title: Effect of the inoculation site of bovine purified protein derivative (PPD) on the skin fold thickness increase in cattle from officially tuberculosis free and tuberculosis-infected herds.
abstract: The official technique for diagnosis of bovine tuberculosis (bTB) worldwide is the tuberculin skin test, based on the evaluation of the skin thickness increase after the intradermal inoculation of a purified protein derivative (PPD) in cattle. A number of studies performed on experimentally infected or sensitized cattle have suggested that the relative sensitivity of the cervical test (performed in the neck) may vary depending on the exact location in which the PPD is injected. However, quantitative evidence on the variation of the test accuracy associated to changes in the site of inoculation in naturally infected animals (the population in which performance of the test is most critical for disease eradication) is lacking. Here, the probability of obtaining a positive reaction (>2 or 4 millimeters and/or presence of local clinical signs) after multiple inoculations of bovine PPD in different cervical and scapular locations was assessed in animals from five bTB-infected herds (818 cattle receiving eight inoculations) using a hierarchical Bayesian logistic regression model and adjusting for the potential effect of age and sex. The effect of the inoculation site was also assessed qualitatively in animals from four officially tuberculosis free (OTF) herds (two inoculations in 210 animals and eight inoculations in 38 cattle). Although no differences in the qualitative outcome of the test were observed in cattle from OTF herds, a statistically important association between the test outcome and the inoculation site in animals from infected herds was observed, with higher probabilities of positive results when the test was performed in the neck anterior area. Our results suggest that test sensitivity may be maximized by considering the area of the neck in which the test is applied, although lack of effect of the inoculation site in the specificity of the test should be confirmed in a larger sample.
authors.affiliation: Mycobacteria Unit, VISAVET Health Surveillance Centre, Complutense University of Madrid, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Casal
authors.affiliation: Department of Veterinary Population Medicine, University of Minnesota, 55108 St. Paul, MN, USA. Electronic address: jalvarez@umn.edu.
authors.forename: Julio
authors.initials: J
authors.lastname: Alvarez
authors.affiliation: MAEVA SERVET S.L. C/ de la Fragua 3, 28749, Alameda del Valle, Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Bezos
authors.affiliation: Centers for Disease Control and Prevention, 4770 Buford Hwy, NE MS F-76, Atlanta 30341-3717, Georgia.
authors.forename: Harrison
authors.initials: H
authors.lastname: Quick
authors.affiliation: MAEVA SERVET S.L. C/ de la Fragua 3, 28749, Alameda del Valle, Madrid, Spain; Department of Animal Health, Faculty of Veterinary Medicine, Complutense University of Madrid, 28040 Madrid, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Díez-Guerrier
authors.affiliation: Mycobacteria Unit, VISAVET Health Surveillance Centre, Complutense University of Madrid, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Romero
authors.affiliation: Ministry of Agriculture, Food and Environment, C/ Almagro 33, 28071 Madrid, Spain.
authors.forename: Jose L
authors.initials: JL
authors.lastname: Saez
authors.affiliation: Mycobacteria Unit, VISAVET Health Surveillance Centre, Complutense University of Madrid, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain.
authors.forename: Emmanouil
authors.initials: E
authors.lastname: Liandris
authors.affiliation: Mycobacteria Unit, VISAVET Health Surveillance Centre, Complutense University of Madrid, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Navarro
authors.affiliation: Department of Veterinary Population Medicine, University of Minnesota, 55108 St. Paul, MN, USA.
authors.forename: Andrés
authors.initials: A
authors.lastname: Perez
authors.affiliation: Mycobacteria Unit, VISAVET Health Surveillance Centre, Complutense University of Madrid, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain; Department of Animal Health, Faculty of Veterinary Medicine, Complutense University of Madrid, 28040 Madrid, Spain.
authors.forename: Lucas
authors.initials: L
authors.lastname: Domínguez
authors.affiliation: Mycobacteria Unit, VISAVET Health Surveillance Centre, Complutense University of Madrid, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain; Department of Animal Health, Faculty of Veterinary Medicine, Complutense University of Madrid, 28040 Madrid, Spain.
authors.forename: Lucía
authors.initials: L
authors.lastname: de Juan
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D002417:Cattle; D005260:Female; D016015:Logistic Models; D008297:Male; D009163:Mycobacterium bovis / Q000276:immunology; D009333:Neck / Q000502:physiology*; D015995:Prevalence; D012680:Sensitivity and Specificity; D012885:Skinfold Thickness; D013030:Spain / Q000453:epidemiology; D014373:Tuberculin / Q000008:administration & dosage*; D014374:Tuberculin Test / Q000662:veterinary*; D014380:Tuberculosis, Bovine / Q000175:diagnosis* / Q000453:epidemiology / Q000382:microbiology
chemical_list: D014373:Tuberculin
keywords: Bovine tuberculosis; Intradermal inoculation; Tuberculin test; bovine PPD