Molecular identification of Giardia duodenalis and Cryptosporidium species in newly arrived migrants and asylum seekers in Greece: Implications for public health

Giardia duodenalis and Cryptosporidium species are important intestinal protozoa. Zoonotic species and assemblages of both have been reported in Greece, although recent demographic and environmental changes may influence their epidemiology. This cross-sectional study aimed to investigate the potential health risks associated with Giardia and Cryptosporidium infections among newly arrived migrants and asylum seekers residing in Reception and Identification Centres (RICs) in Greece. Over a two-year period, 178 faecal samples were collected from individuals at more than 20 RICs across Greece. Samples were examined molecularly for detection and genetic characterization of G. duodenalis and Cryptosporidium spp., targeting the βeta-giardin and 18S ribosomal DNA genes, respectively. Of the samples analyzed, 39 (21.9%) tested positive for G. duodenalis and one for Cryptosporidium . Giardia positive isolates belonged to assemblages A (AI and AII) and B, both predominantly human-related lineages. Genotyping of the single Cryptosporidium positive sample was unsuccessful. These findings highlight a high prevalence of G. duodenalis among newly arrived migrants and asylum seekers in Greece and indicate the need for ongoing surveillance. Implementing targeted health education, routine screening, and enhanced sanitation in RICs is crucial to limit transmission among vulnerable populations. • 21.9% prevalence of Giardia in immigrants. • Cryptosporidium detected only in one sample. • Predominant Giardia assemblages A and B indicate anthroponotic transmission. • Epidemiological patterns highlight public health risks in immigrant populations.