Comparing Cotton Swabs and Cytobrushes for PCR Detection of Female Genital Schistosomiasis

Schistosomiasis is a neglected tropical disease caused by parasitic worms called schistosomes. Schistosoma haematobium worms can cause female genital schistosomiasis (FGS) when their eggs lodge in the female reproductive tract. FGS can lead to gynecological complications, but is poorly diagnosed. A recent study from Senegal aimed to evaluate real-time PCR for detecting S. haematobium DNA in the cervix using two sampling tools - swabs and cytobrushes.

What was the S. haematobium prevalence in the study area?

The study was conducted in northern Senegal where schistosomiasis prevalence is very high, around 79% in adults. Overall 30% of 189 women screened were positive for S. haematobium DNA in cervical samples. Women aged 25-54 years showed the highest prevalence. This indicates significant genital involvement in women living in schistosomiasis endemic areas.

How did the two sampling methods compare?

Cytobrush sampling identified more PCR-positive cases than cotton swabs - 30% versus 17% positive. Among 89 women sampled by both methods, 27 were positive by cytobrush PCR while only 4 were positive by swab PCR. The mean PCR cycle threshold values were similar between cytobrush (31.0) and swab (30.0) samples. There was only slight agreement between the two sampling techniques based on kappa analysis.

What can we conclude about PCR and sampling for FGS?

This study demonstrates that real-time PCR of cervical samples can successfully detect S. haematobium DNA, indicating utility for FGS diagnosis. Cytobrush sampling appears more effective than swabs for collecting cervical samples for PCR analysis. The widely used cytobrush could facilitate integration of FGS evaluation into routine cervical cancer screening programs. Further research is still needed to optimize PCR and sampling methodology for FGS.

This study provides evidence that cervical sampling coupled with real-time PCR can identify genital schistosomiasis in women living in endemic areas. Cytobrush may be the better sampling tool for PCR-based testing. Improving FGS diagnosis is an important step towards tackling this overlooked gynecological disease.

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References

Sow D, Ndiour CN, Thiam O, Ndiaye M, Diagne PN, Doucouré S, Senghor B, Gaye O, Sokhna C, Faye B. Cytobrush and cotton swab as sampling tools for molecular diagnosis of female genital schistosomiasis in the uterine cervix. Curr Res Parasitol Vector Borne Dis. 2023 Oct 1;4:100143. doi: 10.1016/j.crpvbd.2023.100143. PMCID: PMC10570942.