The US Centers
for Disease Control and Prevention (CDC) released new data last week showing
that the number of new hepatitis C virus (HCV) infections reported to the
agency nearly tripled between 2010 and 2015.
A related study
saw a rising rate of hepatitis C among pregnant women – increasing the
likelihood of mother-to-child HCV transmission – while another showed that many
states are not doing all they could to reduce new infections.
A total of 2436
new hepatitis C cases were reported to the CDC in 2015 from 40 states, up from
850 in 2010, according to preliminary data described in a new HCV surveillance report. The number rose each year
during this period. However, a majority of people living with hepatitis C are
thought to be unaware of their status, and the CDC estimates that the actual
number was around 33,900 new cases – the highest level in 15 years.
Traditionally 'baby
boomers' born between 1945 and 1965 have had the highest hepatitis C prevalence
in the US. About three-quarters of the estimated 3.5
million Americans living with HCV fall into this age group, which has a sixfold
greater likelihood of being infected than people of other ages. Liver disease
caused by hepatitis C progresses over time, and a majority of the nearly 20,000
people who died from HCV-related causes were over age 55.
Hepatitis C
incidence is increasing most rapidly among young people age 20-29, in
association with the ongoing opioid epidemic. White
people living in non-urban areas – especially in the Midwest, New England and
Appalachia – are most heavily affected.
The new
surveillance report also gives estimates for hepatitis A and B.
Although levels
fluctuated somewhat over the past five years, the number of reported new cases of hepatitis A virus (HAV) infection in
2015 was almost the same as the 2011 number: 1390 and 1393, respectively. After
adjusting for missed diagnoses and under-reporting, researchers estimated the
total number of new HAV infections in 2015 to be 2800.
HAV
is primarily spread through contaminated food or water and resolves without
treatment. A small spike in 2013 was attributed to an outbreak among people who
ate imported pomegranate seeds.
New
hepatitis B virus (HBV) case reports also fluctuated a bit, with numbers rising
from 2903 in 2011 to 3370 in 2015. This included a substantial 21% increase
from 2014 to 2015. After adjusting for missed diagnoses and under-reporting,
the estimated total number of new HBV infections in 2015 was 21,900.
The
CDC estimates that approximately 850,000 people are living with hepatitis B,
with about half of chronic infections among Asians and Pacific Islanders, and
three-quarters among people born outside the US. HBV is largely transmitted the
same way as HCV, but mother-to-child transmission is more common and it can be
prevented with a vaccine.