Urban Chagas disease in children and women in primary care centres in Buenos Aires, Argentina

The primary objective of this study was to estimate the prevalence of this disease in women of childbearing age and children treated at health centres in underserviced areas of the city of Buenos Aires. Demographic and Chagas disease status data were collected. Samples for Chagas disease serology were obtained on filter paper and the reactive results were confirmed with conventional samples. A total of 1,786 subjects were screened and 73 positive screening results were obtained: 17 were from children and 56 were from women. The Trypanosoma cruziinfection risk was greater in those individuals who had relatives with Chagas disease, who remember seeing kissing bugs, who were of Bolivian nationality or were born in the Argentine province of Santiago del Estero. The overall prevalence of Chagas disease was 4.08%. Due to migration, Chagas disease is currently predominantly urban. The observed prevalence requires health programme activities that are aimed at urban children and their mothers. Most children were infected congenitally, which reinforces the need for Chagas disease screening of all pregnant women and their babies in Argentina. The active search for new cases is important because the appropriate treatment in children has a high cure rate.

Urban Chagas disease in children and women in primary care centres in Buenos Aires, Argentina.

The primary objective of this study was to estimate the prevalence of this disease in women of childbearing age and children treated at health centres in underserviced areas of the city of Buenos Aires. Demographic and Chagas disease status data were collected. Samples for Chagas disease serology were obtained on filter paper and the reactive results were confirmed with conventional samples. A total of 1,786 subjects were screened and 73 positive screening results were obtained: 17 were from children and 56 were from women. The Trypanosoma cruzi infection risk was greater in those individuals who had relatives with Chagas disease, who remember seeing kissing bugs, who were of Bolivian nationality or were born in the Argentine province of Santiago del Estero. The overall prevalence of Chagas disease was 4.08%. Due to migration, Chagas disease is currently predominantly urban. The observed prevalence requires health programme activities that are aimed at urban children and their mothers. Most children were infected congenitally, which reinforces the need for Chagas disease screening of all pregnant women and their babies in Argentina. The active search for new cases is important because the appropriate treatment in children has a high cure rate.

Aetiological treatment of congenital Chagas' disease diagnosed and monitored by the polymerase chain reaction.

OBJECTIVES: This prospective study focused on the evaluation of anti-parasitic therapy in congenital Chagas' disease, diagnosed and monitored by PCR and conventional diagnosis. MATERIALS AND METHODS: We studied 152 children born to seroreactive mothers, living in a non-endemic area. Fifty infants aged 0-6 months (GA) were diagnosed by microhaematocrit and PCR and 102 children aged 7 months to 17 years (GB) were diagnosed by serology and PCR. Forty treated patients were monitored for 2 or 3 years by PCR and conventional methods. A competitive-quantitative PCR was used to determine pre-therapy parasitic loads and follow their post-treatment evolution. RESULTS: In GA, the sensitivities of the PCR and microhaematocrit were 100% and 82.4% and their specificities 97% and 100%, respectively. In GB, the sensitivity of the PCR was 73.8% with a specificity of 100%. Pre-therapy parasitic loads ranged from 12.5 to 125,000 and 12.5 to 125 parasite genomic equivalents/mL of blood in GA and GB, respectively. PCR turned negative in all treated pre-therapy PCR positive patients before or at the end of treatment, which was followed by their seronegativation in 10/10 GA, in 3/5 children initiating therapy at 7 months to 2 years of age but in 0/16 initiating therapy at an older age. Two out of the latter patients were occasionally PCR positive during post-treatment, suggesting no parasitological response. Out of nine pre-therapy PCR negative patients, four turned seronegative after treatment, suggesting that in undetermined patients, undetectable parasitic burdens may lead to better post-treatment prognosis. CONCLUSIONS: PCR was useful for sensitive diagnosis and therapy monitoring, allowing early detection of refractory cases.

[Seroprevalence of Chagas disease in 17 rural communities of "Monte Impenetrable", Chaco Province]. / Seroprevalencia de la enfermedad de Chagas en 17 parajes del "Monte Impenetrable" de la Provincia del Chaco.

In the month of July 1999 and 2000 we studied the presence of Trypanosoma cruzi antibodies in residents of 17 isolated rural communities of "Monte Impenetrable", in Chaco Province. This area has 3,000 km2 inhabited by about 3,000 person and presents all the conditions for the development of Chagas disease. A total of 344 blood samples were analysed for Chagas disease. All samples, stored with SEROKIT, were tested with indirect hemagglutination test, enzyme-linked immunosorbent assay and particle agglutination test. Samples reactive for two assays were considered positive. Serological evidence of human T. cruzi infection was demonstrated in 183 (53.50%) out of 344 individuals. In the 1-15 years age group the percentage of positivity was 45.83% and in the 1-5 years age group 53.85%. a) General infection prevalence in these rural communities was 7 times higher than the national average estimated rate (7.20%). b) Prevalence in the 1-15 years age group was 25 times higher in relation to that found in residents of rural areas under entomology vigilance (1.77%). c) The prevalence in younger than five years old indicated the absence of vectorial control. The Tobas communities presented higher prevalence than Criollos, although the risk factors to acquire the disease were similar in both populational groups. These findings show the urgency of public health policies and sanitary decisions, specially in these zones of the country.

[Anti-F2/3 antibodies as cure marker in children with congenital Trypanosoma cruzi infection]. / Anticuerpos anti-F2/3 como marcador de curación en niños con infeccion congénita por Trypanosoma cruzi.

The F2/3 antigenic fraction isolated from Trypanosoma cruzi trypomastigotes contains epitopes recognised by antibodies which are representative of active infection. The kinetics of disappearance of conventional serology (CS) and anti-F2/3 antibodies were compared in 21 patients with congenital Chagas disease after receiving benznidazole treatment. Patients were divided into 2 groups: (A) Age < 8 months at diagnosis; (B) Age > 9 months at diagnosis. Group A presented negative outcome for CS at 6.6 mo. (CI95 3.4-9.8 mo.) and for anti-F2/3 at 4 mo. (CI95 0.9-7.1 mo.), p = 0.18. Group B exhibited non-reactive CS at 63.1 mo. (CI95 42.1-84.2 mo.) whereas anti-F2/3 antibody determination became negative at 21.9 mo. (CI95 5.7-38.1 mo.), p = 0.0025. In patients belonging to group A, antibodies were undetectable by both CS and anti-F2/3 ELISA soon after receiving chemotherapy. In infants included into group B, a negative result for anti-F2/3 antibody detection significantly anticipated the disappearance of CS reactivity. Consequently, an anti-F2/3 antibody assay becoming negative should be considered as an early marker for assessment of cure, particularly in those patients with prolonged time of infection.

Anticuerpos anti-F2/3 como marcador de curacion en niños con infeccion congenita por Trypanosoma cruzi / Anti-F2/3 antibodies as cure marker in children with congenital Trypanosoma cruzi infection

The F2/3 antigenic fraction isolated from Trypanosoma cruzi trypomastigotes contains epitopes recognised by antibodies which are representative of active infection. The kinetics of disappearance of conventional serology (CS) and anti-F2/3 antibodies were compared in 21 patients with congenital Chagas disease after receiving benznidazole treatment. Patients were divided into 2 groups: (A) Age < 8 months at diagnosis; (B) Age > 9 months at diagnosis. Group A presented negative outcome for CS at 6.6 mo. (CI95 3.4-9.8 mo.) and for anti-F2/3 at 4 mo. (CI95 0.9-7.1 mo.), p = 0.18. Group B exhibited non-reactive CS at 63.1 mo. (CI95 42.1-84.2 mo.) whereas anti-F2/3 antibody determination became negative at 21.9 mo. (CI95 5.7-38.1 mo.), p = 0.0025. In patients belonging to group A, antibodies were undetectable by both CS and anti-F2/3 ELISA soon after receiving chemotherapy. In infants included into group B, a negative result for anti-F2/3 antibody detection significantly anticipated the disappearance of CS reactivity. Consequently, an anti-F2/3 antibody assay becoming negative should be considered as an early marker for assessment of cure, particularly in those patients with prolonged time of infection

Seroprevalencia de la enfermedad de Chagas en 17 parajes del "Monte Impenetrable" de la Provincia del Chaco / Seroprevalence of Chagas disease in 17 rural communities of \"Monte Impenetrable\", Chaco Province

In the month of July 1999 and 2000 we studied the presence of Trypanosoma cruzi antibodies in residents of 17 isolated rural communities of "Monte Impenetrable", in Chaco Province. This area has 3,000 km2 inhabited by about 3,000 person and presents all the conditions for the development of Chagas disease. A total of 344 blood samples were analysed for Chagas disease. All samples, stored with SEROKIT, were tested with indirect hemagglutination test, enzyme-linked immunosorbent assay and particle agglutination test. Samples reactive for two assays were considered positive. Serological evidence of human T. cruzi infection was demonstrated in 183 (53.50%) out of 344 individuals. In the 1-15 years age group the percentage of positivity was 45.83% and in the 1-5 years age group 53.85%. a) General infection prevalence in these rural communities was 7 times higher than the national average estimated rate (7.20%). b) Prevalence in the 1-15 years age group was 25 times higher in relation to that found in residents of rural areas under entomology vigilance (1.77%). c) The prevalence in younger than five years old indicated the absence of vectorial control. The Tobas communities presented higher prevalence than Criollos, although the risk factors to acquire the disease were similar in both populational groups. These findings show the urgency of public health policies and sanitary decisions, specially in these zones of the country