Teacher:Given a passage, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.
Teacher: Now, understand the problem? Solve this instance: Hepatitis B virus (HBV) infections are a matter of concern in hemodialysis units; occult HBV infections (serum HBsAg negative but HBV DNA positive) were demonstrated in this setting, and this involves further concerns regarding possible transmission and pathogenic consequences. This study aimed to investigate the prevalence and correlates of occult HBV infection in a group of patients with reference to a single hemodialysis unit in southeastern Italy.', 'We analyzed HBV serology and DNA (using a qualitative nested PCR) in 128 HBsAg-negative hemodialysis patients, and correlated the results obtained, with sex, age, hemodialysis duration and HCV seropositivity.', 'As a whole, occult HBV infection was demonstrated in 34/128 patients (26.6%); HBV DNA detection was more frequent when anti-HBcAg antibodies were detected in isolation (72%) than when associated with anti-HBsAg antibodies (31%). Among HCV-seropositive patients, occult HBV infection was observed in 66%, and among these as many as 14/15 patients (93%) who were HCV+/anti-HBcAg+ had serum HBV DNA detectable. On multivariate analysis, HCV seropositivity and the presence of anti-HBs were still respectively correlated to the presence and absence of occult HBV infection.
Student:
Is occult HBV infection in hemodialysis setting marked by presence of isolated antibodies to HBcAg and HCV?