Evaluation of species identification and rabies virus characterization among bat rabies cases in the United States.

OBJECTIVE: To evaluate species identification and rabies virus (RABV) characterization among samples from bats submitted for rabies testing in the United States and assess whether a standardized approach to specimen selection for RABV characterization could enhance detection of a sentinel event in virus dissemination among bats. SAMPLE: United States public health rabies surveillance system data collected in January 2010 through December 2015. PROCEDURES: The number of rabies-tested bats for which species was reported and the number of RABV-positive samples for which virus characterization would likely provide information regarding introduction of novel RABV variants and translocation and host-shift events were calculated. These specimens were designated as specimens of epizootiological importance (SEIs). Additionally, the estimated test load that public health laboratories could expect if all SEIs underwent RABV characterization was determined. RESULTS: Species was reported for 74,928 of 160,017 (47%) bats submitted for rabies testing. Identified SEIs were grouped in 3 subcategories, namely nonindigenous bats; bats in southern border states, Florida, Puerto Rico, and the US Virgin Islands; and bats of species that are not commonly found to be inflected with RABV. Annually, 692 (95% CI, 600 to 784) SEIs were identified, of which only 295 (95% CI, 148 to 442) underwent virus characterization. Virus characterization of all SEIs would be expected to increase public health laboratories' overall test load by 397 (95% CI, 287 to 506) samples each year. CONCLUSIONS AND CLINICAL RELEVANCE: Species identification and RABV characterization may aid detection of a sentinel event in bat RABV dissemination. With additional resources, RABV characterization of all SEIs as a standardized approach to testing could contribute to knowledge of circulating bat RABV variants.

Resistance to First-Line Antituberculosis Drugs in Washington State by Region of Birth and Implications for Latent Tuberculosis Treatment Among Foreign-Born Individuals.

The United States has a low burden of drug resistance among tuberculosis (TB) cases compared with other world regions. TB is increasingly concentrated among foreign-born individuals who have higher rates of drug resistance than U.S.-born individuals. While universal drug susceptibility testing is the standard for detecting active tuberculosis, there are limited guidelines for latent tuberculosis infection (LTBI) treatment based on risk factors for drug resistance. To quantify the variable risk of drug resistance among foreign-born individuals, all TB cases in Washington State between 1994 and 2014 with drug resistance data for isoniazid, rifampin, pyrazinamide, and ethambutol were divided into eight regions of birth. Logistic regression was used to characterize regional differences in resistance patterns. Genotypic cluster and lineage data were compared against drug resistance in a subanalysis. Among 4,298 cases, isoniazid resistance was more common in foreign-born individuals (12.6% versus 4.8%; P < 0.001), with the highest burden among individuals from the Asia-Pacific (14.8%) region. Rifampin resistance was slightly higher among foreign-born individuals (1.9% versus 1.1%; P = 0.063). Multivariate logistic regression demonstrated that older age was associated with a lower risk of resistance to isoniazid and rifampin (odds ratio [OR] = 0.86, P = 0.006 and OR = 0.64, P = 0.003 for each 20-year interval, respectively). These data suggest drug resistance in LTBI will remain a challenge and that rifampin-based regimens for treatment of LTBI in non-human immunodeficiency virus-infected adults may be preferable for individuals born in regions with high levels of isoniazid resistance. However, further research is needed to demonstrate whether LTBI treatment based on region of birth further decreases TB reactivation.