03054nas a2200253   4500000000100000008004100001653002200042653000900064653002400073653001400097653002400111653002400135653001200159653001900171100001300190700001500203700001200218245016600230856009800396300001300494490000700507520227200514022001402786       2017                            d10aTrypanosoma cruzi10aDogs10aTexas-Mexico border10aInfection10aDiscordant serology10aParasite genotyping10avectors10aChagas disease1 aMeyers A1 aMeinders M1 aHamer S00aWidespread Trypanosoma cruzi infection in government working dogs along the Texas-Mexico border: Discordant serology, parasite genotyping and associated vectors.  uhttp://journals.plos.org/plosntds/article/file?id=10.1371/journal.pntd.0005819&type=printable  ae00058190 v113 a<p><strong>BACKGROUND: </strong>Chagas disease, caused by the vector-borne protozoan Trypanosoma cruzi, is increasingly recognized in the southern U.S. Government-owned working dogs along the Texas-Mexico border could be at heightened risk due to prolonged exposure outdoors in habitats with high densities of vectors. We quantified working dog exposure to T. cruzi, characterized parasite strains, and analyzed associated triatomine vectors along the Texas-Mexico border.</p>

<p><strong>METHODOLOGY/PRINCIPLE FINDINGS: </strong>In 2015-2016, we sampled government working dogs in five management areas plus a training center in Texas and collected triatomine vectors from canine environments. Canine serum was tested for anti-T. cruzi antibodies with up to three serological tests including two immunochromatographic assays (Stat-Pak and Trypanosoma Detect) and indirect fluorescent antibody (IFA) test. The buffy coat fraction of blood and vector hindguts were tested for T. cruzi DNA and parasite discrete typing unit was determined. Overall seroprevalence was 7.4 and 18.9% (n = 528) in a conservative versus inclusive analysis, respectively, based on classifying weakly reactive samples as negative versus positive. Canines in two western management areas had 2.6-2.8 (95% CI: 1.0-6.8 p = 0.02-0.04) times greater odds of seropositivity compared to the training center. Parasite DNA was detected in three dogs (0.6%), including TcI and TcI/TcIV mix. Nine of 20 (45%) T. gerstaeckeri and T. rubida were infected with TcI and TcIV; insects analyzed for bloodmeals (n = 11) fed primarily on canine (54.5%).</p>

<p><strong>CONCLUSIONS/SIGNIFICANCE: </strong>Government working dogs have widespread exposure to T. cruzi across the Texas-Mexico border. Interpretation of sample serostatus was challenged by discordant results across testing platforms and very faint serological bands. In the absence of gold standard methodologies, epidemiological studies will benefit from presenting a range of results based on different tests/interpretation criteria to encompass uncertainty. Working dogs are highly trained in security functions and potential loss of duty from the clinical outcomes of infection could affect the work force and have broad consequences.</p>
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