Project description:Trypanosoma cruzi, the causative agent of Chagas disease, infects 10-18 million people and may be transmitted to the newborn. Using various data sources, we estimated that nearly 850 congenital cases occurred in Argentina in 1993, or 6.3 expected cases per each reported case in 1994 and in 1994-2001. The congenital transmission of T. cruzi constitutes a sizeable public health problem in the region.
Project description:Trypanosoma cruzi has been divided into Discrete Typing Units I and non-I (II-VI). T. cruzi I is predominant in Mexico and Central America, while non-I is predominant in most of South America, including Argentina. Little is known about congenital transmission of T. cruzi I. The specific aim of this study is to determine the rate of congenital transmission of T. cruzi I compared to non-I.We are conducting a prospective study to enroll at delivery, 10,000 women in Argentina, 7,500 women in Honduras, and 13,000 women in Mexico. We are measuring transmitted maternal T. cruzi antibodies by performing two rapid tests in cord blood (Stat-Pak, Chembio, Medford, New York, and Trypanosoma Detect, InBios, Seattle, Washington). If at least one of the results is positive, we are identifying infants who are congenitally infected by performing parasitological examinations on cord blood and at 4-8 weeks, and serological follow-up at 10 months. Serological confirmation by ELISA (Wiener, Rosario, Argentina) is performed in cord and maternal blood, and at 10 months. We also are performing T. cruzi standard PCR, real-time quantitative PCR and genotyping on maternal venous blood and on cord blood, and serological examinations on siblings. Data are managed by a Data Center in Montevideo, Uruguay. Data are entered online at the sites in an OpenClinica data management system, and digital pictures of data forms are sent to the Data Center for quality control. Weekly reports allow for rapid feedback to the sites.
Project description:Chagas disease is mainly transmitted by vertical transmission (VT) in nonendemic areas and in endemic areas where vector control programs have been successful. For the present study, we isolated natural Trypanosoma cruzi strains vertically transmitted through three generations and proceeded to study their molecular mechanism of VT using mice. No parasitemia was detected in immunocompetent mice, but the parasites were able to induce an immune response and colonize different organs. VT experiments revealed that infection with different strains did not affect mating, pregnancy, or resorption, but despite low parasitemia, VT strains reached the placenta and resulted in higher vertical transmission rates than strains of either moderate or high virulence. While the virulent strain modulated more than 2,500 placental genes, VT strains modulated 150, and only 29 genes are shared between them. VT strains downregulated genes associated with cell division and replication and upregulated immunomodulatory genes, leading to anti-inflammatory responses and tolerance. The virulent strain stimulated a strong proinflammatory immune response, and this molecular footprint correlated with histopathological analyses. We describe a unique placental response regarding the passage of T. cruzi VT isolates across the maternal-fetal interphase, challenging the current knowledge derived mainly from studies of laboratory-adapted or highly virulent strains. IMPORTANCE The main findings of this study are that we determined that there are Trypanosoma cruzi strains adapted to transplacental transmission and completely different from the commonly used laboratory reference strains. This implies a specific strategy for the vertical transmission of Chagas disease. It is impressive that the strains specialized for vertical transmission modify the gene expression of the placenta in a totally different way than the reference strains. In addition, we describe isolates of T. cruzi that cannot be transmitted transplacentally. Taken together, these results open up new insights into the molecular mechanisms of this insect vector-independent transmission form.
Project description:Compared with South America, there is a lack of epidemiologic studies about the risk of congenital transmission of Trypanosoma cruzi in Central America and Mexico. It has been suggested that T. cruzi genotypes might differ by region and that congenital transmission might vary according to the parasite's genotype. Our objective was to compare T. cruzi congenital transmission rates in three countries. We performed an observational prospective study in 2011-2014 enrolling women at delivery in one hospital in Argentina, two hospitals in Honduras, and two hospitals in Mexico. Congenital T. cruzi infection was defined as the presence of one or more of the following criteria: presence of parasites in cord blood (direct parasitological microscopic examination) with positive polymerase chain reaction (PCR) in cord blood, presence of parasites in infant's blood at 4-8 weeks (direct parasitological microscopic examination), and persistence of T. cruzi-specific antibodies at 10 months, as measured by at least two tests. Among 28,145 enrolled women, 347 had at least one antibody rapid test positive in cord blood and a positive enzyme-linked immunosorbent assay in maternal blood. PCR in maternal blood was positive in 73.2% of the cases, and genotyping identified a majority of non-TcI in the three countries. We found no (0.0%; 95% confidence interval [CI]: 0.0, 2.0) confirmed congenital case in Honduras. Congenital transmission was 6.6% (95% CI: 3.1, 12.2) in Argentina and 6.3% (95% CI: 0.8, 20.8) in Mexico. Trypanosoma cruzi non-TcI predominated and risks of congenital transmission were similar in Argentina and Mexico.
Project description:In the Brazilian Amazon, the suspected source of infection in an outbreak of acute Chagas disease involving 10 patients was Euterpe oleracea (açaí berry) juice. Patient blood and juice samples contained Trypanosoma cruzi TcIV, indicating oral transmission of the Chagas disease agent.
Project description:The effect of maternal smoking as a source of exposure to toxic metals Cd and Pb on superoxide dismutase (SOD) and glutathione peroxidase (GPx) activity, metallothionein (MT), Cd, Pb, Cu, Fe, Mn, Se and Zn concentrations were assessed in maternal and umbilical cord blood and placenta in 74 healthy mother-newborn pairs after term delivery. Sparse discriminant analysis (SDA) was used to identify elements with the strongest impact on the SOD, GPx and MT in the measured compartments, which was then quantified by multiple regression analysis. SOD activity was lower in maternal and cord plasma, and higher in the placenta of smokers compared to non-smokers, whereas GPx activity and MT concentration did not differ between the groups. Although active smoking during pregnancy contributed to higher maternal Cd and Pb concentrations, its contribution to the variability of SOD, GPx or MT after control for other elements identified by SDA was not significant. However, an impaired balance in the antioxidant defence observed in the conditions of relatively low-to-moderate exposure levels to Cd and Pb could contribute to an increased susceptibility of offspring to oxidative stress and risk of disease development later in life. Further study on a larger number of subjects will help to better understand complex interactions between exposure to toxic elements and oxidative stress related to maternal cigarette smoking.
Project description:A Trypanosoma cruzi Loopamp kit was recently developed as a ready-to-use diagnostic method requiring minimal laboratory facilities. We evaluated its diagnostic accuracy for detection of acute Chagas disease (CD) in different epidemiological and clinical scenarios. In this retrospective study, a convenience series of clinical samples (venous blood treated with EDTA or different stabilizer agents, heel-prick blood in filter paper or cerebrospinal fluid samples (CSF)) from 30 infants born to seropositive mothers (13 with congenital CD and 17 noninfected), four recipients of organs from CD donors, six orally-infected cases after consumption of contaminated guava juice and six CD patients coinfected with HIV at risk of CD reactivation (N = 46 patients, 46 blood samples and 1 CSF sample) were tested by T. cruzi Loopamp kit (Tc LAMP) and standardized quantitative real-time PCR (qPCR). T. cruzi Loopamp accuracy was estimated using the case definition in the different groups as a reference. Cohen's kappa coefficient (κ) was applied to measure the agreement between Tc LAMP (index test) and qPCR (reference test). Sensitivity and specificity of T. cruzi Loopamp kit in blood samples from the pooled clinical groups was 93% (95% CI: 77-99) and 100% (95% CI: 80-100) respectively. The agreement between Tc LAMP and qPCR was almost perfect (κ = 0.92, 95% CI: 0.62-1.00). The T. cruzi Loopamp kit was sensitive and specific for detection of T. cruzi infection. It was carried out from DNA extracted from peripheral blood samples (via frozen EDTA blood, guanidine hydrochloride-EDTA blood, DNAgard blood and dried blood spots), as well as in CSF specimens infected with TcI or TcII/V/VI parasite populations. The T. cruzi Loopamp kit appears potentially useful for rapid detection of T. cruzi infection in congenital, acute and CD reactivation due to HIV infection.
Project description:Congenital transmission is a major source of new Trypanosoma cruzi infections, and as vector and blood bank control continue to improve, the proportion due to congenital infection will grow. A major unanswered question is why reported transmission rates from T. cruzi-infected mothers vary so widely among study populations. Women with high parasite loads during pregnancy are more likely to transmit to their infants, but the factors that govern maternal parasite load are largely unknown. Better understanding of these factors could enable prioritization of screening programs to target women most at risk of transmission to their infants.We screened pregnant women presenting for delivery in a large urban hospital in Bolivia and followed infants of infected women for congenital Chagas disease. Of 596 women screened, 128 (21.5%) had confirmed T. cruzi infection; transmission occurred from 15 (11.7%) infected women to their infants. Parasite loads were significantly higher among women who transmitted compared to those who did not. Congenital transmission occurred from 31.3% (9/29), 15.4% (4/26) and 0% (0/62) of women with high, moderate and low parasite load, respectively (χx2 for trend 18.2; p<0.0001). Twin births were associated with higher transmission risk and higher maternal parasite loads. Infected women without reported vector exposure had significantly higher parasite loads than those who had lived in an infested house (median 26.4 vs 0 parasites/mL; p<0.001) with an inverse relationship between years of living in an infested house and parasite load.We hypothesize that sustained vector-borne parasite exposure and repeated superinfection by T. cruzi may act as an immune booster, allowing women to maintain effective control of the parasite despite the down-regulation of late pregnancy.
Project description:Maternal antibodies may play a role in protecting newborns against malaria disease. Plasmodium falciparum parasite surface antigens are diverse, and protection from infection requires allele-specific immunity. Although malaria-specific antibodies have been shown to cross the placenta, the extent to which antibodies that respond to the full repertoire of diverse antigens are transferred from the mother to the infant has not been explored. Understanding the breadth of maternal antibody responses and to what extent these antibodies are transferred to the child can inform vaccine design and evaluation. We probed plasma from cord blood and serum from mothers at delivery using a customized protein microarray that included variants of malaria vaccine target antigens to assess the intensity and breadth of seroreactivity to three malaria vaccine candidate antigens in mother-newborn pairs in Malawi. Among the 33 paired specimens that were assessed, mothers and newborns had similar intensity and repertoire of seroreactivity. Maternal antibody levels against vaccine candidate antigens were the strongest predictors of infant antibody levels. Placental malaria did not significantly impair transplacental antibody transfer. However, mothers with placental malaria had significantly higher antibody levels against these blood-stage antigens than mothers without placental malaria. The repertoire and levels of infant antibodies against a wide range of malaria vaccine candidate antigen variants closely mirror maternal levels in breadth and magnitude regardless of evidence of placental malaria. Vaccinating mothers with an effective malaria vaccine during pregnancy may induce high and potentially protective antibody repertoires in newborns.
Project description:BackgroundTrypanosoma cruzi circulates in sylvatic habitats, mainly through blood-feeding triatomines, although other routes also contribute to its dispersion. Sexual transmission of T. cruzi is an understudied topic, especially among wild mammals. Because of the difficulties inherent to field work, experimentally infected mice are frequently used to evaluate the transmission of T. cruzi.ObjectiveThis study aimed to evaluate the sexual transmission of T. cruzi in acutely infected mice.MethodsMale and female mice in the acute phase of Chagas disease were mated with naïve partners. Then, parasitological tests, immunohistochemistry, serological assays, and polymerase chain reaction (PCR) assays were used to detect infection.FindingsParasitological analysis showed trypomastigotes in the blood of 20% of the naïve mice after mating with infected partners. Serological assays detected anti-T. cruzi antibodies in all naïve females mated with infected males and in 60% of naïve males mated with infected females. PCR showed T. cruzi nDNA bands for all naïve mice mated with infected partners. The possibility of sexual transmission was also confirmed by visualisation of amastigotes in the testes.Main conclusionsOur results demonstrate that sexual transmission of T. cruzi is an ordinary event that may contribute to maintenance of the parasite's enzootic cycle.