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Table 1 Results from testing feline serum samples collected 196 and 224 days after experimental infection with 100 third-stage larvae of Dirofilaria immitis(positive results in bold)

From: Heat treatment prior to testing allows detection of antigen of Dirofilaria immitis in feline serum

  Day 196 Day 224
Cat (number of worms recovered) Antigen before heating (O. D.) Antigen after heating (O. D.) Antibody Antigen/antibody ratio Antigen before heating (O. D.) Antigen after heating (O. D.) Antibody Antigen/antibody ratio
1 (0)* 0.157 0.666 0.529 1.259 0.059 0.604 0.396 1.525
2 (6) 0.070 0.587 1.301 0.451 0.099** 1.985 1.605 1.237
3 (1) 0.064 0.289 0.264 1.095 0.056 0.120** 0.509 0.236
4 (2) 0.055 0.081 0.578 0.140 0.060 0.068 0.528 0.129
5 (1) 0.060 0.146 1.111 0.131 0.074 1.921 1.329 1.445
6 (2) 0.050 0.191 0.374 0.511 0.057 0.579 1.387 0.417
Mean (2.0) 0.076 0.327 0.693 0.598 0.068 0.880 0.959 0.832
Number positive 1/6 5/6 6/6   1/6 5/6 6/6  
  1. *No adult worms recovered but severe pulmonary lesions identified on histologic examination of lung sections. **Antigen was detected by visual color change but did not exceed the manufacturer’s specified cutoff (negative control + 0.05) for positive on the spectrophotometric assay used (PetChek® Heartworm PF Antigen Test, IDEXX Laboratories, Inc).
  2. Positive results in bold.