Other Types of Viral Hepatitis

Many people, including health professionals, are sometimes confused about the distinctive features that separate the range of hepatitis viruses and the differences between them. It is common for people to mistake them for each other.

This often leads to situations where transmission risks are mistakenly assumed to exist. These mistakes cause unnecessary fear about exposure and may result in discrimination unless properly explained.

Apart from some of the differences in routes of transmission and long term consequences, two fundamental distinctions are made to describe how these viruses work in a person.

Either; they damage cells directly by invading them or replicating in a way that damages their hosts, thus destroying the structure or undermining their function. This is known as a cytopathic response.

Or; they provoke an immune system response, which in turn causes chemical imbalances that induce malign biochemical processes, known as an immunopathic response.

Hepatitis A

This virus was first identified in 1973 and is a cytopathic virus. It is transmitted by food or liquids exposed to faeces carrying the virus.

Shellfish is known to be at risk of carrying the hepatitis A virus. Areas where shellfish contamination might occur are where sewage is discharged into the sea.

Transmission may be prevented by maintaining rigourous standards of hygiene around activities of food handling and preparation.

An effective vaccine called Havrix™ has been developed and can offer many years of protection. People travelling to undeveloped countries are advised to get vaccinated.

Hepatitis A symptoms include diarrhoea, vomiting, fatigue, fever and jaundice. It causes an acute illness with symptoms that can develop quite quickly but is generally short-lived.

The virus is self-limiting and clears from the body shortly after infection.

Those at greatest risk of dying from this infection are frail elderly patients and people with chronic advanced liver disease, such as cirrhosis.

Exposure to hepatitis A and the ensuing infection can be prevented with an immune globulin shot if detected early. Otherwise there is no treatment and the infection must be allowed to run its course. Those that are infected and clear the virus naturally will have antibody protection against re-infection.

Avoid hepatitis A infection by:

Getting vaccinated

Wash hands thoroughly with soap and water after going to the toilet, before preparing food, and after handling soiled items such as nappies or condoms.

Avoid sharing the same food, eating utensils, cigarettes or drinks with people you suspect may have the virus.

 

Hepatitis B

Hepatitis B was first identified in 1965 and is an immunopathic virus. It is sometimes referred to as serum hepatitis because it is found in the blood and can be transmitted between people blood to blood.

It is the most prevalent hepatitis virus with global estimates of about 350 million people having the virus.

It is also found in other body fluids (semen, vaginal fluid, saliva and breast milk) and can be transmitted sexually or from mother to child at birth.

Transmission is prevented by blood screening, the use of sterile injecting equipment and practicing safe sex.

In New Zealand, a random community screening program in the 1990's revealed we have a particularly high prevalence of hepatitis B, especially amongst Maori and Pacific Island populations.

A National Strategy to address this high prevalence has been put in place, recommending screening of pregnant women for HBV antibodies and the HBV vaccination is now on the pre-school immunisation schedule.

There is an effective vaccine available which is actively contributing to a significantly lower global prevalence of HBV.

Acute HBV infection can cause quite severe symptoms but is rarely fatal.

Only about 5-7% of those infected fail to clear the virus naturally and become chronic carriers. However, babies who acquire HBV at birth or before the age of five have up to a 90% chance of becoming carriers.

Most carriers are healthy and only 10% of them will develop liver disease which may lead to cirrhosis and liver cancer.

To reduce the risk of hepatitis B transmission:

Vaccination.

Using condoms and lubricant every time for anal and vaginal sex.

Using new and sterile injecting equipment every time and ensure there is no blood contamination during injecting practices (e.g. on hands, tourniquets and surfaces).

Wear disposable gloves of prophylactic barrier when administering First Aid or cleaning up blood and body fluid spills.

Hepatitis D, E, F, G

Hepatitis D (HDV, Delta virus)

This virus requires the presence of HBV for its own replication and is therefore found exclusively in HBV patients. The two viruses may be contracted at the same time (co-infection), or an existing HBV carrier may become infected with HDV (super infection).

Both co infection and super infection tend to lead to more acute and chronic liver disease. It is uncommon in New Zealand.

Vaccination against hepatitis B protects against HDV as well.

HEPATITIS E (HEV)

Identified in 1990, this virus is transmitted via the faecal-oral route similar to HAV.

Most commonly, spread amongst humans by contaminated drinking water.

There is 35% chance that a pregnant women will die if infected with this virus.

Hepatitis E is rarely found in New Zealand. It is mostly confined to developing countries.

Work into developing a vaccine for HEV is ongoing.

HEPATITIS F

Originally though to exist but has since been disclaimed.

HEPATITIS G (HGV)

Three new flavivirus-like strains were identified in 1995. Collectively referred to as HGV (hepatitis G virus), the disparate strains are termed GBV (standing for GB virus) types A, B and C. They are most closely related to each other but are also similar to hepatitis C, and may even be a mutation of the same basic virus.

A PCR test is now available.

No antibody test has been developed yet

A survey of UK blood donors revealed a prevalence of 1.5%.

Some doctors have been quick to conclude that the virus is harmless, or at least not a major cause of liver disease.

GBV is thought to be more easily transmitted via sexual intercourse than hepatitis C.

Co-infection

A co-infection occurs when a person is infected with two or more viruses. The most common co-infection is with hepatitis C and hepatitis B. It is estimated that up to 5% of people with hepatitis C are chronically infected with hepatitis B.

HEPATITIS C AND HEPATITIS A

Individuals with chronic hepatitis C may be at an increased risk of developing fulminant hepatic failure and death if infected with HAV.

It is recommended that people with chronic hepatitis C who are planning to travel through developing countries get vaccinated against hepatitis A.

HEPATITIS C AND HEPATITIS B

Some studies have found that people infected with both hepatitis C and HBV have a more aggressive course of disease and are at increased risk of developing cirrhosis and decompensated liver disease.

It is further suggested there is an increased risk of developing heptocellular carcinoma (HCC) when a co-infection exists.

It is recommended people chronically infected with hepatitis C get vaccinated for HBV, especially high-risk groups for HBV infection i.e. injecting drug users (IDU).

HEPATITIS C AND HUMAN IMMUNODEFICIENCY VIRUS (HIV)

It seems a co infection of HIV and hepatitis C does not cause a more aggressive course of HIV-related disease.

Patients with reasonable CD4 counts may not have worse than average hepatitis C symptoms. However, more advanced cases of HIV and the onset of AIDS may be associated with severe liver damage and accelerated progression. The levels of fibrosis may be more advanced than the expected overall severity of liver inflammation, suggesting HIV directly augments liver damage caused by hepatitis C.

Patients with lowered CD4 counts have been found with higher levels of viremia in their blood. This demonstrates the importance of the immune system in countering hepatitis C. If the immune system is under attack, as is the case with HIV, then the damage may proceed more rapidly.

Some hepatitis C antibody markers can disappear when HIV is also present, a factor that may have caused some positive patients to have tested negative for hepatitis C with early tests.

With the advent of highly effective anti-HIV therapy known as HAART, HIV became potentially manageable long-term. AIDS and probable death is no longer inevitable. Therefore, a co-infection of hepatitis C and HIV means priority is given to the management of hepatitis C. The decreased immunity caused by the HIV infection can significantly increase the onset of liver disease. The aim of management is to avoid the hepatitis C infection becoming life-threatening.

People who may be at risk of HIV/hepatitis C co-infection:

People treated with blood products or who received blood prior to July 1992.

People who may have contracted HIV through unsafe injecting practices.

Men who have sex with men and also inject drugs.

Children born to co-infected mothers.

Heterosexual partners of co-infected individuals.

Other major points relating to co-infection:

It is estimated less than 1% of people with hepatitis C also have HIV.

For people who inject drugs and are HIV positive, the prevalence rates are as high as 90%.

In terms of the interaction between the two viruses most is known about the effect of HIV on hepatitis C, rather than the effect on hepatitis C on HIV.

The presence of HIV allows the increase of the amount of hepatitis C virus in the blood.

There is a direct correlation between transmission of hepatitis C and the degree of damage to the immune system (measured by CD4 count).

Being co-infected with HIV and hepatitis C means the risk of transmission is greater because hepatitis C viremia is generally higher given the suppressed immune system.

This means both sexual transmission and vertical transmission are more likely to occur. With HIV present the accuracy of antibody testing is challenged. With those possibly co-infected a PCR test should be the test of choice.

DISEASE PROGRESSION IN CO-INFECTED INDIVIDUALS

Studies have revealed liver disease progresses significantly faster for people with chronic hepatitis C and HIV.

They are also at higher risk of developing cirrhosis and liver failure. This is undoubtedly the result of the damaged immune system caused by HIV.

Co-infection with HIV and hepatitis C is particularly common among patients with haemophilia exposed to blood products.

There is abundant high quality evidence to suggest hepatitis C represents a major threat to morbidity and mortality for patients with co-infection and, as such, there are significant gains for patients with HIV should they have their hepatitis C infection eradicated.

Initial concern over interaction between ribavirin and highly active antiretroviral therapy (HAART) has proven to be unfounded. Both treatment responses and side effect profiles are similar in patients with or without HIV co-infection.

Due to limited experience, it is advisable for patients with HIV co-infection to be treated at specialist clinics where their HIV and hepatitis C can be managed using a joint approach.