High prevalence of Trypanosoma cruzi infection in shelter dogs from southern Louisiana, USA

Abstract

Background Chagas disease is a zoonotic disease caused by the protozoan parasite Trypanosoma cruzi . The role of dogs as sentinels has been proposed in multiple regions, as they are a domestic reservoir for T. cruzi. Our objective was to determine the prevalence of T. cruzi infection in shelter dogs from southern Louisiana, and assess its magnitude and distribution. Results A total of 540 dogs were enrolled, from 20 animal shelters, and tested for T. cruzi infection by serological tests (rapid test, ELISA and western blot) and PCR. We documented a high prevalence of T. cruzi infection with at least 6.9% (95% CI: 5.0–9.3%) seropositive and 15.7% (95% CI: 12.9–19.1%) PCR-positive dogs. Serological tests showed limited agreement, and concordance between serology and PCR was higher when considering reactivity to single serological tests. Trypanosoma cruzi infection was distributed evenly among shelters. Infection was significantly correlated with age ( R 2 = 0.99), indicating an incidence of new cases of 2.27 ± 0.25% per year. Conclusion Trypanosoma cruzi infection is a significant and widespread veterinary problem in shelter dogs in the region, although it is mostly unnoticed by health professionals. This highlights the need for greater awareness of T. cruzi infection among the veterinary community and dog owners. Electronic supplementary material The online version of this article (10.1186/s13071-019-3572-y) contains supplementary material, which is available to authorized users.

Genetic diversity of Trypanosoma cruzi parasites infecting dogs in southern Louisiana sheds light on parasite transmission cycles and serological diagnostic performance

“…In Louisiana, we recently reported a seroprevalence of T . cruzi antibodies of 7% in shelter dogs [ 9 ], in agreement with the widespread circulation of T . cruzi in this region.…”

“…Similarly in Louisiana, we found that only 7% of dogs PCR positive for T . cruzi are also confirmed positive by serology (at least two reactive tests), while 41% have discordant serological test results (only one reactive test) and 52% are completely seronegative, based on three serological tests [ 9 ]. Discordance among tests has also been observed for human samples [ 12 – 14 ] and it is becoming a key issue for the reliable surveillance of Chagas disease and patient care in North America [ 15 , 16 ].…”

In the heart of the city: Trypanosoma cruzi infection prevalence in rodents across New Orleans

“…Though it is well understood that commensal species like Norway rats (Rattus norvegicus), roof rats (Rattus rattus) and house mice (Mus musculus) can carry T. cruzi, remarkably little is known about infection prevalence in urban populations, particularly within the USA [13,14]. So far, there have been more extensive studies of other sentinel hosts commonly found in cities, such as shelter dogs and raccoons [28][29][30]. Smaller scale assays of rodents conducted in South America (e.g.…”

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“…Archived blood DNA samples from a previous study on the prevalence of T. cruzi infection in shelter dogs were used for T. cruzi parasite genotyping [9]. These were derived from a convenience sampling of 540 animals from 20 shelters from southern Louisiana, including from Acadia, Ascension, Calcasieu, East Baton Rouge, Iberia, Iberville, Jackson, Lafourche, Livingston, Natchitoches, Orleans, St. Landry, St. Martin and Tangipahoa parishes (S1 Fig).…”

“…Purified DNA was stored at -20˚C until used, and a total of 73 samples that were PCR positive for T. cruzi were included in this study. Four (5%) of these PCR positive dogs were confirmed seropositive (at least two positive tests including InBios Stat-Pak rapid test, homemade ELISA and western blot), 39 (53%) had discordant serology (a single positive test) and 30 (41%) were seronegative with all tests [9].…”