Updates in Immunoassays: Parasitology

Deborah Josko

doi:10.29074/ascls.25.3.185

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Deborah Josko, Ph.D. MLT (ASCP)M, SM⇑
1. Department of Clinical Laboratory Sciences, University of Medicine and Dentistry of New Jersey, Scotch Plains, NJ

Address for Correspondence: Deborah Josko, Ph.D. MLT(ASCP)M, SM, Department of Clinical Laboratory Sciences, Medical Laboratory Science Program, University of Medicine and Dentistry of New Jersey, 1776 Raritan Road, Scotch Plains, NJ 07076. (908) 889-2422. joskotda{at}umdnj.edu

Review the five parasitic infections targeted by the CDC that require public attention.
Discuss the immunoassays available to detect Toxocara and Toxoplasma.
List FDA-cleared immunoassays used to identify parasitic infections.
Describe issues related to ANA testing.
Examine the role of CRP and procalcitonin as biomarkers in bacterial sepsis.

Extract

Parasitic disease, although once considered a disease acquired abroad or in developing countries, is very much a problem in the US. According to the Centers for Disease Control and Prevention (CDC), there are approximately 7.4 million cases of trichomoniasis; 2 million cases of giardiasis; 300,000 cases of cryptosporidium; and 400–4,000 cases of congenital toxoplasmosis in the US per year.¹ The CDC has targeted five parasitic infections that are often neglected but require public health attention. They include Chagas disease, cysticercosis, toxocariasis, toxoplasmosis, and trichomoniasis.²

Laboratory diagnosis for Chagas disease, cysticercosis, and trichomoniasis relies on either microscopic examination (Chagas disease and trichomoniasis), through magnetic resonance imaging (MRI) or computerized tomography (CT, cysticercosis).^3,4 Toxocariasis and toxoplasmosis are diagnosed through serological methods.

Toxocariasis Although the enzyme-linked immunosorbent assay (ELISA) for Toxocara excretory-secretory antigen (TES-Ag), confirmed by western blot, is the serological assay used to determine a positive result, caution should be taken in interpretation since present-day tests cannot differentiate between a past or recent infection. ^5,6,7 Blood eosinophil counts and total serum IgE levels should also be used in conjunction with exposure history and serological and clinical findings.^5,6,7,8 Most clinical laboratories do not routinely test for toxocariasis and refer specimens to reference laboratories for evaluation.

Toxoplasmosis According to the CDC, toxoplasmosis is one of the primary causes of death in the US due to foodborne illness.⁹ Although it is estimated that more than 60 million individuals harbor the parasite with no significant consequences, caution is taken when a pregnant female or someone in…

ABBREVIATIONS: ANA - anti-nuclear antibody; CDC - Centers for Disease Control and Prevention; CLIA - chemiluminescent immunoassay; CRP - C-reactive protein; CT - computerized tomography; DFA - direct fluorescent antibody; EIA - enzyme immunoassay; ELFA - enzyme-linked fluorescent assay; ELISA - enzyme-linked immunosorbent assay; FDA - Food and Drug Administration; IF - immunofluorescent; IFA - indirect fluorescent antibody; IgE - immunoglobulin E; IgG - immunoglobulin G; IgM - immunoglobulin M; IIF - indirect immunofluorescence; IUIS - International Union of Immunological Societies; MRI - magnetic resonance imaging; O&P - ova and parasite; PCT - procalcitonin; RNP - ribonucleoprotein; Sm - Smith; SS - Sjögren's syndrome; TES-Ag - Toxocara excretory-secretory antigen; WHO = World Health Organization.

Review the five parasitic infections targeted by the CDC that require public attention.
Discuss the immunoassays available to detect Toxocara and Toxoplasma.
List FDA-cleared immunoassays used to identify parasitic infections.
Describe issues related to ANA testing.
Examine the role of CRP and procalcitonin as biomarkers in bacterial sepsis.