Trypanosoma cruzi detection in blood by xenodiagnosis and polymerase chain reaction in the wild rodent Octodon degus.

We detected Trypanosoma cruzi in blood samples of the wild rodent Octodon degus by xenodiagnosis and a polymerase chain reaction (PCR) using the domestic and wild vectors of Chagas disease, Triatoma infestans and Mepraia spinolai, respectively. We captured 35 rodents and extracted DNA from blood samples and intestinal contents of vectors fed on O. degus. Our results indicate that the percentage of rodents naturally infected with T. cruzi depends on the biologic sample used for PCR and on the vector species for xenodiagnosis. The PCR with blood samples did not detect T. cruzi DNA, but the PCR with intestinal contents showed that both vectors were positive for T. cruzi. The PCR performed with M. spinolai intestinal contents detected four times more T. cruzi-positive O. degus than the PCR with Triatoma infestans intestinal contents (22.9% and 5.7%, respectively). We report the improvement of T. cruzi detection in sylvatic animals by a combination of PCR and xenodiagnosis using sylvatic vectors, especially in disease-endemic areas with low parasitemias in mammals.

Campos R ，Botto-Mahan C ，Ortiz S ，Acuña M ，Cattan PE ，Solari A ... -  《AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE》

Susceptibility of Mepraia spinolai and Triatoma infestans to different Trypanosoma cruzi strains from naturally infected rodent hosts.

Trypanosoma cruzi is the causative agent of Chagas disease, a zoonosis involving domestic and sylvatic mammalian reservoirs. Since scarce information has been published about the susceptibility of T. cruzi lineages to other triatomine species besides Triatoma infestans, we evaluate the susceptibility of T. infestans and Mepraia spinolai to different T. cruzi lineages, originated from naturally infected Octodon degus rodents as mammal host. Xenodiagnosis-PCR methods to detect T. cruzi positive rodents and genotyping to differentiate T. cruzi lineages (TcI, TcIIb, TcIId and TcIIe) identified singly and mixed T. cruzi infections. More infections and nearly all mixed infections were identified using the wild vector M. spinolai than T. infestans.

Campos R ，Acuña-Retamar M ，Botto-Mahan C ，Ortiz S ，Cattan PE ，Solari A ... -  《ACTA TROPICA》

Predominance of Trypanosoma cruzi genotypes in two reservoirs infected by sylvatic Triatoma infestans of an endemic area of Chile.

We report results of Trypanosoma cruzi infection and parasite genotypes in the wild Octodon degus and synantropic reservoir Rattus rattus from an endemic area with sylvatic Triatoma infestans as the only detected vector. The infection status was determined by hemi-nested PCR directed to minicircles DNA and genotyping by hybridization tests with a panel of five specific probes, including two probes for TcI subgroups (clones 19 and 20). O. degus was found infected with 13.3% and mainly with sublineage TcIId, and less with TcIIb and TcI. Meantime the synantropic R. rattus was found infected with 27.7% and mainly with TcI and much less with TcIId, TcIIb and TcIIe. The results are discussed to explain the distribution of T. cruzi genotypes between these two reservoirs and the importance of sylvatic foci of T. infestans allowing the permanence of the wild and peridomestic cycle of Chagas disease.

Galuppo S ，Bacigalupo A ，García A ，Ortiz S ，Coronado X ，Cattan PE ，Solari A ... -  《-》

Field assessment of Trypanosoma cruzi infection and host survival in the native rodent Octodon degus.

Chagas disease is a zoonosis caused by the flagellated parasite Trypanosoma cruzi and transmitted by triatomine insects to several mammalian species acting as reservoir hosts. In the present study, we assess T. cruzi-prevalence, survivorship and T. cruzi-infection rate of the endemic rodent Octodon degus from a hyper-endemic area of Chagas disease in Chile. Parasite detection is performed by PCR assays on blood samples of individuals captured in austral summer of 2010, and on non-infected individuals recaptured in 2011 as well as on new captures. Results show a high infection level in this species (up to 70%). Infected O. degus have the same chance of surviving to the next reproductive season as uninfected individuals, irrespective of sex. We suggest that O. degus, an abundant long-lived rodent with high dispersal capability, could be considered an important native reservoir of T. cruzi in the wild transmission cycle of Chagas disease in Chile.

Botto-Mahan C ，Bacigalupo A ，Correa JP ，Oda E ，Solari A ... -  《-》

Within-host temporal fluctuations of Trypanosoma cruzi discrete typing units: the case of the wild reservoir rodent Octodon degus.

Chagas disease caused by Trypanosoma cruzi is considered a major public health problem in America. After an acute phase the disease changes to a chronic phase with very low parasitemia. The parasite presents high genetic variability with seven discrete typing units (DTUs): TcI-TcVI and Tc bat. The aim of this work is to evaluate fluctuation of parasitemia and T. cruzi DTUs in naturally infected Octodon degus. After animal capture parasitemia was obtained by qPCR and later the animals were evaluated by three serial xenodiagnoses using two insect vector species, Mepraia spinolai and Triatoma infestans. The parasites amplified over time by insect xenodiagnosis were analyzed by conventional PCR and after that the infective T. cruzi were characterized by means of hybridization tests. The determination of O. degus parasitemia before serial xenodiagnosis by qPCR reveals a great heterogeneity from 1 to 812 parasite equivalents/ml in the blood stream. The T. cruzi DTU composition in 23 analyzed animals by xenodiagnosis oscillated from mixed infections with different DTUs to infections without DTU identification or vice versa, this is equivalent to 50% of the studied animals. Detection of triatomine infection and composition of T. cruzi DTUs was achieved more efficiently 40 days post-infection rather than after 80 or 120 days. Trypanosoma cruzi DTUs composition fluctuates over time in naturally infected O. degus. Three replicates of serial xenodiagnosis confirmed that living parasites have been studied. Our results allow us to confirm that M. spinolai and T. infestans are equally competent to maintain T. cruzi DTUs since similar results of infection were obtained after xenodiagnosis procedure.

Rojo G ，Sandoval-Rodríguez A ，López A ，Ortiz S ，Correa JP ，Saavedra M ，Botto-Mahan C ，Cattan PE ，Solari A ... -  《Parasites & Vectors》