Risk Factors for Positive Mantoux Tuberculin Skin Tests in Children in San Diego, California: Evidence for Boosting and Possible Foodborne Transmission

Abstract

We identified several new or reemerging associations with positive TST including cross border travel, staying in a foreign home, and eating raw dairy products. The strong associations with BCG receipt and more recent previous TST may represent falsely positive reactions, booster phenomena, or may be markers for a population that is truly at greater risk for TB infection. Unlike studies conducted in nonborder areas, we found no association between positive TB skin tests and contact with a TB case or a foreign visitor. Efforts to control pediatric TB in San Diego need to address local risk factors including consumption of unpasteurized dairy products and cross-border travel. The interpretation of a positive TST in a young child in San Diego who has received BCG is problematic.

Identifying the Sources of Tuberculosis in Young Children: A Multistate Investigation

“…While molecular data alone are not enough to prove recent transmission, the presence of infectious TB patients in the community who share the same strain with a young child without a known source suggests the possibility of casual transmission. Other impediments in identifying source patients may include barriers in completing contact investigations, delays in evaluation, and problems in identifying source patients who reside outside the health department’s jurisdiction (27). Eighty-four percent of young children without a source patient in this study were born in the United States; this observation is likely to underestimate the contribution of the global TB epidemic, because TB surveillance systems in the United States do not routinely monitor the birthplace or travel history of parents or guardians, factors previously identified as significant predictors for pediatric TB (28,29).…”

Comparison of Mantoux and Tine Tuberculin Skin Tests in BCG-Vaccinated Children Investigated for Tuberculosis

“…Several studies have attempted to identify factors associated with TST positivity in order to optimize contact tracing strategies, but the majority of studies have either been small scale, or performed among older children and adults, in developed countries with low TB prevalence, using only the Mantoux method (Table 1) ([24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35], [36], [37]. Few large studies have included young children, in whom the risk of TB disease is highest, particularly in high prevalence regions of sub-Saharan Africa, and there are no such studies that directly compare intradermal Mantoux and percutaneous multi-puncture Tine methods in the same paediatric population[29], [30], [37].…”

Epidemiology of HumanMycobacterium bovisDisease, California, USA, 2003–2011

“…M. bovis transmission to humans most frequently occurs through consumption of unpasteurized, contaminated dairy products, but person-to-person transmission has been reported ( 3 , 4 ). The consumption of contaminated unpasteurized dairy products has been suggested as a major contributor to human M. bovis disease for several reasons: 1) the near absence of M. bovis disease among infants <12 months of age; 2) a high percentage of extrapulmonary disease, particularly abdominal disease, among patients with M. bovis disease; and 3) an association between positive interferon-γ release assay results and consumption of unpasteurized dairy products ( 5 – 11 ). …”