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Background
Hepatitis refers to inflammation of the liver and also refers to a group of viral infections that affect the liver. The most common types are Hepatitis A, Hepatitis B, and Hepatitis C, although Hepatitis D and E viruses have also been identified. An estimated 4.4 million Americans are living with chronic hepatitis, the majority of whom do not know they are infected. Viral hepatitis is the leading cause of liver cancer and the most common reason for liver transplantation (CDC Division of Viral Hepatitis, 2012).
Transmission of hepatitis A, which is caused by hepatitis A virus (HAV), occurs by the fecal-oral route through direct contact with an HAV-infected person or by ingestion of HAV-contaminated food or water. Foodborne or waterborne hepatitis A outbreaks are relatively uncommon in the United States, but food handlers with hepatitis A are frequently identified, and evaluation of the need for immunoprophylaxis and implementation of control measures are a considerable burden on public health resources. It is also notable that HAV-contaminated food may be the source of hepatitis A for an unknown proportion of persons whose source of infection is not identified (Fiore, 2004).
Torner et al (2012) reported that although hepatitis A mass vaccination effectiveness is high, outbreaks continue to occur. They investigated the association between duration and characteristics of hepatitis A outbreaks reported between 1991 and 2007. An outbreak was defined as greater than or equal to 2 epidemiologically-linked cases with greater than or equal o 1 case laboratory-confirmed by detection of HA immunoglobulin M (IgM) antibodies. Between 1991 and 2007, 268 outbreaks (rate 2.45 per million persons-year) and 1,396 cases (rate 1.28 per 10(5) persons-year) were reported. Factors associated with shorter duration were time to intervention (OR = 0.96; 95 % confidence interval [CI]: 0.94 to 0.98) and school setting (OR = 0.39; 95 % CI: 0.16 to 0.92). However, the authors also noted that in person-to-person transmission outbreaks, only time to intervention was associated with shorter outbreak duration (OR = 0.96; 95 % CI: 0.95 to 0.98). Torner et al concluded that making confirmed HA infections statutory reportable for clinical laboratories could diminish outbreak duration.
Wiersma et al (2011) reported that most of the estimated 350 million people with chronic hepatitis B virus (HBV) live in resource-constrained settings and that up to 25 % of those persons will die prematurely of hepatocellular carcinoma or cirrhosis. They further state that an informal World Health Organization consultation of experts concluded that chronic HBV is a major public health problem in emerging nations, all HIV-infected persons should be screened for HBV infection, HIBV/HBV co-infected persons should be treated with therapies active against both viruses and that reduce the risk of resistance, and that standards for the management of chronic HBV infection should be adapted to resource-constrained settings.
Hepatitis B, which is caused by infection with the HBV, is found in highest concentrations in blood and in lower concentrations in other body fluids (e.g., semen, vaginal secretions, and wound exudates). HBV is efficiently transmitted by percutaneous or mucous membrane exposure to infectious blood or body fluids that contain blood. In adults, approximately half of newly acquired HBV infections are symptomatic, and approximately 1 % of reported cases result in acute liver failure and death. Risk for chronic infection is inversely related to age at infection, with approximately 90 % of infected infants and 3 0% of infected children aged less than 5 years becoming chronically infected, compared with 2 % to 6 % of adults. Among persons with chronic HBV infection, the risk for premature death from cirrhosis or hepatocellular carcinoma is 15 % to 25 %. The primary risk factors that have been associated with infection are unprotected sex with an infected partner, birth to an infected mother, unprotected sex with more than one partner, men who have sex with other men, history of other sexually transmitted diseases, and illegal injection drug use (CDC Division of Viral Hepatitis, 2012). The United States Preventive Services Task Force (USPSTF) strongly recommends screening for HBV in pregnant women at their first prenatal visit. The USPSTF recommends against routinely screening the general asymptomatic population for chronic HBV infection (USPSTF, 2004).
Weinbaum et al (2009) reported that “early identification of persons with chronic HBV infection enables infected persons to receive necessary care to prevent or delay onset of liver disease, and enables the identification and vaccination of susceptible household contacts and sex partners, interrupting ongoing transmission.” The authors emphasized that testing had been recommended previously to enable primary prevention of HBV infection among close contacts for pregnant women, household contacts and sex partners of HBV-infected persons, persons born in countries with hepatitis B surface antigen (HBsAg) prevalence of more than 8 %, persons who are the source of blood or body fluid exposures that might warrant post-exposure prophylaxis (e.g., needlestick injury to a healthcare worker or sexual assault), and to enable appropriate treatment for infants born to HBsAg-positive mothers and persons infected with human immunodeficiency virus. With the increasing availability of efficacious hepatitis B treatment, the CDC published updated recommendations for public health evaluation and management for chronically infected persons and their contacts which extended testing recommendations to include persons born in geographic regions with HBsAg prevalence of greater than 2 %, men who have sex with men, and injection drug users.
The CDC, in collaboration with the New York City (NYC) Department of Health and Mental Hygiene (DOHMH), conducted a chronic HBV surveillance, selecting a random sample of newly reported cases and collecting more detailed information from the patients' clinicians. Analysis was presented on 180 randomly selected HBV cases reported during June 2008 to November 2009. Approximately two-thirds (67 %) of the patients were Asian, and the most commonly reported reason for HBV testing was the patient's birth country or race/ethnicity (27 %). In 70 % of cases, the clinician did not know of any patient risk factors and 62 % did not know their patient's hepatitis A vaccination status despite recommendations. Sixty-nine percent of clinicians stated that they counseled their patients about notifying close contacts about their infection, and 75 % counseled about transmission and prevention. This surveillance effort provided quantitative data on health disparities, illustrating that not all patients received recommended prevention and treatment services. In response to these findings, DOHMH now routinely distributes HBV patient education materials to populations in need (CDC, 2012).
HCV infection is the most common chronic bloodborne infection in the United States, with approximately 3.2 million persons chronically infected. Sixty to 70 % of persons newly infected with HCV typically are asymptomatic or have a mild clinical illness. HCV RNA can be detected in blood within 1 to 3 weeks after exposure, the average time from exposure to antibody to HCV (anti-HCV) seroconversion is 8 to 9 weeks, and anti-HCV can be detected in greater than 97 % of persons by 6 months after exposure. Chronic HCV infection develops in 70 % to 85 % of HCV-infected persons and 60 % to 70 % of chronically infected persons have evidence of active liver disease. Although the majority of infected persons may not be aware of their infection, infected persons serve as a source of transmission to others and are at risk for chronic liver disease or other HCV-related chronic diseases decades after infection occurs. HCV is most efficiently transmitted through large or repeated percutaneous exposure to infected blood (e.g., through transfusion of blood from unscreened donors or through use of injecting drugs). Although much less frequent, occupational, perinatal, and sexual exposures also can result in transmission of HCV (CDC Division of Viral Hepatitis, 2012).
Denniston et al (2012) discussed that many persons infected with hepatitis C virus (HCV) are unknown to the healthcare system because they may be asymptomatic for years, have not been tested for HCV infection, and only seek medical care when they develop liver-related complications. The authors analyzed data from persons who tested positive for past or current HCV infection during participation in the National Health and Nutrition Examination Survey (NHANES) during the years 2001 through 2008. They conducted a follow-up survey 6 months after examination to determine (i) how many participants testing positive for HCV infection were aware of their HCV status before being notified by NHANES, (ii) what actions participants took after becoming aware of their first positive test, and (iii) participants' knowledge about hepatitis C. Of the 30,140 participants tested, 393 (1.3 %) had evidence of past or current HCV infection and 170 (43 %) could be contacted during the follow-up survey and interviewed. Only 49.7 % were aware of their positive HCV infection status before being notified by NHANES and only 3.7 % of these respondents reported that they had first been tested for HCV because they or their doctor thought they were at risk for infection. The study results showed that, overall, 85.4 % had heard of hepatitis C and that correct responses to questions about hepatitis C were higher among persons 40 to 59 years of age, white non-Hispanics, and respondents who saw a physician after their first positive HCV test. Eighty percent of respondents indicated they had seen a doctor about their first positive HCV test result. The investigators concluded that these data indicated that fewer than 50 % of those infected with HCV may be aware of their infection. The findings suggest that more intensive efforts are needed to identify and test persons at risk for HCV infection.
Smith et al (2012) reported that many of the 2.7 to 3.9 million persons living with HCV infection, an increasing cause of morbidity and mortality in the United States, are unaware they are infected and do not receive care (e.g., education, counseling, and medical monitoring) and treatment. The CDC estimates that although persons born between 1945 to1965 comprise an estimated 27 % of the population, they account for approximately three-fourths of all HCV infections in the United States, 73 % of HCV-associated mortality, and are at greatest risk for hepatocellular carcinoma and other HCV-related liver disease. The CDC is augmenting previous recommendations for HCV testing to recommend one-time testing without prior ascertainment of HCV risk for persons born during 1945 to1965. These recommendations do not replace previous guidelines for HCV testing that are based on known risk factors and clinical indications, but rather define an additional target population for testing: persons born during 1945 to 1965. The CDC developed these recommendations with the assistance of a work group representing diverse expertise and perspectives. The recommendations are informed by the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework, an approach that provides guidance and tools to define the research questions, conduct the systematic review, assess the overall quality of the evidence, and determine the strength of the recommendations.
The United States Centers for Disease Control currently has in place recommendations regarding screening for both hepatitis B and hepatitis C. The USPSTF is expected to issue updated recommendations for HCV screening prior to 2013.
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