Friday, February 16, 2018

Cross infections in dialysis centres - the hows and the whys

Cross infections with the Hepatitis C virus have become a menace in many dialysis centres. Hepatitis B and HIV viral cross infections are also possible though rare. A viral cross infection occurs when a virus is transmitted from a carrier of the virus to someone who did not carry the virus. Viruses multiply rapidly and typically, if the body is unable to fight and kill the virus completely (which happens rarely and that too, before the virus has got a chance to multiply significantly), the new individual becomes a carrier of the virus as well.

The likelihood of transmission of these viruses in hemodialysis centres is greater because blood is coming out of the body and is passed through the dialyser (artifical kidney) and the bloodlines. Reprocessing of dialyzers and bloodlines increases the chances of this transmission because these items are taken to a reprocessing area where they are washed, sterilised and prepared for next use for the same patient in his or her next dialysis session. In this process however there is a chance of some blood from another patient’s dialyzer and bloodlines entering this set. Though this should not ordinarily happen, the chances are not zero.

Most dialysis centres have separate dialysis machines and reprocessing areas for those infected with these viruses. But this does not preclude the transmission of these viruses due to one major problem with the way in which blood samples are tested for the presence of these viruses before deciding whether the patient is a carrier of the viruses or not.

When the virus first enters a person’s body, within a few weeks, the body develops antibodies to the virus which try to fight the virus and kill it. These antibodies are easier and cheaper to test than the virus itself. So, most tests make use of testing whether the blood of the patient contains these antibodies or not. If it does, it is assumed that the virus also must be there. If not, the patient is certified as a non-carrier of the virus.

The trouble with this method is that typically the body takes a few weeks to develop these antibodies. So, if the patient has acquired the virus recently, even if this test is done, he or she could be certified as a non-carrier of the virus. What this means is that even though the patient is a carrier of the virus, he or she is going to be treated like a non-carrier allowing the chance of other true non-carriers to be infected since the carrier is going to be treated on the machines and reprocessing areas meant for non-carriers.

There is another more reliable test which actually directly tests for the virus itself. This test would give a positive result soon after an infection has happened. However, this test is many times more expensive than the antibodies test. Very few people can afford this test. Also it is not enough if only you pay for the test. This works only if every patient starting dialysis in the centre gets tested by the same method because you can get infected by another patient who decides not to do the more accurate test.

This is a major problem in dialysis centres in much of the developing world today. Research needs to be done to figure out ways by which the cost of the more accurate test can be reduced to bring it within the reach of most patients. Otherwise it would be very difficult to contain this problem.

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