Chagas disease (American trypanosomiasis) in France

Chagas disease is an anthropozoonotic infection caused by Trypanosoma cruzi, transmitted by a hematophagous triatomine insect vector belonging to the Reduviidae family, while taking a blood meal. There is a large reservoir of wild and domestic mammals. Human contamination may come via vectorial, transplacental, and digestive routes, blood transfusion, organ or tissue transplantation, and by accident. The disease has two phases. The acute phase, oligosymptomatic, is frequently undiagnosed. It is followed by a chronic phase. Most of the infected patients remain asymptomatic all life-long. But 10 or 25 years later, one third of infected patients present with cardiac or digestive complications. Chagas disease is endemic in Latin America, from Mexico to Argentina. In French Guyana, the prevalence of the infection was estimated at 0.25% and 0.5% (from 500 to 1000 infected patients) on blood samples collected from 1992 to 1998. In 2000 and 2009, 192 cases were diagnosed. In this district, there is no established domestic vector and the transmission risk is low. The vector is very easily found in forest habitats and even in the peridomestic persistent forest, with an infection rate of 46 to 86%. Vectorial eradication is impossible. Fighting against Chagas disease in French Guyana relies more on individual protection, control of blood transfusion, prevention of mother-to-child transmission, diagnosis, and treatment of infected patients than on vectorial control.     

Chagas disease after organ transplantation--Los Angeles, California, 2006

Chagas disease is an infection caused by the parasite Trypanosoma cruzi. Reduviids (i.e., "kissing bugs") transmit the parasite through infected feces. T. cruzi also can be transmitted congenitally and through blood transfusion or organ transplantation. The infection is lifelong if left untreated; the majority of infected persons are asymptomatic, and their disease remains undiagnosed. Although routine serologic testing of organ and blood donors is performed in areas of Latin America where Chagas disease is endemic, no T. cruzi screening test is licensed in the United States. However, seroprevalence studies using research tests have documented the presence of T. cruzi antibodies in U.S. blood and organ donor populations. This report describes two cases of acute Chagas disease in heart transplant recipients reported by two Los Angeles County hospitals in February 2006. In the United States, one previous report documented T. cruzi transmission through solid organ transplantation, in which three organ recipients were infected.     

Blood donor screening for chagas disease--United States, 2006-2007

Chagas disease, a zoonotic disease caused by the bloodborne parasite Trypanosoma cruzi, affects an estimated 11 million persons throughout much of Latin America. In endemic areas, T. cruzi is transmitted primarily by triatomine insects (i.e., kissing bugs); infection also can occur via blood transfusion, congenital transmission, organ transplantation, laboratory incident, and ingestion of triatomine-contaminated food or drink. To evaluate an investigational assay for detecting T. cruzi infection in blood donations, the American Red Cross conducted a clinical trial during August 2006-January 2007, screening 148,969 blood samples at three blood-collection centers in the United States. In January 2007, after the new assay was licensed by the Food and Drug Administration (FDA), other centers began screening donors for T. cruzi. This report describes the results of the American Red Cross study, which identified 32 donations (approximately one in 4,655) as confirmed positive for T. cruzi antibodies. As blood-donation screening for Chagas disease becomes more widespread, public health officials and health-care providers should anticipate increased numbers of questions regarding the diagnosis, evaluation, and management of Chagas disease.     

Congenital transmission of Chagas disease - Virginia, 2010

Chagas disease, caused by infection with the parasite Trypanosoma cruzi, affects 8-11 million persons globally. In the endemic areas of Mexico, Central America, and South America, most infections are transmitted by triatomine insect (kissing bug) vectors. However, infection also can be acquired congenitally or through blood transfusion, organ transplantation, consumption of triatomine-contaminated food or drink, or laboratory accident. Early detection and treatment are highly effective; however, acute infection often is subclinical, and most persons are unaware of their infection. If left untreated, the infection is lifelong. The majority of persons with chronic infection remain without signs or symptoms, but 20%-30% eventually develop disease manifestations, most commonly, cardiomyopathy. Migration from endemic areas has led to an estimated 300,000 persons in the United States with chronic Chagas disease, including women of reproductive age who risk transmitting the infection to their children. This report describes the first case of congenital Chagas disease in the United States confirmed by CDC and highlights the importance of raising awareness of Chagas disease among health-care providers.     

Risk of transmission of Trypanosoma cruzi by wild Triatoma infestans (Hemiptera: Reduviidae) in Bolivia supported by the detection of human blood meals

We analyzed the food sources of Bolivian wild Triatoma infestans (the main vector of Chagas disease in this country), to assess the role of these populations in the epidemiological context of Chagas disease. Ninety-eight blood meals were identified by heteroduplex assay and sequencing. Most of them were from wild mammals but surprisingly 27 were from humans. This brings to light the occurrence of human–vector contacts at risk of Trypanosoma cruzi transmission in the wild environment by highly infected insects.     

Screening in vitro of natural products against blood forms of Trypanosoma cruzi

Transmission of Chagas disease by blood transfusion is a major health problem in Central and South America. The annual incidence of transfusion-transmitted Chagas disease in Brazil is about 20,000 cases. Crystal violet is the only trypanosomicidal agent available at present, but there are some restrictions on its use. In a search for possible new chemoprophylactic agents, several natural products of different structural types were tested in vitro against infective blood trypomastigotes of Trypanosoma cruzi. Four compounds had high activity at a concentration of 5 x 10(-4) M: the diarylpropanoids (3R)-claussequinone, (R)-4-methoxydalbergione and (S)-4,4'-dimethoxy-dalbergione, and 15-deoxygoyazensolide, a sesquiterpenelactone. Haemoculture and serology of mice inoculated with infected blood treated with these active compounds were negative after 3 and 6 months. The benzoquinone moiety seemed to be important for this activity since lapachol and related naphthoquinones are known to be trypanosomicidal. 15-Deoxygoyazensolide has previously been recognized as a schistosomicide.     

Trypanosoma cruzi in persons without serologic evidence of disease, Argentina

Current diagnosis of chronic Chagas disease relies on serologic detection of specific immunoglobulin G against Trypanosoma cruzi. However, the presence of parasites detected by polymerase chain reaction (PCR) in patients without positive conventional serologic testing has been observed. We determined the prevalence and clinical characteristics of persons with seronegative results and T. cruzi DNA detected by PCR in a population at high risk for chronic American trypanosomiasis. We studied a total of 194 persons from two different populations: 110 patients were recruited from an urban cardiology clinic, and 84 persons were citizens from a highly disease-endemic area. Eighty (41%) of persons had negative serologic findings; 12 (15%) had a positive PCR. Three patients with negative serologic findings and positive PCR results had clinical signs and symptoms that suggested Chagas cardiomyopathy. This finding challenges the current recommendations for Chagas disease diagnosis, therapy, and blood transfusion policies.     

Urbanization of congenital transmission of Trypanosoma cruzi: prospective polymerase chain reaction study in pregnancy

Chagas disease ranks among the world's most neglected tropical diseases and congenital transmission is increasingly responsible for urbanization of Chagas disease in non-endemic areas.Molecular assays for amplification and profiling of parasite minicircle DNA (kDNA) and identification of discrete typing units (DTUs) were prospectively conducted in bloodstream and placental samples from pregnant women cursing chronic Chagas disease residing in Buenos Aires city.Sensitivity of kDNA-PCR increased from 75.6% to 95.6% when one to three sequential blood samples were analysed. Congenital infection (CI) was diagnosed in 3 neonates born to kDNA-PCR positive mothers, one who had transmitted CI in a previous gestation, pointing to family clustering of congenital transmission. Fourteen of 44 placental samples were kDNA-PCR positive, all from non-CI transmitting women, indicating that placental PCR is not useful for CI diagnosis. Placental PCR positivity was not related to maternal bloodstream PCR positivity and placental parasitic subpopulations not observed in bloodstream were detected by minicircle signatures. PCR targeted to intergenic regions of spliced-leader genes and serological tests using trypomastigote small surface recombinant antigens showed predominance of DTU group TcII/V/VI and only one patient infected with TcI.To our knowledge, this is the first PCR-based follow-up study of bloodstream and placental T. cruzi infections during pregnancy, including identification of DTUs. kDNA-PCR assays in serial blood samples provided high sensitivity for detection of T. cruzi DNA in pregnant women with chronic Chagas disease.     

The various meanings of Brazil's certification as free of Chagas disease]

The article discusses Brazil's recent certification as free of Chagas disease transmission by Triatoma infestans, analyzing the various meanings ascribed to this position. Resulting mainly from measures by both the Chagas Disease Control Program (PCDCh) established in Brazil in 1975 and the Southern Cone Initiative launched in 1991, this certification has been interpreted in ways that lead to confusion between the elimination of Chagas disease transmission by T. infestans and eradication of the disease. The present status of vector transmission control in Brazil is discussed, with emphasis on the Northeast, in most States of which T. infestans is not the main species involved in transmission. The article highlights the need to broaden the discussion of the readings and consequences involved in the present control achievements in light of possible harm from misinterpretations that might jeopardize further efforts to control the disease.     

Density-dependent timing of defaecation by Triatoma infestans.

Defaecation timing of the Triatominae vectors of Trypanosoma cruzi directly affects the transmission probability of Chagas disease to mammal hosts. Experimental studies with fifth instar nymphs of Triatoma infestans showed that defaecation time was negatively affected by blood meal size and positively affected by starvation period and bug initial weight. Since blood meal size and starvation period are both density-dependent, low density domestic populations of T. infestans would represent a higher transmission risk than high density populations. As low density populations could occur in recently reinfested houses after control using insecticide, vigilance activities should be reinforced to protect the human population at the highest risk of disease transmission.     

Chagas Disease and Breast-feeding

Chagas disease (infection by the protozoan Trypanosoma cruzi) is a major parasitic disease of the Americas and one of the main neglected tropical diseases. Although various routes of transmission sre recognized, the risk for transmission of the infection through breast-feeding has not clearly been established. We reviewed the literature on transmission of T. cruzi through breast-feeding to provide breast-feeding mothers with Chagas disease with medical guidance. Although data from animal studies and human studies are scarce, we do not recommend that mothers with Chagas disease discontinue breast-feeding, unless they are experiencing the acute phase of the disease, reactivated disease resulting from immunosuppression, or bleeding nipples. In these cases, thermal treatment of milk before feeding the infant may be considered.     

Oral Transmission of Chagas Disease by Consumption of A?aí Palm Fruit,Brazil

In 2006, a total of 178 cases of acute Chagas disease were reported from the Amazonian state of Pará, Brazil. Eleven occurred in Barcarena and were confirmed by visualization of parasites on blood smears. Using cohort and case–control studies, we implicated oral transmission by consumption of açaí palm fruit.     

Prevalence of Trypanosoma cruzi infection in pregnant Latin American women and congenital transmission rate in a non-endemic area: the experience of the Valencian Health Programme (Spain)

This study describes the results of the health programme implemented in the Valencian Community (Spain) to achieve an early diagnosis of Chagas disease in pregnant Latin American women and their newborns. During 2009 and 2010, 1975 women living in the health districts of three university hospitals were enrolled via midwives or at the time of delivery. Diagnosis of disease was performed using two serological tests with different antigens. Congenital infection was diagnosed by parasitological, molecular or serological methods from blood samples obtained at birth or in subsequent controls. The overall seroprevalence of Chagas infection in pregnant women from 16 different endemic countries was 11·4%. Infection was higher in those from countries in the Gran Chaco Region (Bolivia, 34·1%; Paraguay, 7·4%; Argentina, 5·3%). Eight newborn infants from Bolivian mothers had congenital Chagas which represents a vertical transmission rate of 3·7%. In conclusion, this work supports the benefits of offering an early diagnosis to pregnant women and newborns during routine prenatal healthcare.     

Surveillance of Trypanosoma cruzi transmission by serological screening of schoolchildren.

The seroprevalence of Trypanosoma cruzi infection among children is a sensitive indicator for assessing the effectiveness of programmes for control of Chagas disease. In this study we report the result of a cross-sectional serological survey carried out among schoolchildren living in a poor rural area in central Brazil. Eluates of blood collected on filter-paper were tested for anti-T. cruzi antibodies using immunofluorescence, haemagglutination, and enzyme-linked immunosorbent assays. The overall seroprevalence of T. cruzi infection was 7.9%, which compared with the findings of the national survey carried out in 1975-80 indicates that a twofold-to-threefold reduction in prevalence has occurred over the last 10 years. This is consistent with a reduction of transmission in the area, probably related to vector control efforts. Based on our results, the incidence of new cases was estimated to be 44 per annum in the study region. In rural areas with a scattered population, surveillance of T. cruzi transmission by serological screening of children at school entry is more practical and economical than entomological evaluation for assessing both the risk of transmission in the community and the efficacy of vector control measures. A sample size of around 1000 schoolchildren is sufficient to detect prevalences as low as 2%, and such an approach would be practical and applicable to most areas where Chagas disease is endemic.     

Candidate parasitic diseases

This paper discusses five parasitic diseases: American trypanosomiasis (Chagas disease), dracunculiasis, lymphatic filariasis, onchocerciasis and schistosomiasis. The available technology and health infrastructures in developing countries permit the eradication of dracunculiasis and the elimination of lymphatic filariasis due to Wuchereria bancrofti. Blindness due to onchocerciasis and transmission of this disease will be prevented in eleven West African countries; transmission of Chagas disease will be interrupted. A well-coordinated international effort is required to ensure that scarce resources are not wasted, efforts are not duplicated, and planned national programmes are well supported.     

Transfusion-associated transmission of West Nile virus--Arizona, 2004

Blood transfusion-associated transmission (TAT) of West Nile virus (WNV) in the United States was first identified in 2002. In 2003, blood collection agencies (BCAs) responded by screening donations for WNV by using nucleic acid-amplification tests (NATs). The majority of BCAs use a two-tiered NAT-screening algorithm. On the basis of the test manufacturer's format, NATs are conducted on minipools of samples from either six or 16 blood donations. If a minipool is nonreactive, its constituent donations are released for transfusion. If a minipool is reactive, the constituent donations undergo individual testing. If an individual donation is reactive, associated blood components are impounded, and the donor is notified for further testing to confirm the infection. In 2003, blood-donation screening for WNV resulted in the impounding of approximately 800 blood components potentially containing WNV. However, six reported cases of transfusion-associated WNV disease were associated with units of blood components with viral concentrations too small to be detected by minipool NAT. In 2004, to improve the sensitivity of WNV screening, BCAs implemented systems to trigger a switch from minipool NAT to individual NAT in areas with epidemic WNV transmission. This report describes the first transfusion-associated WNV infection identified in 2004; the implicated blood donation was collected before the switch to individual testing. Clinicians should remain aware of the risk for WNV transmission through blood-product transfusion and alert state health officials to hospitalized patients with WNV disease symptoms who have had a transfusion during the preceding 28 days.     

Blood transfusion and spread of variant Creutzfeldt-Jakob disease

Variant Creutzfeldt-Jakob disease (vCJD) may be transmissible by blood. To prevent secondary transmission through blood components, several countries have started to exclude as donors persons who have received a blood transfusion. We investigated the effectiveness of this measure by using a dynamic age-structured model. It is the first such model based on epidemiologic data: 1) blood donor activities, 2) a case-control study on CJD, 3) age distribution of recipients, and 4) death of recipients of blood transfusions. The model predicts that an infection like vCJD, which has been introduced into the population by the alimentary route, could not become endemic by transfusion alone and that only <1% of cases would be avoided by excluding from blood donation those persons who have received a transfusion.     

Triatoma sanguisuga Blood Meals and Potential for Chagas Disease,Louisiana, USA

To evaluate human risk for Chagas disease, we molecularly identified blood meal sources and prevalence of Trypanosoma cruzi infection among 49 Triatoma sanguisuga kissing bugs in Louisiana, USA. Humans accounted for the second most frequent blood source. Of the bugs that fed on humans, ≈40% were infected with T. cruzi, revealing transmission potential.     

Current situation with chagas disease vector control in the Americas

This article identifies and describes various epidemiological aspects in the natural transmission of Chagas disease in the Americas. It also examines the relative importance of the principal vector species in the disease's transmission and the control levels that are feasible in each instance. Estimations of the population at risk, number of infected cases, and number of chronic cases are presented. Prospects for control are discussed on the basis of past results to predict the expected results with introduced species like Triatoma infestans in the Southern Cone and Rhodnius prolixus in Central America and with the other autochthonous species in areas where they are found. Finally, the article discusses the role of other transmission mechanisms in the maintenance of endemic Chagas disease.     

Development of Triatoma rubida sonoriana, Triatoma barberi, and Meccus mazzottii (Heteroptera, Reduviidae) under laboratory conditions

The objective of this study was to determine some of the most important bionomic parameters related to the capacity of transmission of Trypanosoma cruzi and to estimate the potential transmission capacity and role of 3 groups of recent colonized Mexican Triatoma barberi, T. rubida sonoriana, and Meccus (formerly Triatoma) mazzottii in the prevalence of Chagas disease cases based on the distribution area of each species. Among the studied Triatominae species, the life cycle was shorter in T. r. sonoriana and longer in T. barberi, by as much as 4 times. The 1st and 5th instars had the highest rates of mortality in most of the studied species. Statistically significant shorter duration of feeding of instars was observed for T. r. sonoriana and longer duration was found for M. mazzottii when the species were compared. The mean number of blood meals per nymphal stadium was statistically greater in T. barberi than in T. r. sonoriana and M. mazzottii. Triatoma r. sonoriana and M. mazzotti had shorter defecation delay than in T. barberi and the delay was uniform in all instars. Most of the studied parameters showed that T. r. sonoriana and M. mazzotti could have an important potential role in the prevalence of Chagas disease cases where these species are commonly found.