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National Institute of Environmental Health Sciences

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Your Environment. Your Health.

Publication Detail

Title: Antibody levels to recombinant tick calreticulin increase in humans after exposure to Ixodes scapularis (Say) and are correlated with tick engorgement indices.

Authors: Sanders, M L; Glass, G E; Nadelman, R B; Wormser, G P; Scott, A L; Raha, S; Ritchie, B C; Jaworski, D C; Schwartz, B S

Published In Am J Epidemiol, (1999 Apr 15)

Abstract: The antibody responses of subjects who presented with a definite Ixodes scapularis (Say) tick bite were measured to determine the utility of the antibody response against recombinant tick calreticulin (rTC) as a biologic marker of tick exposure. Subjects bitten by I. scapularis evidenced an increase in anti-rTC antibody levels between visit 1 and visit 2 from 24.3 to 27.1 ng/microl serum (n = 88, p = 0.003), and levels remained elevated at visit 3 (p = 0.005). These anti-rTC antibody levels during visits 2 and 3 were significantly higher than those in four non-exposed controls. Tick engorgement indices, measured on the biting ticks, were found to be correlated with anti-rTC antibody levels (e.g., for visit 3: Pearson's r = 0.357, p = 0.001). Tick engorgement index (TEI), ratio of body length to scutal width, was identified to be the only independent predictor of anti-rTC antibody levels in linear regression models. Logistic regression revealed that a bite from an I. scapularis tick that became engorged (TEI >3.4) was a risk factor for anti-rTC antibody seropositivity (adjusted odds ratio for age and bite location = 7.4 (95% confidence interval 2.1-26.4)). The anti-rTC antibody test had a sensitivity of 0.50 and a specificity of 0.86 for a bite from I. scapularis that became engorged. Immunoblotting revealed that subjects made a specific anti-rTC antibody response.

PubMed ID: 10206628 Exiting the NIEHS site

MeSH Terms: Adult; Aged; Animals; Antibodies/immunology*; Bites and Stings/diagnosis; Bites and Stings/immunology*; Calcium-Binding Proteins/immunology*; Calreticulin; Enzyme-Linked Immunosorbent Assay; Erythema Chronicum Migrans/diagnosis; Erythema Chronicum Migrans/immunology; Feeding Behavior; Female; Humans; Immunoblotting; Ixodes/immunology*; Male; Middle Aged; New York; Recombinant Proteins/immunology; Ribonucleoproteins/immunology*; Sensitivity and Specificity

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