Viral hepatitis / by Arie J. Zuckerman

Viral hepatitis by Arie J. Zuckerman V iral hepatitis is a major pub-lic health problem through-out the world. At least five different viruses may be the cause : hepatitis A , referred to in the past as infectious hepatitis or epidemic jaundice; epidemic non-A hepati- tis; hepatitis B , known in the past as serum hepatitis; hepatitis D (Delta hepatitis); and non-A, non-B hepatitis , which is caused by several different viruses. The illness in all types of hepati- tis is similar, and results from acute inflammation of the liver. It is fre- quently heralded by symptoms such as fever, chills, headache , fatigue , generalised weakness , and aches and pains. A few days later, there may be loss of appetite , nausea , vomiting, right upper abdominal pain or tenderness followed closely by dark urine , light-coloured fae- ces, and jaundice (yellowing) of the skin or the sclerae (the white of the eyeballs). Many infections , particu- larly in early life , are without symp- toms or without jaundice. In oth- ers, the symptoms and jaundice may be severe and prolonged ; liver failure may occur, and the patient may lapse into a coma. Hepatitis A is common in all parts of the world , but the exact in- cidence is not known and difficult to estimate, because of the high proportion of asymptomatic cases, infections without jaundice, and differing patterns of disease. Sur- veys of antibody to hepatitis A have shown that while the prevalence of hepatitis A in industrialised coun- tries (particularly northern Europe, North America and Australia) is decreasing , the infection is virtually universal in, most other regions, particularly in warm-climate coun- tries. The antibodies persist for many years, often for life , and provide immunity. The virus is spread by the faecal- oral route, usually by person-to- person contact, and infection is par- ticularly common in conditions of poor sanitation and overcrowding. 24 Outbreaks result most frequently from faecal contamination of drink- ing water and food , although water- borne transmission is not a major factor in industrialised countries or where piped water supply has been adequately treated and chlorinated. It is very rarely transmitted by blood transfusion or inoculation. Food-borne outbreaks , which have become more important and frequent in developed countries , result from the shedding of virus in the faeces of infected food handlers during the incubation period of the illness : the source of the outbreak can often be traced to cooking. The consumption of raw or inad- equately cooked shellfish cultivated in sewage-contaminated tidal or coastal water, or of raw vegetables grown in soil fertilised with un- treated human faeces and excreta , is associated with a high risk of infection. Control of the infection is diffi- cult . Since faecal shedding of the vi- rus is at its highest during the incu- bation period , the strict isolation of cases is not necessary. Spread of infection is reduced by simple hygienic measures and the sanitary disposal of excreta. Normal human immunoglobulin , commonly re- ferred to as gamma-globulin , con- taining hepatitis A antibody will prevent or lessen the severity of the illness . Immunoglobulin injections may be required every four to six months for people at risk , for personal and family contacts of patients with hepatitis A , and for those exposed to contaminated food. Immunoglobulin is recom- mended for travellers without hepatitis A antibody who are visit- ing countries where this infection is very common. Vaccines against hepatitis A are under development. Other measures include com- monsense precautions, strict per- sonal hygiene , avoiding eating raw or inadequately cooked shellfish and raw vegetables, and avoiding drinking untreated water or raw milk. Epidemic non-A hepatitis, simi- lar to hepatitis A and usually trans- mitted by water contaminated with sewage, has been noted in India , Burma , Nepal , central-south USSR, parts of the Middle East, North and East Africa and Mexico and in returning travellers from these areas. This new virus has been seen in the electron micro- scope, but specific laboratory tests are not yet available. General pre- cautions against the infection are as outlined for hepatitis A. Immuno- ., globulin prepared from the plasma obtained in industrialised countries · does not contain antibodies to this virus and is ineffective. There is no specific treatment. Hepatitis B, essentially a blood- borne and sexually-transmitted in- fection, occurs throughout the world. The continued survival of the infection is ensured by a large number of individuals who are car- riers of the virus (persistent infec- tion), estimated to number over 285 million worldwide. It can be spread either from carriers or from people with no apparent infection, or during the incubation period, illness or early convalescence. The prevalence of hepatitis B carriers varies from one region of the world to another. In northern Europe, North America and Aus- tralia , the prevalence of carriers is about 0.1 per cent (at least among blood donors) ; in central and east- ern Europe up to 5 per cent; in southern Europe, countries border- ing the Mediterranean and parts of Central and South America WoRLD HEALTH, December 1987 frequency is higher ; and in parts of Africa, Asia and the Pacific area as many as 20 per cent or more of the apparently healthy population may be carriers. Not all carriers are infectious. The incidence of the disease tends to be higher among adults living in urban communities and among those living in poor socio- economic conditions. Certain groups of people are at consider- ably increased risk of contracting it because of the mode of transmis- sion. These include recipients of blood transfusions and infusions of certain blood products ; health care and laboratory personnel; staff in institutions for the mentally-handi- capped; homosexual males; prosti- tutes; and abusers of injectable drugs and narcotics. Transmission of the infection may result from accidental inocu- lation of minute amounts of blood or body fluids contaminated with blood such as may occur during medical, surgical and dental proce- dures , immunization with inad- equately sterilised syringes and needles, intravenous and percuta- neous drug abuse, tattooing, ear piercing and nose piercing, acu- puncture , laboratory accidents and accidental inoculation with razors and similar objects which have been contaminated with blood; and transfusion of unscreened blood and blood products. But hepatitis B is also found in other body fluids contaminated with blood such as saliva, menstrual W oRLD HEALTH , December 1987 Radio-immunological assay for hepatitis B at a Melbourne hospi- tal, Australia. Photo WHOfT. Farkas Below: Hepatitis B virus in serum. Electron-micrograph by WHO/A. Zuckerman and vaginal discharges and seminal fluid , and these have been implicat- ed as vehicles of transmission of the infection. There is much evidence for transmission by intimate contact and by the sexual route . The sexu- ally promiscuous, particularly male homosexuals, are at very high risk of infection with hepatitis B. Results of investigations into the role that biting insects play in the spread of hepatitis B are conflict- ing, but no convincing evidence of multiplication of the virus in insects has been obtained. Mechanical transmission of the infection via an insect's biting parts remains a possibility. The symptoms and manifes- tations of hepatitis B are similar to those of the other types of viral hepatitis. But the picture is compli- cated by the carrier state and by chronic liver disease, which may follow the infection. Chronic liver disease may be severe and may pro- gress to primary liver cancer which, in some parts of the world, is one of the commonest human cancers, particularly in men. Hepatitis B immunoglobulin is available for use after a single acute accidental inoculation injury in the laboratory. It is not required for travellers, but they should use com- monsense precautions for reducing the risk of hepatitis B, with particu- lar attention to the modes of trans- miSSIOn outlined above. They should employ great caution in any intimate or sexual contacts (par- ticularly any male homosexual con- tacts) with possible hepatitis B car- riers. And they should avoid any procedure involving penetration of the skin, for example tattooing, and so forth. Vaccines against hepatitis B are available for people at high risk of infection and for certain groups of expatriates residing in highly en- demic areas for longer than a few months. Delta hepatitis infection always occurs in association with hepatitis B (the carrier state). The mode of transmission of this infection, its prevention and control are identical to those for hepatitis B. Immuniz- ation against hepatitis also protects against delta infection. Non-A, non-B hepatitis: im- proved laboratory diagnosis of hepatitis A and hepatitis B led to the identification of a previously unrecognised form. It is now the most common form of hepatitis oc- curring after blood transfusion and the administration of blood-clotting factors in areas of the world where blood is screened for hepatitis B. It has been found in every country in which it has been sought, has some features in common with hepatitis B , and has also been detected in patients on dialysis and among drug addicts. In several countries, a sig- nificant number of cases are not as- sociated with transfusion , and such sporadic cases account for up to 15 to 20 per cent of all adult patients with clinical viral hepatitis. In general, the illness is mild, often without jaundice or other symptoms. There are no known methods of preventing non-A, non-B hepatitis, beyond the precautions applicable to hepatitis B. • 25