Comparison of novel and standard diagnostic tools for the detection of Schistosoma mekongi infection in Lao People’s Democratic Republic and Cambodia

Abstract

BackgroundGiven the restricted distribution of Schistosoma mekongi in one province in Lao People’s Democratic Republic (Lao PDR) and two provinces in Cambodia, together with progress of the national control programmes aimed at reducing morbidity and infection prevalence, the elimination of schistosomiasis mekongi seems feasible. However, sensitive diagnostic tools will be required to determine whether elimination has been achieved. We compared several standard and novel diagnostic tools in S. mekongi-endemic areas.MethodsThe prevalence and infection intensity of S. mekongi were evaluated in 377 study participants from four villages in the endemic areas in Lao PDR and Cambodia using Kato-Katz stool examination, antibody detection based on an enzyme-linked immunosorbent assay (ELISA) and schistosome circulating antigen detection by lateral-flow tests. Two highly sensitive test systems for the detection of cathodic and anodic circulating antigens (CCA, CAA) in urine and serum were utilized.ResultsStool microscopy revealed an overall prevalence of S. mekongi of 6.4% (one case in Cambodia and 23 cases in Lao PDR), while that of Opisthorchis viverrini, hookworm, Trichuris trichiura, Ascaris lumbricoides and Taenia spp. were 50.4%, 28.1%, 3.5%, 0.3% and 1.9%, respectively. In the urine samples, the tests for CCA and CAA detected S. mekongi infections in 21.0% and 38.7% of the study participants, respectively. In the serum samples, the CAA assay revealed a prevalence of 32.4%, while a combination of the CAA assay in serum and in urine revealed a prevalence of 43.2%. There was a difference between the two study locations with a higher prevalence reached in the samples from Lao PDR.ConclusionsThe CCA, CAA and ELISA results showed substantially higher prevalence estimates for S. mekongi compared to Kato-Katz thick smears. Active schistosomiasis mekongi in Lao PDR and Cambodia might thus have been considerably underestimated previously. Hence, sustained control efforts are still needed to break transmission of S. mekongi. The pivotal role of highly sensitive diagnostic assays in areas targeting elimination cannot be overemphasised.Electronic supplementary materialThe online version of this article (doi:10.1186/s40249-017-0335-x) contains supplementary material, which is available to authorized users.

Retracted: Urinary circulating DNA and circulating antigen for diagnosis of schistosomiasis mansoni: a field study

“…These false positive results encountered in POC-CCA are considered usual because CCA has common epitopes with certain human compounds known as (Lewis X) structures [33]. Here, it is worth mentioning that the lower specificity of POC-CCA (19.18%) as detected in our study and confirmed in other several studies as fore-mentioned, will not prevent its application in surveys for the following reasons: First, people are more compliant to offer a urine sample rather than stool or blood [34]. Second, while Schistosoma eggs continue to be released in stool for few weeks after treatment (viable eggs 2-3 weeks and dead eggs 4-6 weeks), CCA is lowered quickly within one week after treatment; hence, it is a therapeutic monitor [31,35].…”

Survey and Diagnostic Challenges after Transmission-Stop: Confirming Elimination of Schistosomiasis haematobium in Morocco

“…e status of schistosomiasis in areas that have reached low-transmission was reviewed not long ago [6] and recommendations offered regarding tools and strategies for monitoring, criteria to determine interruption of transmission and validation of elimination. However, these recommendations do not (yet) include the implementation of the newly developed ultrasensitive diagnostic tools [7,8] that allow highly accurate determination of the infection status [9][10][11][12][13][14][15]. It is believed that transmission-stop has been achieved in 19 countries, and currently some already await confirmation of successful steep towards elimination.…”

Poly(amidoamine)-coated magnetic particles for enhanced detection ofSchistosomacirculating anodic antigen in endemic urine samples

“…21 This ultrasensitive method has been successfully applied to 2 ml endemic urine samples from highand low-transmission areas, indicating prevalences much higher than those measured by microscopy. [21][22][23][24] Additionally, the ultrasensitive UCP-LF CAA assay has demonstrated promise for sample pooling strategies that would allow for large-scale testing, enabling precision mapping for targeted interventions while decreasing overall assay cost. 25 In the shift from morbidity control to elimination, detection of low-burden Schistosoma infections at the point of care will become increasingly important.…”