Intestinal protozoa in returning travellers: a GeoSentinel analysis from 2007 to 2019
Authors: Weitzel Thomas , Brown Ashley , Libman Michael , Perret Cecilia , Huits Ralph , Chen Lin , Leung Daniel T , Leder Karin , Connor Bradley A , Menéndez Marta D , Asgeirsson Hilmir , Schwartz Eli , Salvador Fernando , Malvy Denis , Saio Mauro , Norman Francesca F , Amatya Bhawana , Duvignaud Alexandre , Vaughan Stephen , Glynn Marielle ,   the GeoSentinel Network, Larsen Carsten Schade , Wejse Christian , Grobusch Martin P , Goorhuis Abraham , Bottieau Emmanuel , Shaw Marc , Hern Annemarie , Piyaphanee Watcharapong , Matsee Wasin , Muñoz Jose , Molina Israel , Mockenhaupt Frank , Castelli Francesco , Matteelli Alberto , Coyle Christina , Kelly Paul , Zeana Cosmina , Florescu Simin Aysel , Popescu Corneliu Petru , Vaughan Stephen , Kuhn Susan , Anderson Susan , Mavunda Kunjana , Licitra Carmelo , Chappuis Francois , Eperon Gilles , Waggoner Jesse , Wu Henry , Jordan Sabine , Yates Johnnie , Phu Phi Truong Hoang , Pandey Prativa , Beadsworth Michael , Perez-Molina Jose , Gautret Philippe , Javelle Emilie , Hynes Noreen , Barnett Elizabeth , Bourque Dan , Settgast Ann , Greenaway Christina , Barkati Sapha , Yansouni Cedric , Chakravarti Arpita , Rothe Camilla , Schunk Mirjam , Gobbi Federico , Jenks Nancy Piper , Rogova Marina , Cahill John , Wyler Ben , Patterson Frank , McCarthy Anne , Caumes Eric , Itani Oula , van Nood Els , Glans Hedvig , Ujiie Mugen , Kutsuna Satoshi , Morris Shaun , Kazmi Kescha , Sofarelli Terri , Plewes Katherine , Mirzanejad Yazdan , Plourde Pierre , Shackel Jacquie , Yoshimura Yukihiro , Tachikawa Natsuo , Schlagenhauf Patricia , Zinkernage Annelies , Angelo Kristina M 
Published: January 2024

Abstract

Background
Prolonged diarrhoea is common amongst returning travellers and is often caused by intestinal protozoa. However, the epidemiology of travel-associated illness caused by protozoal pathogens is not well described.

Methods
We analysed records of returning international travellers with illness caused by Giardia duodenalis, Cryptosporidium spp., Cyclospora cayetanensis or Cystoisospora belli, reported to the GeoSentinel Network during January 2007–December 2019. We excluded records of travellers migrating, with an unascertainable exposure country, or from GeoSentinel sites that were not located in high-income countries.

Results
There were 2517 cases, 82.3% giardiasis (n = 2072), 11.4% cryptosporidiosis (n = 287), 6.0% cyclosporiasis (n = 150) and 0.3% cystoisosporiasis (n = 8). Overall, most travellers were tourists (64.4%) on long trips (median durations: 18–30 days). Cryptosporidiosis more frequently affected people &lt; 18 years (13.9%) and cyclosporiasis affected people ≥ 40 years (59.4%). Giardiasis was most frequently acquired in South Central Asia (45.8%) and sub-Saharan Africa (22.6%), cryptosporidiosis in sub-Saharan Africa (24.7%) and South-Central Asia (19.5%), cyclosporiasis in South East Asia (31.3%) and Central America (27.3%), and cystoisosporiasis in sub-Saharan Africa (62.5%). Cyclosporiasis cases were reported from countries of uncertain endemicity (e.g. Cambodia) or in countries with no previous evidence of this parasite (e.g. French Guiana). The time from symptom onset to presentation at a GeoSentinel site was the longest amongst travellers with giardiasis (median: 30 days). Over 14% of travellers with cryptosporidiosis were hospitalized.

Conclusions
This analysis provides new insights into the epidemiology and clinical significance of four intestinal protozoa that can cause morbidity in international travellers. These data might help optimize pretravel advice and post-travel management of patients with travel-associated prolonged gastrointestinal illnesses. This analysis reinforces the importance of international travel-related surveillance to identify sentinel cases and areas where protozoal infections might be undetected or underreported.