Liver and pancreatic infections

22. Liver and pancreatic infections




Questions


image What are the clinical features of hepatitis?

image How is the laboratory diagnosis of viral hepatitis made?

image What are the causes of hepatobiliary infection?

Infection of the liver and pancreas occurs via the bloodstream, rarely from the gastrointestinal tract, even when the route of acquisition is faecal–oral. Biliary tract infection and peritonitis are, conversely, caused by locally spread infection.



Hepatitis


The classic clinical triad of jaundice, dark urine and pale stools (Fig. 3. 22.1) accompanying fever is often missing, particularly in children, who are more often asymptomatic. The vast majority of cases have a viral aetiology, with hepatitis A, B and C being the commonest causes.


image

Fig. 3.22.1 Clinical features of viral hepatitis: rash, fever and jaundice (A) (Reproduced with permission from Spicer W J 2008 Clinical microbiology and infectious diseases, 2edn, Churchill Livingstone, Edinburgh) and dark urine (B).


Hepatitis A is spread by the faecal–oral route, has a prodrome of approximately 2–4 weeks and patients usually recover completely, although approximately 1% develop fulminant disease, which can lead to early death.


Hepatitis B is spread sexually and via contaminated blood and serous fluid. It has an incubation period of 1–3 months before patients exhibit fatigue and other classic symptoms of hepatitis. Immune-complex disease may occur, with an urticarial rash, arthritis and glomerulonephritis. Approximately 10% of patients become chronic carriers, with subsequent chronic hepatitis, cirrhosis and possibly hepatocellular carcinoma. Higher prevalence occurs in Southeast Asia.


Hepatitis C is also blood borne and has an incubation period of 2–4 months. Approximately 90% become carriers with the same long-term damage that occurs with hepatitis B.


Hepatitis D is a defective virus that only causes infection in the presence of another virus, usually hepatitis B or herpes simplex. It can recur.


Hepatitis E is spread by the faecal–oral route and is associated with water-borne epidemics. It has an incubation period of 6–8 weeks and has a high (20%) mortality in pregnant women if acquired in the third trimester, caused by the development of disseminated intravascular coagulation.


Less common causes of viral hepatitis include cytomegalovirus,Epstein–Barr virus, herpes simplex, rubella and yellow fever. There are usually other features in addition with these diseases.


Leptospira interrogans is a spirochaete that enters through the skin and causes leptospirosis, also known as Weil’s disease. Sewerage workers classically get the infection from coming into contact with infected rat urine. It can also spread through the faecal–oral route and may be complicated by aseptic meningitis and haemorrhage.


Entamoeba histolytica and parasitic infections are common causes of hepatitis in tropical climates.


Approximately 10% of cases of hepatitis do not have an identifiable cause, and new viruses such as hepatitis G and TT virus have been discovered by modern molecular methods in some cases. Their aetiological role has, however, yet to be defined.



Diagnosis and management


Diagnosis of viral (and leptospiral) infection is serological, by detection of either antigen or specific antibody. The detection of hepatitis B surface antigen (HBsAg) confirms the diagnosis of hepatitis B virus, and the presence of hepatitis B ‘e’ antigen (HBeAg) indicates a high infectious risk (Fig. 3.22.2). Other markers are determined in specific cases. Jaundice in carriers, in whom HBsAg persists for 6 months or more, is most likely to have another cause, which should be sought. Hepatitis A virus infection is diagnosed by specific IgM. Serological assays for the diagnosis of hepatitis C do not offer early diagnosis, as they are based on the detection of specific IgG, which may take several weeks to develop; diagnosis is, therefore, retrospective unless an earlier method such as gene amplification in the polymerase chain reaction is used.


image

Fig. 3.22.2 Serological course of hepatitis B infection. HBsAg, hepatitis B surface antigen; HBeAg, hepatitis B early antigen; HBc, hepatitis B core antigen.

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Jul 3, 2016 | Posted by in MUSCULOSKELETAL MEDICINE | Comments Off on Liver and pancreatic infections

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