Challenging diagnosis of parasitic infection and practical guidance to clinical microbiology laboratories in Korea

Abstract

Parasitic diseases affect over three billion people worldwide and contribute significantly to morbidityand mortality, as reported by the World Health Organization [1]. The landscape of parasitic infections inKorea has undergone a dramatic transformation in recent decades [2]. National surveys show a declinein intestinal parasite prevalence from an alarmingly high 84.3% in the 1970s to just 2.6% by 2012 [2]. Currently, stool ova examination remains the primary diagnostic method of detecting intestinal parasites indomestic clinical laboratories. However, as the prevalence of these infections has become less common, thesensitivity of this diagnostic method has declined. This underscores the critical role of qualified specialistsin accurately diagnosing parasitic diseases. A review article by Sohn et al. [3] offers a comprehensive guideto stool examination techniques and the identification of helminth eggs, providing valuable insights for bothlaboratory and field settings. Since the last national survey in 2012, nationwide epidemiological data onintestinal parasites in Korea have been lacking. Shin et al. [4] addressed this gap by analyzing 10-year datafrom 1,211,799 individuals who visited the regional branches of the Korea Association of Health Promotionbetween 2011 and 2020. Their findings indicated that intestinal helminth infections remained above 2.0%from 2011 to 2014 and decreased to 1.0% by 2020. Notably, fish-borne trematodes, particularly Clonorchissinensis (1.3%) and Metagonimus yokogawai (0.3%), emerged as the primary causes of parasitic intestinalinfections in Korea. Anisakidosis, another fish-borne parasitic infection, is relatively common in Korea due tothe cultural preference for eating raw or undercooked marine fish or cephalopods. Chai et al. [5] extensivelyreviewed the Korean literature on human and animal anisakidosis, detailing the prevalence of anisakidlarvae in fish and cephalopods, larval morphology, molecular analyses, and resistance to physicochemicalagents. This review is particularly relevant for laboratory physicians and clinicians, providing essentialinformation for the accurate diagnosis and effective treatment of anisakidosis. This issue of the Annalsof Clinical Microbiology also explores the advancements and challenges in molecular and serologicaldiagnostics of parasitic diseases [6,7]. Serodiagnosis, commonly employed to detect infections caused bytissue-invading parasites, cannot distinguish between past and current infections and may be prone to cross-reactivity, necessitating careful interpretation. Molecular diagnostic kits have gained popularity but are onlyavailable for certain parasites, such as Giardia lamblia, Entamoeba histolytica, Cryptosporidium hominis,Cryptosporidium parvum, Trichomonas, and Plasmodium. Well-validated molecular assays are essential forbroad application in clinical practice.