Nifurtimox response of Trypanosoma cruzi isolates from an outbreak of Chagas disease in Caracas, Venezuela

Background & objectives: In Venezuela, Chagas disease (ChD) is considered a serious health problem, with about 6 million people at risk; and acute outbreaks due to oral transmission of Chagas Disease (OChD) are becoming increasingly important. In 2007 there was a major outbreak of OChD and although patients from this episode were treated with nifurtimox (Lampit®—Bayer), about 70% therapeutic failure was registered. These results led us to examine whether parasite’s drug susceptibility was related to this therapeutic failure. Methods: The Trypanosoma cruzi parasites were isolated by haemoculture of the peripheral blood drawn from the pre- and post-nifurtimox treated patients infected in the 2007 OChD outbreak at Caracas, Venezuela. The in vitro assays for drug testing were performed by the MTT methodology followed by calculation of inhibitory concentration-50 (IC50) values. Results: Parasite isolates obtained from the infected patients prior and after nifurtimox treatment when subjected to variable concentrations of the drug showed great heterogeneity in susceptibility with IC50 values ranging from 4.07 ± 1.82 to 94.92 ± 7.24 µM. Interpretation & conclusion: The high heterogeneity in nifurtimox IC50 values in the isolates and clones from the OChD patients, suggests that the therapeutic failure to nifurtimox could be due in part to a phenotypic variability that existed in the wild parasite population at the original source of contamination. Though, further pharmacological studies are needed to confirm the existence of natural nifurtimox resistance in the parasite.Fil: Muñoz Calderon, Arturo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Central de Venezuela; VenezuelaFil: Diaz Bello, Zoraida. Universidad Central de Venezuela; VenezuelaFil: Ramirez, José Luis. Fundacion Instituto de Estudios Avanzados Idea; VenezuelaFil: Noya, Oscar. Universidad Central de Venezuela; Venezuela. Ministerio del Poder Popular para la Salud; VenezuelaFil: Alarcón de Noya, Belkisyolé. Universidad Central de Venezuela; Venezuel

Characterization and follow-up of Trypanosoma cruzi natural populations refractory to etiological chemotherapy in oral chagas disease patients

We aimed to characterize the genetic constitution of natural T. cruzi populations involved in an Oral Chagas Disease (OCD) outbreak at a rural school of the community of Chichiriviche de la Costa, Venezuela, which affected patients did not respond to the etiological treatment. Peripheral blood samples and/or hemocultures were obtained from twenty-nine OCD patients at time of diagnosis or along nine years of Post-treatment (Tx) follow-up. The IgG serology, T. cruzi discrete typing units (DTU), satellite DNA-qPCR parasitic loads, and minicircle signatures were determined at Pre-Tx and after Tx. The serological titles and parasitic loads changed after treatment, with a significant decrease of IgG titers (Spearman’s r value= -0.961) and median parasite loads from 2.869 [IQR = 2.113 to 3.720] to 0.105 [IQR = -1.147 to 1.761] log10 par eq. /mL at Pre-Tx and Post-Tx, respectively, suggesting infection evolution from acute to chronic phase, without seroconversion or parasitological eradication, which was indicative of treatment failure. All patients were infected with T. cruzi DTU I populations. At Pre-Tx their median Jaccard genetic distances were 0.775 [IQR = 0.708 to 0.882], decreasing in genetic variability towards the end of follow-up (Mann-Whitney U test p= 0.0031). Interestingly, no Post-Tx minicircle signature was identical to its Pre-Tx counterpart population in a same patient, revealing selection of parasite subpopulations between the primary infection and Post-Tx. The parasitic populations isolated from hemocultures showed a lower number of bands in the minicircle signatures with respect to the signatures obtained directly from the patients’ blood samples, demonstrating a process of parasitic selection and reduction of the population variability that initially infected the patients. Decrease of parasitic loads after treatment as well as Pre- and Post-Tx intra-TcI diversity might be a consequence of both, natural evolution of the acute infection to the chronic phase and persistence of refractory populations due to Tx selection.Fil: Muñoz Calderon, Arturo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Díaz Bello, Zoraida. Universidad Central de Venezuela; VenezuelaFil: Alarcón de Noya, Belkisyolé. Universidad Central de Venezuela; VenezuelaFil: Noya González, Oscar O.. Universidad Central de Venezuela; VenezuelaFil: Schijman, Alejandro Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentin

Target product profile for a test for the early assessment of treatment efficacy in Chagas disease patients: An expert consensus.

Six to 7 million people are estimated to be infected by Trypanosoma cruzi, the parasite causing Chagas disease. Thirty to 40% of them, i.e., 1.8 to 2.4 million people, will suffer cardiac disorders and/or digestive clinical manifestations if they are not treated early during the course of the infection [1, 2]. However, only a small fraction of patients are properly diagnosed and treated [3]. Current clinical guidelines recommend treating T. cruzi–infected people if they are asymptomatic or present early symptoms of the disease (Table 1) [4, 5]. Benznidazole (BNZ) and nifurtimox (NFX) are the first-line antiparasitic treatments currently available, both with long administration regimens (60 days) that can produce adverse side effects [6–8]. Despite the fact they are not 100% effective in patients with chronic disease [9–12], they are the only drugs currently registered, and the benefits of their administration have been confirmed in several clinical studies. Currently, clinical trials with new compounds, using alternative regimens that aim to maintain efficacy whilst reducing toxicity, are ongoing and could lead to new therapeutic opportunities and/or policy change

The immunopathology of human schistosomiasis-III: immunoglobulin isotype profiles and response to praziquantel

Immunoglobulin (Ig) isotype (IgG, IgG1, IgG2, IgG3, IgG4, IgM, IgD and IgE) levels were investigated, both pre- and post-treatment with praziquantel (PZQ), in 43 adults and children chronically infected with Schistosoma mansoni , by means of a two-site, isotype-specific immunoenzymometric assay. The patients were classified as responders (R) or non-responders (NR) on the basis of their circumoval precipitin test (COPT) results 12 months after treatment. In comparison with controls, pre-treatment R children showed significantly higher levels of IgG, IgG1, IgG4 (p<0.001) and IgE (p<0.01), and diminished IgG2 (p<0.05), while NR children showed significantly elevated levels only of IgE (p<0.05). Twelve months after therapy, R children maintained significantly lower levels of IgG2, but showed significantly decreased levels of IgG, IgG1, IgG4, and IgE, while the Ig isotype profile of NR children was unaltered. Adult R and NR showed similar isotype profiles before chemotherapy, with the exception of significantly elevated IgM levels in R. Twelve months after therapy, R adults showed significantly decreased levels of IgG, IgG1, and IgG4, while NR adults showed only diminshed IgG4 levels. These results reveal different Ig isotype profiles in untreated adults and children chronically infected with S. mansoni. The results further show that the pre-treatment Ig isotype profile may be significantly modified after an effective R to chemotherapy, accounted for by down regulation of the IgG1 isotype in association with negative seroconversion of the COPT in R patients. The COPT reaction has been associated with the highly specific egg glycoprotein antigen w1, which shows a significant reduction in reactivity six months after treatment. IgG1 may thus play a main role in the response against the w1 antigen

Venezuela's humanitarian crisis, resurgence of vector-borne diseases, and implications for spillover in the region.

In the past 5-10 years, Venezuela has faced a severe economic crisis, precipitated by political instability and declining oil revenue. Public health provision has been affected particularly. In this Review, we assess the impact of Venezuela's health-care crisis on vector-borne diseases, and the spillover into neighbouring countries. Between 2000 and 2015, Venezuela witnessed a 359% increase in malaria cases, followed by a 71% increase in 2017 (411 586 cases) compared with 2016 (240 613). Neighbouring countries, such as Brazil, have reported an escalating trend of imported malaria cases from Venezuela, from 1538 in 2014 to 3129 in 2017. In Venezuela, active Chagas disease transmission has been reported, with seroprevalence in children (<10 years), estimated to be as high as 12·5% in one community tested (n=64). Dengue incidence increased by more than four times between 1990 and 2016. The estimated incidence of chikungunya during its epidemic peak is 6975 cases per 100 000 people and that of Zika virus is 2057 cases per 100 000 people. The re-emergence of many vector-borne diseases represents a public health crisis in Venezuela and has the possibility of severely undermining regional disease elimination efforts. National, regional, and global authorities must take action to address these worsening epidemics and prevent their expansion beyond Venezuelan borders

LA TRANSMISIÓN ORAL EN LA ENFERMEDAD DE CHAGAS

La Enfermedad de Chagas se transmite al hombre por varios mecanismos participando en algunos, el vector de maneradirecta &oacute; indirecta. En otras ocasiones, la transmisi&oacute;n de hombre a hombre ocurre a trav&eacute;s de transfusiones, trasplantesde &oacute;rganos y transplacentaria, y menos frecuente por la manipulaci&oacute;n de tejidos, l&iacute;quidos de animales infectados &oacute; accidentesde laboratorio. La transmisi&oacute;n oral por contaminaci&oacute;n de alimentos con el contenido intestinal de triatominos infectadoscon Trypanosoma cruzi ha sido un mecanismo demostrado experimentalmente en animales. Esta particular v&iacute;a, probablementela m&aacute;s com&uacute;n entre los animales silvestres, asociado a la constituci&oacute;n bioqu&iacute;mica de los aislados, ha sidoresponsable de numerosos brotes en Brasil. En Venezuela se han descrito cuatro episodios desde 2007 con 228 casos y 6fallecimientos. Las medidas de vigilancia epidemiol&oacute;gica y control sanitario deben basarse en el estudio del comportamiento de los vectores, identificaci&oacute;n de factores de riesgo y la concientizaci&oacute;n del personal de salud y autoridades sanitarias de que es una modalidad de transmisi&oacute;n de T cruzi por alimentos, definitivamente demostrada en VenezuelaABSTRACT: Chagas Disease is transmitted to humans through various mechanisms in which the vector directly or indirectly can participate.In other circumstances, infection from man to man occurs through blood transfusions, organ transplants and transplacentalthrough food contamination with the intestinal content of triatomines infected with Trypanosoma cruzi has been demonstratedexperimentally in animals. This particular way, probably the most common among wild animals, will depend on the biochemicalconstitution of the isolates and it has been responsible for numerous outbreaks in Brazil. In Venezuela, four episodeshave been reported since 2007 with 228 cases and 6 deaths. The measures of surveillance and disease control by the health authoritiesshould by based on the study of the behaivor of the vectors, identification of the main risk factors for the human population and awereness of the health staff and health authorities, that this way of transmission is definitely establishedin Venezuela