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Surveillance for Viral Hepatitis – United States, 2015

Summary of Trends in Viral Hepatitis – United States, 2015

The Centers for Disease Control and Prevention’s (CDC) National Notifiable Diseases Surveillance System (NNDSS) (1) receives viral hepatitis case reports electronically each week from state and territorial health departments in the United States (U.S.) via CDC’s National Electronic Telecommunications System for Surveillance (NETSS), a computerized public health surveillance system. The surveillance system accepts case reports of acute and chronic infections from all states and the District of Columbia, though not all jurisdictions report their data. In 2015, a total of 48 states submitted reports of acute hepatitis B virus (HBV) infection, 40 submitted reports of acute hepatitis C virus (HCV) infection, 40 submitted reports of chronic HBV infection, and 40 submitted reports of chronic HCV infection.

Viral hepatitis cases reported to NNDSS represent persons who were tested for and diagnosed with viral hepatitis infection based on specific surveillance case definitions.  Most persons infected with viral hepatitis are asymptomatic and so are not identified or reported. In 2011, CDC developed a statistical method to account for cases that were neither diagnosed nor reported in estimating the actual number of new (acute) cases of hepatitis A virus (HAV), HBV, and HCV from the number of cases reported for each disease (2); estimates in this report were derived using this method. Since estimates before 2011 were obtained using a different, unpublished method, they cannot be compared with those since 2011. This Summary describes estimated trends during 2011-2015 and reported cases of acute HAV, HBV, and HCV infections in 2015.

Hepatitis A: The number of reported cases of hepatitis A increased from 2011 by 11.7% from 2011 to 2012 (n=1,393 and 1,562, respectively), increased 14% to 1,781 cases in 2013, decreased 30.4% to 1,239 cases in 2014, and increased 12.2% to 1,390 cases in 2015. The 2013 increase was partially due to a large 2013 hepatitis A outbreak among persons who consumed imported pomegranate seeds in several southwestern states and Hawaii (3). Although a few states (i.e., California, Florida, New York, Oregon, Texas, and Washington) reported increased cases in 2015, no hepatitis A outbreaks were reported.  Infant hepatitis A vaccination was first recommended for states west of the Mississippi in 1996, and universal infant vaccination was recommended in 2006. Since then, vaccination rates and evidence of vaccine-induced immunity in young persons have increased in the past decade (4, 5). Yet hepatitis A vaccination coverage levels remain lower than those for other routinely recommended vaccines (6). Additionally, many older adults remain unvaccinated and susceptible to infection. International travel is the most commonly reported risk for HAV infection (7). After adjusting for under-ascertainment and under-reporting (2), the estimated number of new HAV infections in 2015 was 2,800 (95% confidence interval [CI] =1,900–3,100).

Hepatitis B:  The number of reported cases of acute hepatitis B decreased by 0.3% from 2011 to 2012 (n=2,903 and 2,895 cases, respectively), increased 5.4% to 3,050 cases in 2013, decreased 8.5% to 2,791 cases in 2014, and increased 20.7% to 3,370 cases in 2015. After adjusting for under-ascertainment and under-reporting (2), the estimated number of new HBV infections in 2015 was 21,900 (95% CI= 12,500–53,600).

In addition to new cases of hepatitis B, chronic HBV infection remains a major public health challenge. CDC, using most recent national prevalence data, estimates that approximately 850,000 persons are living with HBV in the U.S. (8, 9), although other studies have estimated this number to be as high as 2.2 million (10). Unpublished surveillance data from seven CDC-funded sites indicate about one-half of chronic HBV infections were among Asian/Pacific Islanders, and three quarters of chronic HBV infections were among persons born outside of the U.S. Other data reveal that 47%–70% of persons with HBV infection living in the U.S. were born in other countries where routine hepatitis B immunization was introduced more recently than in the U.S. Among persons born outside of the U.S. with chronic HBV infection, an estimated 58% migrated from Asia (10, 11). CDC mortality data show that disproportionate numbers of Asian/Pacific Islanders are dying with hepatitis B. CDC and the U.S. Preventive Services Task Force (USPSTF) recommend HBV testing for persons born in countries where HBV infection is endemic and for persons with sexual or bloodborne risks for infection because diagnosis of infection is the first step towards receipt of recommended care and treatment (12-14).

Hepatitis C: Reported cases of acute HCV infection increased more than 2.9-fold from 2010 through 2015, rising annually throughout this period. Examining annual trends beginning in 2011, reported cases of acute HCV infection increased 44.3% from 2011 to 2012 (n=1,232 and 1,778 cases, respectively), increased 20.3% to 2,138 cases in 2013, increased 2.6% to 2,194 cases in 2014, and increased 11% to 2,436 cases in 2015. The increase in acute HCV case reports reflects new infections associated with rising rates of injection-drug use, and, to a much lesser extent, improved case detection (15). Several early investigations of newly acquired HCV infections reveal that most occur among young, white persons who live in non-urban areas (particularly in states within the Appalachian, Midwestern, and New England regions of the country) (17); trends in these states likely indicate an overall increase in HCV incidence throughout the country (15, 18). States with the highest rate of new HCV infections (e.g., West Virginia, Kentucky, and Tennessee) did not receive CDC support for case finding during these reporting years (2011-2015). After adjusting for under-ascertainment and under-reporting (2), an estimated 33,900 (95% CI=26,800–115,000) new HCV infections occurred in 2015.

Approximately 3.5 million persons are currently infected with HCV (16).  Mortality among HCV-infected persons—primarily adults aged 55–64 years—increased during 2006-2010 (19, 20). In 2013, HCV associated deaths exceeded the combined number of deaths with 60 other infectious diseases as underlying causes (21). CDC data indicate the number of HCV-associated deaths increased 10.9% from 2011 through 2014 and decreased 0.2% to 19,629 in 2015. Approximately one-half of all deaths in 2015 occurred among persons aged 55-64 years. However, deaths associated with HCV are largely underestimated; the only large U.S. study of deaths among persons with confirmed HCV infection indicated that only 19% had HCV listed anywhere on the death certificate despite 75% having evidence of substantial liver disease (20). To increase the proportion of persons with HCV who are tested and linked to recommended care including curative treatment for HCV (12, 13), CDC and USPSTF recommend one-time testing for HCV infection among all adults born during 1945–1965 and among others at increased risk for HCV infection (22).

References:

  1. Centers for Disease Control and Prevention’s (CDC) National Notifiable Diseases Surveillance System (NNDSS). https://wwwn.cdc.gov/nndss/.
  2. Klevens RM, Liu SJ, Roberts H, Jiles RB, Holmberg SD. Estimating acute viral hepatitis infections from nationally reported cases. Am J Public Health. 2014;104(3):482-7.
  3. Collier MG, Khudyakov YE, Selvage D, Adams-Cameron M, Epson E, Cronquist A, et al. Outbreak of hepatitis A in the USA associated with frozen pomegranate arils imported from Turkey: an epidemiological case study. Lancet Infect Dis. 2014;14(10):976-81.
  4. Centers for Disease Control and Prevention. Prevention of hepatitis A through active or passive immunization: recommendations of the Advisory Committee on Immunization Practices. MMWR. 2006;55(RR-07):1-23.
  5. Klevens RM, Kruszon-Moran D, Wasley AM, Gallagher K, McQuillan GM, Kuhnert WL, et al. Seroprevalence of hepatitis A antibodies in the United States: results from the National Health and Nutrition Examination Survey. Public Health Rep. 2011;126(4):522-32.
  6. Centers for Disease Control and Prevention. Vaccination coverage among children aged 19-35 months – United States, 2015. 2016:65(39):1065-1071
  7. Klevens RM, Miller JT, Iqbal KI, Thomas A, Rizzo EM, Hanson H, et al. The evolving epidemiology of hepatitis A in the United States.  Arch Intern Med 2010; 170(20):1811-18.
  8. Wasley A, Kruszon-Moran D, Kuhnert W, Simard EP, Finelli L, McQuillan G, Bell B. The prevalence of hepatitis B virus infection in the United States in the era of vaccination. J Infect Dis. 2010;202:192-201.
  9. Roberts H, Kruszon-Moran D, Ly KN, Hughes E, Iqbal K, Jiles RB, Holmberg SD. Prevalence of chronic hepatitis B virus (HBV) infection in U.S. households: National Health and Nutrition Examination Survey (NHANES), 1988-2002. Hepatology 2016; 63(2):388-97.
  10. Kowdley KV, Wang CC, Welch S, Roberts H, Brosgart CL. Prevalence of chronic hepatitis B among foreign-born persons living in the United States by country of origin. Hepatology 2012;56(2):422-33.
  11. Centers for Disease Control and Prevention. Recommendations for identification and public health management of persons with chronic hepatitis B virus infection. MMWR. 2008;57(RR-08):1-18.
  12. Spradling PR, Rupp LB, Moorman AC, Lu M, Teshale EH, Gordon SC, et al. Hepatitis B and C virus infection among 1.2 million persons with access to care: factors associated with testing and infection prevalence. Clin Infect Dis. 2012;55(8):1047-55.
  13. Holmberg SD, Spradling PR, Moorman AC, Denniston MM. Hepatitis C in the United States. N Engl J Med 2013;368(20):1859-61.
  14. LeFevre ML, on behalf of the U.S. Preventive Services Task Force. Screening for hepatitis B virus infection in nonpregnant adolescents and adults: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2014;161(1):58-66.
  15. Increases in Hepatitis C Virus Infection Related to Injection Drug Use Among Persons Aged ≤30 Years — Kentucky, Tennessee, Virginia, and West Virginia, 2006–2012. MMWR. May 8, 2015 / 64(17);453-458.
  16. Edlin BR, Eckhardt BJ, Shu MA, Holmberg SD, Swan T. Toward a more accurate estimate of the prevalence of hepatitis C in the United States. Hepatology. 2015 Nov;62(5):1353- 63. Centers for Disease Control and Prevention. Hepatitis C virus infection among adolescents and young adults: Massachusetts, 2002-2009. MMWR. 2011;60(17):537-41.
  17. Centers for Disease Control and Prevention. Hepatitis C virus infection among adolescents and young adults: Massachusetts, 2002-2009. MMWR. 2011;60(17):537-
  18. Suryaprasad AG, White JZ, Xu F, Eichler B, Hamilton J, Patel A, et al. Emerging epidemic of hepatitis C virus among young non-urban persons who inject drugs in the United States, 2006-2011. Clin Infect Dis. 2014;59(10):1411-19.
  19. Ly KN, Xing J, Klevens RM, Jiles RB, Ward JW, Holmberg SD. The increasing burden of mortality from viral hepatitis in the United States between 1999 and 2007. Ann Intern Med. 2012;156(4):271-8.
  20. Mahajan R, Xing J, Liu SJ, Ly KN, Moorman AC, Rupp LB, et al. Mortality among persons in care with hepatitis C virus infection: the Chronic Hepatitis Cohort Study (CheCS), 2006-2010. Clin Infect Dis. 2014;58(8):1055-61.
  21. Ly KN, Hughes EM, Jiles RB, Holmberg SD. Rising mortality associated with hepatitis C virus in the United States.  Clin Infect Dis 2016:62:1287-1288.  Available at: https://academic.oup.com/cid/article/62/10/1287/2462772/Rising-Mortality-Associated-With-Hepatitis-C-Virus.  Accessed on January 29, 2017.
  22. Moyer VA, on behalf of the U.S. Preventive Services Task Force. Screening for hepatitis C virus infection in adults: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2013;159(5):349-57.
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