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. 2023 May-Jun;37(3):1007-1014.
doi: 10.1111/jvim.16726. Epub 2023 Apr 27.

Evaluation of an enzyme immunoassay and immunodiffusion for detection of anti-Histoplasma antibodies in serum from cats and dogs

Rebecca Tims  1   2 , Andrew S Hanzlicek  2   3 , Laura Nafe  4 , Michelle M Durkin  3 , Jennifer Smith-Davis  3 , L Joseph Wheat  3
Affiliations

Evaluation of an enzyme immunoassay and immunodiffusion for detection of anti-Histoplasma antibodies in serum from cats and dogs

Rebecca Tims et al. J Vet Intern Med. 2023 May-Jun.

Abstract

Background: Histoplasma antigen and anti-Histoplasma antibody detection are used to support the diagnosis of histoplasmosis. There is a paucity of published data on antibody assays.

Objectives: Our primary hypothesis was that anti-Histoplasma immunoglobulin G (IgG) antibody detection using enzyme immunoassay (EIA) will be more sensitive as compared to immunodiffusion (ID).

Animals: Thirty-seven cats and 22 dogs with proven or probable histoplasmosis; 157 negative control animals.

Methods: Residual stored sera were tested for anti-Histoplasma antibodies using EIA and ID. Results of urine antigen EIA were reviewed retrospectively. Diagnostic sensitivity was calculated for all three assays and compared between immunoglobulin G (IgG) EIA and ID. The diagnostic sensitivity of urine antigen EIA and IgG EIA, interpreted in parallel, was reported.

Results: Sensitivity of IgG EIA was 30/37 (81.1%; 95% confidence interval [CI], 68.5%-93.4%) in cats and 17/22 (77.3%; 95% CI, 59.8%-94.8%) in dogs. Diagnostic sensitivity of ID was 0/37 (0%; 95% CI, 0%-9.5%) in cats and 3/22 (13.6%; 95% CI, 0%-28.0%) in dogs. Immunoglobulin G EIA was positive in all animals (2 cats and 2 dogs) with histoplasmosis but without detectable antigen in urine. Diagnostic specificity of IgG EIA was 18/19 (94.7%; 95% CI, 74.0%-99.9%) in cats and 128/138 (92.8%; 95% CI, 87.1%-96.5%) in dogs.

Conclusion and clinical importance: Antibody detection by EIA can be used to support the diagnosis of histoplasmosis in cats and dogs. Immunodiffusion has an unacceptably low diagnostic sensitivity and is not recommended.

Keywords: canine; feline; fungal infection; histoplasmosis; invasive fungal infection; serology.

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Conflict of interest statement

Andrew Hanzlicek, Michelle Durkin, Jennifer Smith‐Davis, and L. Joseph Wheat are employed by MiraVista Diagnostics which commercially offers the antigen and antibody detection tests used in this study. No other authors declare a conflict of interest.

Figures

FIGURE 1
FIGURE 1
IgG EIA concentrations in serum in 37 cats with proven and probable histoplasmosis and 19 control cats without histoplasmosis. Each dot represents an individual cat's EIA result. The dashed line is the diagnostic cutoff (>10 EU).
FIGURE 2
FIGURE 2
IgG EIA concentrations in serum in 22 dogs with proven and probable histoplasmosis and 120 control dogs without histoplasmosis. Each dot represents an individual dog's EIA result. The dashed line is the diagnostic cutoff (>10 EU).
See this image and copyright information in PMC

References

    1. Ludwig HC, Hanzlicek AS, KuKanich KS, et al. Candidate prognostic indicators in cats with histoplasmosis treated with antifungal therapy. J Feline Med Surg. 2018;20:985‐996. - PMC - PubMed
    1. Wilson AG, KuKanich KS, Hanzlicek AS, et al. Clinical signs, treatment, and prognostic factors for dogs with histoplasmosis. J Am Vet Med Assoc. 2018;252:201‐209. - PubMed
    1. Fielder SE, Meinkoth JH, Rizzi TE, Hanzlicek AS, Hallman RM. Feline histoplasmosis presenting with bone and joint involvement: clinical and diagnostic findings in 25 cats. J Feline Med Surg. 2019;21:887‐892. - PMC - PubMed
    1. Smith KM, Strom AR, Gilmour MA, et al. Utility of antigen testing for the diagnosis of ocular histoplasmosis in four cats: a case series and literature review. J Feline Med Surg. 2017;19:1110‐1118. - PMC - PubMed
    1. Emmons CW, Rowley DA, Olson BJ, et al. Histoplasmosis; proved occurrence of inapparent infection in dogs, cats and other animals. Am J Hyg. 1955;61:40‐44. - PubMed