Trichomonas vaginalis infections are rare in the young STI population in Sweden
Helena Pellrud1, Daniel Golparian2, Christian Steczkó Nilsson1, My Falk1, Hans Fredlund2 and Magnus Unemo2
1STD Clinic, Department of Dermatovenereology, Örebro University Hospital, Örebro, and 2WHO Collaborating Centre for Gonorrhoea and other Sexually Transmitted Infections, Swedish Reference Laboratory for Pathogenic Neisseria, Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden.
Trichomonas vaginalis infections represent the most common curable non-viral sexually transmitted infections (STIs) worldwide. Despite the high prevalence of infections, T. vaginalis has historically been underemphasized in STI control efforts. Trichomoniasis may cause vulvar irritation with malodorous discharge, dysuria and pelvic pain in women, and urethral discharge, dysuria and testicular pain in men. However, the infection may be asymptomatic in 50% of infected women and 70-80% in men. For diagnosis of trichomoniasis, microscopic examination of a wet mount preparation of vaginal secretions is the most frequently used method. This is a rapid and simple point-of-care test. If performed by an experienced microscopist, the specificity of wet mount microscopy can be high, however, the sensitivity is suboptimal, i.e. ranging from about 44% to 68% in women and even lower in men in comparison with highly sensitive and specific nucleic acid amplification tests (NAATs). The aim of this study was to investigate the prevalence of T. vaginalis infections among patients attending an STI clinic in Sweden using the APTIMA Trichomonas vaginalis assay. During the study period, urine specimens from 501 males and 460 females, and vaginal swabs from additional 160 females were collected. Only one specimen positive in the APTIMA T. vaginalis assay was identified and the prevalence of T. vaginalis infection was accordingly 0.09% in this STI population in Sweden. T. vaginalis infections have previously been associated with higher age of females as well as with ethnicity, i.e. black race. In the present study, only 9% of the females were more than 40 years of age and ethnicity was not adequately recorded. The limitations of this study were the low number of women ≥40 years and the lack of appropriate recording of ethnicity. Additional studies are crucial to provide evidence-based data regarding the prevalence of T. vaginalis infections in Sweden as well as in additional countries.