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Update on viral hepatitis

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VOL: 101, ISSUE: 20, PAGE NO: 55

Angela Narbey, RGN, is clinical nurse specialist, liver disease, Homerton University Hospital NHS Foundation Trust, London

Angela Narbey, RGN, is clinical nurse specialist, liver disease, Homerton University Hospital NHS Foundation Trust, London

The word 'hepatitis' means inflammation of the liver. Viral hepatitis is caused by a group of viruses that attack the liver specifically. There are three potential stages of hepatitis: acute, chronic and fulminant (Desmet, 1994). Inflammation of the liver that lasts for six months or less is classed as acute. If it is not resolved after six months it is described as chronic. Although it is not always possible to predict the progression of chronic hepatitis, patients in whom it has developed are at risk of fibrosis (scarring), which can progress to cirrhosis (permanent scarring) of the liver. Cirrhosis is associated with a number of complications, including hepatocellular carcinoma.

Fulminant hepatitis is a particularly serious form of acute hepatitis that causes liver failure, usually within eight weeks of the onset of symptoms.

Transmission routes
The faecal-oral route

The modes of transmission of hepatitis vary according to individual viruses.

A virus transmitted by the faecal-oral route has been shed in the stool of an infected person and is transmitted to another person when that person eats a small amount of the infected stool. This may happen when food has been prepared by an infected person who has not washed his/her hands adequately. Some outbreaks are also caused by drinking contaminated water; for example, during swimming, eating food that has been washed in contaminated water or ingesting seafood that has been caught in contaminated water. It can also be spread by the faecal-oral route from one sexual partner who is infected to another.

The parenteral route

Viruses transmitted by this route enter the body by any route other than the intestinal tract. This may be by coming into contact with contaminated blood, following sexual contact (when the seminal or vaginal fluids contain virus), and by vertical transmission (from mother to child during pregnancy and childbirth).

Signs and symptoms
The symptoms associated with viral hepatitis are similar for all types of hepatitis. Frequently, patients are free of symptoms but they may have some, or all, of those listed in Box 1.

Symptoms associated with hepatitis A or E will improve as the disease resolves, but patients with other types of hepatitis may experience symptoms as a consequence of a chronic infection.

Some patients are diagnosed with viral hepatitis after presenting with extrahepatic manifestations. The symptoms, which may not appear to be linked to hepatitis, can include vasculitis, glomerulonephritis or polyarteritis nodosa. These are known collectively as immune-modulated diseases and occur when the body's immune system mounts an attack on the virus. There is no correlation between the severity of these diseases and the severity of the hepatitis itself.

Hepatitis A
Before the hepatitis A virus (HAV) was identified in 1973, this form of disease was known as infectious hepatitis because of its extremely high rate of cross-infection. The virus is transmitted via the faecal-oral route.

HAV does not cause chronic hepatitis or cause complications such as cirrhosis and liver cancers, but in rare cases it can cause fulminant hepatitis. A large number of people who contract HAV have mild symptoms that resolve quickly, or have no symptoms. The treatment is conservative, but some patients need hospitalisation if they are particularly unwell. These patients should be advised to avoid alcohol, which could prolong the symptoms of nausea and fatigue.

HAV may be more serious if it is contracted when the individual is already infected with another form of viral hepatitis, usually B or C (Keefe, 1995). Anyone who is chronically infected with either of these viruses should be vaccinated against HAV.

Diagnosis and treatment

During an outbreak of hepatitis A, certain groups of people are at higher risk, including men who have sex with men, injecting drug-users and those with chronic liver disease (Villano et al, 1997). In these cases, vaccination is recommended, as is special attention to hand-washing. Hepatitis A is confirmed with specific hepatitis A serology.

Hepatitis E
Transmission and treatment of hepatitis E (HEV) is identical to that for hepatitis A. The outcomes are also the same, except for pregnant women. There is up to 20 per cent mortality rate in this group and unfortunately there is no vaccine available to prevent the spread of this form of hepatitis (World Health Organization, 2004). As HEV is spread mainly by contaminated water, the only way to prevent infection with this virus is to ensure a clean water supply. HEV outbreaks occur mainly in Asia and the Indian sub-continent.

Hepatitis B
Hepatitis B (HBV) is transmitted parenterally in one of three ways:

- Blood or blood products (including intravenous drug use);

- Sexual contact;

- Vertical transmission.

It can also be transmitted via the sharing of personal items such as toothbrushes and razors and from tattooing and piercing with inadequately sterilised equipment.

There are around 400 million people worldwide infected with the hepatitis B virus and it is endemic in some areas, including South East Asia, China, Africa and the Middle East (WHO, 2000). HBV is an acute infection and can progress to one that is chronic.

Acute HBV

If HBV is contracted in adulthood, the resulting illness is usually acute, as an adult's immune system is usually strong enough to overcome the virus by developing antibodies against it and achieving immunity.

Signs and symptoms of acute HBV appear between 15 and 180 days after initial infection (the incubation period). Jaundice may occur after the other symptoms disappear.

Because symptoms sometimes appear vague and are often described as being 'flu-like', many patients seek a consultation with their doctor only if they develop jaundice, rashes, severe muscle aches and pains, or right upper quadrant pain.

Chronic HBV

Because the immune system of young people is more immature than that of adults', the chances of their developing a chronic form of HBV are higher. Thus only 1-5 per cent of adults with acute HBV will develop the chronic form. If children have been infected between the ages of one and four years, 30-50 per cent will develop chronic HBV, while those who contracted HBV in infancy - by vertical transmission, for instance - have a 90 per cent chance of developing chronic HBV (WHO, 2000).

As with all of the hepatitis viruses, chronic HBV can be either 'silent' or carry with it non-specific symptoms. Because of this, some patients are diagnosed with chronic hepatitis B when they have already progressed 'silently' to liver cirrhosis.

Diagnosis of chronic HBV

Patients with chronic HBV have been described as chronic 'healthy' carriers or chronic 'infectious' carriers.

'Chronic healthy' carriers have certain serology markers (Table 1), and have no symptoms of chronic hepatitis. They are regarded as a 'low transmission risk' and are unlikely to develop any complications of liver disease. However, these patients are at a higher risk of developing cirrhosis and liver cancer than the general population and should have annual liver function and alpha-fetoprotein tests and be referred to specialist services if there is any sign that their disease is progressing. (Alpha-fetoprotein is a marker for hepatocellular carcinoma.)

'Chronic 'infectious' carriers have a different set of HBV serological markers (Table 1), and may or may not have abnormal liver function tests. Again, they may be asymptomatic. These patients are classed as a high transmission risk as they have active circulating virus. If their liver function is normal with low or no HBV replication, a six- monthly review is indicated in a specialist clinic.

If, however, liver function is abnormal and a blood test for HBV DNA is positive, further investigations need to be performed, including a liver biopsy in order to establish the progression of the disease and determine the best course of treatment.

Another form of chronic hepatitis B, known as HBV pre-core mutant, has slightly different serological markers owing to a mutation in the virus. Patients with this form of hepatitis need to be investigated in the same way as those who are 'high-risk' carriers.

Vaccination

An effective course of vaccinations is available for the prevention of hepatitis B. These should be offered to anyone at high risk of contracting HBV, including household contacts of HBV positive patients, intravenous drug-users, babies born to HBV-positive mothers, health care workers and men who have sex with men.

Treatment

Several licensed treatments for chronic hepatitis B are available: alpha interferon, lamivudine, and adefovir dipivoxil. The outcome of the patient's medical assessment will determine which of these will be prescribed.

Hepatitis D
Hepatitis D (HDV) is known as a 'passenger' virus as it causes illness only in the presence of hepatitis B. It is transmitted in the same way as HBV. If it is contracted at the same time as HBV is it called a co-infection; if it is contracted at a different time it is called a 'super-infection' (Lin et al, 1989).

Co-infected patients will eliminate both HBV and HDV; around 90 per cent avoid developing chronic infection. In contrast, around 90 per cent of individuals will develop chronic hepatitis if they are super-infected (WHO, 2001).

Hepatitis C
According to the World Health Organization (WHO, 2000a), 170 million individuals worldwide are chronically infected with hepatitis C (HCV). As with HBV, HCV cannot be transmitted by casual contact. Transmission in the majority of cases is by the 'blood to blood' parenteral route. HCV differs from HBV in that sexual transmission, although not unknown, is uncommon (between three and five per cent) (Tibbs, 1995).

As all blood and blood products in this country are now screened for HCV, the majority of infections result from intravenous drug use. The virus continues to be spread by the shared use of drug preparation equipment. Intranasal use of drugs, including cocaine and amphetamines, cannot be ruled out as a route of transmission as damage can occur to the nasal mucosa as a result of drug use and contaminated drug-taking equipment may be shared. However, this link is not proven.

As with HBV, the sharing of personal items such as razors and toothbrushes, which may draw tiny amounts of blood, also carry a transmission risk.

Diagnosis and treatment

It is hard to diagnose HCV on symptoms alone. Many diagnoses in the UK are incidental and based on risk factors. Chronic infection is established with a test known as HCV RNA (also known as HCV PCR (polymerase chain reaction).

Around 15-20 per cent of people who have a positive test for the HCV antibody will have a negative HCV RNA, showing an immune response, which results in natural clearance of the virus at the acute stage (WHO, 2000a).

The prognosis for chronic HCV is influenced by three main factors: age at acquisition, gender, and alcohol consumption. A female under 40 years of age who does not drink alcohol is likely to have a better prognosis than an older male with a high alcohol intake.

Patients with HCV should be referred to a specialist unit for assessment and treatment. The current licensed treatment is a combination of interferon and ribavirin. These are given for 24 or 48 weeks, according to the HCV genotype. There is no vaccination available at present for the prevention of HCV.

Conclusion
Although it is well known that all types of hepatitis are a significant health risk, it is important to bear in mind that transmission is preventable if standard infection control precautions are always applied by those working in a health care environment.

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