From rare to recognized: enhanced detection uncovers Cryptosporidium endemicity and species diversity in Denmark

Human cryptosporidiosis, a diarrheal disease caused by Cryptosporidium species, has previously been considered rare in Denmark and primarily associated with travel abroad. Cryptosporidium in humans came under national surveillance in 2023. Here, we assess all cases identified in Denmark from 2010 to...

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Main Authors: Tine Graakjær Larsen, Steen Ethelberg, Hans Linde Nielsen, Gitte Nyvang Hartmeyer, Lene Nielsen, Mike Zangenberg, Jonas Kähler, Jørgen Harald Engberg, Christen Rune Stensvold
Format: Article
Language:English
Published: Taylor & Francis Group 2025-12-01
Series:Emerging Microbes and Infections
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Online Access:https://www.tandfonline.com/doi/10.1080/22221751.2025.2529893
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author Tine Graakjær Larsen
Steen Ethelberg
Hans Linde Nielsen
Gitte Nyvang Hartmeyer
Lene Nielsen
Mike Zangenberg
Jonas Kähler
Jørgen Harald Engberg
Christen Rune Stensvold
author_facet Tine Graakjær Larsen
Steen Ethelberg
Hans Linde Nielsen
Gitte Nyvang Hartmeyer
Lene Nielsen
Mike Zangenberg
Jonas Kähler
Jørgen Harald Engberg
Christen Rune Stensvold
author_sort Tine Graakjær Larsen
collection DOAJ
description Human cryptosporidiosis, a diarrheal disease caused by Cryptosporidium species, has previously been considered rare in Denmark and primarily associated with travel abroad. Cryptosporidium in humans came under national surveillance in 2023. Here, we assess all cases identified in Denmark from 2010 to 2024, presenting the identified species, the trends in time and place, and relate the findings to recent changes in diagnostic methods. After 2021, the number of new cases increased substantially, coinciding with the adoption of gastrointestinal syndromic testing in several local hospitals. During seasonal peaks (August-October), Cryptosporidium was detected in the stool of >2% of patients tested. Infections predominantly occurred in individuals without known comorbidities, and hospitalization rates exceeded 10% in recent years. Co-infections with enteropathogenic bacteria were rare (6%), suggesting that Cryptosporidium alone was the causative agent in the patients. Most cases had no history of travel outside Denmark. Beyond C. parvum (56.9%), and C. hominis (11.3%), species of zoonotic relevance were implicated, e.g., C. mortiferum (2.5%), C. meleagridis (1.7%), C. felis (1.2%) and C. erinacei (0.8%). The transition to high-throughput molecular diagnostic methods and the testing of more patients, including those without recent travel history, has dramatically improved the detection of Cryptosporidium in stool samples in Denmark. Cryptosporidiosis appears to be a common and endemic disease in Denmark. The wide heterogeneity of infecting species suggests a number of transmission routes; these are yet to be uncovered. Cryptosporidiosis should be considered a common gastrointestinal infection by clinicians in Denmark and preventive measures should be prioritized.
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spelling doaj-art-8af3894809cb4c7c8221d716ebc0edef2025-08-20T03:32:37ZengTaylor & Francis GroupEmerging Microbes and Infections2222-17512025-12-0114110.1080/22221751.2025.2529893From rare to recognized: enhanced detection uncovers Cryptosporidium endemicity and species diversity in DenmarkTine Graakjær Larsen0Steen Ethelberg1Hans Linde Nielsen2Gitte Nyvang Hartmeyer3Lene Nielsen4Mike Zangenberg5Jonas Kähler6Jørgen Harald Engberg7Christen Rune Stensvold8Department of Infectious Disease Epidemiology and Prevention, Statens Serum Institut, Copenhagen, DenmarkDepartment of Infectious Disease Epidemiology and Prevention, Statens Serum Institut, Copenhagen, DenmarkDepartment of Clinical Microbiology, Aalborg University Hospital, Aalborg, DenmarkDepartment of Clinical Microbiology, Odense University Hospital, Odense, DenmarkDepartment of Clinical Microbiology, Copenhagen University Hospital, Herlev and Gentofte, DenmarkDepartment of Infectious Diseases, Copenhagen University Hospital, Hvidovre, DenmarkDepartment of Data Integration and Analysis, Infectious Disease Preparedness, Statens Serum Institut, Copenhagen, DenmarkDepartment of Clinical Microbiology, Zealand University Hospital, Koege, DenmarkLaboratory of Parasitology, Department of Bacteria, Parasites and Fungi, Statens Serum Institut, Copenhagen, DenmarkHuman cryptosporidiosis, a diarrheal disease caused by Cryptosporidium species, has previously been considered rare in Denmark and primarily associated with travel abroad. Cryptosporidium in humans came under national surveillance in 2023. Here, we assess all cases identified in Denmark from 2010 to 2024, presenting the identified species, the trends in time and place, and relate the findings to recent changes in diagnostic methods. After 2021, the number of new cases increased substantially, coinciding with the adoption of gastrointestinal syndromic testing in several local hospitals. During seasonal peaks (August-October), Cryptosporidium was detected in the stool of >2% of patients tested. Infections predominantly occurred in individuals without known comorbidities, and hospitalization rates exceeded 10% in recent years. Co-infections with enteropathogenic bacteria were rare (6%), suggesting that Cryptosporidium alone was the causative agent in the patients. Most cases had no history of travel outside Denmark. Beyond C. parvum (56.9%), and C. hominis (11.3%), species of zoonotic relevance were implicated, e.g., C. mortiferum (2.5%), C. meleagridis (1.7%), C. felis (1.2%) and C. erinacei (0.8%). The transition to high-throughput molecular diagnostic methods and the testing of more patients, including those without recent travel history, has dramatically improved the detection of Cryptosporidium in stool samples in Denmark. Cryptosporidiosis appears to be a common and endemic disease in Denmark. The wide heterogeneity of infecting species suggests a number of transmission routes; these are yet to be uncovered. Cryptosporidiosis should be considered a common gastrointestinal infection by clinicians in Denmark and preventive measures should be prioritized.https://www.tandfonline.com/doi/10.1080/22221751.2025.2529893Surveillanceclinical microbiologyApicomplexadiagnosisoutbreakScandinavia
spellingShingle Tine Graakjær Larsen
Steen Ethelberg
Hans Linde Nielsen
Gitte Nyvang Hartmeyer
Lene Nielsen
Mike Zangenberg
Jonas Kähler
Jørgen Harald Engberg
Christen Rune Stensvold
From rare to recognized: enhanced detection uncovers Cryptosporidium endemicity and species diversity in Denmark
Emerging Microbes and Infections
Surveillance
clinical microbiology
Apicomplexa
diagnosis
outbreak
Scandinavia
title From rare to recognized: enhanced detection uncovers Cryptosporidium endemicity and species diversity in Denmark
title_full From rare to recognized: enhanced detection uncovers Cryptosporidium endemicity and species diversity in Denmark
title_fullStr From rare to recognized: enhanced detection uncovers Cryptosporidium endemicity and species diversity in Denmark
title_full_unstemmed From rare to recognized: enhanced detection uncovers Cryptosporidium endemicity and species diversity in Denmark
title_short From rare to recognized: enhanced detection uncovers Cryptosporidium endemicity and species diversity in Denmark
title_sort from rare to recognized enhanced detection uncovers cryptosporidium endemicity and species diversity in denmark
topic Surveillance
clinical microbiology
Apicomplexa
diagnosis
outbreak
Scandinavia
url https://www.tandfonline.com/doi/10.1080/22221751.2025.2529893
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