5% of symptomatic persons have prolonged or relapsing disease lasting up to 6 months (6). The case-fatality rate for HAV infection increases with age: 1.8% for persons adults aged >50 years compared with 0.6% for persons aged <50 years. The case-fatality rate is also increased among persons with chronic liver disease, who are at increased risk for acute liver failure (7).
In making its recommendation, ACIP considered the likelihood that a child adopted by parents in the United States might be actively infected with HAV and shedding virus at the time of adoption. During 1998--2008, approximately 18,000 children (range: 15,583 to 22,884) were adopted from foreign countries by families in the United States each year.* Approximately 99.8% of these children came from countries where hepatitis A is considered to be of high or intermediate endemicity (2), and approximately 85% of were aged <5 years. Country-specific policies pertaining to foreign adoption are changing constantly, leading to rapid changes in the numbers of international adoptees entering the United States from various countries. Although South Korea was the most common country of origin for adoptions in the United States in the early 1990s, Russia and China became prominent in international adoption in the late 1990s, and currently the largest numbers of adopted children come from Guatemala, China, Russia, and Ethiopia. The incidence of HAV infection is highest in these countries among children aged <5 years, when HAV infection is likely to be asymptomatic.
ACIP also considered recent reports of HAV infection among persons in close contact with new adoptees from countries of high or intermediate hepatitis A endemicity. Such persons are at greater risk for HAV infection. In 2007, CDC was notified of a case of fulminant hepatitis A in a nontraveling household contact of an asymptomatic Ethiopian adoptee confirmed to have acute hepatitis A (immunoglobulin M [IgM] antibody to HAV [anti-HAV] positive). This case prompted further investigation that led to identification of 20 other cases of acute hepatitis A among persons who had close personal contact with newly arriving internationally adopted children and no history of traveling abroad (8). Two acute hepatitis A cases were identified among traveling parents who had not been vaccinated. This same study found that 98% of parents traveling to pick up their children had been vaccinated against hepatitis A in accordance with existing ACIP recommendations (8).
Since 2007, CDC has received 14 additional reports of acute hepatitis A following exposure to nonjaundiced adoptees newly arriving from countries of high or intermediate hepatitis A endemicity. Although these numbers are small compared with the total number of hepatitis A cases (2,979) reported to CDC in 2007 (9), they likely represent an underestimate of the number of hepatitis A cases associated with international adoptions because contact with an international adoptee is not asked routinely as part of national hepatitis A surveillance. All of the 14 adoptee-associated cases identified since 2007 were in close contacts who had not been vaccinated against hepatitis A and had no history of travel and no other risk factors for hepatitis A. In one instance, both adoptive parents developed hepatitis A that required hospitalization (CDC, unpublished data, 2008). In another instance, a 2008 community outbreak with 12 hepatitis A cases was associated with an asymptomatic HAV-infected international adoptee; two infected contacts were hospitalized, and disease was identified among tertiary contacts in an elementary school (CDC, unpublished data, 2009).
Data from a study conducted at three adoption clinics in the United States, each screening 100--200 incoming adoptees for hepatitis A each year, indicate that 1%--6% of newly arrived international adoptees are acutely infected with HAV (non-jaundiced; IgM anti-HAV positive). A proportion of these adoptees represent a source of infection for susceptible close contacts (9). The risk for hepatitis A among close personal contact