Real-time polymerase chain reaction for detection of Schistosoma DNA in small-volume urine samples reflects focal distribution of urogenital Schistosomiasis in primary school girls in KwaZulu Natal, South Africa

Abstract

Schistosoma haematobium eggs and Schistosoma DNA levels were measured in urine samples from 708 girls recruited from 18 randomly sampled primary schools in South Africa. Microscopic analysis of two 10-mL urine subsamples collected on three consecutive days confirmed high day-to-day variation; 103 (14.5%) girls had positive results at all six examinations, and at least one positive sample was seen in 225 (31.8%) girls. Schistosoma-specific DNA, which was measured in a 200-μL urine subsample by using real-time polymerase chain reaction, was detected in 180 (25.4%) cases, and levels of DNA corresponded significantly with average urine egg excretion. In concordance with microscopic results, polymerase chain reaction results were significantly associated with history of gynecologic symptoms and confirmed highly focal distribution of urogenital schistosomiasis. Parasite-specific DNA detection has a sensitivity comparable to single urine microscopy and could be used as a standardized high-throughput procedure to assess distribution of urogenital schistosomiasis in relatively large study populations by using small sample volumes.

Figures

Figure 1.

Flow chart of study participation and adherence by 708 school girls in KwaZulu Natal, South Africa. PCR = polymerase chain reaction.

Figure 2.

Scatter plots of 708 school girls 10–12 years of age in KwaZulu-Natal, South Africa. (A) Comparison of urine microscopy of the first 10-mL sample of day 1 (sample 1A) and the first 10-mL sample of day 3 (sample 3A). (B) Comparison of urine microscopy of the first 10-mL sample of day 1 (sample 1A) and urine Schistosoma DNA loads determined in the same day sample (200 μL) by using real-time polymerase chain reaction (PCR).

Figure 3.

Scatter plot comparing school-based prevalence of Schistosoma DNA in urine samples and reported history of genital symptoms in school girls in KwaZulu Natal, South Africa. Schools (n = 13) with at least 20 participants were included, which included 666 school girls of 10–12 years of age. PCR = polymerase chain reaction.