Almost all infections in the neonate are asymptomatic, but more than ninety per cent become chronic carriers themselves and are at high risk of chronic livery disease, including cirrhosis and liver cancer, by middle age. Screening of all pregnancies for HBsAg and in the future, universal immunisation against hepatitis B will eventually reduce the burden of the disease to the affected individuals and the community. It is easily mistaken for rubella and like this illness can also cause joint symptoms in adults. Approximately fifty per cent of adults are susceptible and transmission rates in households reach fifty per cent, while within schools or day care centres rates of twenty to thirty per cent are observed. Foetal infection occurs in thirty per cent of maternal infections with ten per cent foetal death occurring predominantly in the second trimester from severe anaemia and hydrops foetalis.
Infection is transmitted transplacentally, during delivery or from breast milk.
The transmission rate is between ten an thirty per cent. It is believed that the virus is transmitted predominantly at delivery. However, in nearly fifteen per cent of perinatal HIV infections, breast feeding has been implicated. Infected neonates can be asymptomatic for several years but up to thirty per cent will develop symptoms and become very ill within the first few months of life. This sexually transmitted infection is often asymptomatic in the mother, although infected women may have inflammation of the cervix, fallopian tubes or urethra.