Good Practice Guidance for working with Children and Families affected by Substance Misuse
Appendix IV: Blood-Borne Viruses
Hepatitis means inflammation of the liver and can be caused by many irritants, including chemicals, viruses and bacteria, and by other disease processes such as allergic and immunity diseases. There are several types of viral hepatitis, the most common being hepatitis B and C, but hepatitis A can also be caused by injection (the most common cause of hepatitis A is hand to mouth). Individuals injecting any form of drugs are at great risk of also transmitting blood-borne infection and contamination. One of the most serious manifestations of such transmission is the acquisition of blood-borne viruses causing hepatitis.
Infection with hepatitis B and hepatitis C may initially be associated with an acute illness, characterised by fevers, nausea, jaundice and abdominal pain. The majority of cases, however, have only a transitory or no illness at all at the time of first infection. This asymptomatic state may continue for many years and indeed in some cases the virus is cleared from the system without the patient ever having been aware of having had the illness. A significant percentage will, however, proceed to ongoing illness over a period of many years with liver damage culminating in chronic and debilitating liver disease, sometimes cirrhosis in the advanced stages and, in a small minority of cases, liver failure or cancer of the liver.
The presence of current or past viral infection can be detected in most cases by tests for Hepatitis B or Hepatitis C antibodies in the blood. These tests may indicate past infection now resolved or show as a marker of ongoing infection. Additional tests can be carried out when antibodies are present to demonstrate the presence or absence of active infection. The polymerase chain reaction (PCR) test is a highly sensitive technique for measuring the presence or absence of viral genetic material in the blood and a positive PCR test usually indicates the presence of ongoing virus activity.
Monitoring of individuals with positive antibody tests includes measuring antigen tests, another marker of the presence of virus, PCR and clinical symptoms and signs, in order to decide whether or not there is active infection or ongoing disease. It can be derived from this whether or not the patient is likely to remain well, become ill in the future, or represent an infectious risk to drug using partners or sexual partners.
Human Immunodeficiency Virus (HIV)
Human immunodeficiency virus is similarly associated with an acute infection in a minority (less than 20%) of cases at the time of infection. This may be a mild flu-like illness, a glandular fever-type reaction with sore throats, swollen glands and malaise or a more severe acute illness involving all systems. The majority of individuals, however, acquire the virus with minimum symptoms which often go unnoticed. The virus can be detected by antibody testing a few weeks after initial infection and this antibody positive state is likely to persist indefinitely once acquired. Other tests include the measurement of the white cells specifically attacked by the virus (CD4 or T4 cells). This CD4 count is used as a measure or monitoring tool throughout the course of the infection of the severity of the progression from a normal white count to a depleted or immunologically 'at risk' state in the later stages of the disease. An additional, and perhaps more sensitive test, is the viral load which measures virus activity. This can be particularly useful in monitoring the beneficial effects of antiviral chemotherapy when this is being used.
Routes of transmission
Hepatitis and HIV are transmitted by infected body fluids, including blood, semen and genital tract secretions and can therefore be passed by injecting drug use, sexual intercourse or from mother to baby around the time of birth. Since HIV can be transmitted by breast-feeding this is not recommended. The vertical transmission rate will depend largely on the mother's viral load at the time of delivery. Consequently, while such interventions have been reported to reduce vertical transmission to <5% overall, individual rates will vary. They will depend on the mother's initial viral load and the efficacy of treatment in reducing this. Thus while various treatment protocols have been used, management should be determined after assessment of the individual. Because effective treatment is available, all pregnant women should be offered an HIV test to enable them to receive care for themselves and management to reduce the risk of vertical transmission. Routine offer of antenatal testing should be available in all NHS Board areas in Scotland. As in the case of hepatitis C infection, HIV antibody will be passed from mother to baby in all cases, so all babies born to HIV positive mothers will test antibody positive at birth. Other tests, including testing for presence of virus, are therefore required and can identify infected babies from around 3 months of age.
Immunisation is available for hepatitis A and hepatitis B. Because hepatitis A does not seem to occur very frequently in drug users (although epidemics have been described), no active immunisation is currently recommended. Some authorities recommend that hepatitis A and B vaccines should be given to drug users routinely. Hepatitis B immunisation, however, has been recommended for injecting drug users for many years and is increasingly carried out in drug clinics and by general practitioners. This is an important and effective way of preventing epidemics in drug-using populations, but also in protecting individuals at risk from drug using contacts or from infected sexual partners. Immunisation of children of infected drug users can prevent the onset of active infection and screening of pregnant women during the antenatal period allows this to be predicted and planned.
There is no immunisation currently available for hepatitis C or HIV infection.
Viral transmission and prevention
Hepatitis B infection is readily transmitted sexually, by injection and at the time of birth. Vertical transmission, as stated, can be prevented or reduced in frequency by the process of screening and active immunisation. Active immunisation of drug users or those at risk of injecting is increasingly likely to prevent infection of drug users and their sexual partners. Infection at birth carries a very high risk of chronic and persistent illness compared to a relatively lower risk when the virus is acquired during adulthood.
The majority of those individuals infected by injecting drug use will therefore be positive for an antibody test for hepatitis B but negative for signs of ongoing or active disease and probably represent little risk to sexual partners. Those with persistent virus infection fall into a number of different categories of infectivity and ongoing damage being done to the liver. This can be detected by an additional range of antigen tests. Hepatitis B vertical transmission probably carries a higher risk of persistent infection than infection in adulthood.
Hepatitis C is also easily transmitted by injecting drug use. Transmission by sexual intercourse appears to occur less frequently and the risk of vertical transmission during pregnancy and at the time of delivery is probably less than 10%. The transmission rate may be higher if the mother is also infected with HIV but there is no evidence that the hepatitis C virus is transmitted by breast-feeding and indeed available evidence suggests that this does not occur. The presence of antibody to hepatitis C does not confer immunity, so those infected in the past who have cleared the virus and are therefore antigen and PCR negative may subsequently become re-infected at the time of re-exposure. It is unclear why hepatitis C seems to be transmitted much less frequently by sexual intercourse than hepatitis B and it is difficult to counsel antibody-positive individuals on whether or not they need to use barrier contraception in the longer term.
HIV is transmitted by all three routes. The risk of transmission by injecting drug use may be less than that for hepatitis B or hepatitis C and the risk of sexual transmission is lower than for hepatitis B but higher than for hepatitis C. The risk of vertical transmission is less than for hepatitis B but greater than for hepatitis C. Unlike hepatitis C, HIV infection is transmitted by breast-feeding. While there is some evidence that in rare cases the virus may be cleared from the body, it is usually regarded as permanently present in all those infected with HIV.
For all three viruses, it may be generally accepted that the risk of infectivity depends on the amount of circulating virus in the system. This can be measured by PCR and viral load tests, and it makes sense to consider that the higher the viral load, the higher the degree of infectivity.
Antiviral treatments are available for the treatment of hepatitis C infection and are variably beneficial. Such treatments are not currently available during pregnancy or licensed in young infants. There is little experience in treating children with antivirus drugs. For this reason, routine testing of pregnant women is not recommended, but may be in the future. The transmission of antibody from mother to baby gives rise to a positive test in new-borns of mothers with hepatitis C antibodies but this does not necessarily indicate the presence of virus or active infection so much as the presence of maternal antibodies. The presence of active infection should be sought later in the first year of life.
In those with active infection or ongoing illness, the specialist treatment of hepatitis C is increasingly effective. Treatment with Interferon, Ribavirin, or a combination of drugs is complicated and expensive and requires drugs by injection, but can be effective in excluding the virus from the body and possibly effecting long-term cure. This is likely to be increasingly available.
There is now a wide range of treatments, including many antiviral drugs, available for management of HIV infection. These drugs can be given during pregnancy so women already on treatment before they become pregnant can continue their medication throughout pregnancy. Treatment with antivirals will also reduce vertical transmission, therefore women who are not already receiving treatment should be offered treatment during pregnancy. Treatment given to the mother to prevent vertical transmission can be discontinued at delivery if she wishes, but the baby should then receive treatment for the first few weeks of life. Delivery by elective Caesarean section has also been shown to reduce vertical transmission.