Rapid Chagas testing reached high accuracy in pregnant women at the point of care
A prospective diagnostic study in Colombia found that four rapid diagnostic tests for Chagas disease performed well when used under point-of-care conditions in pregnant women, a population in which missed diagnosis carries direct consequences for maternal care and for preventing congenital transmission. The work compared each assay with Colombia’s official serological algorithm based on enzyme-linked immunosorbent assay, then modeled how two rapid tests might work together in parallel or serial strategies.
The cohort included 771 pregnant women living in Colombia. Whole blood was used for the rapid tests, while serum supported the reference testing workflow. All participants were enrolled through the country’s maternal health routes, with clinical and laboratory follow-up guaranteed for mothers and newborns. In a disease where delayed serology can leave infection hidden until after pregnancy or childbirth, the practical question is simple: can a fast test used where care is delivered be accurate enough to change who gets identified in time?
The answer from this study was yes, with caveats around implementation and confirmation.
Individual assays showed strong sensitivity and very high specificity
Across the four evaluated tests — STAT PAK, ADBIO, BIOLINE, and WL Check Chagas — point estimates of sensitivity ranged from 88.6% to 97.5%, while specificity ranged from 98.1% to 100%. STAT PAK delivered the best individual performance.
Those figures matter because serologic screening in pregnancy has to do two things at once: catch as many infected women as possible and avoid flooding referral pathways with false positives. In congenital Chagas disease, a missed maternal diagnosis can mean a missed opportunity to evaluate the infant and interrupt preventable transmission through follow-up and treatment pathways. High specificity also matters in resource-limited settings, where confirmatory testing is often slower and harder to access than the first screening step.
One result stands out with immediate clinical relevance: the rapid tests, when used individually, already approached the accuracy needed for front-line screening in a setting where laboratory infrastructure may be uneven.
Modeled test combinations pushed performance higher
The study also examined combined strategies, but these were modeled mathematically from the individual results rather than prospectively implemented as real-time workflows. In parallel use, where rapid tests are applied simultaneously, point estimates of sensitivity ranged from 92.4% to 98.7% and specificity from 97.5% to 99.6%. Serial use, in which one rapid test is followed by a second if the first is positive, yielded point estimates of sensitivity from 86.1% to 96.2% and specificity from 99.7% to 100%.
Parallel testing predictably favored sensitivity. If the biological goal is to minimize missed infection in pregnancy, especially in areas where care may be fragmented or delayed, a parallel strategy can capture more true cases at the cost of a modest decline in specificity. Serial testing moved in the opposite direction, tightening specificity to near-perfect levels while giving up some sensitivity. That tradeoff is clinically familiar in infectious disease diagnostics: a broader net finds more cases, while a second-step confirmation filters out false alarms.
The modeled serial strategies are especially appealing for programs that want a streamlined diagnostic algorithm without sending every positive screen through a complex laboratory chain. Still, the models remain models. They do not replace evidence from a prospectively deployed workflow in routine care.
Why pregnancy is the decisive setting for screening
Chagas disease remains a public health problem in endemic countries across the Americas, and Colombia carries a substantial burden with many municipalities at risk of infection. Pregnancy concentrates the importance of diagnosis because congenital transmission is one of the persistent routes by which Trypanosoma cruzi continues to spread. Once a pregnant woman is diagnosed, the care pathway widens to include maternal management and newborn follow-up, which is where the public health value of screening becomes tangible.
Rapid testing at the point of care can shorten the distance between the patient and the diagnosis. In rural or remote areas, that distance is often the real barrier, not the biology of the assay. A test that performs well in the laboratory but fails in the clinic leaves the transmission chain untouched. A test that can be done where pregnancy care already happens creates a different operational reality: fewer lost results, faster counseling, and earlier infant evaluation.
Simplified confirmation still needs local validation
These findings support the idea that rapid tests can serve as a valuable screening tool for T. cruzi infection in pregnant women, especially when paired with simplified confirmation strategies adapted to local health systems. The strongest signal here is not that one assay should replace every other diagnostic step. It is that selected rapid tests, and some paired strategies, can make screening more reachable in settings where standard laboratory algorithms are difficult to complete quickly.
The study also carries an important implementation message. The combined strategies were derived from the underlying rapid-test results, not from actual prospective use of those combinations in routine care. Before any health system adopts a specific dual-test workflow, local validation should establish how the strategy performs with the operators, devices, and patient flow that exist in practice.
Even so, the data are hard to ignore. In a maternal health setting where delayed diagnosis can leave both mother and infant outside the treatment pathway, a rapid and accurate first-line screen changes the timing of care itself. The remaining challenge is to move from promising diagnostic performance to durable implementation in the places where Chagas disease is still missed most often.