American trypanosomiasis

American trypanosomiasis is a parasitic disease caused by the flagellate protozoan Trypanosoma cruzi. Chagas disease is endemic in Latin America, where an estimated 10-14 million people are infected, and an emerging disease in Europe and the USA. Trypanosoma cruzi is transmitted by blood-sucking bugs of the family Reduviidae. Rhodnius prolixus, Panstrongylus megistus, Triatoma infestans, and T. dimidiata are the main vectors in the sylvatic cycle. Non vector-borne transmission includes blood transfusion, congenital and oral transmission, transplantation, and accidental infections. Most cases of acute infection occur in childhood and are usually asymptomatic, although severe myocarditis and meningoencephalitis may occur. Approximately 30% of T. cruzi-infected people will develop the chronic stage of the disease. Chronic chagasic cardiomyopathy is characterized by progressive heart failure, arrhythmias, intraventricular conduction defects, sudden death, and peripheral thromboembolism. Acute exacerbation can occur in individuals with involvement of cellular immunity such as advanced AIDS (acquired immunodeficiency syndrome), and transplant-associated immunosuppression. Neurological involvement may present with encephalitis, meningoencephalitis, or a space-occupying cerebral lesion called chagoma. Chagas disease is a major cause of ischemic stroke in Latin America. Several epidemiological studies have found an association between T. cruzi infection and cardioembolic ischemic stroke. Benznidazole and nifurtimox are the two available trypanocide drugs against T. cruzi.

Trypanosoma cruzi experimental congenital transmission associated with TcV and TcI subpatent maternal parasitemia

The congenital transmission of Chagas disease is associated with an increase in parasitemia during pregnancy, maternal and fetal immunity, and populations of Trypanosoma cruzi. In this study, the biological behavior of TcI and TcV (isolated from a human congenital case) strains and their potential for experimental congenital transmission were evaluated in female BALB/C mice. Parasitemia was estimated by fresh blood examination, semiquantitative microhematocrit, and hemoculture, while congenital transmission was evaluated by culture in the liver infusion tryptose medium and by polymerase chain reaction (PCR) of the pups' tissues on postnatal day 7 and of the pups' blood sample at 30 days after birth. Infection was detected in 100 % of the females. Both strains showed subpatent parasitemia, which was higher for TcV infection. The presence of amastigote nest was detected only in an animal infected with TcI. The inflammatory process was more frequent (p = 0.001) in the tissues of the animals infected with TcV (58.6 %) than TcI (31.1 %). The fertility rates of females mated after 35 days postinfection were similar (90 % for TcV, 88.9 % for TcI; p = 0.938). Parasitemia did not change during pregnancy. The average number of pups/female was greater (p = 0.03) in mice with TcV infection (8.30) than in those with TcI infection (4.78). Congenital transmission was detected exclusively by PCR in 50.9 % of the pups, 46.6 % for TcV and 58.1 % for TcI. The PCR positivity for TcI was higher in the blood than in the tissue (p = 0.003). These results demonstrate the T. cruzi experimental congenital infection associated with subpatent maternal parasitemia of TcI and TcV.

Prevalence and risk factors for Chagas disease in pregnant women in Casanare, Colombia

Knowledge of the prevalence and risk factors associated with maternal infection is the first step to develop a surveillance system for congenital transmission of Chagas disease. We conducted a cross-sectional study in Casanare, a disease-endemic area in Colombia. A total of 982 patients were enrolled in the study. A global prevalence of Trypanosoma cruzi infection of 4.0% (95% confidence interval [CI] = 2.8-5.3%) was found. Multivariate analysis showed that the most important risk-associated factors were age > 29 years (adjusted odds ratio [aOR] = 3.4, 95% CI = 0.9-12.4), rural residency (aOR = 2.2, 95% CI = 1.0-4.6), low education level (aOR = 10.2, 95% CI = 1.6-82.7), and previous knowledge of the vector (aOR = 2.2, 95% CI = 1.0-4.9). Relatives and siblings of infected mothers showed a prevalence of 9.3%. These findings may help physicians to investigate congenital cases, screen Chagas disease in siblings and relatives, and provide early treatment to prevent the chronic complications of Chagas disease.

Chagas disease in non-endemic countries: epidemiology, clinical presentation and treatment

Imported Chagas disease (Trypanosoma cruzi infection) is increasingly recognized as an emerging problem in the USA and Europe due to immigration from Latin America. Most migrants from endemic countries will have been infected during childhood. Based on the natural history of the disease, up to 35 % of those infected may develop cardiac and/or gastrointestinal manifestations during the third or fourth decade of life. This disease was described more than 100 years ago, yet many challenges still remain such as the identification of risk factors for visceral involvement, effective treatment for chronic cases, and reliable markers of cure following treatment. Transmission of the infection may occur even in non-endemic areas through non-vectorial routes and many countries are therefore currently facing the challenge of this emerging public health problem.

Prevalence of Chagas disease in pregnant women and incidence of congenital transmission in Santa Cruz de la Sierra, Bolivia

Congenital transmission of Chagas disease stand out as a major public health problem since the vector control was performed in all endemic areas and has shown its effectiveness. An epidemiological study was performed in three maternity hospitals of the city of Santa Cruz de la Sierra, Bolivia from 2006 to 2008. The serological screening for Trypanosoma cruzi infection was carried out in 15,767 pregnant women. Chagas infection was detected in 3725 women (23.6%), who gave birth to 125 newborns infected by T. cruzi at birth, representing an incidence of 790 per 100,000 births during a period of 16 months and a vertical transmission rate by 3.4%. There was a significant difference between hospitals that might be explained by socio-economic origins of mothers and diagnostic constraints.

Congenital and oral transmission of American trypanosomiasis: an overview of physiopathogenic aspects

Chagas disease or American trypanosomiasis is a pathology affecting about 8-11 million people in Mexico, Central America, and South America, more than 300 000 persons in the United States as well as an indeterminate number of people in other non-endemic countries such as USA, Spain, Canada and Switzerland. The aetiological agent is Trypanosoma cruzi, a protozoan transmitted by multiple routes; among them, congenital route emerges as one of the most important mechanisms of spreading Chagas disease worldwide even in non-endemic countries and the oral route as the responsible of multiple outbreaks of acute Chagas disease in regions where the vectorial route has been interrupted. The aim of this review is to illustrate the recent research and advances in host-pathogen interaction making a model of how the virulence factors of the parasite would interact with the physiology and immune system components of the placental barrier and gastrointestinal tract in order to establish a response against T. cruzi infection. This review also presents the epidemiological, clinical and diagnostic features of congenital and oral Chagas disease in order to update the reader about the emerging scenarios of Chagas disease transmission.

Vaccine development against Trypanosoma cruzi and Chagas disease

The pathology of Chagas disease presents a complicated and diverse picture in humans. The major complications and destructive evolutionary outcomes of chronic infection by Trypanosoma cruzi in humans include ventricular fibrillation, thromboembolism and congestive heart failure. Studies in animal models and human patients have revealed the pathogenic mechanisms during disease progression, pathology of disease and features of protective immunity. Accordingly, several antigens, antigen-delivery vehicles and adjuvants have been tested to elicit immune protection to T. cruzi in experimental animals. This review summarizes the research efforts in vaccine development against Chagas disease during the past decade.

Acute and congenital Chagas disease

The acute phase of Chagas disease lasts 4-8 weeks and is characterized by microscopically detectable parasitaemia. Symptoms are usually mild with severe acute disease occurring in less than 1% of patients. Orally transmitted Trypanosoma cruzi outbreaks can have more severe acute morbidity and higher mortality than vector-borne infection. Congenital T. cruzi infection occurs in 1-10% of infants of infected mothers. Most congenital infections are asymptomatic or cause non-specific signs, requiring laboratory screening for detection. A small proportion of congenital infections cause severe morbidity with hepatosplenomegaly, anaemia, meningoencephalitis and/or respiratory insufficiency, with an associated high mortality. Infected infants are presumed to carry the same 20-30% lifetime risk of cardiac or gastrointestinal disease as other infected individuals. Most control programs in Latin America employ prenatal serological screening followed by microscopic examination of cord blood from infants of seropositive mothers. Recent data confirm that polymerase chain reaction (PCR) is more sensitive and detects congenital infections earlier than conventional techniques. For infants not diagnosed at birth, conventional serology is recommended at at 6 to 9 months of age. In programs that have been evaluated, less than 20% of at risk infants completed all steps of the screening algorithm. A sensitive, specific and practical screening test for newborns is needed to enable Chagas disease to be added to newborn screening programs.

[Serological profile of immigrant pregnant women against HIV, HBV, HCV, rubella, Toxoplasma gondii, Treponema pallidum, and Trypanosoma cruzi]

INTRODUCTION

The increase in immigration is changing the prevalence of mother to child infectious diseases. Our aim is to determine the serological profile of foreign pregnant women against these infections.

METHODS

A retrospective cross sectional study was performed in a tertiary hospital from Madrid between August 2007 and October 2008. The seroprevalence against HIV, HBV, HCV, rubeola, T. gondii, T. pallidum and T. cruzi was determined in every pregnant immigrant, as well as in a representative group of Spanish pregnant women.

RESULTS

A total of 2526 immigrant and 157 Spanish pregnant women were studied. None of the Spanish and 0.5% of the foreigners showed antibodies against HIV; 18.9% of them were Sub-Saharan women. Antigen HBs was detected in 2% of the immigrant women and in 1.1% of the Spanish women. Asian women had the highest rate of type B Hepatitis (10.9%). There was 0.9% of type C Hepatitis among the immigrants and 1% among the Spanish. Within the cases with RPR ≥ 1/8, 1.6% were immigrants, most of whom were Latin American. Thirty-one per cent of the immigrants showed antibodies against T. gondii (37.5% from Central America, 2.5% from the Far East). More than 95% of the Spanish women had antibodies against Rubella, this being lower in the rest of the areas (75.5% in Sub-Saharan Africa). T. cruzi infection was detected in 12.1% of the Bolivian women studied.

CONCLUSION

The prevalence of mother-to-child transmitted infections depends on the origin of pregnant women. Knowledge of these differences may lead to improved control these diseases.

Trypanosoma cruzi and Chagas' Disease in the United States

Chagas' disease is caused by the protozoan parasite Trypanosoma cruzi and causes potentially life-threatening disease of the heart and gastrointestinal tract. The southern half of the United States contains enzootic cycles of T. cruzi, involving 11 recognized triatomine vector species. The greatest vector diversity and density occur in the western United States, where woodrats are the most common reservoir; other rodents, raccoons, skunks, and coyotes are also infected with T. cruzi. In the eastern United States, the prevalence of T. cruzi is highest in raccoons, opossums, armadillos, and skunks. A total of 7 autochthonous vector-borne human infections have been reported in Texas, California, Tennessee, and Louisiana; many others are thought to go unrecognized. Nevertheless, most T. cruzi-infected individuals in the United States are immigrants from areas of endemicity in Latin America. Seven transfusion-associated and 6 organ donor-derived T. cruzi infections have been documented in the United States and Canada. As improved control of vector- and blood-borne T. cruzi transmission decreases the burden in countries where the disease is historically endemic and imported Chagas' disease is increasingly recognized outside Latin America, the United States can play an important role in addressing the altered epidemiology of Chagas' disease in the 21st century.

In Vitro Infection of Trypanosoma cruzi Causes Decrease in Glucose Transporter Protein-1 (GLUT1) Expression in Explants of Human Placental Villi Cultured under Normal and High Glucose Concentrations

Trypanosoma cruzi, the etiologic Chagas' disease agent, induces changes in protein pattern of the human placenta syncytiotrophoblast. The glucose transporter protein-1 (GLUT1) is the primary isoform involved in transplacental glucose transport. We carried out in vitro assays to determine if T. cruzi infection would induce changes in placental GLUT1 protein expression under normal and high concentration of glucose. Using Western blot and immunohistological techniques, GLUT1 expression was determined in normal placental villi cultured under normal or high concentrations of glucose, with or without in vitro T. cruzi infection, for 24 and 48 hours. High glucose media or T. cruzi infection alone reduced GLUT1 expression. A yet more accentuated reduction was observed when infection and high glucose condition took place together. We inform, for the first time, that T. cruzi infection may induce reduction of GLUT1 expression under normal and high glucose concentrations, and this effect is synergic to high glucose concentrations.

Economic evaluation of Chagas disease screening of pregnant Latin American women and of their infants in a non endemic area

Migration is a channel through which Chagas disease is imported, and vertical transmission is a channel through which the disease is spread in non-endemic countries. This study presents the economic evaluation of Chagas disease screening in pregnant women from Latin America and in their newborns in a non endemic area such as Spain. The economic impact of Chagas disease screening is tested through two decision models, one for the newborn and one for the mother, against the alternative hypothesis of no screening for either the newborn or the mother. Results show that the option "no test" is dominated by the option "test". The cost effectiveness ratio in the "newborn model" was 22€/QALYs gained in the case of screening and 125€/QALYs gained in the case of no screening. The cost effectiveness ratio in the "mother model" was 96€/QALYs gained in the case of screening and 1675€/QALYs gained in the case of no screening. Probabilistic sensitivity analysis highlighted the reduction of uncertainty in the screening option. Threshold analysis assessed that even with a drop in Chagas prevalence from 3.4% to 0.9%, a drop in the probability of vertical transmission from 7.3% to 2.24% and with an increase of screening costs up to €37.5, "test" option would still be preferred to "no test". The current study proved Chagas screening of all Latin American women giving birth in Spain and of their infants to be the best strategy compared to the non-screening option and provides useful information for health policy makers in their decision making process.

Door-to-door screening as a strategy for the detection of congenital Chagas disease in rural Bolivia

OBJECTIVE

To demonstrate the feasibility of a house-to-house screening system used for congenital Chagas disease in rural areas based on an active search for pregnant women and newborns in their homes in addition to passive case detection in health facilities.

METHODS

Exploratory phase conducted by the research team followed by an operational period coordinated by municipal health service. A blood sample was taken for serological and parasitological tests of Trypanosoma cruzi from pregnant women who were searching antenatal care or visited at home by field investigators. Infants born to T. cruzi-infected women were examined for infection at birth and again at 1 and 7 months of age.

RESULTS

64.5% of the pregnant women were infected. Congenital infection was diagnosed at birth in 4.0% (12/299) of the children born to seroreactive mothers. Twelve additional cases of infection (4%) were diagnosed in children between 1 and 7 months of age. Finally, 37% of the children were lost to follow-up in the exploratory phase and 53% during the operational phase (P=0.002), significantly fewer than in most passive case detection studies.

CONCLUSION

Despite poorer outcomes after door-to-door screening activities have been transferred to the health system, a combined strategy based on active and passive case detection appeared to be efficient for identifying rural cases of congenital Chagas disease.