Low prevalence of Schistosoma haematobium infection in pregnant women in Buffalo City district

Abstract

Adverse pregnancy outcomes such as stillbirth, pre-term birth and low birth weight are common in South Africa. The aetiology of these conditions is multifactorial and infections play an important role. Studies have shown an increased risk of adverse pregnancy outcomes associated with sexually transmitted infection (STI) during pregnancy. 1 Urogenital Schistosoma haematobium is another infection that should be considered for adverse pregnancy outcomes. 2 Schistosomiasis, also known as bilharzia, is a parasitic infection acquired through contact with contaminated surface water. Adult worms mainly live in the venous plexus surrounding the bladder and genital tissue, depositing eggs in the urogenital tract. Female genital schistosomiasis may present as genital burning, vaginal discharge and pain and has an increased risk of HIV infection. 3 In pregnancy, schistosomiasis has been associated with anaemia, miscarriage, stillbirth, pre-term delivery and low birth weight, although infection intensity may play a role. 4,5,6 Schistosomiasis prevalence studies are generally conducted in schoolchildren in whom haematuria is an important manifestation. In contrast, there is a paucity of epidemiological data of schistosomiasis in pregnant women despite the health implications for mother and foetus. 2 We conducted a prevalence study of S. haematobium infection in pregnant women in the Buffalo City Metropolitan (BCM) health district, Eastern Cape province, South Africa. Adult women (≥ 18 years) were enrolled within an ongoing implementation-effectiveness trial of the effects of STI screening on pregnancy outcomes at four healthcare facilities between March 2021 and October 2022. 7 These facilities represent good geographic coverage of the BCM district. In brief, women were recruited and consented at their first antenatal care visit. Study activities included: administering of a questionnaire, a physical examination, and on-site STI testing. Midstream urine specimens were collected for urinalysis using dipstick (LifeSADX, Houston, United States) and shipped to the Department of Medical Microbiology at the University of Pretoria for microscopy. After centrifugation (3000 g; 5 min) of the urine sample, S. haematobium eggs were quantified using light microscopy (40x); observation of ≥ 1 egg was classified a positive read. The slide microscopy method has suboptimal sensitivity when compared with antigen and molecular detection; however, those tests were not available to the team. Microscopy was performed of urine samples from 966 pregnant women. Median age was 28 years (range: 18-44 years), median gestational age at enrolment was 13.7 weeks (range: 2.4 to 26.8 weeks) and 287 women (29.7%) were living with HIV. Water contact with a stream, river or lake was reported by 104 participants (11%): frequent crossings by 75 (7.8%), doing laundry 18 (1.9%), collecting water 8 (9.8%), bathing 5 (0.5%) and fishing 1 (0.1%). Urine dipstick was positive for erythrocytes in 23 women (2.4%); these were diagnosed with urinary tract infection with or without STIs. Microscopy was positive for S. haematobium (Figure 1) in only one urine specimen (0.1%; 95% confidence interval: 0.0%-0.3%). This pregnant woman (7 weeks; 0 days) was living in an informal settlement, used a community tap for drinking water and reported frequent water crossing. She did not report travelling to other districts in recent years. No symptoms were reported, she tested negative for HIV, and the urine dipstick result was normal. The participant was treated with Low prevalence of Schistosoma haematobium infection in pregnant women in Buffalo City district Read online: Scan this QR code with your smart phone or mobile device to read online.