![]() 2016 reproduced courtesy of the Centers for Disease Control and Prevention 2016.) In 2015, the most recent year for which data are available, 1398 cases were reported to NNDSS after correcting for underreporting, it is estimated that ∼2800 cases occurred (see cdc.gov/hepatitis/statistics/2015surveillance/commentary.htm).Īnnual average incidence of reported cases of acute hepatitis A in the United States by county, pre-vaccine (1987–1997) and post-vaccine (2007) introduction. In 1996, 31,032 cases were reported to the CDC National Notifiable Diseases Surveillance System (NNDSS) after correcting for underreporting, it is estimated that around 80,000 cases occurred ( Bell et al. As vaccination coverage increased, incidence rates declined and temporal and geographic variability disappeared ( Fig. In 1995, the incidence of HAV infection in the United States ranged from 1.1 per 100,000 per year in Kentucky and New Hampshire to 86.7 per 100,000 in Oregon ( Daniels et al. Geographic variability of HAV disease was also more extreme in the United States prior to the availability of vaccine ( Daniels et al. In the United States, during the transition from intermediate-to-low HAV endemicity, temporal increases in HAV infection and community outbreaks arose every 10–15 years ( Fig. Countries with adequate sanitation infrastructure have low rates of infection and infrequent outbreaks as long as the disease is not introduced into the population from an external source ( Shapiro and Margolis 1993 Klevens et al. Countries with intermediate levels of disease experience increased numbers of susceptible adults and occasional, large outbreaks ( Shapiro and Margolis 1993). In developing countries with poor sanitary infrastructure, high infection rates occur among exposed children who develop immunity without ever being symptomatic, and outbreaks are infrequent ( Shapiro and Margolis 1993). Patterns of HAV disease occur in three distinct ways according to endemicity of disease ( Shapiro and Margolis 1993). (Source: CDC, National Notifiable Diseases Surveillance System, 2015.) 2016 reproduced courtesy of the Centers for Disease Control and Prevention © 2016.) ( B) Incidence of hepatitis A virus by age group-United States, 2000–2015. ( A) Cases of acute hepatitis A per 100,000 population reported to the National Notifiable Diseases Surveillance System, United States, 1966–2013. Incidence of hepatitis A in the United States. These isolated clinical cases were traditionally associated with travel to endemic areas however, in the past two decades, locally acquired (autochthonous) HEV infection has been increasingly recognized in developed countries, including the United States. HEV infection has two distinct epidemiological profiles: in developing countries HEV genotype (gt)1 (and occasionally gt2 and gt4) presents as sporadic disease and as large outbreaks primarily associated with fecally contaminated drinking water, although in developed countries HEV gt3 presents as sporadic disease ( Teshale et al. 2012 Global Burden of Disease 2015 Mortality and Causes of Death Collaborators 2016). In developing countries, there are an estimated 20 million incident HEV infections annually, 3.3 million of which are symptomatic, resulting in an estimated 26,700 deaths in 2015 ( Rein et al. Hepatitis E virus (HEV), also an enterically transmitted RNA virus, is a significant cause of acute viral hepatitis worldwide. Despite being a vaccine-preventable disease, the changing epidemiology of HAV has led to increased susceptibility in older persons who are more likely to suffer from more severe disease, highlighting the significance of HAV as an important pathogen in terms of public health and its burden on the medical system. 2014 Centers for Disease Control and Prevention, unpubl.). Community-wide outbreaks continue to occur in high-risk populations, such as men who have sex with men (MSM), the homeless, and persons who use illicit drugs, and appear to be more severe in older populations and populations with underlying medical conditions ( Villano et al. Infections in the United States are typically seen in travelers returning from endemic countries, but outbreaks have increasingly been linked to foods imported from endemic countries ( Klevens et al. The incidence of hepatitis A virus (HAV) infection has been declining in the United States since infant vaccination was initially recommended in 1996 (see cdc.gov/hepatitis/statistics/2015surveillance/commentary.htm). ![]()
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