Most infections remain completely without symptoms, while 10% of cases develop mild symptoms only, such as fever, malaise, nausea, and vomiting.
Večina okužb ostane povsem brez simptomov, medtem ko se v 10 % primerov pojavijo samo blagi simptomi, kot so povišana telesna temperatura, slabo počutje, slabost in bruhanje.