All of the following statements are true for hepatitis- E except:

The incubation period ranges from 2-9 weeks with an average of six weeks. Most cases occur in young to middle-aged adults (15-40 years old).  The disease is generally mild and self-limited, with a low case fatality of about 1 percent. A unique feature is the clinical severity and high case fatality rate of 20-40 percent in pregnant women, especially in the last trimester of pregnancy.   Reference: Ananthanarayan Microbiology  8th edition page no  554