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1.
Vet Res ; 52(1): 53, 2021 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-33823911

RESUMO

Trypanosoma cruzi is a zoonotic parasite endemic in the southern US and the Americas, which may frequently infect dogs, but limited information is available about infections in cats. We surveyed a convenience sample of 284 shelter cats from Southern Louisiana to evaluate T. cruzi infection using serological and PCR tests. Parasites from PCR positive cats were also genotyped by PCR and deep sequencing to assess their genetic diversity. We detected a seropositivity rate for T. cruzi of at least 7.3% (17/234), and 24.6% of cats (70/284) were PCR positive for the parasite. Seropositivity increased with cat age (R2 = 0.91, P = 0.011), corresponding to an incidence of 7.2% ± 1.3 per year, while PCR positivity decreased with age (R2 = 0.93, P = 0.007). Cats were predominantly infected with parasites from TcI and TcVI DTUs, and to a lesser extent from TcIV and TcV DTUs, in agreement with the circulation of these parasite DTUs in local transmission cycles. These results indicate that veterinarians should have a greater awareness of T. cruzi infection in pets and that it would be important to better evaluate the risk for spillover infections in humans.

2.
PLoS Negl Trop Dis ; 14(12): e0008932, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33332357

RESUMO

BACKGROUND: Chagas disease is a neglected zoonosis of growing concern in the southern US, caused by the parasite Trypanosoma cruzi. We genotyped parasites in a large cohort of PCR positive dogs to shed light on parasite transmission cycles and assess potential relationships between parasite diversity and serological test performance. METHODOLOGY/PRINCIPAL FINDINGS: We used a metabarcoding approach based on deep sequencing of T. cruzi mini-exon marker to assess parasite diversity. Phylogenetic analysis of 178 sequences from 40 dogs confirmed the presence of T. cruzi discrete typing unit (DTU) TcI and TcIV, as well as TcII, TcV and TcVI for the first time in US dogs. Infections with multiple DTUs occurred in 38% of the dogs. These data indicate a greater genetic diversity of T. cruzi than previously detected in the US. Comparison of T. cruzi sequence diversity indicated that highly similar T. cruzi strains from these DTUs circulate in hosts and vectors in Louisiana, indicating that they are involved in a shared T. cruzi parasite transmission cycle. However, TcIV and TcV were sampled more frequently in vectors, while TcII and TcVI were sampled more frequently in dogs. CONCLUSIONS/SIGNIFICANCE: These observations point to ecological host-fitting being a dominant mechanism involved in the diversification of T. cruzi-host associations. Dogs with negative, discordant or confirmed positive T. cruzi serology harbored TcI parasites with different mini-exon sequences, which strongly supports the hypothesis that parasite genetic diversity is a key factor affecting serological test performance. Thus, the identification of conserved parasite antigens should be a high priority for the improvement of current serological tests.


Assuntos
Doença de Chagas/veterinária , Éxons/genética , Variação Genética , Trypanosoma cruzi/genética , Animais , Doença de Chagas/epidemiologia , Doença de Chagas/parasitologia , Doença de Chagas/transmissão , Estudos de Coortes , Cães , Genótipo , Humanos , Louisiana/epidemiologia , Filogenia , Testes Sorológicos/veterinária , Trypanosoma cruzi/imunologia , Trypanosoma cruzi/fisiologia , Zoonoses
3.
Parasit Vectors ; 12(1): 322, 2019 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-31238941

RESUMO

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 (R2 = 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.


Assuntos
Doença de Chagas/veterinária , Doenças do Cão/epidemiologia , Cães/parasitologia , Animais , Anticorpos Antiprotozoários/sangue , Doença de Chagas/epidemiologia , Doenças do Cão/parasitologia , Ensaio de Imunoadsorção Enzimática , Feminino , Louisiana/epidemiologia , Masculino , Prevalência , Testes Sorológicos , Trypanosoma cruzi/genética , Trypanosoma cruzi/isolamento & purificação
4.
Parasit Vectors ; 10(Suppl 2): 483, 2017 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-29143645

RESUMO

BACKGROUND: The diagnosis and management of canine heartworm disease is a growing concern for shelter veterinarians. Although the accuracy of commercial antigen test kits has been widely studied, recent reports have renewed interest in antigen blocking as a causative factor for false "no antigen detected" results. The objectives of this study were to determine the prevalence of false "no antigen detected" results in adult dogs entering shelters in northern, southern, and western regions of the country and to identify historical and clinical risk factors for such results. METHODS: Serum samples were evaluated for Dirofilaria immitis antigen using a commercially available point-of-care ELISA; samples in which no antigen was detected underwent a heat treatment protocol and repeat antigen testing. Whole blood samples underwent Knott testing to identify the presence of microfilariae. Historical and clinical findings were analyzed using exact logistic regression. RESULTS: A total of 616 samples were analyzed. Overall prevalence of positive antigen test results (prior to heat treatment) was 7.3% and frequency of false "no antigen detected" results due to antigen blocking (ie, samples with no antigen detected prior to heat treatment and positive after heat treatment) was 5.2%. Among dogs that had no detectable antigen on the initial tests, dogs that had microfilariae detected via modified Knott testing (OR = 32.30, p-value = 0.013) and dogs that previously received a heartworm preventive (OR = 3.81, p-value = 0.016) had greater odds of antigen blocking than dogs without these factors. Among dogs that were heartworm positive, those without microfilariae detected had greater odds of antigen blocking than dogs with this factor (OR = 11.84, p-value = 0.0005). Geographic region of origin was significantly associated with occurrence of antigen blocking (p = 0.0036); however, blocking occurred in all regions sizably contributing to heartworm diagnoses. Of the 74 dogs found to be infected with heartworms in this study, 39.2% (29) had no detectable antigen prior to heat treatment. CONCLUSIONS: Heat treatment of serum samples should be considered to improve diagnostic test accuracy, particularly in dogs that reportedly received a heartworm preventive prior to antigen testing regardless of region of origin.


Assuntos
Antígenos de Helmintos/sangue , Testes Diagnósticos de Rotina/métodos , Dirofilaria immitis/isolamento & purificação , Dirofilariose/diagnóstico , Doenças do Cão/diagnóstico , Ensaio de Imunoadsorção Enzimática/métodos , Animais , Antígenos de Helmintos/química , Testes Diagnósticos de Rotina/instrumentação , Dirofilaria immitis/fisiologia , Dirofilariose/sangue , Dirofilariose/parasitologia , Doenças do Cão/sangue , Doenças do Cão/parasitologia , Cães , Ensaio de Imunoadsorção Enzimática/instrumentação , Temperatura Alta , Sistemas Automatizados de Assistência Junto ao Leito
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