Abstract
A total of 179 individuals with acute Chagas disease mainly transmitted by oral source, from Pará and Amapá State, Amazonian, Brazil were included during the period from 1988 to 2005. Blood samples were used to survey peripheral blood for T. cruzi hemoparasites by quantitative buffy coat (QBC), indirect xenodiagnosis, blood culture and serology to detection of total IgM and anti-T. cruzi IgG antibodies by indirect immunofluorescence assay (IFA) and indirect hemagglutination assay (HA). All assays were performed pre-treatment (0 days) and repeated 35 (±7) and 68 (±6) days after the initiation of treatment with benznidazol and every 6 months while remained seropositive. The endpoint of collection was performed in 2005. Total medium period of follow-up per person was 5.6 years. Also, a blood sample was collected from 72 randomly chosen treated patients to perform polimerase chain reaction (PCR) method. Proportions of subjects with negative or positive serology according to the number of years after treatment were compared. In the endpoint of follow-up we found 47 patients (26.7%) serologically negative, therefore considered cured and 5 (2.7%) exhibited mild cardiac Chagas disease. Other 132 patients had persistent positive serologic tests. The PCR carried out in 72 individuals was positive in 9.8%. Added, there was evidence of therapeutic failure immediately following treatment, as demonstrated by xenodiagnosis and blood culture methods in 2.3% and 3.5% of cases, respectively. There was a strong evidence of antibody clearing in the fourth year after treatment and continuous decrease of antibody titers. Authors suggest that control programs should apply operational researches with new drug interventions four years after the acute phase for those treated patients with persistently positive serology.
Highlights
During the acute phase of Chagas disease, most patients have a benign prognosis, and the nearly complete remission of symptoms is commonly described to occur between 60 and 90 days, with or without drug intervention
Blood samples were used to survey peripheral T. cruzi hemoparasites by quantitative buffy coat (QBC), for blood smear, for indirect xenodiagnosis, for blood culture and for serology for the detection of total IgM and anti-T. cruzi IgG antibodies by indirect immunofluorescence assay and indirect hemagglutination assay (IHA)
We studied 179 patients between 2 and 72 years of age that had been diagnosed with acute Chagas disease between 1988 and 2005
Summary
During the acute phase of Chagas disease, most patients have a benign prognosis, and the nearly complete remission of symptoms is commonly described to occur between 60 and 90 days, with or without drug intervention At this stage, specific antibodies help drive the disappearance of parasites from peripheral blood, likely establishing a host-parasite balance. After the establishment of this dynamic equilibrium between the parasite and the host’s immune system, three types of disease progression can ensue: development of chronic disease, with detectable lesions in the heart, esophagus and intestines; persistence of anti-parasite antibodies throughout all life of the affected individual combined with incipient cardiac lesions [3]; or, in the indeterminate clinical form, no evidence of established disease with positive serology Among these possible outcomes, the most serious form of the disease is that which affects heart and digestive tract. It is characterized by low or under levels of parasitemia, persistent levels of anti-Trypanosoma cruzi antibodies and serious clinical manifestations in conformity with the location and the extent of injuries that invariably occur decades after initial infection [2]
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