The development of an indirect fluorescent antibody test for Trypanosoma vivax in Colombia : a thesis /
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| Format: | Thesis Book |
| Language: | English |
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[College Station, Tex.] :
[Texas A&M University],
[1974]
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| Abstract: | ABSTRACT: An indirect fluorescent antibody test (IFAT) for Trypanosoma vivax infections was developed for a survey involving over 2000 cattle distributed thoughout 11 departments and territories in Colombia. Antigen for the IFAT was derived from a strain of T. vivax isolated from a cow in the Department of Cordoba, Colombia. The strain was maintained via serial passage in hemoparasite-free calves. Inoculation of apporximately 2 x 10⁹ trypanosomes into splenectomized, triamcinolone acetonide-treated calves resulted in parasitemias suitable for IFAT antigen production at 66 to 69 hours post inoculation. Thin blood smears were prepared from citrated T. vivax laden blood, air dried and fixed in acetone:methanol::60:40, -20 C for 30 minutes. Fixed antigen slides were stored dry at -35 and -70 C and used successfully in the IFAT for 144 and 116 days respectively. Indirect fluorescent antibody test serum titers of 1:100 or greater were observed at a mean time of 15.9 days post parasitemia (PP) with a range of 6 to 32 days. Maximum titers of 1:400 developed in 14 to 33 days PP in 8 calves. In one calf, 109 days PP were required before the maximum titer was attained. Serum titers persisted in calves up to 278 days PP. Maternal antibodies capable of causing a positive fluorescent reaction at 1:100 serum dilution persisted for 29 days after birth in 1 calf. At serum dilutions of 1:100, the IFAT detected positive reactions in 80.4% of 133 serum samples obtained from 9 calves at various times during the course of T. vivax infections. At serum dilutions of 1:50, the percentage of positive reactions increased to 97%. The IFAT was specific for T. vivax. No cross reactivity was observed between T. vivax and Anaplasma marginale, Babesia argentina, Babesia bigemina, Eperythrozoon spp. or Trypanosoma theileri at 1:50 serum dilutions. Suspicious reactions were occasionally observed when Trypanosoma evansi-positive serum diluted 1:50 and 1:100 was used in the IFAT for T. vivax. No false positive reactions were observed when serums from 36 hemoparasite-free calves were tested. Results from the IFAT were repeated within plus or minus 1 dilution approximately 80% of the time using different antigen lots on the same and different days. Samples obtained for the IFAT by eluting serum from dried blood-impregnated filter paper that had been stored at -20 C for 10 days or less, produced results nearly equal to those obtained by using conventional serum samples. In field cases of trypanosomiasis, the IFAT was up to 21 times more effective in detecting T. vivax-positive cattle on the basis of antibody presence than the thick blood smear technique. Results of the survey revealed the presence of T. vivax antibodies in cattle from the departments of Boyaca, Cordoba, Meta, Sucre and Valle. No T. vivax IFAT antibodies were detected in serums obtained from cattle in the departments of Antioquia, Cauca, Caqueta, Cundinamarca, Tolima and Vichada. |
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| Item Description: | Vita. "Major Subject: Veterinary Microbiology". "Submitted to the Graduate College of Texas A & M University in partial fulfillment of the requirement for the degree of Master of Science May 1974". |
| Physical Description: | xiv, 146 leaves : illustrations ; 28 cm |
| Bibliography: | Includes bibliographical references. |