but usually only about 0.05 per cent in the SAT and 0.005 per cent in the CFT. Brucella suis was never isolated by cultural examination. In 1988 the level of CFT reactions > or = 20 icftu rose to 0.42 per cent (1.04 per cent in the last quarter of the year) but the SAT reactions remained relatively unchanged. In 1989 the levels of both CFT and SAT reactions increased further with CFT reactions again predominating. Analyses of the serological reaction patterns in individual herds suggested that infection with brucella or some other organism capable of causing serological cross-reactions had become widespread in Great Britain, although signs of disease typical of swine brucellosis had not been observed. Some herds had reactions which persisted for many months whereas others showed them for only a short time. In early 1990 Yersinia enterocolitica serogroup O:9 was isolated from some pigs purchased from one of the reactor herds and this organism is probably responsible for the increased numbers of seroreactions. It had not previously been found in pigs in Great Britain.

A FIELD TRIAL TO DETERMINE THE FEASIBILITY OF DELIVERING ORAL VACCINES TO WILD SWINE

A field study was conducted on Ossabaw Island, Georgia (USA) to determine the feasibility of delivering oral vaccines to wild swine (Sus scrofa). Baits were made of polymerbound fish meal and contained a gelatin capsule as a potential vaccine chamber. Two biomarkers, iophenoxic acid and tetracycline, were incorporated into each bait, and soured chicken mash was used as an attractant. Baits (n = 1,980) were distributed in a grid pattern on a 405-ha test site and monitored for animal disturbance. Within 72 hr, 88% of 393 monitored baits were gone, and observations of track-beds surrounding 100 baits indicated that at least 52% were taken by wild swine. Subsequent testing of 80 wild swine for the biomarkers revealed that 95% of the animals had consumed bait. Track-bed observations indicated that raccoons (Procyon lotor) were the only non-target animal that frequently took baits. Biomarker analyses indicated 44% of 16 raccoons tested had eaten bait. It was concluded that oral vaccine delivery to wild swine should be considered as a feasible method of control or eradication of pseudorabies and/or swine brucellosis in wild swine if effective vaccines become available.

Swine brucellosis in Indonesia.

Brucella suis biotype 1 was isolated from 13.1% of the pigs slaughtered in Kapuk Jakarta, West Java and from 15.09% of the pigs slaughtered in Surabaya, East Java. The prevalence of B. suis by means of the Rose Bengal Plate Test, was 22.3% for West Java and 14.9% for East Java. The Rose Bengal Plate Test detected more B. suis infected animals (73% of the infected animals) than did the Complement Fixation Test (41%) and the Serum Agglutination Test (54.5%). The high infection rate is a potential health danger for the abattoir workers.

Brucellosis in the United States, 1970.

Abstract The review covers the incidence of human brucellosis in the United States for the period, 1960 to 1970. During this period, the incidence of disease has declined from about 2,000 to less than 200 cases. The prevalence in animal disease, especially in cattle, has dropped precipitously in this period and explains the sharp decline in human disease. Veterinarian authorities hope that by 1976 the country will be free of bovine brucellosis. There is little or no brucellosis in sheep and goats in the United States; the only problem remaining is in swine, where the rate is about one case per 1,000 animals. On the basis of 90 million swine slaughtered annually, this would expose meat dealers to possibly 90,000 infected pigs. It is anticipated that swine brucellosis will receive increasing attention in the decade ahead.

Genetic Resistance to Brucellosis in Swine

Genetic Resistance to Brucellosis in Swine

CHAPTER IX: RELATION OF SWINE BRUCELLOSIS TO INFECTIOUS ABORTION IN CATTLE

Acta Pathologica Microbiologica ScandinavicaVolume 11, Issue S21 p. 171-185 CHAPTER IX: RELATION OF SWINE BRUCELLOSIS TO INFECTIOUS ABORTION IN CATTLE First published: July 1934 https://doi.org/10.1111/j.1600-0463.1934.tb05452.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Volume11, IssueS21July 1934Pages 171-185 RelatedInformation

The Etiology of Abortion in Cows

Brucellosis is a wide spread zoonotic disease that causes abortion and infertility in mammals and leads to debilitating, febrile illness in humans. Brucella abortus, Brucella melitensis and Brucella suis are the major pathogenic species to humans. Vaccination with live attenuated B. suis strain 2 (S2) vaccine is an essential and critical component in the control of brucellosis in China. The S2 vaccine is very effective in preventing brucellosis in goats, sheep, cattle and swine. However, there are still debates outside of China whether the S2 vaccine is able to provide protection against heterologous virulent Brucella species. We investigated the residual virulence, immunogenicity and protective efficacy of the S2 vaccine in BALB/c mice by determining bacteria persistence in spleen, serum antibody response, cellular immune response and protection against a heterologous virulent challenge. The S2 vaccine was of low virulence as there were no bacteria recovered in spleen four weeks post vaccination. The vaccinated mice developed Brucella-specific IgG in 2–3 weeks, and a burst production of IFN-γ at one week as well as a two-fold increase in TNF-α production. The S2 vaccine protected mice from a virulent challenge by B. melitensis M28, B. abortus 2308 and B. suis S1330, and the S2 vaccinated mice did not develop any clinical signs or tissue damage. Our study demonstrated that the S2 vaccine is of low virulence, stimulates good humoral and cellular immunity and protects animals against infection by heterologous, virulent Brucella species.