The incidence of symptomatic hepatitis C in six US counties has fallen
dramatically since 1982, when active surveillance began. A study of all
reported cases from diverse counties across the country shows a sharp fall
of around 90% between 1989 and 1994. Incidence then stabilised and remained
low for the next 12 years, averaging 0.7 cases per 100?000 population.
Surveillance finally ended in 2006 when the money needed to recruit new
county health departments failed to materialise.
The authors identified 2075 new symptomatic infections over the 25 year
study period. The patients were young, with a median age under 40, both
before and after 1989. Three quarters of infected people had jaundice,
around a fifth were admitted to hospital, and 1.2% (24/2047) died. Previous
infections with other hepatitis viruses were common.
Drug use was the most common risk factor by far among the 1748 people
interviewed, accounting for 31.8% (402/1266) of cases before 1989, 33.5%
(71/212) of cases between 1990 and 1993, and 45.6% (103/226) of cases
between 1994 and 2006. Presumed infection from blood transfusion was rare
after transfusion authorities began screening donors. These authors
identified five possible cases presenting after 1994. Two of the affected
people also had other risk factors. Donor tracing failed to find the source
of infection for the other three.