HEPATITIS
The hepatitis viruses are a group of DNA and RNA viruses that produce symptoms associated with inflammation of the liver. Patients infected may range from asymptomatic to experiencing flu-like symptoms only. In addition, fever, nausea, joint muscle pain, jaundice, and hepatomegaly along with abdominal pain can result from infection with one of the hepatitis viruses. The virus also can create an acute or chronic infection. Usually following these early symptoms or the asymptomatic period, the patient may recover or may go on to develop chronic liver dysfunction.
Hepatitis A
Hepatitis A virus is an enteric virus that is a member of the Picornavirus family along with Coxsackie viruses and poliovirus. Previously known as infectious hepatitis, hepatitis A has been detected in humans for centuries. It causes acute hepatitis, often transmitted by oral-fecal contamination and having an incubation period of approximately 30 days. Typically, constitutional symptoms are present and jaundice may occur. Drug therapy that the dentist may encounter in a patient being treated for hepatitis A would primarily include immunoglobulin. Hepatitis A vaccine (inactivated) is an FDA-approved vaccine indicated in the prevention of contracting hepatitis A in exposed or high-risk individuals. Candidates at high risk for HAV infection include persons traveling internationally to highly endemic areas, individuals with chronic liver disease, individuals engaging in high-risk sexual behavior, illicit drug users, persons with high-risk occupational exposure, hemophiliacs or other persons receiving blood products, pediatric populations, and food handlers in high-risk environments. Two formulations of hepatitis A vaccine are available, Havrix® and VAQTA®. Each is administered as an injection in the deltoid region and both are available in pediatric and adult dosages.
Hepatitis B
Hepatitis B virus is previously known as serum hepatitis and has particular trophism for liver cells. Hepatitis B virus causes both acute and chronic disease in susceptible patients. The incubation period is often long and the diagnosis might be made by serologic markers even in the absence of symptoms. No drug therapy for acute hepatitis B is known; however, chronic hepatitis has recently been successfully treated with alfa-interferon. There are vaccines available for hepatitis A and B. See Hepatitis A Inactivated and Hepatitis B (Recombinant) Vaccine (Twinrex®)
Hepatitis C
Hepatitis C virus was described in 1988 and has been formerly classified as non-A/non-B. It is clear that hepatitis C represents a high percentage of the transfusion-associated hepatitis that is seen. Treatment of acute hepatitis C infection is generally supportive. Interferon Alfa-2a therapy has been used with some success recently and interferon-alfa may be beneficial with hepatitis C related chronic hepatitis.
Hepatitis D
Hepatitis D, previously known as the delta agent, is a virus that is incomplete in that it requires previous infection with hepatitis B in order to be manifested. Currently, no antiviral therapy is effective against hepatitis D.
Hepatitis E
Hepatitis E virus is an RNA virus that represents a proportion of the previously classified non-A/non-B diagnoses. There is currently no antiviral therapy against hepatitis E.
Hepatitis F
Hepatitis F, as was mentioned, remains a diagnosis of exclusion. There are no known immunological tests available for identification of hepatitis F at present and currently the Centers for Disease Control have not come out with specific guidelines or recommendations. It is thought, however, that hepatitis F is a bloodborne virus and it has been used as a diagnosis in several cases of post-transfusion hepatitis.
Hepatitis G
Hepatitis G virus (HGV) is the newest hepatitis and is also assumed to be a bloodborne virus. Similar in family to hepatitis C, it is thought to occur concomitantly with hepatitis C and appears to be even more prevalent in some blood donors than hepatitis C. Occupational transmission of HGV is currently under study (see the references for updated information) and currently there are no specific CDC recommendations for postexposure to an HGV individual as the testing for identification remains experimental.
TYPES OF HEPATITIS
VIRUS
|
Features |
A |
B |
C |
D |
E |
F |
G |
|
Incubation Period |
2-6 wks |
8-24 wks |
2-52 wks |
3-13 wks |
3-6 wks |
Unknown |
Unknown |
|
Onset |
Abrupt |
Insidious |
Insidious |
Abrupt |
Abrupt |
Insidious |
Insidious |
|
Symptoms |
|
|
|
|
|
|
|
|
Jaundice |
Adults: 70% to 80%; Children: 10% |
25% |
25% |
Varies |
Unknown |
Unknown |
Unknown |
|
Asymptomatic patients |
Adults: 50%; Children: Most |
~75% |
~75% |
Rare |
Rare |
Common |
Common |
|
Routes of Transmission |
|||||||
|
Fecal/Oral |
Yes |
No |
No |
No |
Yes |
Unknown |
Unknown |
|
Parenteral |
Rare |
Yes |
Yes |
Yes |
No |
|
|
|
Sexual |
No |
Yes |
Possible |
Yes |
No |
|
|
|
Perinatal |
No |
Yes |
Possible |
Possible |
No |
|
|
|
Water/Food |
Yes |
No |
No |
No |
Yes |
|
|
|
Sequelae (% of patients) |
|||||||
|
Chronic state |
No |
Adults: 6% to 10%; Children: 25% to 50%; Infants: 70% to 90% |
>75% |
10% to 15% |
No |
Unknown |
Likely |
|
Case-Fatality Rate |
0.6% |
1.4% |
1% to 2% |
30% |
1% to 2% Pregnant women: 20% |
Unknown |
Unknown |