Zika might not be acting alone: Using an ecological study approach to investigate potential co-acting risk factors for an unusual pattern of microcephaly in Brazil.

Zika virus infections can cause a range of neurologic disorders including congenital microcephaly. However, while Zika infections have been notified across all regions in Brazil, there has been an unusual number of congenital microcephaly case notifications concentrated in the Northeast of the country. To address this observation, we investigated epidemiological data (2014-2016) on arbovirus co-distribution, environmental and socio-economic factors for each region in Brazil. Data on arbovirus reported cases and microcephaly were collected from several Brazilian Ministry of Health databases for each Federal unit. These were complemented by environmental management, social economic and Aedes aegypti infestation index data, extracted from multiple databases. Spatial time "ecological" analysis on the number of arboviruses transmitted by Aedes mosquitoes in Brazil show that the distribution of dengue and Zika was widespread in the whole country, with higher incidence in the West-Central region. However, reported chikungunya cases were higher in the Northeast, the region also with the highest number of microcephaly cases registered. Social economic factors (human development index and poverty index) and environmental management (water supply/storage and solid waste management) pointed the Northeast as the less wealthy region. The Northeast is also the region with the highest risk of Aedes aegypti house infestation due to the man-made larval habitats. In summary, the results of our ecological analysis support the hypothesis that the unusual distribution of microcephaly might not be due to Zika infection alone and could be accentuated by poverty and previous or co-infection with other pathogens. Our study reinforces the link between poverty and the risk of disease and the need to understand the effect on pathogenesis of sequential exposure to arboviruses and co-viral infections. Comprehensive large-scale cohort studies are required to corroborate our findings. We recommend that the list of infectious diseases screened, particularly during pregnancy, be regularly updated to include and effectively differentiate all viruses from ongoing outbreaks.

Genome-wide mutagenesis and multi-drug resistance in American trypanosomes induced by the front-line drug benznidazole.

Chagas disease is caused by the protozoan parasite Trypanosoma cruzi and affects 5-8 million people in Latin America. Although the nitroheterocyclic compound benznidazole has been the front-line drug for several decades, treatment failures are common. Benznidazole is a pro-drug and is bio-activated within the parasite by the mitochondrial nitroreductase TcNTR-1, leading to the generation of reactive metabolites that have trypanocidal activity. To better assess drug action and resistance, we sequenced the genomes of T. cruzi Y strain (35.5 Mb) and three benznidazole-resistant clones derived from a single drug-selected population. This revealed the genome-wide accumulation of mutations in the resistant parasites, in addition to variations in DNA copy-number. We observed mutations in DNA repair genes, linked with increased susceptibility to DNA alkylating and inter-strand cross-linking agents. Stop-codon-generating mutations in TcNTR-1 were associated with cross-resistance to other nitroheterocyclic drugs. Unexpectedly, the clones were also highly resistant to the ergosterol biosynthesis inhibitor posaconazole, a drug proposed for use against T. cruzi infections, in combination with benznidazole. Our findings therefore identify the highly mutagenic activity of benznidazole metabolites in T. cruzi, demonstrate that this can result in multi-drug resistance, and indicate that vigilance will be required if benznidazole is used in combination therapy.

Benznidazole-resistance in Trypanosoma cruzi: evidence that distinct mechanisms can act in concert.

Benznidazole is the main drug used to treat Trypanosoma cruzi infections. However, frequent instances of treatment failure have been reported. To better understand potential resistance mechanisms, we analysed three clones isolated from a single parasite population that had undergone benznidazole-selection. These clones exhibited differing levels of benznidazole-resistance (varying between 9 and 26-fold), and displayed cross-resistance to nifurtimox (2 to 4-fold). Each clone had acquired a stop-codon-generating mutation in the gene which encodes the nitroreductase (TcNTR) that is responsible for activating nitroheterocyclic pro-drugs. In addition, one clone had lost a copy of the chromosome containing TcNTR. However, these processes alone are insufficient to account for the extent and diversity of benznidazole-resistance. It is implicit from our results that additional mechanisms must also operate and that T. cruzi has an intrinsic ability to develop drug-resistance by independent sequential steps, even within a single population. This has important implications for drug development strategies.

The in vivo activity of 1,3,4-thiadiazolium-2-aminide compounds in the treatment of cutaneous and visceral leishmaniasis.

OBJECTIVES: Researchers have recently investigated the biological activities of mesoionic (MI) compounds, which have shown in vitro activity against many species of Leishmania, as well as Trypanosoma cruzi. The main goal of this study was to evaluate and compare the activity of three MI compounds against Leishmania amazonensis and Leishmania infantum infection in vivo. METHODS: The experiments were carried out using BALB/c mice infected with L. amazonensis or L. infantum as a highly sensitive murine model. The infected mice were treated with MI-HH, MI-4-OCH(3), MI-4-NO(2) or meglumine antimoniate by different routes (intralesional, topical or intraperitoneal). RESULTS: Treatment with MI-4-OCH(3) and MI-4-NO(2) efficiently contained the progression of cutaneous and visceral leishmaniasis in comparison with the control group or mice treated with meglumine antimoniate. Interestingly, these MI compounds did not produce toxicological effects after treatment. Furthermore, treatment with these compounds led to a modulation of the immune response that was correlated with disease control. In this study, MI compounds, and MI-4-NO(2) in particular, exhibited high activity in the L. infantum murine model. In the L. amazonensis model, intralesional treatment with MI-4-OCH(3) or MI-4-NO(2) showed greater therapeutic efficacy than treatment with meglumine antimoniate, and the new topical formulations of these compounds also displayed great activity in the cutaneous leishmaniasis model. CONCLUSIONS: Upon comparison of each MI compound, MI-4-NO(2) was clearly the compound with the greatest activity in these two in vivo infection models by each administration route tested.

Croton cajucara crude extract and isolated terpenes: activity on Trypanosoma cruzi.

Croton cajucara is a plant found in the Amazon region and is known for its medicinal properties. The effects of the methanolic extract of the stem bark of C. cajucara (MCC) and of the isolated terpenes, trans-dehydrocrotonin (t-DCTN) and acetyl aleuritolic acid (AAA), were investigated using four isolates of Trypanosoma cruzi. In assays with trypomastigotes, the extract was more active than the isolated compounds, presenting IC(50) in the range of 10 to 50 µg/mL. The trypanocidal effect of MCC, AAA and benznidazole was significantly higher in the GLT291 and C45 strains, which were recently isolated from wild animals. MCC and AAA caused a dose-dependent inhibition of epimastigote proliferation. In assays using intracellular amastigotes, AAA and MCC reduced the percent of infection and the endocytic index after 96 h of treatment, at concentrations that were non-toxic to the host cells. MCC inhibited the trypanothione reductase pathway in both epimastigotes and trypomastigotes of all the subpopulations. The absence of AAA activity on the trypanothione reductase pathway in epimastigotes of Dm28c suggests heterogeneity of the biochemical profile between this clone and the three strains. Epimastigotes and trypomastigotes (GLT291) were treated for 24 h with MCC or AAA, and both induced alterations of the plasma membrane, while AAA-treated epimastigotes also displayed mitochondrial damage.