SUMMARY: Nearly 75% of people with chronic hepatitis C virus (HCV) infection in 3 U.S. states have HCV genotype 1, the hardest type to treat, according to public health surveillance data presented at the recent 50th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC 2010) in Boston. Among African-Americans -- a group known to respond poorly to interferon-based therapy -- more than 90% had genotype 1.

By Liz Highleyman

Hepatitis C virus genotype is a key factor in predicting how well interferon-based therapy will work. Patients with HCV genotype 1 are treated with pegylated interferon plus ribavirin for a standard duration of 48 weeks, with a sustained virological response (SVR) rate just under 50%, while those with genotypes 2 or 3 are typically treated for 24 weeks and have an SVR rate of 70%-80%. Genotypes 4 (which is also considered hard to treat), 5, and 6 are seldom seen in the U.S.

Monina Klevens from the Centers for Disease Control and Prevention (CDC) and colleagues collected data on hepatitis C cases reported during 2009 to health departments in Connecticut, Minnesota, 34 counties in New York State, and New York City, as part of an enhanced population-based surveillance project.

Results

	A total of 16,620 confirmed cases of HCV infection were reported by the participating sites.
	3081 of these individuals (18.5%) had an available HCV genotype test result
	62.2% were reported in New York City; 20.2% were from elsewhere in New York State; 15.5% were from Minnesota; 2.1% were from Connecticut.
	Overall, the genotype distribution in these cases was as follows:
	HCV genotype 1: 73.3% overall (range 64.6%-77.5% across sites); HCV genotype 2: 11.9% (range 10.2%-16.6%); HCV genotype 3: 11.6% (range 8.0%-18.5%); HCV genotypes 4, 5, or 6: 3.3%.
	Younger adults (age 18-39 years) were more likely to have HCV genotype 3 than people age 40-59 years or those age 60 and older (16.6%, 11.9%, and 5.5%, respectively).
	Genotype 1 frequency varied across racial/ethnic groups:
	Blacks (non-Hispanic): 90.7%; Hispanics/Latinos: 78.7%; Whites (non-Hispanic): 68.1%.
	Most people with HCV genotypes 1, 2, and 3 were born in the U.S. (87.4%, 81.2%, and 70.8%, respectively)
	In contrast, most people (71.4%) with genotype 4 and all those with genotype 6 were foreign-born.

Based on these findings, the investigators concluded, "In 2009, there was limited variability in genotype by geographic area, but surveillance is needed as more persons are screened and those with HCV infection are referred for medical care including treatment."

Investigator affiliations: Centers for Disease Control and Prevention, Atlanta, GA; Colorado Dept. of Public Health, CO; Connecticut Dept. of Public Health, CT; Minnesota Dept. of Health, MN; New York State Dept. of Health, NY; New York City Dept. of Health and Mental Hygiene, New York, NY.

10/1/10

Reference
M Klevens, R Jiles, D Daniels, and others. Distribution of Reported Hepatitis C Genotypes in Sites Conducting Enhanced Hepatitis Surveillance, 2009. 50th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC 2010). Boston, September 12-15, 2010. Abstract V-1789.