350
Brief communications
Table 1. Sensitivity and specificity by serum dilution of the encephalomyocarditis virus microtiter serum neutralization test for swine.
Sources and manufacturers a. US Department of Agriculture, National Veterinary Services Laboratories, Ames, IA.
References
ated with nonspecific neutralizing substances.7,9 Regarding cross-reactions, studies between EMCV and 62 human enterovirus serotypes9 and 11 porcine serotypes showed no cross-neutralization (D. Jutting, personal communication). Neutralization studies have also been done against at least 27 other viruses without evidence of cross-reactions1,8 Although cricket paralysis virus (CPV) and EMCV have antigens in common, CPV antiserum will not neutralize the infectivity of EMCV in cell culture or mice10 The prospect of antigenic differences between the SN challenge strain and a field strain of EMCV producing false negative test reactions was considered. However, complete crossneutralization between strains or isolates of EMCV has been reported repeatedly, 1,3–5,11 whereas the lack of cross-neutralization between strains or isolates has not. In conclusion, the microtiter SN test was a relatively specific and sensitive test for the diagnosis of infection by EMCV. Antibody titers of 8 were highly suggestive of infection, using the protocol described. Antibody titers of ≥16 were definitive for EMCV infection, based on a test specificity of 100% at these dilutions. Because the data indicate that SN titers persist for months, it is mandatory to test paired serum samples from individual animals in the serologic diagnosis of clinical infection.
1. Dick GWA: 1949, The relationship of Mengo encephalomyelitis, encephalomyocarditis, Columbia-SK, and MM viruses. J Immunol 62:375-386. 2. Gainer JH, Murchison TE: 1961, Encephalomyocarditis virus infection of swine. Vet Med 56: 173-175. 3. Joo HS, Kim HS, Leman AD: 1988, Detection of antibody to encephalomyocarditis virus in mummified or stillborn pigs. Arch Virol 100: 131-134. 4. Jungeblut CW: 1952, Experimental studies with F virus. Arch Gesamte Virusforsch 4:568-578. 5. Luya M J, Romanenke V, Hernandez H, et al.: 1979, [Biological characteristics of encephalomyocarditis virus isolated from swine in Cuba.] Caracteristicas biologicas de1 virus de la encefalomiocarditis (EMC) aislado en cerdos en Cuba. Cienc Tee Agric Vet 1:73-90. 6. Murnane TG, Craighead JE, Mondragon H, et al.: 1960, Fatal disease of swine due to encephalomyocarditis virus. Science 131: 498-499. 7. Sangar DV, Rowlands DJ, Brown F: 1977, Encephalomyocarditis virus antibodies in sera from apparently normal pigs. Vet Rec 100:240-241. 8. Smithburn KC: 1952, Studies on certain viruses isolated in the tropics of Africa and South America. Immunological reactions as determined by cross-neutralization tests. J Immunol 68:441460. 9. Tesh RB: 1978, The prevalence of encephalomyocarditis virus neutralizing antibodies among various human populations. Am J Trop Med Hyg 27:144-149. 10. Tinsley TW, MacCallum FO, Robertson JS, et al.: 1984, Relationship of encephalomyocarditis virus to cricket paralysis virus of insects. Intervirology 21: 181-186. 11. Warren J, Smadel JE, Russ SB: 1949, The family relationship of encephalomyocarditis, Columbia-SK, M.M., and Mengo encephalomyelitis viruses. J Immunol 62:387-398.
J Vet Diagn Invest 2:350-352 (1990)
Evaluation of two commercial ELISA test kits for the detection of pseudorabies antibodies in pigs Sagar M. Goyal, Traci L. Laughlin Pseudorabies control programs have been initiated in several US states, with an ultimate goal of national eradication by the year 2000. An effective control program is based on the rapid detection of pseudorabies virus (PRV) infection in From the Department of Veterinary Diagnostic Investigation, College of Veterinary Medicine, University of Minnesota, St. Paul, MN 55108. Received for publication June 6, 1990.
swine herds by testing sera from a representative number of animals for the presence of PRV antibodies. A number of tests are available for the detection of PRV antibodies, 1–8 but the serum neutralization (SN),4 enzyme-linked immunosorbent assay (ELISA),9 and latex agglutination10 tests are the 3 approved techniques. Of these, the SN test is most widely used because of its sensitivity and specificity. The ELISA and SN tests were compared5 by testing 2,024 swine sera; 201 of them were positive for PRV antibody by
Downloaded from vdi.sagepub.com at UNIV OF MASSACHUSETTS on April 6, 2015
Brief communications
351
Table 1. Comparison of 2 commercial ELISA tests with the seboth tests. Five samples showed discrepant results; 3 sera positive by SN were negative by ELISA, and 2 sera negative rum neutralization (SN) test for detection of pseudorabies virus anby SN were considered weak positive by ELISA. A modified tibody. form of ELISA was later introduced as a commercial test (ELISA-A) a and has found widespread acceptance as a screening test for PRV antibodies. Another commercial ELISA test (ELISA-B) b has recently become available. The purpose of the present study was to compare these 2 ELISA tests with the SN test for sensitivity and specificity. A total of 1,266 porcine serum samples were used in this study. All of these samples were received at the Minnesota Veterinary Diagnostic Laboratory. The ELISA-A is available in 2 formats, but only the screening test was used in this study. The test was run according to the kit insert using a 1:20 dilution of the test sample (100 animals would have been missed because samples negative µ1). Negative, weak positive, and strong positive serum con- by ELISA-B would not have been tested further. However trols were included. The test was read in an ELISA reader for most of the PRV testing, only a certain proportion of the at 410 nm, and the results were calculated according to the herd is tested. Therefore, missing 3 animals out of a total of test kit directions. An s/p ratio of ≥0.4 was considered pos1,266 animals should not affect the results of herd monitoritive. ing. However, if a single infected pig remains undetected in The ELISA-B was run according to the directions obtained a herd it may create potential problems for that herd. with the test kit. A 100-µ1 undiluted serum sample was placed Samples with s/p ratios of ≤1.0 in the ELISA-A test are in an antigen-coated well at 1 sample per well. Blank, neg- usually negative by the SN test (Goyal, unpublished data). ative, and positive control wells were included. The reaction In this study, 168 of the 182 samples false positive by ELIwas read in an ELISA reader at 410 nm, and a threshold SA-A test had s/p ratios between 0.4 and 1.0. Only 14 of the point was calculated according to the test kit directions. Sam- false positive samples had s/p ratios > 1.0. However, some ples with optical density values of less than or equal to the samples that have s/p ratios of ≤ 1.0 are positive on SN test. threshold point were considered positive. Four samples that were ELISA-B positive/ELISA-A negative The suspect or positive samples on the 2 ELISA tests were were not tested by SN test because they were not available. confirmed by the SN test.4 Of the 1,266 serum samples tested, In summary, both ELISA tests are sensitive and both are 674 were positive and 403 were negative by both ELISA equal in ease of performance, but ELISA-B is more specific tests, with an overall agreement of 85% between the 2 tests. than ELISA-A. An advantage of the ELISA-B test is that it Seventy-one of the 674 positive samples were negative by can be done on undiluted samples, whereas with ELISA-A, the SN test (Table 1). One hundred eighty-nine samples were the sample needs to be diluted to 1:20. ELISA-A is a screening discordant between the 2 assays. Four samples were negative assay, and the kit directions state that all suspect and positive by ELISA-A but positive by ELISA-B, whereas 185 samples samples should be retested by one of the confirmatory tests, positive by ELISA-A were negative by ELISA-B. Of these e.g., an accompanying verification ELISA, SN, or LA test. 185 samples, 182 were negative by SN test but 3 were positive ELISA-B does not have an accompanying verification ELISA at titers of 1:2, 1:2, and 1:32, respectively. For ELISA-A, test but did produce false positive results in 10.5% of samples 168 of 182 samples had s/p ratios ≥0.4 but ≤1.0. The re- tested. It is prudent, therefore, to confirm positive ELISA maining 14 samples had s/p ratios of ≤ 2.3. samples by 1 of the confirmatory tests cited above. Of the samples positive by ELISA-A (n = 859), 606 (70.5%) were positive by the SN test, giving a false positive rate of Sources and manufacturers 29.5%. Of the 678 samples positive by ELISA-B, 674 were a. HerdChek, Idexx Corp., Portland, ME. tested by SN. Of these, 603 were positive, giving a false b. Diasystems Celisa PRV, Fermenta Animal Health Co., Kansas positive rate of 10.5%. City, MO. For a control and eradication program to be successful, the availability of a simple, rapid, and inexpensive test to References detect infected animals/herds is a necessity. In recent years, the ELISA test has fulfilled this need for the detection of PRV 1. Goyal SM, Joo HS, Mourning JR, et al.: 1987, Comparison of three serotests to detect antibodies against pseudorabies virus antibodies in swine sera. However, because of its high senin pigs. Comp Immunol Microbiol Infect Dis 10: 167-171. sitivity, the screening ELISA produces a certain number of 2. Gutekunst DE, Pertle EC, Mengeling WL: 1978, Development false positive samples that need to be confirmed by another and evaluation of a microimmunodiffusion test for detection of test, such as ELISA, SN, or LA tests. In our laboratory, the antibodies to pseudorabies virus in swine serum. Am J Vet Res sera are screened initially by ELISA-A, followed by confir39:207-210. mation of the positive samples by the SN test. 3. Haffer K, Gustafson DP, Kanitz CL: 1980, Indirect hemaggluIn general, ELISA-A produced more false positive reactination tests for pseudorabies antibody detection in swine. J tions than ELISA-B, indicating that ELISA-B might be a Clin Microbiol 11:217-219. better test. However, 3 samples that were negative by ELISA-B 4. Hill HT, Crandell RA, Kanitz CL, et al.: 1977, Recommended were positive by SN at dilutions of 1:2-1:32. The infected minimum standards for diagnostic tests emploved in the diaa-
Downloaded from vdi.sagepub.com at UNIV OF MASSACHUSETTS on April 6, 2015
Brief Communications
352
nosis of pseudorabies (Aujeszky’s disease). Proc Annu Meet Am Assoc Vet Lab Diagn 20:375-390. 5. Hill HT, Seymore CL, Egan IT, Harris DL: 1983, Evaluation of the enzyme-linked immunosorbent assay and the microtitration serum-virus-neutralization tests as used in an epidemiological survey of Iowa, Illinois, and Missouri swine. Proc 3rd Int Symp World Assn Vet Lab Diagn 1:235-240. 6. Joo HS, Molitor TW, Leman AD: 1984, Radial immunodiffusion enzyme assay for detection of antibodies to pseudorabies virus in swine serum. Am J Vet Res 45:2096-2098. 7. Kelling CL, Standinger WL, Rhodes MB: 1978, Indirect solidphase microradioimmunoassay for detection of pseudorabies virus antibody in swine sera. Am J Vet Res 39: 1955-1957.
8. Scherba G, Gustafson DP, Kanitz CL, et al.: 1980, Delayed hypersensitivity reaction to pseudorabies virus as a field diagnostic test in swine. J Am Vet Med Assoc 173: 1490-1493. 9. Synder ML, Erickson GA: 1981, Recommended minimum standards for an enzyme-linked immunosorbent assay (ELISA) in pseudorabies serodiagnosis. National Veterinary Services Lab, US Department of Agriculture, Ames, IA. 32 pp. 10. Wade TW, Brees J, Goyal SM: 1986, Comparison of latex agglutination and serum neutralization tests for the detection of pseudorabies antibodies in swine sera. Proc Annu Meet Am Assoc Vet Lab Diagn 29:401-408.
J Vet Diagn Invest 2:352-354 (1990)
A mycological evaluation and in vivo toxicity evaluation of feed from 41 farms with equine leukoencephalomalacia Terrance M. Wilson, Paul E. Nelson, W. F. O. Marasas, Pieter G. Thiel, Gorden S. Shephard, Erick W. Sydenham, Hillman A. Nelson, P. Frank Ross Equine leukoencephalomalacia (ELEM) is of worldwide distribution and is caused by the mycotoxin fumonisin B1 (FB1), a metabolite of Fusarium moniliforme. 4,6 Studies also indicate that metabolites from various strains of F. moniliforme may be hepatocarcinogenic to rats.2,8 A recent review of the history, disease, seasonality, clinical syndromes, epidemiology, and differential diagnosis of equine leukoencephalomalacia has been published.7 The purpose of this study was to mycologically analyze commercial and noncommercial feeds associated with ELEM From the US Department of Agriculture, Animal and Plant Health Inspection Service, Science and Technology, National Veterinary Services Laboratories, PO Box 844, Ames, IA 50010 (Wilson, H. Nelson, Ross), the Fusarium Research Center, Department of Plant Pathology, Pennsylvania State University, University Park, PA 16802 (P. Nelson), and the Research Institute for Nutritional Disease, South African Medical Research Council, Tygerberg 7505, South Africa (Marasas, Thiel, Shephard, Sydenham). Received for publication April 3, 1990.
and to evaluate the toxigenicity of selected cultures of F. moniliforme. A mail and telephone survey was conducted with veterinary diagnostic laboratories in the East and Midwest between 1983 and 1986 to locate confirmed cases of ELEM. Telephone calls and correspondence were initiated to follow up all reported cases. Feed samples were collected on all farms, with emphasis on those feeds used l-3 weeks prior to the diagnosis of ELEM. Based on the feeding practices, the farms were divided into 5 groups (Table 1): 1) commercial nonpelleted feed, 2) commercial pelleted feed, 3) corn plus commercial pelleted feed, 4) mixed feeding—some on corn, some on corn plus commercial pelleted feed, and 5) corn or corn screenings. Clinical necropsy information, as well as macroscopic and microscopic material from most cases, was reviewed. In all cases, a necropsy and, in most cases, a histopathologic evaluation of brain tissue were conducted on at least 1 animal from each farm. Forty-one farms were surveyed with a wide range of breeds
Table 1. Number of farms and type of ration fed to horses exposed to Fusarium moniliforme and diagnosed as having ELEM.
Downloaded from vdi.sagepub.com at UNIV OF MASSACHUSETTS on April 6, 2015
Brief communications
Table 1. Sensitivity and specificity by serum dilution of the encephalomyocarditis virus microtiter serum neutralization test for swine.
Sources and manufacturers a. US Department of Agriculture, National Veterinary Services Laboratories, Ames, IA.
References
ated with nonspecific neutralizing substances.7,9 Regarding cross-reactions, studies between EMCV and 62 human enterovirus serotypes9 and 11 porcine serotypes showed no cross-neutralization (D. Jutting, personal communication). Neutralization studies have also been done against at least 27 other viruses without evidence of cross-reactions1,8 Although cricket paralysis virus (CPV) and EMCV have antigens in common, CPV antiserum will not neutralize the infectivity of EMCV in cell culture or mice10 The prospect of antigenic differences between the SN challenge strain and a field strain of EMCV producing false negative test reactions was considered. However, complete crossneutralization between strains or isolates of EMCV has been reported repeatedly, 1,3–5,11 whereas the lack of cross-neutralization between strains or isolates has not. In conclusion, the microtiter SN test was a relatively specific and sensitive test for the diagnosis of infection by EMCV. Antibody titers of 8 were highly suggestive of infection, using the protocol described. Antibody titers of ≥16 were definitive for EMCV infection, based on a test specificity of 100% at these dilutions. Because the data indicate that SN titers persist for months, it is mandatory to test paired serum samples from individual animals in the serologic diagnosis of clinical infection.
1. Dick GWA: 1949, The relationship of Mengo encephalomyelitis, encephalomyocarditis, Columbia-SK, and MM viruses. J Immunol 62:375-386. 2. Gainer JH, Murchison TE: 1961, Encephalomyocarditis virus infection of swine. Vet Med 56: 173-175. 3. Joo HS, Kim HS, Leman AD: 1988, Detection of antibody to encephalomyocarditis virus in mummified or stillborn pigs. Arch Virol 100: 131-134. 4. Jungeblut CW: 1952, Experimental studies with F virus. Arch Gesamte Virusforsch 4:568-578. 5. Luya M J, Romanenke V, Hernandez H, et al.: 1979, [Biological characteristics of encephalomyocarditis virus isolated from swine in Cuba.] Caracteristicas biologicas de1 virus de la encefalomiocarditis (EMC) aislado en cerdos en Cuba. Cienc Tee Agric Vet 1:73-90. 6. Murnane TG, Craighead JE, Mondragon H, et al.: 1960, Fatal disease of swine due to encephalomyocarditis virus. Science 131: 498-499. 7. Sangar DV, Rowlands DJ, Brown F: 1977, Encephalomyocarditis virus antibodies in sera from apparently normal pigs. Vet Rec 100:240-241. 8. Smithburn KC: 1952, Studies on certain viruses isolated in the tropics of Africa and South America. Immunological reactions as determined by cross-neutralization tests. J Immunol 68:441460. 9. Tesh RB: 1978, The prevalence of encephalomyocarditis virus neutralizing antibodies among various human populations. Am J Trop Med Hyg 27:144-149. 10. Tinsley TW, MacCallum FO, Robertson JS, et al.: 1984, Relationship of encephalomyocarditis virus to cricket paralysis virus of insects. Intervirology 21: 181-186. 11. Warren J, Smadel JE, Russ SB: 1949, The family relationship of encephalomyocarditis, Columbia-SK, M.M., and Mengo encephalomyelitis viruses. J Immunol 62:387-398.
J Vet Diagn Invest 2:350-352 (1990)
Evaluation of two commercial ELISA test kits for the detection of pseudorabies antibodies in pigs Sagar M. Goyal, Traci L. Laughlin Pseudorabies control programs have been initiated in several US states, with an ultimate goal of national eradication by the year 2000. An effective control program is based on the rapid detection of pseudorabies virus (PRV) infection in From the Department of Veterinary Diagnostic Investigation, College of Veterinary Medicine, University of Minnesota, St. Paul, MN 55108. Received for publication June 6, 1990.
swine herds by testing sera from a representative number of animals for the presence of PRV antibodies. A number of tests are available for the detection of PRV antibodies, 1–8 but the serum neutralization (SN),4 enzyme-linked immunosorbent assay (ELISA),9 and latex agglutination10 tests are the 3 approved techniques. Of these, the SN test is most widely used because of its sensitivity and specificity. The ELISA and SN tests were compared5 by testing 2,024 swine sera; 201 of them were positive for PRV antibody by
Downloaded from vdi.sagepub.com at UNIV OF MASSACHUSETTS on April 6, 2015
Brief communications
351
Table 1. Comparison of 2 commercial ELISA tests with the seboth tests. Five samples showed discrepant results; 3 sera positive by SN were negative by ELISA, and 2 sera negative rum neutralization (SN) test for detection of pseudorabies virus anby SN were considered weak positive by ELISA. A modified tibody. form of ELISA was later introduced as a commercial test (ELISA-A) a and has found widespread acceptance as a screening test for PRV antibodies. Another commercial ELISA test (ELISA-B) b has recently become available. The purpose of the present study was to compare these 2 ELISA tests with the SN test for sensitivity and specificity. A total of 1,266 porcine serum samples were used in this study. All of these samples were received at the Minnesota Veterinary Diagnostic Laboratory. The ELISA-A is available in 2 formats, but only the screening test was used in this study. The test was run according to the kit insert using a 1:20 dilution of the test sample (100 animals would have been missed because samples negative µ1). Negative, weak positive, and strong positive serum con- by ELISA-B would not have been tested further. However trols were included. The test was read in an ELISA reader for most of the PRV testing, only a certain proportion of the at 410 nm, and the results were calculated according to the herd is tested. Therefore, missing 3 animals out of a total of test kit directions. An s/p ratio of ≥0.4 was considered pos1,266 animals should not affect the results of herd monitoritive. ing. However, if a single infected pig remains undetected in The ELISA-B was run according to the directions obtained a herd it may create potential problems for that herd. with the test kit. A 100-µ1 undiluted serum sample was placed Samples with s/p ratios of ≤1.0 in the ELISA-A test are in an antigen-coated well at 1 sample per well. Blank, neg- usually negative by the SN test (Goyal, unpublished data). ative, and positive control wells were included. The reaction In this study, 168 of the 182 samples false positive by ELIwas read in an ELISA reader at 410 nm, and a threshold SA-A test had s/p ratios between 0.4 and 1.0. Only 14 of the point was calculated according to the test kit directions. Sam- false positive samples had s/p ratios > 1.0. However, some ples with optical density values of less than or equal to the samples that have s/p ratios of ≤ 1.0 are positive on SN test. threshold point were considered positive. Four samples that were ELISA-B positive/ELISA-A negative The suspect or positive samples on the 2 ELISA tests were were not tested by SN test because they were not available. confirmed by the SN test.4 Of the 1,266 serum samples tested, In summary, both ELISA tests are sensitive and both are 674 were positive and 403 were negative by both ELISA equal in ease of performance, but ELISA-B is more specific tests, with an overall agreement of 85% between the 2 tests. than ELISA-A. An advantage of the ELISA-B test is that it Seventy-one of the 674 positive samples were negative by can be done on undiluted samples, whereas with ELISA-A, the SN test (Table 1). One hundred eighty-nine samples were the sample needs to be diluted to 1:20. ELISA-A is a screening discordant between the 2 assays. Four samples were negative assay, and the kit directions state that all suspect and positive by ELISA-A but positive by ELISA-B, whereas 185 samples samples should be retested by one of the confirmatory tests, positive by ELISA-A were negative by ELISA-B. Of these e.g., an accompanying verification ELISA, SN, or LA test. 185 samples, 182 were negative by SN test but 3 were positive ELISA-B does not have an accompanying verification ELISA at titers of 1:2, 1:2, and 1:32, respectively. For ELISA-A, test but did produce false positive results in 10.5% of samples 168 of 182 samples had s/p ratios ≥0.4 but ≤1.0. The re- tested. It is prudent, therefore, to confirm positive ELISA maining 14 samples had s/p ratios of ≤ 2.3. samples by 1 of the confirmatory tests cited above. Of the samples positive by ELISA-A (n = 859), 606 (70.5%) were positive by the SN test, giving a false positive rate of Sources and manufacturers 29.5%. Of the 678 samples positive by ELISA-B, 674 were a. HerdChek, Idexx Corp., Portland, ME. tested by SN. Of these, 603 were positive, giving a false b. Diasystems Celisa PRV, Fermenta Animal Health Co., Kansas positive rate of 10.5%. City, MO. For a control and eradication program to be successful, the availability of a simple, rapid, and inexpensive test to References detect infected animals/herds is a necessity. In recent years, the ELISA test has fulfilled this need for the detection of PRV 1. Goyal SM, Joo HS, Mourning JR, et al.: 1987, Comparison of three serotests to detect antibodies against pseudorabies virus antibodies in swine sera. However, because of its high senin pigs. Comp Immunol Microbiol Infect Dis 10: 167-171. sitivity, the screening ELISA produces a certain number of 2. Gutekunst DE, Pertle EC, Mengeling WL: 1978, Development false positive samples that need to be confirmed by another and evaluation of a microimmunodiffusion test for detection of test, such as ELISA, SN, or LA tests. In our laboratory, the antibodies to pseudorabies virus in swine serum. Am J Vet Res sera are screened initially by ELISA-A, followed by confir39:207-210. mation of the positive samples by the SN test. 3. Haffer K, Gustafson DP, Kanitz CL: 1980, Indirect hemaggluIn general, ELISA-A produced more false positive reactination tests for pseudorabies antibody detection in swine. J tions than ELISA-B, indicating that ELISA-B might be a Clin Microbiol 11:217-219. better test. However, 3 samples that were negative by ELISA-B 4. Hill HT, Crandell RA, Kanitz CL, et al.: 1977, Recommended were positive by SN at dilutions of 1:2-1:32. The infected minimum standards for diagnostic tests emploved in the diaa-
Downloaded from vdi.sagepub.com at UNIV OF MASSACHUSETTS on April 6, 2015
Brief Communications
352
nosis of pseudorabies (Aujeszky’s disease). Proc Annu Meet Am Assoc Vet Lab Diagn 20:375-390. 5. Hill HT, Seymore CL, Egan IT, Harris DL: 1983, Evaluation of the enzyme-linked immunosorbent assay and the microtitration serum-virus-neutralization tests as used in an epidemiological survey of Iowa, Illinois, and Missouri swine. Proc 3rd Int Symp World Assn Vet Lab Diagn 1:235-240. 6. Joo HS, Molitor TW, Leman AD: 1984, Radial immunodiffusion enzyme assay for detection of antibodies to pseudorabies virus in swine serum. Am J Vet Res 45:2096-2098. 7. Kelling CL, Standinger WL, Rhodes MB: 1978, Indirect solidphase microradioimmunoassay for detection of pseudorabies virus antibody in swine sera. Am J Vet Res 39: 1955-1957.
8. Scherba G, Gustafson DP, Kanitz CL, et al.: 1980, Delayed hypersensitivity reaction to pseudorabies virus as a field diagnostic test in swine. J Am Vet Med Assoc 173: 1490-1493. 9. Synder ML, Erickson GA: 1981, Recommended minimum standards for an enzyme-linked immunosorbent assay (ELISA) in pseudorabies serodiagnosis. National Veterinary Services Lab, US Department of Agriculture, Ames, IA. 32 pp. 10. Wade TW, Brees J, Goyal SM: 1986, Comparison of latex agglutination and serum neutralization tests for the detection of pseudorabies antibodies in swine sera. Proc Annu Meet Am Assoc Vet Lab Diagn 29:401-408.
J Vet Diagn Invest 2:352-354 (1990)
A mycological evaluation and in vivo toxicity evaluation of feed from 41 farms with equine leukoencephalomalacia Terrance M. Wilson, Paul E. Nelson, W. F. O. Marasas, Pieter G. Thiel, Gorden S. Shephard, Erick W. Sydenham, Hillman A. Nelson, P. Frank Ross Equine leukoencephalomalacia (ELEM) is of worldwide distribution and is caused by the mycotoxin fumonisin B1 (FB1), a metabolite of Fusarium moniliforme. 4,6 Studies also indicate that metabolites from various strains of F. moniliforme may be hepatocarcinogenic to rats.2,8 A recent review of the history, disease, seasonality, clinical syndromes, epidemiology, and differential diagnosis of equine leukoencephalomalacia has been published.7 The purpose of this study was to mycologically analyze commercial and noncommercial feeds associated with ELEM From the US Department of Agriculture, Animal and Plant Health Inspection Service, Science and Technology, National Veterinary Services Laboratories, PO Box 844, Ames, IA 50010 (Wilson, H. Nelson, Ross), the Fusarium Research Center, Department of Plant Pathology, Pennsylvania State University, University Park, PA 16802 (P. Nelson), and the Research Institute for Nutritional Disease, South African Medical Research Council, Tygerberg 7505, South Africa (Marasas, Thiel, Shephard, Sydenham). Received for publication April 3, 1990.
and to evaluate the toxigenicity of selected cultures of F. moniliforme. A mail and telephone survey was conducted with veterinary diagnostic laboratories in the East and Midwest between 1983 and 1986 to locate confirmed cases of ELEM. Telephone calls and correspondence were initiated to follow up all reported cases. Feed samples were collected on all farms, with emphasis on those feeds used l-3 weeks prior to the diagnosis of ELEM. Based on the feeding practices, the farms were divided into 5 groups (Table 1): 1) commercial nonpelleted feed, 2) commercial pelleted feed, 3) corn plus commercial pelleted feed, 4) mixed feeding—some on corn, some on corn plus commercial pelleted feed, and 5) corn or corn screenings. Clinical necropsy information, as well as macroscopic and microscopic material from most cases, was reviewed. In all cases, a necropsy and, in most cases, a histopathologic evaluation of brain tissue were conducted on at least 1 animal from each farm. Forty-one farms were surveyed with a wide range of breeds
Table 1. Number of farms and type of ration fed to horses exposed to Fusarium moniliforme and diagnosed as having ELEM.
Downloaded from vdi.sagepub.com at UNIV OF MASSACHUSETTS on April 6, 2015
