Hepatitis A Virus (HAV)
Hepatitis A Virus (HAV) was once a relatively common source of infection and disease in the United States, especially in the western half of the United States, with a handful of western states accounting for almost all infections. This profile radically changed with the introduction of the two dose Hepatitis A vaccine in 1995 which has greatly reduced the number of infections and illnesses associated with HAV in the United States, although because immunization isn’t universal, although by every rational measure it should be, cases continue to occur.
HAV usually causes a mild illness that resolves on its own almost all of time, which is a good thing since there is no specific treatment for the infection beyond supportive care to minimize the worst of the symptoms, including vomiting and fluid loss resulting in dehydration in the worst cases. Many people never know they were infected until routine blood tests performed for other reasons reveals the infection itself or lingering liver damage that causes a healthcare provider to probe for potential causes, which in the case of liver dysfunction almost always includes screening for the hepatitis viruses, including HAV.
HAV is transmitted exclusively through the fecal-oral route, meaning that an infected person at some point and time orally consumed fecal material from an infected person. For most people, this is not something they would knowingly or willingly do, but transmission occurs because even microscopic fecal particles are more than large enough to carry an adequate number of HAV to cause infection because the HAV itself is smaller than a single human cell. The fecal material consumed can’t be smelled, seen, or tasted, but it is still present in an adequate amount. This risk is why people known to be actively infected with HAV are legally prohibited from employment in the food service industry and also why there are signs in every food service establishment restroom reminding employees of their legal obligation to wash their hands before returning to work after visiting the restroom. While these measures help, they are, of course, nowhere near as effective as vaccination in the prevention of HAV.
The HAV vaccine is very effective and very safe as it has absolutely zero ability to cause infection itself. Practically anyone is a candidate for the vaccine and anyone who hasn’t been immunized, especially those who were beyond the usual age of vaccination when the vaccine became available, should discuss being vaccinated with their healthcare provider as a part of routine preventative care. While HAV infections are at their lowest in 40 years, there are still approximately 25,000 known cases, and without doubt many more that go unreported because people do not know they are infected either because they experience no, or mild, symptoms, or because for some other reason they don’t seek medical care and testing. The actual number of cases could easily be double that which is reported.
HAV and Travel
Anyone planning travel outside the United States or Western Europe should seriously consider being vaccinated if they have not already been or if they have not already had the natural infection, either of which will effectively prevent future infections. Contaminated food and water are very common sources of infection throughout the developing world. There are many reliable and accurate sources of information about preventing infections while travelling, so repeating such information doesn’t seem important.
HAV in Daycare and the Home Setting
However, a common risk factor that many people may not be aware of is either having a child in daycare, working in daycare, or being the secondary contact of a child in daycare. Daycare contacts account for at least 8% of all known cases, while other household contact with an infected person accounts for almost 15% of reported cases. That adds up to over 20% of cases being transmitted either at home and/or through an association with children in daycare settings, and that can include grandparents and other caregivers who were well beyond the usual age of vaccination when the HAV vaccine became available in 1995.