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Chicken Pox and Crohn's Disease |
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An Article written for the CCSG by Dr Mark Lane (Director of Gastroenterology & Hepatology, Auckland Hospital). Crohn's disease Crohn's disease is a disorder of unknown cause, which results in fluctuating inflammation of segments of the gut. Most commonly it involves the last part of the small bowel (the terminal ileum) but may involve any area of the gut. It is a condition characterised by flares and remissions and typical symptoms during attacks include abdominal pain and changes in bowel habit, commonly diarrhoea and sometimes with blood in the motions. Untreated attacks may last many months and result in severe weight loss due to the effects of malnutrition and the extra energy use caused by the inflammation. Treatment of acute attacks is with drugs that reduce inflammation. These drugs may also reduce the ability of a person's immune system to cope with infection. In contrast, the drugs used to treat mild attacks (a group of drugs called the "5-aminosalicylates" or 5-ASAs) do this minimally but are not effective for more severe attacks. Corticosteriods are the most potent drugs we have for treating acute flares and may be given intravenously in hospital, or orally, usually as a tablet called prednisone. A dose of 30-60mg will be given initially and the dose tapered over the next few weeks or months as the attack settles. A few patients have ongoing symptoms and need ongoing steroids at various doses to keep their symptoms under control. Because of frequent attacks or continuing symptoms, patients may be given "maintenance drugs" for milder disease (ie. 5-ASAs), while for more severe disease (characterised by frequent or severe relapses, including patients who have had operations), a drug called azathioprine may be used. Azathioprine is also an immunosupressive drug. Maintenance drugs reduce the frequency and severity of relapses. Immunosupressive drugs have benefits as discussed above but also risks. Infections may be more common and the body's ability to cope with them is reduced. For the drugs used to treat Crohn's disease, infections that are more common are skin infections such as tinea, warts and acne. Thrush infection of the vagina in women may be a little more common. Severe infections caused by these drugs in the doses used are very rare. Chickenpox Most of the population of NZ (about 95% of adults) have been exposed to chickenpox and have had an infection during childhood. Some may not have been aware of the infection as only about 70% of adults can recall having had chickenpox. If the body's immune system is very suppressed and one is exposed to chickenpox for the first time and then becomes infected, the infection may be severe and even fatal. There is a significant body of medical literature on patients taking steroids developing severe chickenpox infections. The risks for a severe infection seem to be:
What is the risk? Is this a significant risk for patients with Crohns disease (or other inflammatory bowel diseases such as ulcerative colitis) on immunosupressive drugs such as prednisone or azathioprine? The published medical literature on this topic is not large. That is, there are only 7 reported cases of first chickenpox infections in patients with IBD in the world literature over the last 30 years. Of these seven, two died. Thus it would appear that this is an exceptionally rare problem in patients with IBD on steroids, but with the potential for a serious or even fatal outcome (as happened in the unfortunate patient in the Waikato). It is probably rare because most people with IBD have already had chickenpox, the doses of drugs we use are relatively low, and other immune suppressing diseases are not present. There are probably more than 3000 people in New Zealand with some form of IBD up to one third will have a relapse in any one year and many of those (maybe 20%) will need steroids to help settle and attack. About 10-20% will need ongoing treatment with azathioprin therapy. At least 75% of patient's given these drugs will get benefit from the treatment with more rapid return to normal or improved health. Thus hundreds of pateints benefit from the use of steriods while the risk of chickenpox is extremely low. The potential benefits far outweigh the risk of a severe chickenpox infection. However, the risk does exist so what should be done? For patients on steroids at higher doses (more than 20 mg/day for an adult) who cannot recall ever having had chickenpox and who then come into close contact with a person with chickenpox infection (either childhood chickenpox or shingles*) should immediately see their family doctor for a blood test to determine if they have had chickenpox before. If there is no evidence of previous infection, an injection of immunoglobulin will provide temporary immunity to infection. This should be done within a few days of exposure. If chickenpox develops in a person taking immunosuppressive drugs, they should immediately see their family doctor who will arrange admission for specialist assessment and possible intravenous treatment with antiviral drugs. This is also true for recurrent chickenpox as well as a first attack. Thus, chickenpox is a very rare complication in patients with IBD. However, awareness of this possibility is important, as early action and intervention is important. * Shingles is a form of recurrent chickenpox Back to Newsletters |
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