Characteristics and outcomes of patients with COVID-19 who return to the emergency department: a multicentre observational study by the Canadian COVID-19 Emergency Department Rapid Response Network (CCEDRRN).

OBJECTIVE: Unplanned return emergency department (ED) visits can reflect clinical deterioration or unmet need from the original visit. We determined the characteristics and outcomes of patients with COVID-19 who return to the ED for COVID-19-related revisits. METHODS: This retrospective observational study used data for all adult patients visiting 47 Canadian EDs with COVID-19 between 1 March 2020 and 31 March 2022. Multivariable logistic regression assessed the characteristics associated with having a no return visit (SV=single visit group) versus at least one return visit (MV=return visit group) after being discharged alive at the first ED visit. RESULTS: 39 809 patients with COVID-19 had 44 862 COVID-19-related ED visits: 35 468 patients (89%) had one visit (SV group) and 4341 (11%) returned to the ED (MV group) within 30 days (mean 2.2, SD=0.5 ED visit). 40% of SV patients and 16% of MV patients were admitted at their first visit, and 41% of MV patients not admitted at their first ED visit were admitted on their second visit. In the MV group, the median time to return was 4 days, 49% returned within 72 hours. In multivariable modelling, a repeat visit was associated with a variety of factors including older age (OR=1.25 per 10 years, 95% CI (1.22 to 1.28)), pregnancy (1.86 (1.46 to 2.36)) and presence of comorbidities (eg, 1.72 (1.40 to 2.10) for cancer, 2.01 (1.52 to 2.66) for obesity, 2.18 (1.42 to 3.36) for organ transplant), current/prior substance use, higher temperature or WHO severe disease (1.41 (1.29 to 1.54)). Return was less likely for females (0.82 (0.77 to 0.88)) and those boosted or fully vaccinated (0.48 (0.34 to 0.70)). CONCLUSIONS: Return ED visits by patients with COVID-19 within 30 days were common during the first two pandemic years and were associated with multiple factors, many of which reflect known risk for worse outcomes. Future studies should assess reasons for revisit and opportunities to improve ED care and reduce resource use. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov, NCT04702945.

Organs infected with Trypanosoma cruzi and DTU identification in the naturally infected rodent Octodon degus.

Chagas disease is a public health problem in America. Its parasite, Trypanosoma cruzi, presents different discrete typing units (DTUs), colonizes organs of mammalian hosts in chronic infections, and presents tropism for particular organs in experimental infections. We evaluated T. cruzi tropism towards organs on the naturally infected rodent Octodon degus, identifying the parasites' DTUs, by means of conventional PCR and hybridization. Almost all the analyzed organs presented T. cruzi. More than 42% of the tested oesophagus, skin, skeletal muscle, brain and intestine showed T. cruzi DNA. Other nine types of organs were infected in over 15%. These results suggest that there is some tropism by T. cruzi in chronically infected O. degus. DTU TcV was present in 92.5% of infected organs with identified DTUs; this DTU is frequently reported in human infections in the Southern Cone of South America. Few organs showed mixed DTU infections. This is one of the few reports on the outcome of chronic natural T. cruzi-infection in wild mammal hosts exposed to naturally infected vectors.

Methyl Paraben and Carbamazepine in Water and Striped Catfish (Pseudoplatystoma magdaleniatum) in the Cauca and Magdalena Rivers.

Between 2017 and 2019, samplings were carried out in the San Jorge, Cauca and Magdalena River basins in Colombia, to determine the presence of methyl paraben and carbamazepine in water and Pseudoplatystoma magdaleniatum. For the analysis of the samples, a validation of the analytical method was performed, following the EPA method 1694 (Pharmaceutical and personal care products in water), with slight modifications. This was done by liquid-chromatography tandem mass spectrometry, for quantification of methyl paraben and carbamazepine, including parameters of linearity, accuracy precision and veracity. Carbamazepine was found in the Magdalena River at 8.03 ± 0.01 µg/L in transition season. In fish samples, methyl paraben and carbamazepine were detected in a range between 32 and 90.80 µg/kg in transition and dry seasons.

Trypanosoma cruzi burden, genotypes, and clinical evaluation of Chilean patients with chronic Chagas cardiopathy.

There are currently no biomarkers to assess which patients with chronic indeterminate Chagas disease will develop heart disease and which will spend their entire life in this state. We hypothetize that the parasite burden and Trypanosoma cruzi genotypes are related to the presence of heart disease in patients with Chagas disease. This study is aimed to investigate the parasite burden and T. cruzi genotypes in chagasic cardiopaths versus chagasic individuals without cardiac involvement according to the New York Heart Association. Patients with chronic Chagas disease, 50 with and 50 without cardiopathy (controls), groups A and B, respectively, were submitted to anamnesis, physical examination, and electrocardiogram. Echo-Doppler was performed for group A; all important known causes of cardiopathy were discarded. Xenodiagnosis, conventional PCR, and quantitative PCR were performed on patients of both groups. T. cruzi genotyping was done for 25 patients of group A and 20 of group B. The 50 cardiopaths had 80 electrocardiographic alterations, most of them in grade II of the New York Heart Association classification; 49 were classified in grade I by Echo-Doppler, and only one patient was in grade III. The difference in average parasitemia in patients of groups A and B was not significant. The most frequent T. cruzi DTU found was TcV. The parasite burden and genotype of the groups with and without cardiopathy were similar. Graphical abstract Imagen 1 Chronic chagas cardiopathy chest X-ray heart enlargement Figure 2 Chronic Chagas cardiopathy microaneurism of left ventricle. Cineangiography.

Evaluation of nifurtimox treatment of chronic Chagas disease by means of several parasitological methods.

Currently, evaluation of drug efficacy for Chagas disease remains a controversial issue with no consensus. In this work, we evaluated the parasitological efficacy of Nifurtimox treatment in 21 women with chronic Chagas disease from an area of endemicity in Chile who were treated according to current protocols. Under pre- and posttherapy conditions, blood (B) samples and xenodiagnosis (XD) samples from these patients were subjected to analysis by real-time PCR targeting the nuclear satellite DNA of Trypanosoma cruzi (Sat DNA PCR-B, Sat DNA PCR-XD) and by PCR targeting the minicircle of kinetoplast DNA of T. cruzi (kDNA PCR-B, kDNA PCR-XD) and by T. cruzi genotyping using hybridization minicircle tests in blood and fecal samples of Triatoma infestans feed by XD. In pretherapy, kDNA PCR-B and kDNA PCR-XD detected T. cruzi in 12 (57%) and 18 (86%) cases, respectively, whereas Sat DNA quantitative PCR-B (qPCR-B) and Sat DNA qPCR-XD were positive in 18 cases (86%) each. Regarding T. cruzi genotype analysis, it was possible to observe in pretherapy the combination of TcI, TcII, and TcV lineages, including mixtures of T. cruzi strains in most of the cases. At 13 months posttherapy, T. cruzi DNA was detectable in 6 cases (29.6%) and 4 cases (19.1%) by means of Sat DNA PCR-XD and kDNA PCR-XD, respectively, indicating treatment failure with recovery of live parasites refractory to chemotherapy. In 3 cases, it was possible to identify persistence of the baseline genotypes. The remaining 15 baseline PCR-positive cases gave negative results by all molecular and parasitological methods at 13 months posttreatment, suggesting parasite response. Within this follow-up period, kDNA PCR-XD and Sat DNA qPCR-XD proved to be more sensitive tools for the parasitological evaluation of the efficacy of Nifurtimox treatment than the corresponding PCR methods performed directly from blood samples.

Natural Trypanosoma cruzi Infection and Climatic Season Influence the Developmental Capacity in Field-Caught Mepraia spinolai Nymphs.

In this study, we evaluated the effect of the climatic season and infection by Trypanosoma cruzi, etiological agent of Chagas disease, on the molting capacity of the triatomine vector Mepraia spinolai endemic to Chile. We used wild-caught first-to-fourth instar nymphs during cooling (fall and winter) and warming (spring) periods. After capturing, nymphs were fed at the laboratory, and maintained under optimal rearing conditions. Feeding was repeated 40 days later. We followed-up the molting events on 709 nymphs, recording one, two or the absence of molts after two feeding opportunities. Within the same climatic period, only infected second- and fourth-instar nymphs from the warming period showed a larger proportion of double molting compared to uninfected nymphs. Regarding the climatic period, infected and uninfected first- and fourth-instar nymphs exhibited a larger proportion of double molting in the warming and cooling periods, respectively. The pattern of non-molting nymph occurrence suggests they probably reach diapause by environmental stochasticity. The effect of the climatic period and T. cruzi infection on the development of M. spinolai is an instar-dependent phenomenon, highlighting the occurrence of finely synchronized processes at different moments of the life cycle of such an hemimetabolous insect as triatomines.

Trypanosoma cruzi infection follow-up in a sylvatic vector of Chagas disease: Comparing early and late stage nymphs.

Chagas disease is caused by Trypanosoma cruzi and transmitted by the triatomine Mepraia spinolai in the southwest of South America. Here, we examined the T. cruzi-infection dynamics of field-caught M. spinolai after laboratory feeding, with a follow-up procedure on bug populations collected in winter and spring of 2017 and 2018. Bugs were analyzed twice to evaluate T. cruzi-infection by PCR assays of urine/fecal samples, the first evaluation right after collection and the second 40 days after the first feeding. We detected bugs with: the first sample positive and second negative (+/-), the first sample negative and second positive (-/+), and with both samples positive or negative (+/+; -/-). Bugs that resulted positive on both occasions were the most frequent, with the exception of those collected in winter 2018. Infection rate in spring was higher than winter only in 2018. Early and late stage nymphs presented similar T. cruzi-infection rates except for winter 2017; therefore, all nymphs may contribute to T. cruzi-transmission to humans. Assessment of infection using two samples represents a realistic way to determine the infection a triatomine can harbor. The underlying mechanism may be that some bugs do not excrete parasites unless they are fed and maintained for some time under environmentally controlled conditions before releasing T. cruzi, which persists in the vector hindgut. We suggest that T. cruzi-infection dynamics regarding the three types of positive-PCR results detected by follow-up represent: residual T. cruzi in the rectal lumen (+/-), colonization of parasites attached to the rectal wall (-/+), and presence of both kinds of flagellates in the hindgut of triatomines (+/+). We suggest residual T. cruzi-infections are released after feeding, and result 60-90 days after infection persisting in the rectal lumen after a fasting event, a phenomenon that might vary between contrasting seasons and years.

Effect on Intermediary Metabolism and Digestive Parameters of the High Substitution of Fishmeal with Insect Meal in Sparus aurata Feed.

Hermetia illucens and Tenebrio molitor were tested on account of their potential to replace fish protein in feed. Two levels of replacement for H. illucens, 30% and 50% (H30 and H50), and one for T. molitor, 50% (T50), as well as an additional diet with a modified fatty acid fraction (H50M), were investigated in relation to juvenile Sparus aurata growth indices, enzyme activities and gut microbiome. A T50 diet showed similar results to a control (C) diet, with no significant differences regarding morphological indices and minor differences for nutritional indices. Regarding the gut microbiome, H50M was the diet which showed the more similar prokaryotic community to C, which suggests that fatty acid fractions might influence the composition of the gut microbiome. Nevertheless, differences appeared to be related to a redistribution of dominant species, while changes in species affiliation were limited to minoritary species. The positive correlation between some of these minoritary species (Peptostreptococcus russellii, Streptococcus dysgalactiae and Weisella confusa) and several fish growth parameters might explain differences between control and insect diets. Deciphering such uncertainty and revealing the potential role these unusual species may play on fish performance should be addressed in future investigations.

Vertical transmission of Trypanosoma cruzi in the Province of Choapa, IV Region, Chile: Preliminary Report (2005-2008).

Congenital Chagas disease acquired special importance in Chile after the certification of the control of Triatoma infestans and transmission by blood donors affected with Trypanosoma cruzi. In order to establish adequate protocols for intervention and control in infected mother-neonate pairs in endemic zones of Chagas disease, we present partial results (2005-2008) of a pilot project which is being carried out in the Province of Choapa, IV Region, Chile, whose objectives are: determine the current prevalence of the disease in pregnant women, estimate the incidence of vertical transmission of T. cruzi to newborns, determine the lineages of the parasite present in mothers who do and do not transmit the disease, determine the prevalence of Chagas disease in maternal grandmothers of neonates and study placental histopathology. Preliminary results indicated that in this study period, 3.7% of the women who gave birth in the Province have Chagas disease and 2.5% of their newborns were infected. The most frequent T. cruzi genotypes found in mothers studied during pregnancy were TCI and TCIId, either alone or in mixed infections. A high percentage (74.3%) of the grandmothers studied was infected with the parasite. In 29 placentas from mothers with Chagas disease we observed edema, necrosis, fibrinoid deposits and slight lymphoplasmocyte infiltration. In three placentas we found erythroblastosis and in one of them amastigote forms of T. cruzi; this was one of the cases of congenital infection. The evaluation of the diagnostic and control protocols generated will allow us to determine if it has been possible to modify the natural history of vertical transmission of T. cruzi in Chile.

Influence of Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae) Infection on Mortality of the Sylvatic Triatomine Vector, Mepraia spinolai (Heteroptera: Reuviidae), Under Fasting.

The etiologic agent of Chagas disease, Trypanosoma cruzi, is transmitted by hematophagous insect vectors that subsist on repeated blood meals over their lives separated by periods of fasting. Using naturally infected Mepraia spinolai, we measured the influence of parasite infection on this host vector's mortality during regular feeding and after fasting. After their capture, the insects were fed twice with uninfected mice to evaluate parasitic infection in their fecal samples by microscopic observation and PCR. Then the insects were subjected to a fasting period, followed by a third (final) feeding. After each feeding, a fecal sample was obtained to evaluate T. cruzi infection. To determine its progress through ontogeny, mortality and ecdysis of the infected and uninfected nymphs and adults were recorded on three occasions, over 140 d, and analyzed. Detections of infection by T. cruzi between the two first feedings increased, but this detection level was generally reduced after final feeding unless reinfected. For nymphs (stages III-V), their mortality was highest when infected after the fasting period, whereas adults were equally resistant to death after fasting when infected with T. cruzi. Metacyclic trypomastigotes were principally excreted in the fecal samples. Our results confirm that T. cruzi is pathogenic to its invertebrate hosts under nutritional stress conditions, when nymphs' mortality is higher while infected than uninfected when they were hungry. These results are epidemiologically important because T. cruzi harms the fasting vector M. spinolai, reducing its lifespan and competence as a disease vector, and thereby its rates of parasite transmission.

Comparing vector competence of Mepraia gajardoi and Triatoma infestans by genotyping Trypanosoma cruzi discrete typing units present in naturally infected Octodon degus.

Chagas disease is a vector-borne disease caused by the parasite Trypanosoma cruzi, and transmitted by triatomine insects to several mammal species. In Chile, the wild triatomine species are the endemic Mepraia species, and the only domestic vector of Chagas disease is Triatoma infestans. The aim of this study was to determine the competence of M. gajardoi compared to T. infestans as a T. cruzi vector using the naturally infected rodent Octodon degus. M. gajardoi amplified T. cruzi present in all O. degus studied while T. infestans only in half of the infected rodents. Both triatomine species excrete metacyclic trypomastigotes and amplified the same three T. cruzi DTUs, however, M. gajardoi showed differences in their ability to amplify TcI. TcV and TcVI had the same probability to be amplified by both triatomine species. Both species amplified mixed infections, with TcI-TcVI as the most represented. This study reports the higher vector competence of M. gajardoi in comparison to T. infestans.

Spatio-temporal characterization of Trypanosoma cruzi infection and discrete typing units infecting hosts and vectors from non-domestic foci of Chile.

BACKGROUND: Trypanosoma cruzi is a protozoan parasite that is transmitted by triatomine vectors to mammals. It is classified in six discrete typing units (DTUs). In Chile, domestic vectorial transmission has been interrupted; however, the parasite is maintained in non-domestic foci. The aim of this study was to describe T. cruzi infection and DTU composition in mammals and triatomines from several non-domestic populations of North-Central Chile and to evaluate their spatio-temporal variations. METHODOLOGY/PRINCIPAL FINDINGS: A total of 710 small mammals and 1140 triatomines captured in six localities during two study periods (summer/winter) of the same year were analyzed by conventional PCR to detect kDNA of T. cruzi. Positive samples were DNA blotted and hybridized with specific probes for detection of DTUs TcI, TcII, TcV, and TcVI. Infection status was modeled, and cluster analysis was performed in each locality. We detected 30.1% of overall infection in small mammals and 34.1% in triatomines, with higher rates in synanthropic mammals and in M. spinolai. We identified infecting DTUs in 45 mammals and 110 triatomines, present more commonly as single infections; the most frequent DTU detected was TcI. Differences in infection rates among species, localities and study periods were detected in small mammals, and between triatomine species; temporally, infection presented opposite patterns between mammals and triatomines. Infection clustering was frequent in vectors, and one locality exhibited half of the 21 clusters found. CONCLUSIONS/SIGNIFICANCE: We determined T. cruzi infection in natural host and vector populations simultaneously in a spatially widespread manner during two study periods. All captured species presented T. cruzi infection, showing spatial and temporal variations. Trypanosoma cruzi distribution can be clustered in space and time. These clusters may represent different spatial and temporal risks of transmission.

Trypanosoma cruzi infection in the sylvatic kissing bug Mepraia gajardoi from the Chilean Southern Pacific Ocean coast.

The Southern Pacific Ocean coast has been traditionally considered a non-active transmission area for Chagas disease. In this report, we show evidence of Trypanosoma cruzi infection in the sylvatic kissing bug Mepraia gajardoi from the northern Chilean coast.

Congestive heart failure admissions: factors related to hospital length of stay.

Congestive heart failure (CHF) is an illness that affects millions of Americans each year; the cost associated with treatment and care is extensive. This study was based on a total of 480 patients admitted to the Mercy Hospital in Miami, Florida, during 2005. Average length of stay was significantly different based upon type of health insurance, race/ethnicity, marital status, admission source, attending physician specialty, discharge disposition, number of consultations while admitted, surgical procedure, and illness severity. The study results provide hospital executives with vital information for clinical and administrative CHF-related admissions management.

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.

Coexistence of Trypanosoma cruzi genotypes in wild and periodomestic mammals in Chile.

Epidemiologic evidence suggests a preferential association of Trypanosoma cruzi genotypes TCI and TCII with marsupials and placental mammals, respectively. We identify T. cruzi genotypes from 117 infected mammals. Minicircle DNA amplified by polymerase chain reaction and hybridization with a panel of four specific probes showed frequencies for the T. cruzi genotypes TCI, TCIIb, TCIId, and TCIIe of 38%, 41%, 26%, and 9%, respectively, in wild mammals. In peridomestic mammals, frequencies for the same clones were 29%, 33%, 43%, and 14%, respectively. As a whole, mixed infections are found in more than 31% of the cases, which indicates the coexistence of multiclonal strains circulating in nature, and the absence of specific associations between T. cruzi genotypes and reservoir hosts, including marsupials. The direct characterization of parasite genotypes emphasizes the importance of obtaining unbiased epidemiologic information from parasite-endemic areas. Results are discussed in the context of competition or facilitation of T. cruzi genotypes within hosts.

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.

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Variation in Trypanosoma cruzi clonal composition detected in blood patients and xenodiagnosis triatomines: implications in the molecular epidemiology of Chile.

To identify Trypanosoma cruzi clones from chronically infected individuals, they were transferred to triatomines by the xenodiagnosis test (XD) with Triatoma infestans. Polymerase chain reaction (PCR) and hybridization assays were performed to detect minicircle DNA in human blood samples and triatomine feces, using probes to determine the T. cruzi clones present. T. cruzi clone 19 (TcI) resulted the most prevalent in humans, with a frequency of 0.70 compared with a frequency of 0.53 in triatomines. T. cruzi clone 39 (TcIId) was the most prevalent in T. infestans, with a frequency of 0.65 compared with 0.33 in humans. The T. cruzi clone 43 (TcIIe) was not detected in blood samples; nevertheless, it was present at a rate of 0.17 in T. infestans feces. In conclusion, the T. cruzi clones are associated to each host, suggesting that selective amplification of clones occurs in human and triatomines.

Fluctuations in Trypanosoma cruzi discrete typing unit composition in two naturally infected triatomines: Mepraia gajardoi and M. spinolai after laboratory feeding.

Mepraia species are hematophagous insects and the most important wild vectors of Trypanosoma cruzi, the causative agent of Chagas disease in southeastern South America. Because the domestic Triatoma infestans is already controlled, the transmission of different T. cruzi discrete typing units (DTUs) by Mepraia species deserves attention. Our aim is to gather information on the diversity of T. cruzi DTUs circulating in natural insect populations. Two groups of naturally infected bugs 21 Mepraia gajardoi and 26 Mepraia spinolai were followed-up after two or more laboratory feedings by means of minicircle-PCR assays to evaluate the composition of four T. cruzi DTUs by hybridization tests. Fluctuations from positive T. cruzi detection to negative and the converse, as well as single to mixed infections with different T. cruzi DTUs and the opposite were frequent observations after laboratory feeding in both Mepraia species. Single and mixed infections with more than two T. cruzi DTUs were detected after the first feeding; however mainly mixed infections prevailed after the second feeding. Laboratory feeding on three or more occasions resulted in a decreasing trend of the parasite burden. In a comparison with 28 infected and fed M. gajardoi collected one year before from the same vector colony T. cruzi DTUs composition changed, indicating that temporal variations occur in T. cruzi. Natural populations of Mepraia species can transmit complex mixtures T. cruzi DTUs which fluctuate over time after feeding, with a tendency to eliminate the parasitism after prolonged feeding.