1. Hepatitis A
What is the infectious agent (pathogen) that causes this infectious
disease? For example, the name of the bacteria, virus, or parasite
Sewage includes wash water, water from toilets, and storm run-off. These fluids may carry the
pathogens for many waterborne diseases, including giardiasis and hepatitis A; therefore, to
ensure public safety the U.S. government (and the governments of other developed countries)
requires that sewage be treated to eliminate pathogens. The minimal acceptable level of
treatment involves collection and sedimentation of sewage waters, separating solid matter
(sludge) from the liquid (effluent) portion of sewage. The effluent is chlorinated to kill pathogens
before it is released to rivers or lakes. The sludge is burned or dumped.
More advanced methods of treatment use a secondary treatment following this primary treatment.
The effluent is transferred to tanks containing a population of microorganisms that decompose
more than 90 percent of the organic wastes and eliminate pathogens by competition (this is
another example of the important role of microorganisms in preventing disease). The resulting
effluent is chlorinated before it is released to the environment. Some sewage treatment plants
include a tertiary treatment that involves additional chemicals that also eliminate pathogens.
How is this infectious agent transmitted through food or water?
What is an example of a real life outbreak of this food borne illness in the
United States? Hepatitis A is the only common vaccine-preventable food borne disease
in the United States (Fiore, 2004). It is one of five human hepatitis viruses that primarily
infect the human liver and cause human illness. Unlike hepatitis B and C, hepatitis A
doesn’t develop into chronic hepatitis or cirrhosis, which is both potentially fatal
conditions; however, infection with the hepatitis A virus (HAV) can still lead to acute
liver failure and death.
Hepatitis A is much more common in countries with underdeveloped sanitation systems.
This includes most of the world: an increased transmission rate is seen in all countries
other than the United States, Canada, Japan, Australia, New Zealand, and the countries of
Western Europe. Nevertheless, it continues to occur in the United States; approximately
one-third of the population has been previously infected with HAV (Fiore, 2004; Centers
for Disease Control and Prevention [CDC], 2009a). Each year, approximately 30,000 to
50,000 cases of hepatitis A occur in the United States. Historically, acute hepatitis A rates
have varied cyclically, with nationwide increases every 10 to 15 years. The national rate
of HAV infections has declined steadily since the last peak in 1995. Although the
national incidence (1.0 case per 100,000 populations) of hepatitis A was the lowest ever
recorded in 2007, it is estimated that 25,000 new infections occurred that year after
asymptomatic infection and underreporting were taken into account. Although the rates
of HAV infection have declined over the years, rates are twice as high among American
Indians/Alaskan Natives (AIAN) and Hispanics compared to non-Hispanic Whites in the

2. United States (Rawls & Vega, 2005). Rates among AIAN have decreased dramatically,
though, coincident with the implementation of routine hepatitis A vaccination of AIAN
children, both in urban and rural communities (Bialek et al., 2004).
In 2007, a total of 2,979 acute symptomatic cases of hepatitis A were reported (CDC,
2009b). Among the 1,047 cases with available information regarding food borne or
waterborne exposure, 6.5% were found to be food borne or waterborne related, about
one-third the proportion reported at the last peak in 2003. However, 2500 cases remained
without known risk factors.
What are the clinical symptoms, duration of the disease, and treatment if
any?
Children infected with hepatitis A virus often have no symptoms. Most adults have
symptoms that develop over several days. Symptoms include:
• Fever
• Tiredness
• Loss of appetite
• Nausea, vomiting, or stomach ache
• Dark urine
• Jaundice (yellowing of the skin and whites of the eyes)
If symptoms do occur, they usually last less than 2 months, although 10% to 15% of
persons have prolonged or relapsing disease that can last up to 6 months. Once a clinical
infection is established, there is no specific treatment for hepatitis A. Affected
individuals generally suffer from loss of appetite, so the main concern is ensuring a
patient receives adequate nutrition and avoids permanent liver damage. An individual’s
perception of the severity of fatigue or malaise is the best determinant of the need for
rest.
Treatment of those suffering from fulminant hepatic failure depends largely on the
affected person’s status. Those who have not become encephalopathic generally undergo
an intense course of supportive treatment. But for those whose liver failure is so
complete that it has lead to encephalopathy or cerebral edema, timely liver
transplantation is often the only option. Unfortunately, many individuals with irreversible
liver failure do not receive a transplant because of contraindications or the unavailability
of donor livers
What steps can be taken to prevent further outbreaks? Include

3. individual as well as environmental precautions and methods.
1. Hepatitis A vaccine provides long-term protection. The vaccine is licensed for use in
persons 2 years of age and older. It must be given before exposure to the hepatitis A
virus. Two shots are needed for long-term protection.
Hepatitis A vaccine is recommended for:
• Persons who travel to or work in areas where hepatitis A is common. The first
dose should be given at least 4 weeks before travel.
• Children living in communities with high rates of hepatitis A, such as Alaska
native villages, American Indian reservations, and Pacific Islander and some
religious communities
• Men who have sex with men
• Persons who use street drugs
• Persons with chronic liver disease
• Persons with clotting factor disorders, such as hemophilia
• Persons who work with animals infected with hepatitis A virus or who work with
hepatitis A virus in a research setting
The vaccine is not recommended for children under age 2. Immune globulin is
recommended in this age group for short-term protection.
2. To prevent person-to-person spread, good personal hygiene and proper sanitation are
important. Always wash hands with soap and warm water after using the toilet and
changing a diaper and before eating or preparing food.
3. Immune globulin is recommended for short-term prevention against hepatitis A in all
age groups. Immune globulin is a sterile preparation of antibodies. Immune globulin
shots can lower the risk of disease in close contacts, household members, and sex
partners of infected persons. However, immune globulin must be given within 2 weeks of
exposure to hepatitis A virus, and protection lasts only 3 to 5 months, depending on the
dosage. Immune globulin is currently in short supply.