Congenital Transmission of Trypanosoma cruzi in Argentina, Honduras, and Mexico: An Observational Prospective Study

Abstract

Compared with South America, there is a lack of epidemiologic studies about the risk of congenital transmission of in Central America and Mexico. It has been suggested that genotypes might differ by region and that congenital transmission might vary according to the parasite's genotype. Our objective was to compare congenital transmission rates in three countries. We performed an observational prospective study in 2011-2014 enrolling women at delivery in one hospital in Argentina, two hospitals in Honduras, and two hospitals in Mexico. Congenital infection was defined as the presence of one or more of the following criteria: presence of parasites in cord blood (direct parasitological microscopic examination) with positive polymerase chain reaction (PCR) in cord blood, presence of parasites in infant's blood at 4-8 weeks (direct parasitological microscopic examination), and persistence of -specific antibodies at 10 months, as measured by at least two tests. Among 28,145 enrolled women, 347 had at least one antibody rapid test positive in cord blood and a positive enzyme-linked immunosorbent assay in maternal blood. PCR in maternal blood was positive in 73.2% of the cases, and genotyping identified a majority of non-TcI in the three countries. We found no (0.0%; 95% confidence interval [CI]: 0.0, 2.0) confirmed congenital case in Honduras. Congenital transmission was 6.6% (95% CI: 3.1, 12.2) in Argentina and 6.3% (95% CI: 0.8, 20.8) in Mexico. non-TcI predominated and risks of congenital transmission were similar in Argentina and Mexico.

Using prenatal blood samples to validate COVID-19 rapid serologic tests

“…Discrepancies were resolved by an independent blinded trained evaluator. This is similar to the approach we used earlier for Chagas RDTs (Buekens et al, 2013;Buekens et al, 2018).…”

Estimating the current burden of Chagas disease in Mexico: a systematic review of epidemiological surveys from 2006 to 2017

“…Based on current birth rate in Mexico (2,293,000 births in 2016), this would correspond to 22,930 births from T. cruzi infected pregnant women per year. With a congenital transmission rate of 6.3% [21], there may be 1,445 cases of congenitally infected newborns per year in the country.…”

“…Our analysis of data from the last decade thus suggests that the magnitude of T. cruzi infection in Mexico may have been underestimated in these previous reports. In addition, recent studies pointing out a low sensitivity of commercial serological tests for T. cruzi diagnostic [21,31,60], some of which are well used in Mexico (Table 8) also raise concerns that the seroprevalence of T. cruzi infection may even be higher than currently detected. Improvements in serological tests are thus urgently needed for a more reliable disease surveillance [61].…”

Comparison of methodologies for detecting Trypanosoma cruzi parasites by microscopic observation of microhematocrit capillary tubes

“…Method 1 (Rotating). The mHCT is held laterally over one edge of a slide using masking tape previously placed at both ends with a small space between the tape and the carrier, to be able to rotate the tube to get different angles of observation 9,12 in the microscope using the 40× objective (Figure 1, Row A).…”

“…The sensitivity of this method is equivalent to examining parasites after tube dissection 8 . Different studies have shown a lack of sensitivity of the mHCT parasitological detection in congenital infection 13 ; however, the sensitivity of the rotating method increases significantly by using more tubes, and repeating blood examination at different times after birth, since neonatal parasitic loads can increase up to 1 to 3 months after delivery, allowing the correct diagnosis of most cases of congenital infection 9,12 .…”