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Keywords:

  • Chagas disease;
  • congenital;
  • epidemiology;
  • maternal health;
  • child health
  • maladie de Chagas;
  • congénitale;
  • épidémiologie;
  • santé maternelle;
  • santé des enfants
  • enfermedad de Chagas;
  • congénita;
  • epidemiología;
  • salud materna;
  • salud infantil

Summary

  1. Top of page
  2. SummaryLe dépistage de porte-à-porte comme stratégie pour la détection de la maladie de Chagas congénitale dans les zones rurales en BolivieCribado puerta a puerta como estrategia para la detección de la enfermedad de Chagas congénita en zonas rurales de Bolivia
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgements
  9. References

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.

Le dépistage de porte-à-porte comme stratégie pour la détection de la maladie de Chagas congénitale dans les zones rurales en Bolivie

Objectif:  Démontrer la faisabilité d’un système de dépistage de maison en maison de la maladie de Chagas congénitale dans les zones rurales, basé sur une recherche active des femmes enceintes et des nouveau-nés dans leurs foyers, en plus de la détection passive des cas dans les services de santé.

Méthodes:  Phase exploratoire menée par l’équipe de recherche, suivie d’une période opérationnelle coordonnée par les services de santé municipaux. Un échantillon de sang a été prélevé pour des tests sérologiques et parasitologiques de Trypanosoma cruzi chez les femmes enceintes recourant à des soins prénataux ou visitées à domicile par les enquêteurs sur le terrain. Les nourrissons nés de femmes infectées par T. cruzi ont été examinés pour l’infection à la naissance et de nouveau à 1 et à 7 mois d’âge.

Résultats:  64.5% des femmes enceintes étaient infectées. L’infection congénitale a été diagnostiquée à la naissance chez 4.0% (12/299) des enfants nés de mères séro-réactives. 12 cas supplémentaires d’infection (4%) ont été diagnostiqués chez des enfants de 1 à 7 mois d’âge. Enfin, 37% des enfants ont été perdus au suivi dans la phase exploratoire et 53% au cours de la phase opérationnelle (= 0.002), significativement moins que dans la plupart des études de détection passive des cas.

Conclusion:  Malgré des résultats plus faibles après que les activités de dépistage de porte-à-porte aient été transférées au système de santé, une stratégie combinée basée sur le dépistage actif et passif semble être efficace pour l’identification des cas en milieu rural de la maladie de Chagas congénitale.

Cribado puerta a puerta como estrategia para la detección de la enfermedad de Chagas congénita en zonas rurales de Bolivia

Objetivo:  Demostrar la factibilidad de un sistema de cribado puerta a puerta, utilizado para detectar en áreas rurales la enfermedad de Chagas congénita basándose en una búsqueda activa en los hogares de mujeres embarazadas y de recién nacidos, además de la detección pasiva de casos en los centros sanitarios.

Métodos:  Fase exploratoria conducida por el equipo de investigación, seguida por un periodo operativo coordinado por el servicio municipal de salud. Se tomó una muestra de sangre para realizar pruebas serológicas y parasitológicas de Trypanosoma cruzi a mujeres embarazadas que buscaban cuidados antenatales o eran visitadas en sus hogares por los investigadores de campo. Los niños nacidos de mujeres infectadas con T. cruzi eran examinados en busca de infección al momento del parto y de nuevo con 1 y 7 meses de edad.

Resultados:  Un 64.5% de las mujeres embarazadas estaban infectadas. Se diagnosticó la infección congénita, en el momento del parto, a un 4.0% (12/299) de los niños nacidos de madres seroreactivas. Otros 12 casos de infección (4%) se diagnosticaron en niños con edades entre 1 y 7 meses. Finalmente, 37% de los niños se perdieron durante el seguimiento en la fase exploratoria y 53% durante la fase operativa (= 0.002), cifra significativamente menor que en la mayoría de los estudios de detección pasiva.

Conclusión:  A pesar de los peores resultados, después de que las actividades de cribado puerta a puerta se hayan transferido al sistema sanitario, la estrategia combinada basada en la detección activa y pasiva de casos parecía ser eficiente para identificar los casos rurales de enfermedad congénita de Chagas.


Introduction

  1. Top of page
  2. SummaryLe dépistage de porte-à-porte comme stratégie pour la détection de la maladie de Chagas congénitale dans les zones rurales en BolivieCribado puerta a puerta como estrategia para la detección de la enfermedad de Chagas congénita en zonas rurales de Bolivia
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgements
  9. References

Up to 10 million people are estimated to suffer from Chagas disease globally. Multinational initiatives for Chagas disease control were remarkably successful at reducing transmission of Trypanosoma cruzi by domestic vectors or blood transfusions in vast areas of South America (Dias 2009). Meanwhile, congenital transmission has become a public health problem in all countries, including the industrialized North American and European countries where many T. cruzi-infected people migrate (Oliveira et al. 2010). Neonatal infection by T. cruzi induces an acute phase of Chagas disease, which may cause anasarca and respiratory distress and may be fatal to the newborn on rare occasions (Carlier & Truyens 2010).

The health of infected newborns improves if the disease is diagnosed and treated in the first year of life (Schijman et al. 2003; Oliveira et al. 2010). Parasites can be obtained directly from the newborns at birth by direct parasitological methods, but microscopic examination by untrained health staff often lacks sensitivity (Torrico et al. 2007). Confirmation of congenital infection comes from positive serology after 7 months of age, which is after the disappearance of IgG antibodies that are actively transferred from the infected mother (Chippaux et al. 2010). Concerning congenital Chagas disease, diagnosis can be delayed and there is a high risk of losing children during follow-up.

Previous epidemiological studies in endemic areas of Bolivia and elsewhere in Southern Cone countries have focused on estimating prevalence and incidence rates in hospital-based populations of pregnant women and newborns (Oliveira et al. 2010). According to these studies, the prevalence in Bolivian mothers was between 21% and 51%, and the incidence of congenital Chagas disease ranged from 12 to 25 per 1000 live births. Despite the availability of staff and proper logistics in third-level hospitals and the proximity of transport infrastructure in large cities, at times these studies had reduced coverage rates among pregnant women and high rates of babies that were lost to follow-up.

Since 2004, the National Chagas Control Program (NChCP) has been progressively establishing a hospital-based screening program for those with congenital Chagas disease in second-level and third-level hospitals of several endemic departments (Torrico et al. 2007). Despite a marked improvement in the frequency of hospital births in Bolivia, the proportion of home births was 32% during 2004–2008 (56% in rural areas); a significant proportion of congenital cases might have escaped the hospital-based screening program (Coa & Ochoa 2008).

Few studies sought to establish a large-scale operational screening program for those with congenital Chagas disease and none attempted to include home deliveries in the screening strategy for an entire rural municipality (Blanco et al. 2000; Russomando et al. 2005). This study aimed to demonstrate the feasibility of a house-to-house screening system in rural areas using an active search method for identifying pregnant women and their newborns in their homes in addition to passive case detection in health facilities. The study lasted 40 months and was divided into two phases: an exploratory phase and an operational period.

Materials and methods

  1. Top of page
  2. SummaryLe dépistage de porte-à-porte comme stratégie pour la détection de la maladie de Chagas congénitale dans les zones rurales en BolivieCribado puerta a puerta como estrategia para la detección de la enfermedad de Chagas congénita en zonas rurales de Bolivia
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgements
  9. References

The municipality of Carapari is situated 800–1300 m above sea level in the Chaco region, which is south of Bolivia. According to the last census in 2001, the municipality had 9035 inhabitants including 1623 women of childbearing age. There are two first-level hospitals (one in Carapari and one in Itau) that coordinate several health centres each (four and three, respectively). The NChCP and Non-Governmental Organizations conducted vector control operations against Triatoma infestans, the only domestic vector of T. cruzi, by using insecticidal spray and home improvement.

In January 2004, the research team recruited two nurses who realized blood sampling and served as field investigators. Over 2 months, they visited all houses in the municipality of Carapari and assessed all women of childbearing age using a standardized questionnaire. The census of the women of childbearing age was then updated monthly to identify all ongoing pregnancies. Women-targeted IEC (Information, education and communication) campaigns focusing on congenital Chagas disease were also conducted in the municipality.

The first phase of the project was initiated in March 2004 and ended in November 2005 (21 months). The second phase lasted 19 months, from December 2005 to June 2007. During the first phase of the study, the research team in charge of the investigative process had trained salaried staff (two field investigators and one laboratory technician), supplied 2 motorcycles, laboratory equipment and reagents and actively supervised all activities. During the second phase of the study, new staff was contracted and trained, and activities were transferred to the municipal health service to ensure coordination. The research team continued to provide reagents and continuous training. During each phase of the study, only one technician has performed all parasitological tests. The laboratory of Parasitology from INLASA (JAS) in La Paz realized all serological tests and assumed quality control for the whole study.

The protocol of this study received ethical clearance from the Bolivian Ministry of Health and Sports and full support from the municipality of Carapari.

Diagnosis of pregnant women

Pregnant women in their third trimester who voluntarily attended antenatal care in the municipal health facilities were examined clinically; an individual record containing details of family members, current residence and medical, obstetrical and perinatal history was kept for each patient. A blood sample was taken for serological and parasitological tests of T. cruzi. Pregnant women lacking antenatal care were visited in their homes by one field investigator and examined in the same way before delivery.

Blood samples were collected from fingers, after obtaining signed informed consent. A first, immediate diagnosis was performed using an immunochromatographic test, Chagas Stat-Pak (Chembio Diagnostic Systems, Medford, NY, USA), giving a result within 15 min. Meanwhile, a blood sample was collected in 600 μl Microtainer tubes with lithium heparin and plasma separator (Becton Dickinson, Franklin Lakes, NJ, USA). Before centrifugation of the microtainer, parasitaemia in mothers was diagnosed using microscopic examination of the buffy coat from four 75-μl-capillary tubes centrifuged for 5 min at 12 000 g (Freilij et al. 1983). The interface of the buffy coat was examined at 100x and 400x magnifications through the capillary tubes without breaking them. After centrifugation, the Microtainer tube was frozen at −20 °C, until a conventional serological determination using commercially available kits for indirect haemagglutination (IHA Chagas Polychaco, Buenos Aires, Argentina) and enzyme-linked immunosorbent assay (ELISA Chagatest Wiener, Rosario, Argentina) could be performed. Positive blood samples, shown by two serological techniques, were considered seroreactive to T. cruzi.

T. cruzi-infected mothers were given a document with serological results and instructions for follow-up with the child after birth. The document also informed the mothers of the possibility of transmission of T. cruzi to the child and emphasized the importance of follow-up to diagnose the infection and start treatment as early as possible. Because of the 15.6% illiteracy rate in rural populations (Coa & Ochoa 2008), this document was orally explained for those women who required it.

Diagnosis and treatment of infants

Infants born to T. cruzi-infected women were examined for infection at birth before leaving the maternity ward or during the first week of life at home. Approximately 600 μl of blood were taken from the heel for parasitological and serological studies. The blood samples were examined for T. cruzi by the microhematocrit concentration technique using four 75 μl-capillary tubes per infant. Infants with a positive parasitological test were immediately treated as described below. Infants with a negative microhematocrit at birth were re-examined by the same technique at 1 month of age; if they were persistently negative, they were scheduled for a serological examination for T. cruzi infection at 7 months of age by IHA (Polychaco) and ELISA (Wiener). The follow-up occurred in two ways: the mother took the infant directly to the hospital laboratory according to schedule, or field investigators sought out mother and child in their home. The same procedures used at birth were followed to diagnose T. cruzi infection. Infants with a negative microhematocrit test and a decrease in specific antibodies below the cut-off titres were considered seronegative and did not undergo further follow-up. When the decrease in antibody titres did not fall below the cut-off titres, the infant was scheduled for another examination before 12 months of age.

All infants with T. cruzi detected by the microhematocrit test or persistence of IgG antibodies to T. cruzi above the cut-off titres at 7 months of age were considered infected. 24 infants were then referred to the hospital for specific treatment with benznidazole at a daily dose of 10 mg/kg for 60 days, according to international guidelines (WHO 2002). The outcome was evaluated immediately after treatment and at least once a year post-treatment by means of clinical, serological and parasitological examinations. The same procedures for evaluation were used.

Definition of a congenital case

A child that was born from a T. cruzi-infected mother and had parasites in the bloodstream at birth was considered to be a true congenital Chagas disease case. Because vector transmission persisted in the area, the detection of parasites or specific antibodies in 1- to 7-month-old children was not regarded as evidence of congenital disease.

Categorical variables were compared with Pearson’s χ2 or Fisher’s exact tests and relative risks (RR) were calculated using Stata MP/11 (StataCorp, College Station, TX, USA).

Results

  1. Top of page
  2. SummaryLe dépistage de porte-à-porte comme stratégie pour la détection de la maladie de Chagas congénitale dans les zones rurales en BolivieCribado puerta a puerta como estrategia para la detección de la enfermedad de Chagas congénita en zonas rurales de Bolivia
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgements
  9. References

In March 2004, a total of 1730 women of childbearing age were identified in 65 communities. During the 40-month period, 526 pregnant women were actively monitored (Figure 1 and Table 1). Of these, 64.5% (95% CI: 60.2–68.6) were seroreactive to T. cruzi. The prevalence rate of seroreactivity to T. cruzi was 62.2% in the first phase and 67.4% in the second phase; the difference was not statistically significant (P = 0.22). The mean age of the 526 pregnant women was 25.6 years (range 13–46 years) and did not differ over the periods. The presence of T. cruzi parasites was observed in the bloodstream of 6.2% (95% CI: 3.9–9.3) of the seroreactive pregnant women, and this proportion did not vary over the two phases (Table 1). For pregnant women, the estimated coverage rate of the screening program was 95.9% in the first phase and 76.6% in the second phase (P < 0.001).

image

Figure 1.  Flow diagram of the study.

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Table 1.   Key indicators of the screening program for congenital Chagas disease in Carapari according to the phases of the study (March 2004–June 2007)
Key indicatorsFirst phase (21 months)Second phase (19 months) P-value*Whole survey (95% CI)
  1. *P-value for Pearson chi-squared test.

  2. †Number of congenital cases at birth divided by the number born from chagasic mothers.

  3. ‡Number of congenital cases at birth divided by the total number of live births.

  4. §Proportion babies lost to follow-up that were born from infected mothers.

Number of pregnant women295231 526
Mean age of pregnant women (range)25.6 (13–46)25.6 (14–43) 
Prevalence of T. cruzi-infected pregnant women62.2% (183/294)67.4% (155/230)0.2264.5% (60.2–68.6)
Proportion of women with parasites in blood stream7.6% (14/183)4.5% (7/155)0.266.2% (3.9–9.3)
Proportion of women lost to follow-up before delivery4.1% (12/295)23.4% (54/231)<0.001
Total number of newborns287181 468
Proportion of hospital births52.6% (151/287)61.3% (111/181)0.06
Number of infants born from infected mothers178121 299
Transmission rate of congenital T. cruzi infection†4.5% (8/178)3.3% (4/121)0.614.0% (2.1–6.9)
Incidence rate of congenital T. cruzi infection (number of live births)‡2.8% (287)2.2% (181)0.7026% (13–44)
Proportion of infants lost to follow-up at 1 month of age§15.3% (26/170)21.4% (25/117)0.19
Number of infants negative at birth and screened at 1 month14492 236
Proportion of infected infants at 1 month of age2.8% (4/144)2.2% (2/92)0.772.5% (0.9–5.4)
Proportion of children lost to follow-up at 7 months of age§28.6% (40/140)43.3% (39/90)0.02
Number of children negative at 1 month and screened at 7 months10051 151
Proportion of seropositive children at 7 months of age5.0% (5/100)2.0% (1/51)0.364.0% (1.5–8.4)
Total number of children lost to follow-up that were born from infected mothers during survey37.1% (66/178)52.9% (64/121)0.007

A total of 468 newborns were identified in the study (Figure 1). The hospital birth rate slightly increased from the first phase (52.6%) to the second phase (61.3%) (P = 0.06). Of these newborns, 299 born to seroreactive mothers were examined for T. cruzi infection by microhematocrit at birth (Table 1). Congenital infection, as determined by detecting T. cruzi parasites at birth, was diagnosed in 12 of the 299 newborns (4.0%; 95% CI: 2.1–6.9). The mother-to-child transmission rate of T. cruzi was constant over time, and the incidence rate reached 26/1000 live births for the 40-month period.

During the first phase, 15.3% of the children were lost to follow-up before the age of 1 month by the research team. By contrast, slightly more children (21.4%) were lost before reaching this age in the second phase under the direction of the municipal health service. The difference did not reach statistical significance (P = 0.19). The main causes for loss to follow-up were mothers’ refusal to participate (40%) or move outside the municipality (25%). Of 236 negative newborns at delivery, 6 (2.5%) were found infected at 1 month of age, probably by mother-to-child transmission.

Finally, 28.6% and 43.3% of the children were lost to follow-up at 7 months in the first and second phases, respectively. The difference was statistically significant (P = 0.02). The main causes for loss to follow-up were refusals (40%) and removals (40%). A total of 151 (65%) out of the 230 infants who had been microhematocrit-negative at 1 month of age were examined by serological methods at 7 months of age (Table 1). Six (4.0%) T. cruzi-infected infants were detected at 7 months of age, and these were not considered congenital cases in the probable presence of triatomine infestation in their houses.

Maternal parasitaemia during the third trimester was a risk factor for neonatal infection before 1 month of age: 27.8% (5/18) of infected newborns from parasitaemic women compared to 5.6% (13/230) from non-parasitaemic women (RR 4.9 (2.0–12.2); P = 0.0005). No difference in mother-to-child transmission rate of T. cruzi was observed between home births (9.3%, n = 54) and hospital births (7.1%, n = 98) during the first phase of the study (P = 0.61). All infected babies appeared clinically healthy at birth. During the first phase, the rate of low birthweight (weight <2500 g) was higher for congenitally infected newborns (8.3%) compared to non-infected babies (2.1%), but the difference did not reach statistical significance (P = 0.20).

Over a 40-month period, a total of 24 children infected by T. cruzi were detected and treated. During the first phase, 10 of 12 treated children tolerated the treatment well. Two children experienced mild transient cutaneous maculopapular rash at week 2 of treatment, and one discontinued treatment after 30 days (due to a change in the place of residence). All 8 infants that were controlled 1 year after treatment with benznidazole had negative parasitological and serological tests when examined. The other children (second phase) were followed-up by the municipal health service and no information was available at time of this paper.

Discussion

  1. Top of page
  2. SummaryLe dépistage de porte-à-porte comme stratégie pour la détection de la maladie de Chagas congénitale dans les zones rurales en BolivieCribado puerta a puerta como estrategia para la detección de la enfermedad de Chagas congénita en zonas rurales de Bolivia
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgements
  9. References

It is likely that passive case detection in hospitals, which depends on regular attendance of mothers to health centres, is not the optimal strategy for identifying congenital cases of Chagas disease in rural areas of Bolivia, where most births occur at home. In fact, such a strategy may lead to underestimation of the true incidence of congenital Chagas disease. By contrast, active case detection by using a door-to-door visits can be more efficient, but also more costly, time-consuming, and unethical if investigators use coercion to encourage women to participate. Door-to-door strategies are currently being tested for active case detection of tuberculosis and for HIV screenings in industrialized and emergent countries. These studies are showing good results (Miller et al. 2010; Sena et al. 2010).

In this study, the coverage rate of pregnant women dropped from 96% in the first exploratory phase to 77% in the second operational phase under the direction of the municipal health service. The significant decline in coverage between the two phases may be related to lesser involvement of the research team, greater confidence of the women in a foreign team than in local authorities, and lower motivation of staff members assigned to other routine duties. Despite the decline, the coverage rate has remained higher than the rates found in passive case detection studies of congenital Chagas disease in Paraguay (65%) and Argentina (69%) (Russomando et al. 1998; Blanco et al. 2000).

Adherence to a passive case detection program, for a congenital disease such as Chagas, is closely related to the confidence, understanding and willingness of mothers to participate in the program. In this matter, free health care is probably not the most important parameter to consider in assessing the coverage rate. In Bolivia, a law was promulgated in 2002 establishing free maternal and child health care. Notwithstanding, results from the national screening program for congenital syphilis in Bolivia, based on passive case detection in hospitals, are disappointing; the coverage rate of pregnant women does not exceed 20% (Southwick et al. 2001; Villazon-Vargas et al. 2009). Good quality of care and reception from staff are also likely to encourage women to attend health facilities during their pregnancies. During this study, the hospital birth rate increased from the first phase (53%) to the second phase (61%) (P = 0.06); the rate increase can be due to increased screening activities during prenatal care. However, this difference can also be due to bias because more pregnant women were lost to follow-up during the second phase of the study. Those women who delivered their babies at home might have been even more likely to be lost to follow-up.

Most passive case detection studies on congenital Chagas disease reported high rates of children that were lost to follow-up, from 65–67% at 1 month (Blanco et al. 2000; Salas et al. 2007) to 71–95% after 6 months of age (Blanco et al. 2000; Russomando et al. 2005; Torrico et al. 2007). According to the phases of our study, 15–21% of children were lost to follow-up at 1 month and 29–43% were lost at 7 months of age. A hospital-based active detection case study conducted in Santa Cruz (Bolivia) in 2006–2007 found similar results with 25% of babies lost to follow-up at birth and 42% of children lost at 9 months (Bern et al. 2009). Again, active case detection appeared to have better results than passive case detection. As a whole, only 37% of the children were lost to follow-up in the exploratory phase and 53% in the operational phase; the difference was statistically significant. The difference between the two periods of the study can be related to the slackening of door-to-door activities during the operational phase. These results may question the viability of this screening system once its activities have been transferred to municipal health services. Despite IEC campaigns, refusal to participate in the program and movement outside the study area were the two main reasons that led to the interruption of monitoring of children. It is likely that the refusal from women stemmed from both the fear of diagnosis and fear of causing pain to their child.

In this study, the prevalence rate in 524 pregnant women was 64.5%, one of the highest actually reported in Bolivia. Others studies conducted in this country have estimated seroprevalence among hospitalized pregnant women to be the following: 17% in Cochabamba in 1999–2001, up to 29% in Santa Cruz in 2006–2007, 34% in Bermejo in 2003–2004, and 42% in Yacuiba in 2003–2004 (Torrico et al. 2004; Salas et al. 2007; Brutus et al. 2008; Bern et al. 2009; Chippaux et al. 2009). Mother-to-child transmission rate of T. cruzi was estimated at 4.0% (12/299) at birth. Twelve additional cases of infection (4%) were diagnosed in children between 1 and 7 months of age. Similar rates of vertical transmission of T. cruzi were observed in Paraguay and Argentina: 7.1% of infected children after 6 months of age (Blanco et al. 2000; Russomando et al. 2005). At Yacuiba and Bermejo, our team found a 5% transmission rate in infants from birth (Salas et al. 2007; Brutus et al. 2008). Other teams have found 6.5% at 9 months in Santa Cruz and between 4.9% and 5.9% before 30 days of life in Cochabamba (Torrico et al. 2004; Bern et al. 2009). It is worth mentioning that the prevalence rate among pregnant women and the incidence rate among newborns have not changed from one period to another in this study; this is probably because the population of women was not very biased, despite a lower coverage rate in the operational phase. In fact, pragmatic door-to-door active case detection was very efficient for identifying congenital T. cruzi infections in such a rural setting.

Presence of trypomastigotes of T. cruzi in the maternal bloodstream of seroreactive mothers was estimated at 6.2% at the end of the third trimester and represented a significant risk factor for congenital transmission of T. cruzi (RR 4.9; 95% CI: 2.0–12.2). In a similar study in Yacuiba, our team found that 4.5% of maternal parasitaemia in infected women at delivery was also associated with a comparable risk for mother-to-child transmission (RR 7.3; 95% CI: 4.3–12.2) (Salas et al. 2007). It has been reported elsewhere in Bolivia that parasite loads measured by quantitative PCR were higher in mothers of congenitally infected children than in mothers of non-infected children (Bern et al. 2009). The detection of circulating parasites in a high number of women before delivery suggests that a phenomenon of immunological tolerance reactivates the parasitaemia (Brutus et al. 2010). Indeed, increased maternal parasite loads and defective immunological responses are involved in mother-to-child transmission of T. cruzi (Hermann et al. 2004).

Congenital Chagas disease is mostly asymptomatic (Freilij & Altcheh 1995; Oliveira et al. 2010). Logically, congenitally infected newborns appeared clinically healthy in our study. A greater proportion of low birthweight babies were found among the congenitally infected children than among the non-infected infants, but, due to limited sample size, the difference did not reach statistical significance. A significant relationship between congenital disease and low birth weight was observed by Torrico et al. (2004). Moreover, in highly endemic areas, maternal re-infections could be related to a possible worsening of clinical conditions of congenitally infected newborns (Torrico et al. 2006). The treatment of congenitally infected infants with benznidazole appeared to be well tolerated. We found only two cases of mild allergic reactions among 12 treated babies, and neither stopped his treatment. One in 12 children had their treatment interrupted before the end, indicating an excellent level of coverage rate as has already been reported in similar studies (Blanco et al. 2000). At 1-year follow-up, all of the children treated before the age of 1 month were cured. As mentioned, treatment of congenital Chagas disease is highly effective when initiated soon after birth (Chippaux et al. 2010).

Conclusion

  1. Top of page
  2. SummaryLe dépistage de porte-à-porte comme stratégie pour la détection de la maladie de Chagas congénitale dans les zones rurales en BolivieCribado puerta a puerta como estrategia para la detección de la enfermedad de Chagas congénita en zonas rurales de Bolivia
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgements
  9. References

Nearly 5% (24/468) of all live newborns and almost 8% of those born from seroreactive mothers in this rural area were found to be infected by T. cruzi before reaching their first year of life. A well-organized and widely accepted hospital-based screening program would probably have found half of the infected newborns because the hospital birth rate is less than 44% in rural Bolivia. In reality, the situation could be worse. Elsewhere in Bolivia, the NChCP has found an unexpectedly low transmission rate of 2.5% in operational conditions (Torrico et al. 2007). In Argentina, it has been estimated that there could be six congenital cases for each case reported by the health care system (Gurtler et al. 2003). When it is correctly managed, door-to-door active case detection appears to be a good strategy for searching and treating congenital cases of Chagas disease in rural areas in addition to passive case detection. However, it is probably more costly and time-consuming for the health systems than passive case detection only. By now, it is likely that the majority of cases of congenital Chagas disease are not currently identified by the health systems of endemic countries.

References

  1. Top of page
  2. SummaryLe dépistage de porte-à-porte comme stratégie pour la détection de la maladie de Chagas congénitale dans les zones rurales en BolivieCribado puerta a puerta como estrategia para la detección de la enfermedad de Chagas congénita en zonas rurales de Bolivia
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusion
  8. Acknowledgements
  9. References
  • Bern C, Verastegui M, Gilman RH et al. (2009) Congenital Trypanosoma cruzi transmission in Santa Cruz, Bolivia. Clinical Infectious Diseases 49, 16671674.
  • Blanco SB, Segura EL, Cura EN et al. (2000) Congenital transmission of Trypanosoma cruzi: an operational outline for detecting and treating infected infants in north-western Argentina. Tropical Medicine and International Health 5, 293301.
  • Brutus L, Schneider D, Postigo J, Romero M, Santalla J & Chippaux JP (2008) Congenital Chagas disease: diagnostic and clinical aspects in an area without vectorial transmission, Bermejo, Bolivia. Acta Tropica 106, 195199.
  • Brutus L, Castillo H, Bernal C et al. (2010) Detectable Trypanosoma cruzi parasitemia during pregnancy and delivery as a risk factor for congenital Chagas disease. American Journal of Tropical Medicine and Hygiene 83, 10441047.
  • Carlier Y & Truyens C (2010) Maternal–fetal transmission of Trypanosoma cruzi. In: American Trypanosomiasis – Chagas disease, One Hundred Years of Research. First edition (eds J Telleria & M Tibayrenc) Elsevier, London, pp. 539581.
  • Chippaux JP, Santalla J, Postigo J et al. (2009) Sensitivity and specificity of Chagas Stat-Pak test in Bolivia. Tropical Medicine and International Health 14, 14.
  • Chippaux JP, Clavijo AN, Santalla JA, Postigo JR, Schneider D & Brutus L (2010) Antibody drop in newborns congenitally infected by Trypanosoma cruzi treated with benznidazole. Tropical Medicine and International Health 15, 8793.
  • Coa R & Ochoa L (2008) [Bolivia. National Demographic and Health Survey]. Available at: http://www.measuredhs.com/pubs/pdf/FR228/FR228%5B08Feb2010%5D.pdf. Accessed September 1, 2010.
  • Dias JC (2009) Elimination of Chagas disease transmission: perspectives. Memórias do Instituto Oswaldo Cruz 104(Suppl 1), 4145.
  • Freilij H & Altcheh J (1995) Congenital Chagas disease: diagnostic and clinical aspects. Clinical Infectious Diseases 21, 551555.
  • Freilij H, Muller L & Gonzalez Cappa SM (1983) Direct micromethod for diagnosis of acute and congenital Chagas’ disease. Jounal of Clinical Microbiology 18, 327330.
  • Gurtler RE, Segura EL & Cohen JE (2003) Congenital transmission of Trypanosoma cruzi infection in Argentina. Emerging Infectious Diseases 9, 2932.
  • Hermann E, Truyens C, Alonso-Vega C et al. (2004) Congenital transmission of Trypanosoma cruzi is associated with maternal enhanced parasitemia and decreased production of interferon-gamma in response to parasite antigens. Journal of Infectious Diseases 189, 12741281.
  • Miller AC, Golub JE, Cavalcante SC et al. (2010) Controlled trial of active tuberculosis case finding in a Brazilian favela. International Journal of Tuberculosis and Lung Disease 14, 720726.
  • Oliveira I, Torrico F, Munoz J & Gascon J (2010) Congenital transmission of Chagas disease: a clinical approach. Expert Review of Anti Infective Therapy 8, 945956.
  • Russomando G, de Tomassone MM, de Guillen I et al. (1998) Treatment of congenital Chagas’ disease diagnosed and followed up by the polymerase chain reaction. American Journal of Tropical Medicine and Hygiene 59, 487491.
  • Russomando G, Almiron M, Candia N, Franco L, Sanchez Z & de Guillen I (2005) Implementation and evaluation of a locally sustainable system of prenatal diagnosis to detect cases of congenital Chagas disease in endemic areas of Paraguay. Revista da Sociedade Brasileira de Medicina Tropical 38(Suppl. 2), 4954.
  • Salas NA, Cot M, Schneider D et al. (2007) Risk factors and consequences of congenital Chagas disease in Yacuiba, south Bolivia. Tropical Medicine and International Health 12, 14981505.
  • Schijman AG, Altcheh J, Burgos JM et al. (2003) Aetiological treatment of congenital Chagas’ disease diagnosed and monitored by the polymerase chain reaction. Journal of Antimicrobial Chemotherapy 52, 441449.
  • Sena AC, Hammer JP, Wilson K, Zeveloff A & Gamble J (2010) Feasibility and acceptability of door-to-door rapid HIV testing among latino immigrants and their HIV risk factors in North Carolina. AIDS Patient Care and STDS 24, 165173.
  • Southwick KL, Blanco S, Santander A et al. (2001) Maternal and congenital syphilis in Bolivia, 1996: prevalence and risk factors. Bulletin of the World Health Organization 79, 3342.
  • Torrico F, Alonso-Vega C, Suarez E et al. (2004) Maternal Trypanosoma cruzi infection, pregnancy outcome, morbidity, and mortality of congenitally infected and non-infected newborns in Bolivia. American Journal of Tropical Medicine and Hygiene 70, 201209.
  • Torrico F, Alonso Vega C, Suarez E et al. (2006) Are maternal re-infections with Trypanosoma cruzi associated with higher morbidity and mortality of congenital Chagas disease? Tropical Medicine and International Health 2, 628635.
  • Torrico F, Alonso VegaC, Billot C, Truyens C & Carlier Y (2007) Maternal–fetal relationships in infection with T. cruzi and implementing a national program of detection and treatment of congenital Chagas disease in Bolivia. Enfermedades Emergentes 9(Suppl. 1), 3739.
  • Villazon-Vargas N, Conde-Glez CJ, Juarez-Figueroa L & Uribe-Salas F (2009) Evaluation of a rapid diagnostic test to assess the prevalence of maternal syphilis in Bolivia. Revista Medica de Chile 137, 515521.
  • WHO (2002) Control of Chagas disease. World Health Organ Technical Report Series 905, i–vi, 1109, back cover.