Clinical Follow-Up of Responses to Treatment with Benznidazol in Amazon: A Cohort Study of Acute Chagas Disease

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.

Follow-up of an Asymptomatic Chagas Disease Population of Children after Treatment with Nifurtimox (Lampit) in a Sylvatic Endemic Transmission Area of Colombia

“…In contrast, these tests are most recommended for use in the acute phase of the disease due to the high parasitemia [33]. In this study, blood cultures showed a very low sensitivity in patients with a latent asymptomatic phase.…”

2 nd Brazilian Consensus on Chagas Disease, 2015

“…A serologic response to treatment was found in 26.3% of patients, most evident four years after treatment; 2.7% developed a chronic mild-tomoderate cardiomyopathy; and 73.7% had persistently reactive serology, although with a significant decrease in the levels of antibodies (156) .…”

“…The World Health Organization (WHO) estimates that approximately 6-7 million people are infected worldwide, mostly in Latin America (14) .Recent estimates for the 21 Latin American countries, based on data from 2010, showed that 5,742,167 people were infected by Trypanosoma cruzi, of which 3,581,423 (62.4%) were living in the countries of the Southern Cone Initiative against Chagas disease, especially Argentina (1,505,235), Brazil (1,156,821), Mexico (876,458), and Bolivia (607,186) (5) . However, these data differ from the estimates of other research groups using other methods to define T. cruzi infection in many countries; this hinders accurate establishment of the prevalence of Chagas disease in the Americas.…”

Trypanosoma cruzi strain TcI is associated with chronic Chagas disease in the Brazilian Amazon

“…Gaining knowledge about the biological properties of the TcI lineage, which certainly plays an important role in the CD pathogenesis and response to the specific chemotherapy in the Amazon region, represents a challenge for future research [39-41]. …”