Evaluation of a novel monoclonal antibody‐based enzyme immunoassay for detection of Histoplasma antigen in urine of dogs

Abstract

Background: Commercially available, noninvasive testing options for histoplasmosis are limited outside of the United States. Objectives: To describe the diagnostic performance of a novel Histoplasma antigen enzyme immunoassay (IM EIA) for the diagnosis of histoplasmosis in dogs. Animals: Twenty dogs with histoplasmosis, 79 dogs without histoplasmosis, and 11 unclassified dogs providing 202 urine samples. Methods: This a prospective study using stored urine samples. Samples were analyzed with the IM EIA and with the commercially available Histoplasma antigen EIA (MV EIA). Dogs were classified based on final proven diagnosis and performance of the IM EIA was described and compared with the MiraVista enzyme immunoassay (MV EIA). Results: The diagnostic sensitivity (DSe), specificity (DSp), and accuracy (DAc) of the IM EIA were 70% (51%-89%), 99% (97%-100%), and 93% (81%-100%), respectively. The DSe, DSp, and DAc for the MV EIA were 95% (85%-100%), 99% (97%-100%), and 98% (95%-100%), respectively. The area under the receiver operator characteristic curve was significantly smaller for IM EIA (0.87) as compared with MV EIA (0.97, P = .03). This was primarily due to 6 false negative IM EIA results, 4 from dogs with disease localized to the gastrointestinal tract. The MV EIA was positive in 5/6 of these dogs. Conclusions and Clinical Importance: The IM EIA might be useful for the diagnosis of disseminated histoplasmosis in dogs, but clinical usefulness will be limited in dogs with histoplasmosis localized to the GI tract.

Evaluation of serum 25‐hydroxyvitamin D, C‐reactive protein, and haptoglobin as biomarkers in dogs newly diagnosed with histoplasmosis

“…The most commonly used commercially available Histoplasma antigen EIA has a sensitivity of 89.5% to 95% for the diagnosis of histoplasmosis in dogs. 7 , 10 In the 5% to 10% of cases that have no detectable Histoplasma antigen in urine at the time of diagnosis, future antigen testing is not useful for treatment monitoring. The measurement of serum CRP concentration has potential to fill this role as in other diseases.…”

“…Clinical disease in dogs can be limited to the lungs, or disseminate via blood and lymphatics to a wide array of extra‐pulmonary sites. 2 , 4 , 5 , 6 , 7 , 8 , 9 , 10 …”

“…After inhalation, microconidia convert to the yeast form in the terminal bronchioles of the lungs. Clinical disease in dogs can be limited to the lungs, or disseminate via blood and lymphatics to a wide array of extra‐pulmonary sites 2,4‐10 …”

Animal Histoplasmosis in Europe: Review of the Literature and Molecular Typing of the Etiological Agents

“…The best method for the health surveillance of H. capsulatum in animals remains an open question. Seroepidemiological studies have been done in dogs with different methods [ 65 , 66 ], however, the sensitivity and specificity of serologic tests in different animal populations is poorly studied and may be decreased in animals without disseminated disease [ 67 ]. The detection of such environmental foci might shed light onto the suspected autochthonous human cases and help target the efforts to culture H. capsulatum belonging to this lineage for more in-depth molecular and virulence studies.…”

Evaluation of urine for Dirofilaria immitis antigen detection in dogs

“…Antigenuria following antigenemia is a common result of many infectious processes in humans and animals [21,22]. Therefore, urine has been used as a diagnostic template for antigen detection in other infectious diseases in dogs and humans, including histoplasmosis and blastomycosis [23]. Parasitic nematode infections of the urinary tract can be diagnosed via detection of eggs with sedimentation and urinalysis [24,25,26], but urine has not been extensively explored for detection of nematode infections present outside the urinary tract.…”