Confirmed acute hepatitis B infections are reported to the Public Health La
boratory Service Communicable Disease Surveillance Centre by laboratories i
n England and Wales, These reports have been used to monitor trends in the
incidence of hepatitis B virus (HBV) infection over time, and between expos
ure categories and age groups. Between 1985 and 1996 a total of 9252 cases
of acute HBV infection were reported; the number of reports fell from 1761
in 1985 to 581 in 1996. Most infections were reported in adults aged 15-44
years [n = 7365 (80 %)], and infections were more commonly reported in male
s [n = 6390 (70 %)] than females [n = 2658 (29 %)], The probable means of a
cquisition was known for just over half of all adult cases [4827/8956 (54 %
)]. Injecting drug use was the most common exposure [n = 1901 (21 %)], foll
owed by sex between men and women [n = 1140 (13 %)] and sex between men [n
= 1025 (11 %)]. The number of infections in injecting drug users fell in th
e late 1980s, but increased again from 1991 onwards. In children aged under
15 years, infections acquired by mother to baby transmission accounted for
35/170 (21%) of the total. Surveillance indicates that the incidence of ac
ute hepatitis B infection fell in the late 1980s, probably reflecting chang
ed behaviour in injecting drug users. An increase in the number of infectio
ns in injecting drug users since 1993 may indicate ongoing transmission tha
t has not been contained by the introduction of needle exchange schemes or
by selective vaccination.