Cryptosporidium chipmunk genotype I - An emerging cause of human cryptosporidiosis in Sweden.

Ioana Bujila,Jessica Beser,Marie Nordahl,Marianne Lebbad,Robert Söderlund,Karolina Fischerström,Karin Troell,Anette Hansen,Gustav Killander

doi:10.1016/j.meegid.2021.104895

Abstract

Most cases of cryptosporidiosis in humans are caused by Cryptosporidium parvum or Cryptosporidium hominis. However, more uncommon species are increasingly being recognised to cause infection in humans. Here we report that Cryptosporidium chipmunk genotype I, which has various rodents as its natural host, is the third most common source of human cryptosporidiosis in Sweden. We also describe the first small outbreak of cryptosporidiosis caused by Cryptosporidium chipmunk genotype I and report the first case of zoonotic transmission of Cryptosporidium chipmunk genotype I from a red squirrel to a human. Cryptosporidium chipmunk genotype I was identified in 20 human cases, including 16 sporadic cases, three outbreak-related cases, and one zoonotic case, as well as in two squirrel samples. Gp60 subtyping which was successful for 19 human cases and two squirrel samples showed that all samples harboured the same subtype, XIVaA20G2T1. The work presented here suggests that red squirrel is a natural host of Cryptosporidium chipmunk genotype I and that infection with Cryptosporidium chipmunk genotype I is an emerging cause of domestic cryptosporidiosis in Sweden and a potential source of outbreaks.

Highlights

Cryptosporidium is a protozoan parasite that can cause disease in both humans and animals
C. hominis is the dominant species in developing countries, while both C. parvum and C. hominis are common in industrialised countries (Feng et al, 2018)
Most cases of Cryptosporidium acquired in Sweden are caused by C. parvum and to a lesser extent C. hominis, but less common species such as Cryptosporidium chipmunk genotype I play a role in transmission

Summary

Introduction

Cryptosporidium is a protozoan parasite that can cause disease in both humans and animals. The majority of human cryptosporidiosis cases are caused by either of two species, namely Cryptosporidium hominis and Cryptosporidium parvum. The latter has the broadest host range and in fects several vertebrates, while C. hominis is mainly restricted to humans. C. hominis is the dominant species in developing countries, while both C. parvum and C. hominis are common in industrialised countries (Feng et al, 2018). These two species are responsible for the majority of all investigated outbreaks of cryptosporidiosis (Zahedi and Ryan, 2020). The natural hosts of Cryptospo ridium chipmunk genotype I are mainly squirrels, chipmunks, and deer mice (Guo et al, 2015)

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