The word hepatitis has Greek origins dating
back to the early 1700s, with hêpar meaning
“liver” and -itis meaning “inflammation”.
Hepatitis can sometimes be caused by heavy
alcohol use or certain medical conditions
and medications, but most commonly, hepatitis
is caused by a virus.
There are five main strains of the hepatitis
virus, which we call A, B, C, D, and E. While
all five cause liver disease, there are some
major differences between them, including
the way that they spread, the severity and
timing of illness, prevention tactics, and
their geographical distribution.
Thinking globally, the World Health Organization
estimates that 325 million people live with
hepatitis B and/or C worldwide, and for many
of them, testing and treatment aren’t easily accessible.
Within the United States, the most common
hepatitis viruses are A, B and C. Hepatitis
A is typically a short-term infection and
does not become chronic, while hepatitis B
and C begin as short-term, acute infections
that, in some people, lead to chronic disease
and long-term liver problems.
Finally, there are vaccines available that
prevent hepatitis A and B, while there is
no vaccine for hepatitis C.
Let’s dig into hepatitis A, which is sometimes
called infectious hepatitis.
This disease is caused by a picornavirus, which is a small RNA virus with a naked capsid structure.
Once the virus is ingested, it enters the
bloodstream through the oropharynx or the
epithelial lining of the intestines, and travels
to the liver.
After replicating in liver cells, the virus
is released into the bile and then into the stool.
In fact, a large quantity of the virus is shed into the stool about 10 days before symptoms appear.
Hepatitis A is spread by the fecal-oral route
and has an incubation period of approximately
1 month.
After that time, icteric symptoms begin abruptly,
meaning jaundice, which is a yellowing of
the skin or whites of the eyes.
The hepatitis A virus is found in the blood
and stool of people who are infected and is
spread when someone ingests even microscopic
amounts of the virus.
The disease can be spread from close, personal
contact with an infected person or ingesting
contaminated food or drink, and is so contagious
that people can spread the virus before they
even feel sick.
The virus can also survive in fresh and salt
water for months at a time, so any raw or
improperly treated sewage can taint the water
supply.
As a result, shellfish -- especially oysters,
mussels, and clams -- can be significant sources
of the virus during an epidemic.
Hepatitis A is typically a mild disease, especially
in children.
In fact, most cases in children are asymptomatic
altogether.
For people that do experience symptoms, the
disease usually begins 15 to 40 days after
exposure with nausea, fever, fatigue, abdominal
pain, or lack of appetite.
Then symptoms intensify for 4 to 6 days before
the jaundice phase begins.
70 to 80% of adults experience jaundice, while
just 10% of children do, and 99% of cases
end with a complete recovery.
For the most part, diagnosis of hepatitis
A is made from the time course of symptoms,
identification of a known source, and/or blood
tests for antibodies to the virus.
Because of the long incubation time of several
weeks, it can be difficult to identify the
source of infection.
Daycare settings are a major hot spot for
hepatitis A transmission, and in general,
poor hygienic conditions and overcrowding can increase the risk of hepatitis A transmission as well.
Luckily, once antibodies are developed, immunity
against reinfection is lifelong.
To reduce the spread of hepatitis A, CDC recommends
vaccination with the hepatitis A vaccine and
frequent hand washing, especially if you’re doing daily diaper changes or routinely preparing food.
