Encyclopedia (Apr 2022)
Clinical Applications of Isothermal Diagnosis for Human Schistosomiasis
Abstract
About 250 million people affected, 779 million people at risk of infection, and 440 million people with residual morbidity are globally attributable to schistosomiasis. Highly sensitive and specific, simple, and fast to perform diagnostics are required for detecting trace infections, and applications in resource-poor settings and large-scale assessments. Research assessing isothermal diagnoses of S. japonicum, S. haematobium, S. mansoni, mixed infections, and schistosomal hybrids among clinical human specimens was investigated. Loop-mediated isothermal amplification (LAMP), recombinase polymerase amplification (RPA) and combined techniques were identified. Both LAMP and RPA reached species-dependent 100% sensitivity, and detection levels within femtogram and nanogram amounts for pure and hybridale breeds. Cross-reactivity among Schistosoma species and co-endemic pathogens was rare, though research on diagnostic markers and primer optimization should continue. Operating with ready-to-use lyophilized reagents, simplified and inexpensive nucleic acid extraction, tolerability to likely inhibitors, and enzyme stability at ambient temperature is advantageous. RPA performed optimal at 35–39 °C within 5–10 min. while LAMP operated at 61–65 °C for up to 120 min.; properties are preferable over assays requiring expensive laboratory equipment. DNA degradation could be prevented by stabilizing substances. A limitation throughout warranting future research is the small sample size reaching a few hundred participants at the maximum. Isothermal diagnostics are highly valuable in detecting trace infections seen subsequent to chemotherapeutic treatment, and among apparently healthy individuals, both constituting likely sources of ongoing pathogen transmission. Its expansion to the vaccine field for assessing parasitological trial endpoints could be considered.
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