Increased detection of Dirofilaria immitis antigen in cats after heat pretreatment of samples.
Objectives To determine whether pretreating diagnostic samples with heat increases the detection of Dirofilaria immitis antigen in adult cats, we evaluated feline serum and plasma samples collected in heartworm-endemic areas of the southern United States. Methods Commercial microtiter well assays for detection of D immitis antigen were used to evaluate serum or plasma samples from 385 shelter and free-roaming cats from the southcentral and southeastern United States before and after heat treatment; commercial antibody tests were performed on a subset of samples. Results Prior to sample heat treatment, 1/220 (0.5%) shelter cats and 4/165 (2.4%) free-roaming cats had detectable D immitis antigen. After heat pretreatment, the detection rate increased to 13/220 (5.9%) and 13/165 (7.9%), respectively. Antibody reactive to D immitis was significantly more common ( P <0.001) in the serum of cats that were antigen positive after heat treatment (10/13; 76.9%) than serum from cats that remained antigen negative after heat treatment (22/163; 13.5%). Conclusions and relevance Heat pretreatment of feline samples increased antigen detection by commercial assays for D immitis and improved overall concordance of antigen and antibody test results in antigen-positive samples in this population. Although further work to investigate the specificity of D immitis antigen assays when using pre-treated samples is warranted, this approach may be useful in the diagnosis of heartworm infection in individual cats and may increase the accuracy of surveys based on antigen detection.
1 Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, USA.
Jeff M
JM
Gruntmeir
2 Zoetis, Florham Park, NJ, USA.
Chris B
CB
Adolph
1 Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, USA.
Jennifer E
JE
Thomas
1 Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, USA.
Mason V
MV
Reichard
3 Department of Veterinary Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, AL, USA.
Byron L
BL
Blagburn
1 Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, USA.
Susan E
SE
Little
D000818:Animals; D000835:Animals, Wild; D000947:Antigens, Helminth / Q000097:blood*; D002371:Cat Diseases / Q000097:blood / Q000175:diagnosis / Q000469:parasitology*; D002415:Cats; D004183:Dirofilaria immitis / Q000276:immunology / Q000302:isolation & purification*; D004184:Dirofilariasis / Q000097:blood / Q000175:diagnosis* / Q000469:parasitology; D006358:Hot Temperature; D013048:Specimen Handling / Q000379:methods / Q000662:veterinary
D000947:Antigens, Helminth
Vet Parasitol. 2004 Feb 6;119(4):319-26
15154596
Am J Vet Res. 1984 Oct;45(10):2055-61
6497105
Vet Ther. 2000 Summer;1(3):169-75
19757579
J Am Anim Hosp Assoc. 2004 Sep-Oct;40(5):376-84
15347617
J Am Vet Med Assoc. 2000 Mar 1;216(5):693-700
10707684
Vet Ther. 2007 Winter;8(4):293-304
18183548
Parasit Vectors. 2012 Nov 13;5:258
23148786
Vet Parasitol. 2015 Jul 30;211(3-4):303-5
26116456
Parasit Vectors. 2014 Jan 13;7:1
24411014
Clin Microbiol Rev. 2012 Jul;25(3):507-44
22763636
Vet Parasitol. 2008 Dec 10;158(3):183-90
18922639
Parasit Vectors. 2015 Feb 04;8:68
25648086
J Feline Med Surg. 2008 Apr;10(2):137-44
18042416
Vet Parasitol. 2014 Nov 15;206(1-2):67-70
24785291
J Am Anim Hosp Assoc. 2003 Nov-Dec;39(6):533-7
14736717
J Immunol. 1985 Feb;134(2):1185-91
2578155
Vet Parasitol. 2008 Dec 10;158(3):171-6
18977090