RESUMO
Domestic animals may affect human-vector contact and parasite transmission rates. We investigated the relationships between host-feeding choices, site-specific host availability, bug nutritional status, stage and abundance of Triatoma infestans Klug (Heteroptera: Reduviidae) in rural houses of Pampa del Indio during spring. We identified the bloodmeal sources of 865 triatomines collected in 70 sites from four main ecotopes. The main sources in domiciles were human (65.9%), chicken (23.4%) and dog (22.4%); dog (64.4%, 35.3%) and chicken (33.1%, 75.4%) in kitchens and storerooms, respectively; and chicken (94.7%) in chicken coops. Using random-intercept logistic regression clustered by domicile, the fraction of human-fed triatomines strongly decreased with increasing proportions of chicken- and dog-fed bugs, dropping from 96.4% when no chicken or dog slept indoors at night to 59.4% when both did. The fraction of dog-fed bugs significantly decreased with increasing human and chicken blood indices, and marginally increased with an indoor-resting dog. Mixed blood meals occurred 3.62 times more often when a chicken or a dog slept indoors. Host blood source did not affect mean body weight adjusted for body length and bug stage. Indoor-resting chickens and dogs greatly modified human-bug contact rates, and may be targeted with long-lasting systemic insecticides to suppress infestation.
Assuntos
Doença de Chagas/transmissão , Galinhas/parasitologia , Cães/parasitologia , Triatoma , Animais , Argentina/epidemiologia , Doença de Chagas/veterinária , Comportamento Alimentar , Humanos , Controle de Insetos , Insetos Vetores/parasitologia , Insetos Vetores/fisiologia , Características de Residência , População Rural , Estações do Ano , Triatoma/parasitologia , Triatoma/fisiologia , Doenças Transmitidas por VetoresRESUMO
Dogs play an important role as reservoirs and hosts of multiple pathogens shared with humans and wildlife, which contribute significantly to the global burden of disease. Here, we assessed the occurrence of a broad range of zoonotic and non-zoonotic parasites in dogs from a rural area in the humid Chaco; determined the occurrence of polyparasitism; and explored its association with selected risk factors. In total, 212 dogs were examined serologically to determine Trypanosoma cruzi infection and 152 of them also were examined for Ehrlichia canis, Borrelia bugderfori, Anaplasma phagocitophylum, Dirofilaria immitis and Toxoplasma gondii. Fecal samples from 85 dogs were examined for intestinal parasites. Seventeen parasite species were seen, 77% of which are zoonotic. The most prevalent parasites were Ancylostoma caninum (68.2%), T. gondii (55.3%, first report for dogs in Argentina), Giardia sp. (25.9%), Cryptosporidium sp. (20.0%), T. cruzi (16.5%), trematodes (15.3%) and Toxocara canis (14.1%). Polyparasitism was found in 96% of the dogs, with up to six parasite species in a single dog, and was significantly associated with age of dog but not with host body condition or sex. The most frequent pair of parasites found together were T. gondii-A. caninum (46%), A. caninum-T. cruzi (34%) and T. gondii-T. cruzi (27%). The prevalence of anemia and leukocytosis was significantly higher in dogs showing the worst body condition. Our findings likely reflect structural poverty, poor sanitation and lack of a safe water supply. Importantly, many of the prevalent parasites seen are threats to human health. 243 words.
Assuntos
Doenças do Cão/parasitologia , Doenças Parasitárias em Animais/parasitologia , Zoonoses/parasitologia , Animais , Argentina/epidemiologia , Doenças do Cão/epidemiologia , Doenças do Cão/transmissão , Cães , Feminino , Enteropatias Parasitárias/epidemiologia , Enteropatias Parasitárias/parasitologia , Enteropatias Parasitárias/transmissão , Enteropatias Parasitárias/veterinária , Masculino , Doenças Parasitárias em Animais/epidemiologia , Doenças Parasitárias em Animais/transmissão , Prevalência , Fatores de Risco , População Rural , Toxoplasmose Animal/epidemiologia , Toxoplasmose Animal/parasitologia , Toxoplasmose Animal/transmissão , Doenças Transmitidas por Vetores/epidemiologia , Doenças Transmitidas por Vetores/parasitologia , Doenças Transmitidas por Vetores/transmissão , Doenças Transmitidas por Vetores/veterinária , Zoonoses/epidemiologia , Zoonoses/transmissãoRESUMO
Interactions among different species of parasites co-infecting the same host could be synergistic or antagonistic. These interactions may modify both the frequency of infected hosts and their infectiousness, and therefore impact on transmission dynamics. This study determined the infectiousness of Trypanosoma cruzi-seropositive dogs (using xenodiagnosis) and their parasite load (quantified by qPCR), and tested the association between both variables and the presence of concomitant endoparasites. A cross-sectional serosurvey conducted in eight rural villages from Pampa del Indio and neighboring municipalities (northeastern Argentina) detected 32 T. cruzi-seropositive dogs out of 217 individuals examined for infection. Both the infectiousness to the vector Triatoma infestans and parasite load of T. cruzi-seropositive dogs examined were heterogeneous. A statistically significant, nine-fold higher mean infectiousness was registered in T. cruzi-seropositive dogs co-infected with Ancylostoma caninum and a trematode than in T. cruzi-seropositive dogs without these infections. The median parasite load of T. cruzi was also significantly higher in dogs co-infected with these helminths. An opposite trend was observed in T. cruzi-seropositive dogs that were serologically positive to Toxoplasma gondii or Neospora caninum relative to dogs seronegative for these parasites. Using multiple logistic regression analysis with random effects, we found a positive and significant association between the infectiousness of T. cruzi-seropositive dogs and co-infections with A. caninum and a trematode. Our results suggest that co-infections may be a modifier of host infectiousness in dogs naturally infected with T. cruzi.
Assuntos
Doença de Chagas/veterinária , Coinfecção/veterinária , Doenças do Cão/parasitologia , Trypanosoma cruzi/isolamento & purificação , Animais , Doença de Chagas/complicações , Doença de Chagas/parasitologia , Cães , Helmintíase Animal/complicações , Helmintíase Animal/parasitologia , Helmintíase Animal/patologiaRESUMO
We assessed the prevalence of infection with Trypanosoma cruzi, parasite genotypes (discrete typing units, DTUs), and the host-feeding sources of domestic and peridomestic Triatoma infestans Klug and Triatoma eratyrusiformis Del Ponte in eight rural communities of the subandean Calchaqui valleys in northwestern Argentina. We sought to analyze their epidemiological role in the context of routine vector surveillance and control actions. Infection with T. cruzi was determined by optic microscopy or polymerase chain reaction (PCR) amplification of the hypervariable region of kinetoplast DNA minicircles. Parasite genotypes were identified through a multi PCR-based strategy. Bloodmeal contents were tested with a direct ELISA assay against nine antisera. Human sleeping quarters (domiciles) and peridomestic dry-shrub fences concentrated most of the T. infestans and T. eratyrusiformis infected with T. cruzi, respectively. The most frequent host-feeding sources of T. infestans were chickens (73.1%) in peridomiciles and humans (73.3%) in domiciles, whereas T. eratyrusiformis fed more often on cavid rodents (92.6%), which thrived in the dry-shrub fences. The main T. cruzi DTU identified in both vectors was T. cruzi I (TcI). Triatoma eratyrusiformis was implicated in the local circulation of TcI among cavies and perhaps mice, but infection with other typically domestic DTUs (TcVI and TcII/TcV/TcVI) indicated overlap between (peri)domestic transmission cycles in both vector species. Because dry-shrub fences were not targeted for routine insecticide spraying, they may act as sources of (peri)domestic reinfestation. Triatoma eratyrusiformis is an emergent secondary vector of T. cruzi and plays a significant role in the local transmission of T. cruzi.
Assuntos
Doença de Chagas/parasitologia , Insetos Vetores/parasitologia , Triatoma/parasitologia , Trypanosoma cruzi/fisiologia , Animais , Argentina , Doença de Chagas/transmissão , Comportamento Alimentar , Humanos , Insetos Vetores/fisiologia , Roedores/fisiologia , Triatoma/fisiologia , Trypanosoma cruzi/genética , Trypanosoma cruzi/isolamento & purificaçãoRESUMO
The control of nondomiciliated triatomine species adapted to peridomestic habitats represents a challenge because they are connected to sylvatic colonies, and pyrethroid insecticides have limited effects outdoors. The effects of residual insecticide spraying have rarely been assessed on secondary triatomines. Triatoma garciabesi (Carcavallo, Martinez, Cichero, Prosen & Ronderos, 1967) is a nontarget vector that inhabits the dry western Chaco region, and a member of the Triatoma sordida Stål 1859 complex. Little is known on the capacity of T. garciabesi to invade and establish viable domestic or peridomestic colonies, and on its response to residual insecticide sprays directed against Triatoma infestans Klug 1834. The presence and abundance of triatomines were assessed by timed manual collections annually or biannually (spring and fall) during 10 yr after a community-wide insecticide spraying campaign and selective insecticide sprays directed against T. infestans in a rural village of northwestern Argentina. T. garciabesi mainly occupied peridomestic habitats associated with chickens, and was unable to colonize human sleeping quarters. Trees with chickens occurred in nearly all houses and were infested in >25% of the occasions. The abundance of bugs at house-compound level was best explained by a generalized estimating equation model that included selective insecticide sprays during the previous semester (negative effects), chicken abundance (positive effects), seasonality, and their interactions. Our results suggest that insecticide applications targeting T. infestans affected the abundance of T. garciabesi, and reduced the likelihood of future infestation.
Assuntos
Insetos Vetores , Inseticidas , Piretrinas , Triatoma , Animais , Argentina , Doença de Chagas/transmissão , GalinhasRESUMO
Understanding the complex epidemiology of Trypanosoma cruzi transmission cycles requires comparative studies in widely different environments. We assessed the occurrence of T. cruzi infection in sylvatic mammals, their infectiousness to the vector, and parasite genotypes in a protected area of the Argentine Chaco, and compared them with information obtained similarly in a nearby disturbed area. A total of 278 mammals from >23 species in the protected area were diagnosed for T. cruzi infection using xenodiagnosis, kDNA-PCR and nuclear satellite DNA-PCR (SAT) from blood samples. The relative abundance and species composition differed substantially between areas. Didelphis albiventris opossums were less abundant in the protected area; had a significantly lower body mass index, and a stage structure biased toward earlier stages. The capture of armadillos was lower in the protected area. The composite prevalence of T. cruzi infection across host species was significantly lower in the protected area (11.1%) than in the disturbed area (22.1%), and heterogeneous across species groups. The prevalence of infection in D. albiventris and Thylamys pusilla opossums was significantly lower in the protected area (nil for D. albiventris), whereas infection in sigmodontine rodents was three times higher in the protected area (17.5 versus 5.7%). Parasite isolates from the two xenodiagnosis-positive mammals (1 Dasypus novemcinctus and 1 Conepatus chinga) were typed as TcIII; both specimens were highly infectious to Triatoma infestans. Fat-tailed opossums, bats and rodents were kDNA-PCR-positive and xenodiagnosis-negative. Desmodus rotundus and Myotis bats were found infected with T. cruzi for the first time in the Gran Chaco.
Assuntos
Animais Selvagens/parasitologia , Doença de Chagas/veterinária , Reservatórios de Doenças/parasitologia , Mamíferos/parasitologia , Animais , Argentina/epidemiologia , Tatus/parasitologia , Doença de Chagas/epidemiologia , Doença de Chagas/transmissão , Quirópteros/parasitologia , Didelphis/parasitologia , Mephitidae/parasitologia , Gambás/parasitologia , Doenças dos Roedores/epidemiologia , Doenças dos Roedores/parasitologia , Doenças dos Roedores/transmissão , Roedores , Trypanosoma cruzi/isolamento & purificaçãoRESUMO
The competence of reservoir hosts of vector-borne pathogens is directly linked to its capacity to infect the vector. Domestic dogs and cats are major domestic reservoir hosts of Trypanosoma cruzi, and exhibit a much higher infectiousness to triatomines than seropositive humans. We quantified the concentration of T. cruzi DNA in the peripheral blood of naturally-infected dogs and cats (a surrogate of intensity of parasitemia), and evaluated its association with infectiousness to the vector in a high-risk area of the Argentinean Chaco. To measure infectiousness, 44 infected dogs and 15 infected cats were each exposed to xenodiagnosis with 10-20 uninfected, laboratory-reared Triatoma infestans that blood-fed to repletion and were later individually examined for infection by optical microscopy. Parasite DNA concentration (expressed as equivalent amounts of parasite DNA per mL, Pe/mL) was estimated by real-time PCR amplification of the nuclear satellite DNA. Infectiousness increased steeply with parasite DNA concentration both in dogs and cats. Neither the median parasite load nor the mean infectiousness differed significantly between dogs (8.1Pe/mL and 48%) and cats (9.7Pe/mL and 44%), respectively. The infectiousness of dogs was positively and significantly associated with parasite load and an index of the host's body condition, but not with dog's age, parasite discrete typing unit and exposure to infected bugs in a random-effects multiple logistic regression model. Real-time PCR was more sensitive and less time-consuming than xenodiagnosis, and in conjunction with the body condition index, may be used to identify highly infectious hosts and implement novel control strategies.
Assuntos
Doenças do Gato/diagnóstico , Doença de Chagas/veterinária , Reservatórios de Doenças , Doenças do Cão/diagnóstico , Triatoma/parasitologia , Trypanosoma cruzi/isolamento & purificação , Animais , Doenças do Gato/parasitologia , Gatos , Doença de Chagas/parasitologia , DNA Satélite/genética , Doenças do Cão/parasitologia , Cães , Feminino , Humanos , Insetos Vetores/parasitologia , Parasitemia/parasitologia , Parasitemia/veterinária , Reação em Cadeia da Polimerase em Tempo Real , Trypanosoma cruzi/genética , Trypanosoma cruzi/patogenicidade , XenodiagnósticoRESUMO
Domestic dogs and cats are major domestic reservoir hosts of Trypanosoma cruzi and a risk factor for parasite transmission. In this study we assessed the relative performance of a polymerase chain reaction assay targeted to minicircle DNA (kDNA-PCR) in reference to conventional serological tests, a rapid dipstick test and xenodiagnosis to detect T. cruzi infection in dogs and cats from an endemic rural area in northeastern Argentina. A total of 43 dogs and 13 cats seropositive for T. cruzi by an immunosorbent assay (ELISA) and an indirect hemagglutination assay (IHA), which had been examined by xenodiagnosis, were also tested by kDNA-PCR. kDNA-PCR was nearly as sensitive as xenodiagnosis for detecting T. cruzi-infectious dogs and cats. kDNA-PCR was slightly more sensitive than xenodiagnosis in seropositive dogs (91% versus 86%, respectively) and cats (77% against 54%, respectively), but failed to detect all of the seropositive individuals. ELISA and IHA detected all xenodiagnosis-positive dogs and both outcomes largely agreed (kappa coefficient, κ=0.92), whereas both assays failed to detect all of the xenodiagnosis-positive cats and their agreement was moderate (κ=0.68). In dogs, the sensitivity of the dipstick test was 95% and agreed closely with the outcome of conventional serological tests (κ=0.82). The high sensitivity of kDNA-PCR to detect T. cruzi infections in naturally infected dogs and cats supports its application as a diagnostic tool complementary to serology and may replace the use of xenodiagnosis or hemoculture.
Assuntos
Doenças do Gato/diagnóstico , Doença de Chagas/veterinária , Testes Diagnósticos de Rotina/métodos , Doenças do Cão/diagnóstico , Parasitologia/métodos , Trypanosoma cruzi/isolamento & purificação , Medicina Veterinária/métodos , Animais , Argentina , Doenças do Gato/parasitologia , Gatos , Doença de Chagas/diagnóstico , Doença de Chagas/parasitologia , Doenças do Cão/parasitologia , Cães , Técnicas de Diagnóstico Molecular/métodos , Sensibilidade e Especificidade , Testes Sorológicos/métodos , Trypanosoma cruzi/genética , Trypanosoma cruzi/imunologiaRESUMO
The discrete typing units (DTUs) of Trypanosoma cruzi that infect domestic dogs and cats have rarely been studied. With this purpose we conducted a cross-sectional xenodiagnostic survey of dog and cat populations residing in 2 infested rural villages in Pampa del Indio, in the humid Argentine Chaco. Parasites were isolated by culture from 44 dogs and 12 cats with a positive xenodiagnosis. DTUs were identified from parasite culture samples using a strategy based on multiple polymerase-chain reactions. TcVI was identified in 37 of 44 dogs and in 10 of 12 cats, whereas TcV was identified in 5 dogs and in 2 cats -a new finding for cats. No mixed infections were detected. The occurrence of 2 dogs infected with TcIII -classically found in armadillos- suggests a probable link with the local sylvatic transmission cycle involving Dasypus novemcinctus armadillos and a potential risk of human infection with TcIII. Our study reinforces the importance of dogs and cats as domestic reservoir hosts and sources of various DTUs infecting humans, and suggests a link between dogs and the sylvatic transmission cycle of TcIII.
Assuntos
Doenças do Gato/parasitologia , Doença de Chagas/veterinária , Doenças do Cão/parasitologia , População Rural , Trypanosoma cruzi/classificação , Trypanosoma cruzi/genética , Animais , Argentina/epidemiologia , Doenças do Gato/epidemiologia , Doenças do Gato/transmissão , Gatos , Doença de Chagas/epidemiologia , Doença de Chagas/parasitologia , Doença de Chagas/transmissão , Reservatórios de Doenças/parasitologia , Doenças do Cão/epidemiologia , Doenças do Cão/transmissão , Cães , Humanos , Insetos Vetores/parasitologia , Triatoma/parasitologia , Trypanosoma cruzi/isolamento & purificação , XenodiagnósticoRESUMO
We assessed the distribution of Trypanosoma cruzi Discrete Typing Units (DTUs) in domestic and peridomestic Triatoma infestans and Triatoma sordida specimens collected in a well-defined rural area in Pampa del Indio, northeastern Argentina. Microscopically-positive bugs were randomly selected with a multi-level sampling design, and DTUs were identified using direct PCR strategies. TcVI predominated in 61% of 69 T. infestans and in 56% of 9 T. sordida. TcV was the secondary DTU in T. infestans (16%) and was found in 1 T. sordida specimen (11%). Three T. sordida (33%) were found infected with TcI, a DTU also identified in local Didelphis albiventris opossums. Mixed DTU infections occurred rarely (5%) and were detected both directly from the bugs' rectal ampoule and parasite cultures. The identified DTUs and bug collection sites of T. infestans were significantly associated. Bugs infected with TcV were almost exclusively captured in domiciles whereas those with TcVI were found similarly in domiciles and peridomiciles. All mixed infections occurred in domiciles. TcV-infected bugs fed more often on humans than on dogs, whereas TcVI-infected bugs showed the reverse pattern. T. sordida is a probable sylvatic vector of TcI linked to D. albiventris, and could represent a secondary vector of TcVI and TcV in the domestic/peridomestic cycle.