It seems that each week brings new warnings about hepatitis outbreaks across the country, urging everyone from hospital patients to restaurant customers to get tested. But how likely is it that “at-risk” individuals will actually contract the virus?

Since the start of 2013, Hep has reported over a dozen news stories about potential scares and outbreaks for hepatitis A, B and C. The incidents span from unsanitary dentists who potentially exposed thousands of patients at their practices, to dessert chefs who didn’t know they had the virus but then scared entire New York City neighborhoods thanks to the resulting “get tested” public service campaigns.

In some cases, these alerts are the result of an actual infection—outbreaks of the hepatitis virus that push many into emergency treatment. In other instances, the announcements are simply obligatory warnings, which eventually pass without an actual viral incident.

Ever been implicated in a mass hepatitis warning? Here, we break down the ABCs of determining your real risk for hepatitis infection during an official alert or outbreak:

Hepatitis A
Outbreaks of the hepatitis A virus (HAV) in the news are usually associated with food-borne transmissions. Hep A spreads primarily through fecal-oral or close personal contact with an infected person (trace amounts of fecal matter can contaminate food, which is then eaten). In outbreak terms, this means anyone who unknowingly has hep A and handles food at a restaurant or in the food-packaging industry can potentially expose thousands of customers to the virus relatively easily.

In 2009, nearly 21,000 new hepatitis A infections were reported in the United States, or a rate of 0.5 per 100,000 in the population.

Hep A is actually the sixth most commonly reported infectious disease in the country, and experts suggest that the majority of HAV cases remain unreported. For instance, the Centers for Disease Control and Prevention (CDC) estimates that more than 90,000 Americans are actually infected with hepatitis A each year. Also, for unknown reasons, western regions of the United States report substantially higher infection rates than the rest of the country.

Symptoms of hep A include fatigue, fever, nausea, diarrhea, vomiting, weight loss, joint pain and jaundice (yellowing of the skin, whites of eyes and under the fingernails). Symptoms can typically last from a week to a month, but not everyone experiences them. Fortunately, since 1995, when vaccines for HAV were made available in the United States, the rates of infection have gradually declined. Most children born since the ’90s have been immunized against it. Thanks to improved vaccines and awareness of proper employee hand-washing procedures, between 2006 and 2010, hep A rates have actually gone down 53 percent.

Hepatitis A is also relatively easy to cure, which helps bring down infection stats during outbreaks. If taken within 14 days of exposure to the virus, immune globulin shots are an almost surefire way to cure a person infected with hepatitis A. Also, after getting HAV once, it is impossible to contract the virus again.

To date, the yearly odds of being infected with hepatitis A in the United States are one in 83,330.

Hepatitis B
The hepatitis B virus (HBV) is transmitted most commonly through exposure to infected blood or mucous. It is also 50 to 100 times easier to transmit sexually than HIV. The CDC estimates that 35,000 new HBV infections occurred in 2010. But in order to calculate our real risk during an outbreak, it’s important to look into the reasons many of these infections initially occurred.

Most alerts about potential hep B outbreaks focus on medical facilities—hospitals or dental clinics where invasive instruments have been incorrectly sanitized or mistakenly re-used on patients. However, it’s important to note that between 2008 and 2012, CDC statistics show that among 100,000 people considered “at-risk” for acquiring the virus in hospital settings, only 19 hepatitis B cases were actually confirmed.

In fact, it is estimated that more than 94 percent of all new hepatitis B infections occur in non-hospital settings (such as when injection drug users share needles). Simply refraining from risky behavior automatically reduces your outbreak risk to almost zero.

Of those actually infected at hospital facilities, most hepatitis B infections came from cross-contaminated finger-stick devices, as well as from re-used syringes or blood glucose meters. The CDC data suggests that the chance for being infected with HBV after an infected needle-stick injury is between 6 and 30 percent. 

Fortunately, hepatitis B vaccines have been available in the United States since 1981. Most infants today are vaccinated against the virus at birth. And in nine out of 10 cases, the body will naturally clear HBV in three to six months. The symptoms of hep B are similar to those of hep A, and chronic HBV infections are possible.

Overall, the annual risk of acquiring a hepatitis B virus in the United States is about one in 62,500.

Hepatitis C
The hepatitis C virus (HCV) is transmitted primarily through the blood. It is the most common blood-borne infection in the United States, with an estimated 3.2 million people living with hep C nationwide.

Before the 1990s, the most common way to contract HCV was through a simple blood transfusion. However, since testing for the virus has become a reliable standard in the medical community, which means that infected blood and organs can be weeded out, the risk for getting hepatitis C through transfused blood products in the United States is considered to be less than one in 2 million.

In 2010, the CDC reported 17,000 new HCV infections. This means the rate of hep C in America has actually been increasing. However, despite the news stories of unsanitary doctors and needle re-use tied to HCV outbreaks, the majority of hep C infections also occur outside of hospital or medical settings.

For example, between 2008 and 2012, more than 88,000 patients were notified for screening as a result of their potential hepatitis C exposure in a hospital setting. In total, only 16 hep C infections were confirmed. Sexual transmission is considered low, but it has been recorded, especially among men who have sex with men.

If you are in fact stuck by an infected syringe or needle at a medical clinic, the chances of contracting hep C are still only about 1.8 percent. Also, studies show that 15 to 25 percent of people, for unknown reasons, can actually clear HCV from their bodies without undergoing any treatment.

Unfortunately, there is no vaccine for hepatitis C and over 90 percent of those infected with the virus face chronic liver disease (until this stage, symptoms are often mild and vague, such as feeling “blah”). However, drug advancements are pushing up treatment success rates. HCV’s landscape is expected to change dramatically over the next few years.

Overall, the yearly odds of being infected with hepatitis C in the United States are about one in 333,300.

The moral of the story? In the unlikely event that you are included in an “at-risk” population of a hepatitis outbreak at a restaurant, hospital or other care facility, you’ll probably be fine. And even if you do contract HAV, HBV or HCV there are a variety of options that can help you treat and cure even the toughest of diagnoses.

For a full statistical report on recent hepatitis outbreaks from the CDC, click here.