How to Improve the Early Diagnosis of Trypanosoma cruzi Infection: Relationship between Validated Conventional Diagnosis and Quantitative DNA Amplification in Congenitally Infected Children

Abstract

BackgroundAccording to the Chagas congenital transmission guides, the diagnosis of infants, born to Trypanosoma cruzi infected mothers, relies on the detection of parasites by INP micromethod, and/or the persistence of T. cruzi specific antibody titers at 10–12 months of age.Methodology and Principal FindingsParasitemia levels were quantified by PCR in T. cruzi-infected children, grouped according to the results of one-year follow-up diagnosis: A) Neonates that were diagnosed in the first month after delivery by microscopic blood examination (INP micromethod) (n = 19) had a median parasitemia of 1,700 Pe/mL (equivalent amounts of parasite DNA per mL); B) Infants that required a second parasitological diagnosis at six months of age (n = 10) showed a median parasitemia of around 20 Pe/mL and 500 Pe/mL at 1 and 6 months old, respectively, and C) babies with undetectable parasitemia by three blood microscopic observations but diagnosed by specific anti - T. cruzi serology at around 1 year old, (n = 22), exhibited a parasitemia of around 5 Pe/mL, 800 Pe/mL and 20 Pe/mL 1, 6 and 12 month after delivery, respectively. T. cruzi parasites were isolated by hemoculture from 19 congenitally infected children, 18 of which were genotypified as DTU TcV, (former lineage TcIId) and only one as TcI.SignificanceThis report is the first to quantify parasitemia levels in more than 50 children congenitally infected with T. cruzi, at three different diagnostic controls during one-year follow-up after delivery. Our results show that the parasite burden in some children (22 out of 51) is below the detection limit of the INP micromethod. As the current trypanocidal treatment proved to be very effective to cure T. cruzi - infected children, more sensitive parasitological methods should be developed to assure an early T. cruzi congenital diagnosis.

Toward Improving Early Diagnosis of Congenital Chagas Disease in an Endemic Setting

“…The most sensitive technique was qPCR, which has emerged as a promising diagnostic test, particularly for infections with parasite burdens below the detection limit of microscopy [25]. Nevertheless, multiple infant specimens were still needed to achieve optimal detection.…”

Congenital Chagas disease as an ecological model of interactions between Trypanosoma cruzi parasites, pregnant women, placenta and fetuses

“…The DTU TcV has been reported in 80-100% of congenital cases in Argentina, Bolivia, Southern Brazil, Chile, and Paraguay (Virreira et al, 2006a(Virreira et al, , 2007Burgos et al, 2007;Corrales et al, 2009;Diez et al, 2010;Bisio et al, 2011;Ortiz et al, 2012;Bua et al, 2013;Garcia et al, 2014;Llewellyn et al, 2015). DTUs TcII and TcVI have been reported in neonates from Argentina, Bolivia, Brazil (Bahia state) and Chile (Virreira et al, 2006a;Burgos et al, 2007;Ortiz et al, 2012;Garcia et al, 2014), whereas TcIII has been identified in Paraguay (del Puerto et al, 2010) and TcI in some neonates from Argentina, Chile and Colombia (Pavia et al, 2009;Ortiz et al, 2012;Bua et al, 2013).…”

Serum Cytokines as Biomarkers of Early Trypanosoma cruzi infection by Congenital Exposure

“…In the face of new negative findings in parasite detection, a third control visit is pursued around 10 mo after delivery for detection of parasitespecific Abs through serological assays, which will confirm the positive or negative diagnosis for T. cruzi infection. Nowadays, this is changing due to the development of new tools that allow the confirmation of T. cruzi infection (7)(8)(9)(10).…”

“…Although the production of proinflammatory cytokines like IL-1b, IL-6, and TNF-a in response to T. cruzi Ags and the spontaneous release of TNF-a in uninfected infants born to T. cruzi-infected mothers (B 2 M + ) have been described, the levels of these cytokines in congenitally infected newborns are rather low (11,(13)(14)(15)(16), suggesting that the immune response might be an important factor in vertical transmission (17). By using a quantitative PCR (qPCR), we have previously demonstrated that the parasitemia of congenitally infected infants is highly variable at birth (7,18), and this fact posed the question whether T. cruzi-infected children also exhibit variable levels of chemokines and cytokines that might correlate with parasite burden and predict congenital infection. In this context, our study aimed to evaluate the chemokine and cytokine profiles in groups of congenitally infected and uninfected infants born to T. cruzi- Received for publication December 1, 2015.…”