hepatitis A infections

​A retrospective analysis from the CDC  was done of hospitalizations for hepatitis A, using the National Inpatient Sample -- the largest population-based hospital inpatient database in the US, with annual data from about 1000 non-federal hospitals (see hepatitis A hospitalizations hepatol 2015 in dropbox, or HEPATOLOGY 2015;61:481-485). they looked at data from 2002 to 2011. results:

--hospitalizations for hep A decreased from 0.72/100K to 0.29/100K (which has been attributed to universal vaccination of kids 12-23 months old)

--BUT there was 

        --an increase in the mean age of the hospitalized patient (37.6 to 45.5 years), with increases in those 40-64 and >64 yo groups but decreases in those <18 and 18-39 yo

        --an increase in discharge comorbid medical conditions and other liver diseases

        --an increase in % of hospitalizations for hep A covered by Medicare (12.4% to 22.7%) -- reflecting the more advanced age of those hospitalized

        --extrapolating from the NIS data, there were 641-935 hospitalizations for hep A in 2011 (and, keep in mind, only a minority of those infected are likely to be hospitalized)

hepatitis A is still a common cause of viral acute hepatitis in the US. this study highlights the continuing problem, and really supports universal hepatitis A immunization (which is already recommended in kids, but only in certain groups in adults). this is especially an issue, since

--hepatitis A is more severe in older people (increased hospitalizations both related to increased severity of the liver disease plus increase in comorbid conditions with aging)

--many people come from and travel to endemic areas. in my experience, with many  of my patients coming from endemic areas, i usually check hepatitis A serology (which is positive in probably 80+%), then immunize if negative (because these nonimmune patients are likely to visit their home countries at some point and may be exposed there).

--there is a strong recommendation from the CDC to make sure that people with any chronic liver disease are immunized against hepatitis A (this is one of their "high risk" groups).  i think this recommendation is based on patients with chronic hepatitis B and C infections, who, if then infected with hepatitis A, are more susceptible to developing fulminant hepatitis (the data seem most compelling for hepatitis C -- see N Engl J Med 1998;338:286-90​).  however, the CDC guidelines are more general with "chronic liver disease" as an indication for vaccination, which i assume would apply to the burgeoning epidemic of non-alcoholic fatty liver disease, largely attributed to the huge numbers of people with obesity/insulin resistance, which also increases with age.

--those of us in high income, resource-rich countries are likely more susceptible to developing hepatitis A than we might expect, given that more foods are grown in resource-poor countries and imported (eg, the hepatitis A outbreak about a decade ago which was attributed to green onions imported from Mexico). also, with the increasing industrialization/consolidation of farming and with, for example, cattle in extremely crowded conditions and vast quantities of their excrement filling the streams which provide water to plants, there may be more food contamination, as with the e. coli outbreak a few years ago. these conditions make it more likely that there could be spread of food-related infections.

so, bottom line: i think it makes sense to make sure everyone is either vaccinated or naturally immune to hepatitis A infection.