Laboratory and field validation of the recombinase polymerase amplification assay targeting the Schistosoma mansoni mitochondrial minisatellite region (SmMIT-RPA) for snail xenomonitoring for schistosomiasis

Detecting Schistosoma infections in endemic countries: a diagnostic accuracy study in rural Madagascar

BACKGROUND

Schistosoma haematobium and S. mansoni are endemic in Madagascar, but reliable diagnostic tools are often lacking, contributing to exacerbate transmission and morbidity. This study evaluated the diagnostic accuracy of three tests for schistosome infection in Malagasy adults from areas of medium to high endemicity.

METHODS

This cross-sectional study enrolled adults from three primary health care centres in Madagascar. Urine and blood samples were tested for schistosome infection using polymerase chain reaction (PCR), up-converting reporter particle lateral flow for the circulating anodic antigen (UCP-LF CAA), and point-of-care circulating cathodic antigen (POC-CCA) tests. Bayesian latent class models were used to assess diagnostic accuracies and disease prevalence.

RESULTS

Of 1339 participants, 461 were from S. haematobium and 878 from S. mansoni endemic areas. Test detection rates were 52% (POC-CCA), 60% (UCP-LF CAA), and 66% (PCR) in the S. haematobium area, and 54%, 55%, and 59% respectively in the S. mansoni area. For S. haematobium, PCR and UCP-LF CAA showed high sensitivity (Se, median 95.2% and 87.8%) but moderate specificity (Sp, 60.3% and 66.2%), while POC-CCA performed moderately (Se: 64.5%; Sp: 59.6%). For S. mansoni, PCR and POC-CCA demonstrated high diagnostic accuracy (Se > 90%, Sp > 80%), while UCP-LF CAA showed good sensitivity (79.9%) but moderate specificity (69.7%).

CONCLUSIONS

While population-level prevalence estimates were similar across tests, individual-level agreement was only low to moderate. Our findings suggest that optimal diagnostic strategies should be tailored to specific endemic settings, continued development of accurate diagnostics suitable for highly endemic settings remains a priority.

A RAPID DIAGNOSTIC PCR ASSAY FOR THE DETECTION OF SCHISTOSOMA MANSONI IN THEIR SNAIL VECTORS

Accurate detection of schistosome infections in snails is vital for epidemiologic and laboratory studies. Traditional microscopy methods to detect schistosomes in snails are hindered by long prepatent periods and snail survivorship, leading to inaccurate assessment of infections. A rapid, multiplexed PCR assay targeting Biomphalaria sudanica or Biomphalaria glabrata (internal control) and Schistosoma mansoni DNA is described. The method takes less than 90 min starting from extracted snail DNA and is successful at amplifying schistosome DNA in snail tissue as soon as 30 min following exposure. Accurate measures of schistosome infection success in snails (compatibility) are possible by 4-7 days postexposure.

A Recent Advance in the Diagnosis, Treatment, and Vaccine Development for Human Schistosomiasis

Schistosomiasis, which affects a large number of people worldwide, is among the most overlooked parasitic diseases. The disease is mainly prevalent in sub-Saharan Africa, southeast Asian countries, and South America due to the lack of adequate sanitation. The disease is mainly associated with poor hygiene, sanitation, and contaminated water, so it is also known as a disease of poverty. Three Schistosoma species (S. mansoni, S. japonicum, and S. haematobium) cause significant human infections. Co-infections with Schistosoma and other parasites are widely common. All these parasites may cause intestinal or urogenital schistosomiasis, where the disease may be categorized into the acute, sensitized, and chronic phases. The disease is more prevalent among school children, which may cause anemia and reduce development. Chronic infections frequently cause significant liver, intestinal, and bladder damage. Women exposed to contaminated water while performing normal duties like washing clothes might acquire urogenital schistosomiasis (UGS), which can cause tissue damage and raise the risk of blood-borne disease transmission, including human immunodeficiency virus (HIV) transmission. Praziquantel (PZQ) is the World Health Organization (WHO)-prescribed treatment for individuals who are known to be infected, but it does not prevent further re-infections with larval worms. Vaccine development and new molecular-based diagnosis techniques have promised to be a reliable approach to the diagnosis and prevention of schistosomiasis. The current review emphasizes the recent advancement in the diagnosis of schistosomiasis by molecular techniques and the treatment of schistosomiasis by combined and alternative regimes of drugs. Moreover, this review has also focused on the recent outbreak of schistosomiasis, the development of vaccines, and their clinical trials.