WEDNESDAY, July 27 (HealthDay News) -- About 10 million injection drug users worldwide have hepatitis C, and 1.3 million have hepatitis B, a new study reports.

Hepatitis can lead to cirrhosis, liver failure and liver cancer.

Researchers analyzed international data and found that rates of hepatitis C infection among injection drug users (IDUs) were 60 to 80 percent in 25 countries and greater than 80 percent in 12 other countries.

These countries included Spain (80 percent), Norway (76 percent), Germany (75 percent), France (74 percent), United States (73 percent), China (67 percent), Canada (64 percent), Italy (81 percent), Portugal (83 percent), Pakistan (84 percent), the Netherlands (86 percent), Thailand (90 percent) and Mexico (97 percent).

Lower rates were seen in New Zealand (52 percent), Australia (55 percent) and the United Kingdom (50 percent), the researchers noted.

The countries believed to have the largest number of IDUs infected with hepatitis C virus (HCV) are China (1.6 million), the United States (1.5 million) and Russia (1.3 million), the investigators found.

Rates of hepatitis B infection were 5 to 10 percent in 21 countries and more than 10 percent in 10 countries. The highest rates were in Vietnam (20 percent), Estonia (19 percent), Saudi Arabia (18 percent) and Taiwan (17 percent). The United Kingdom had the highest rate in Western Europe at 9 percent. The rate in the United States was 12 percent.

The study, released to coincide with World Hepatitis Day, is published online July 28 in The Lancet.

"The public-health response to blood-borne virus transmission in IDUs has mainly centered on HIV. Maintenance and strengthening of the response to HIV in IDUs remains crucial, but the significance of viral hepatitis needs to receive greater attention than it does at present," Paul Nelson, from the National Drug and Alcohol Research Centre at the University of New South Wales in Sydney, and colleagues wrote.

"Efforts to prevent, treat, and reduce harms related to liver disease in IDUs are essential -- especially in situations in which HIV has successfully been prevented or managed -- because the large numbers of IDUs infected with HCV and significant morbidity resulting from this infection mean that the health and economic costs of HCV transmitted by injected drug use might be as high as (or higher than) those of HIV," the authors added.

"Nonetheless, HCV treatment is underused. Part of the reason for this neglect is the high cost, which will remain a substantial barrier to increasing of treatment coverage in low-resource settings until costs are reduced," the researchers concluded.

More information

The U.S. National Institute of Diabetes and Digestive and Kidney Diseases has more about viral hepatitis.