ABC of Safety in the Biological Sciences

 

 

HEPATITIS (Viral)

There at least seven types of hepatitis caused by different viruses:⁹⁵

• Hepatitis A
• Hepatitis B
• Hepatitis C
• Hepatitis D (co-exists only with hepatitis B).
• Hepatitis E
• For Hepatitis F see Hepatitis C.
• Hepatitis G

Hepatitis A:

This virus is excreted in faeces and can spread through poor personal hygiene. Hepatitis A can be contracted directly through contact with an infected person or by ingestion of contaminated water or food particularly clams, mussels or oysters. Symptoms may include fatigue, poor appetite, fever and vomiting. Urine may become darker in colour after which jaundice may appear.

Those at risk from acquiring hepatitis A are persons exposed to unsanitary conditions where contaminated food or water is consumed. A fever occurs in 60% of cases, however, the disease generally resolves without long term ill effects.

Hepatitis B:

Hepatitis B is a double stranded DNA virus found in all body fluids of infected persons including blood, semen, saliva and urine. Infection is by intimate contact with an infected person or contact with a body fluid infected with the virus. Hepatitis B virus can remain viable on dried surfaces or in syringes, at room temperature, for at least seven days with infection occurring from amounts as small as 0.04 µl.⁹⁶ The use of a contaminated needle, such as those used in tattooing, ear piercing, acupuncture or medical and dental procedures also offer a source of infection. The virus can be transmitted from mother to infant at the time of delivery. Those who have intimate contact with an infected person or their body fluid (a splash to the eye is sufficient to cause infection) or an instrument used by that person which can pierce skin are at risk from acquiring hepatitis B.

Hepatitis B can have a broad range of clinical symptoms which may include an initial rash and accompanying arthritis followed by malaise, anorexia, nausea, vomiting and fever. This is followed by darkened urine and liver pain. Usually 85 to 90% of infected persons fully recover, however 10 to 15% develop chronic liver disease which may progress to neoplasia. Death occurs in 1 to 2% of cases.

A vaccine to prevent Hepatitis B has been available for several years and is recommended for all 'at risk' staff.

Hepatitis C (Also called Non A, Non B Hepatitis):

More than one agent may be responsible for this form of hepatitis. Recently, viruses designated Hepatitis E and Hepatitis F, which were hitherto classified as non A, non B, have been identified. To date laboratory tests are unable to identify the specific causative agent for all forms of Non A, Non B Hepatitis. Spread of the infection appears to be through close contact with an infected person but positive proof cannot be obtained until the virus responsible can be identified.

Those most at risk of acquiring Hepatitis C (non A or non B hepatitis) appear to be those who have received a blood transfusion or blood products. It has recently been determined that hepatitis C can be transmitted by needlestick injury or inoculation of an open wound^{96 97} or sexual contact.⁹⁸ This form of hepatitis carries a 20 to 40% risk of developing into lifelong liver disease.

Hepatitis D:

Hepatitis D virus is a defective negative-strand RNA virus which cannot propagate alone. It requires the presence of another virus to initiate an infection. It acts together with Hepatitis B to produce a more severe form of infection than that produced by Hepatitis B alone. Spread of Hepatitis D virus occurs in the same way as the Hepatitis B virus.⁹⁷

Those at risk of acquiring hepatitis D are persons already infected with Hepatitis B or persons who are carriers of Hepatitis B.

Hepatitis D is the most severe form of hepatitis. Few infected persons ever fully recover with most dieing or developing chronically active and debilitating hepatitis.

Hepatitis E

Also called enterically transmitted non A, non B hepatitis. It is clinically indistinguishable from Hepatitis A. Symptoms include malaise, anorexia, abdominal pain, arthralgia and fever.

It is transmitted by the faecal-oral route. It can be transmitted in foodstuffs or drinks. Pregnant women appear to be exceptionally susceptible to severe disease.⁹⁹

Good sanitation and personal hygiene are the best preventative measures.

Hepatitis G

Recently an RNA virus that may cause acute and chronic hepatitis in humans has been described. Various groups have referred to the organism as hepatitis G or hepatitis GB-C virus. Two other forms of RNA virus which have been called GB-A and GB-B, have also been identified.

The virus may be transmitted by blood transfusions. The exact role of the virus in humans is unknown.

Treatment

There is no specific treatment for any form of hepatitis. Complete rest and inactivity are usually recommended. A Complete recovery from any form of hepatitis may take many months. Often those infected never regain their former levels of well being.

Preventive measures

All fresh tissue should be handled as potentially infectious and relevant preventive measures taken. Specimens from persons infected with the hepatitis B virus should carry a warning label with the international bio-hazard symbol and be transported in waterproof bags or containers. If the specimen is a known bio-hazard gloves and gown should be worn by those who handle the material or come into contact with a surface contaminated by the specimen. If splattering is likely to occur protective eye wear and a mask should also be worn. Always wash hands in soap and water immediately after contact. Wherever possible, equipment used for known cases of Hepatitis B should be disposable otherwise combustible material should be incinerated and everything else autoclaved at a minimum temperature of 121°C for 20 minutes. Higher temperatures may be used for shorter periods of time. If a chemical disinfectant is used the instruments should be rinsed with disinfectant before immersion as a blood coagulum could protect the virus.

Contaminated surfaces, floors, walls or benches should be cleaned with swabs soaked in 5% aqueous sodium hypochlorite or 2% glutaraldehyde. If the contamination is heavy 10 to 12.5% aqueous sodium hypochlorite should be used. For transportation between institutions fresh specimens should be placed in an inner container surrounded by absorbent padding and a durable, sealed outer container. The outer container should bear a bio-hazard symbol.

All personnel at risk from handling potentially infectious material should consider vaccination against Hepatitis B.

 

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