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Saudi Journal of Kidney Diseases and Transplantation
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ORIGINAL ARTICLE Table of Contents   
Year : 1995  |  Volume : 6  |  Issue : 2  |  Page : 174-178
The Effect of Chemical and Heat Disinfection of the Hemodialysis Machines on the Spread of Hepatitis C Virus Infection: A Prospective Study


1 Division of Nephrology, Department of Medicine, King Khalid University Hospital, Riyadh, Saudi Arabia
2 Department of Microbiology, King Khalid University Hospital, Riyadh, Saudi Arabia

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   Abstract 

Seventeen of our 42 regular hemodialysis (HD) patients (40.5%), and six of our 16 patients on continuous ambulatory peritoneal dialysis (CAPD) (37%) were found to be positive for hepatitis C virus (HCV) antibody in June, 1992. Since the virus was considered susceptible to eradication by the available disinfection methods of the HD machines, the most likely source of transmission was considered to be incomplete application of the universal infection control techniques. These recommendations were strictly applied, but no attempt was made towards designating specific machines for anti-HCV positive patients. Review of data revealed that seven of our 25 previously negative patients (28%) turned positive in the following 12 months. Risk factors such as blood transfusions were excluded in all these patients. A strict protocol of careful chemical disinfection using Citrosteril run at 85° C for 35 minutes after each dialysis session was adopted. Over the following 18 months, six of the remaining 17 negative patients (35.2%) seroconverted. They all had received blood transfusions, 7 to 14 months before (mean 10.5 months). The blood had been screened and had tested negative for anti-HCV antibody. By contrast, none of our CAPD patients who were anti-HCV negative in June 1992, and remained on CAPD, turned positive. The HD machine disinfection techniques were thoroughly reviewed and found to be as prescribed In the absence of other sources of infection with HCV we conclude that the HD machines were the most likely source of transmission of HCV infection and therefore, it is important to assign specific HD machines for anti­HCV positive patients. We have now adopted such a system.

Keywords: Hepatitis C virus, Hemodialysis, CAPD, Seroconversion.

How to cite this article:
Abu-Aisha H, Mitwalli A, Huraib SO, Al-Wakeel J, Abid J, Yousif KI, Algayyar F, Ramia S. The Effect of Chemical and Heat Disinfection of the Hemodialysis Machines on the Spread of Hepatitis C Virus Infection: A Prospective Study. Saudi J Kidney Dis Transpl 1995;6:174-8

How to cite this URL:
Abu-Aisha H, Mitwalli A, Huraib SO, Al-Wakeel J, Abid J, Yousif KI, Algayyar F, Ramia S. The Effect of Chemical and Heat Disinfection of the Hemodialysis Machines on the Spread of Hepatitis C Virus Infection: A Prospective Study. Saudi J Kidney Dis Transpl [serial online] 1995 [cited 2020 Jun 6];6:174-8. Available from: http://www.sjkdt.org/text.asp?1995/6/2/174/40862

   Introduction Top


Hepatitis C virus (HCV) infection has become a major problem in dialysis units in many parts of the world, and is particularly highly prevalent in developing countries. In Saudi Arabia, the prevalence in dialysis units ranges between 14.5% and 94.7% with an overall average of 68% [1] . Blood and blood products transfusion used to be most important source for the transmission of non-A, non-B hepatitis, most of which we now know is due to HCV; but this source has become less important with the advent of excluding anti­HCV positive blood donors [2] . Factors that play a role in maintaining the high prevalence of anti-HCV positivity among dialysis population are not very clear, but there seem to be a positive correlation between anti-HCV positivity and the number of years on dialysis [3] . There is general agreement that the universal infection control techniques (UICT) should be strictly observed in dialysis units to combat spread of infection by agents like HCV and human-immuno-deficiency-virus (HIV) [4] . While many investigators seem to think that following those recommendations is enough to keep HCV at bay [5],[6] , others recommend that dialyzing positive patients using separate hemodialysis (HD) machines is necessary to stop the spread of HCV [7],[8],[9] . We have recently analyzed the rate of conversion from anti-HCV negative to positive in our dialysis population (both HD and CAPD), arid followed a cohort of our negative patients from June, 1992. We report here various measures taken to combat seroconversion and in the process, we have investigated various possible sources of spread of HCV in our dialysis population.


   Materials and Methods Top


Study-phases

Patients on regular hemodialysis (HD) at the King Khalid University Hospital, Riyadh, were prospectively evaluated at intervals regarding their anti-HCV status. The study period was divided into four phases.

Phase "A": This was the state of anti-HCV positivity before June, 1992. From this date, we decided to strictly observe implementation of the UICT. Although our nurses did implement UICT all the time, we decided that strict observation for "correct" application of the precautions was needed to combat HCV infection. Thus, Phase "A" represented a period when we were not very certain of the proper application of UICT.

Phase "B": This was between July, 1992 and June, 1993 and was the period when the UICT were applied to our satisfaction, but only abbreviated (15 minutes) chemical disinfection, followed by warm rinsing was applied to the HD machines after each use to dissolve the bicarbonate used in the session before. Heat disinfection (at 85° C) was applied at the end of each working day, and full chemical disinfection (see below) was applied at the end of the week. Patients shared machines indiscriminately.

Phase "C": This was from June, 1993 to December, 1994 and was the period when we decided to do full chemical disinfection after each dialysis, but patients still continued to share machines.

Phase "D": This is from January 1995 to date. On 1st January 1995 we decided to designate specific HD machines for anti-HCV negative patients, and also to specify machines for groups of patients according to their anti-HCV status. The same patients (usually six patients) would always share the same HD machine.

Disinfection Methods

'Warm rinsing' was used during Phases "A" and "B", after each dialysis during weekdays. This entailed rinsing the HD machine after each use with water at 37-40° C run for 30minutes. A brief chemical disinfection using Citrosteril run at 60-70° C for 15 minutes was used before the rinse. Citrosteril is a citric­acid-1-hydrate, malic acid and lactic acid solution which is said (Fresenius manual) to be bactericidal and virucidal (for hepatitis B and HIV) at temperatures above 60° C.

Full chemical disinfection

In Phase "C" a strict protocol of careful chemical disinfection using Citrosteril, run at 85° C for 35 minutes after each dialysis session was adopted before using the machine for the next patient. It was hoped that both the high temperature bath and the low pH offered by Citrosteril would be enough to combat HCV.

Heat-disinfection

Hot water, at 80-90° C, was run at a high flow-rate after full chemical disinfection for 60 minutes. This procedure was performed at the end of the day on every machine in preparation for the next day's work.

Test for HCV antibodies

Only results obtained after application of the second generation enzyme-linked immu­nosorbent assays (ELISA-2) for anti-HCV are included in this study. This test became available in our hospital in June 1992.


   Results Top


Phase "A": 17 of our 42 regular HD patients (40.5%), and six of our 16 CAPD patients (37%) were found to be positive for HCV antibody in June, 1992. Since it was considered that the virus was quite susceptible to eradication by the available disinfection methods, the most likely source of the problem was considered to be incomplete application of the UICT recommended for patient handling. These recommendations were strictly applied.

Phase "B": Review of data in June, 1993 revealed that seven of our 25 previously anti­HCV negative HD patients (28%), and none of our 12 negative CAPD patients, turned positive in the 12 month period. The overall anti-HCV positivity rate, thus rose to 57.1% among the HD patients. Risk factors such as blood transfusions were examined carefully. Four patients had two-to-four units of blood transfused during Phase "B", but the blood had been screened for anti-HCV using ELISA­2 assay, and found negative. At this juncture, the efficacy of the abbreviated chemical disinfection followed by 'warm rinsing' between successive uses of HD machines was thought to be inadequate to kill the virus. A new policy of applying full chemical disinfection after every use of the HD machine was adopted.

Phase "C": Over the following 18 months, six of the remaining 18 anti-HCV negative HD patients (33.3%), but none of 12 negative CAPD patients, turned positive to HCV antibody. [Table - 1] shows a summary of the follow-up of this cohort. The patients who turned anti-HCV positive were again studied in detail, and so was the application of dialysis techniques and handling of materials. Four of the six patients who seroconverted had received blood transfusions from anti-HCV negative donors, 7 to 14 months before (mean 10.5 months). Samples from three of those blood-bags were retested for anti-HCV and found negative. Three non-dialysis patients who shared those blood transfusions with our patients were traced and tested for HCV antibody. They were all found to be negative. The HD machine disinfection techniques were thoroughly reviewed and found to be as prescribed. In the absence of other sources of infection with HCV, we concluded that, in spite of apparently adequate heat (85° C) and chemical (Citrosteril) disinfection, it appeared that our HD machines were still the most likely source of transmission of HCV.

Phase "D": This was implemented, where anti-HCV negative patients are dialyzed on "negative" HD machines, and positive patients shared designated HD machines so as to minimize the spread of so far undetectable non-A, non-B viral infections.

A graphic representation of the number of the new cases turning positive for anti-HCV in relation to the duration of the study is given in [Figure - 1].


   Discussion Top


There is no agreement as yet, regarding the best way of controlling HCV infection in dialysis units. The virus has been classified as a member of the Flaviviridae family, which is lipid-enveloped, and therefore highly susceptible to inactivation by the solvent/detergent method of chemical treatment [11] . Application of the UICT has been said to be sufficient to control the alarmingly high rate of seropositivity for anti­HCV in dialysis units [1],[4],[5] . The role of blood transfusion as a source of infection has greatly declined since the institution of routine screening of blood donors for HCV [2],[12] . However, a recent study demonstrated that those patients who seroconverted had received significantly more transfusions than those who did not, though seroconversion also occurred in patients who had not received any transfusions at all [12] . Our study suggests that neither strict application of UICT, on its own, nor chemical disinfection (reducing the pH to 5.0) coupled with heat at 85° C for 35 minutes, were enough to stop the march of seroconversion in our dialysis unit. Other units in the country are also likely to be having the same trouble. We, therefore, recommend that at least patients negative for anti-HCV should be dialyzed on designated machines which are not used by positive patients. Furthermore, since there is evidence that sharing the dialysis environment alone may be enough to transmit HCV infection [13] more drastic measures may be needed to combat the problem of HCV in dialysis units.

 
   References Top

1.Huraib S, Al-Rasheed R, Aldrees A, Al Jefrey M, Arif M, Faleh FA. High prevalence and risk factors for hepatitis C in Saudi Arabia: A need for new strategies in dialysis practice (Abst). Saudi Kidney Dis and Transplant Bull 1993;4:S73.  Back to cited text no. 1    
2.Donahue JG, Munoz A, Ness PM, et al. Thedeclining risk of post-transfusion hepatitis C virus infection. N Engl J Med 1992;327:369-73.  Back to cited text no. 2    
3.Muller GY, Zabaleta ME, Arminio A, et al. Risk factors for dialysis associated hepatitis C in Venezuela. Kidney Int 1992;41:1055-8.  Back to cited text no. 3  [PUBMED]  
4.Favero MS. Recommended precautions for patients undergoing hemodialysis who have AIDS or non-A, non-B hepatitis. Infect Control 1985;6:301-5.  Back to cited text no. 4  [PUBMED]  
5.Garcia-Valdecasas J, Bernal C, Cerezo S, Garcia F, Pereira BJ. Strategies to reduce the transmission of HCV infection in hemodialysis units, (abstract) J Am Soc Nephrol 1993;4:347.  Back to cited text no. 5    
6.Okuda K, Hayashi H, Yolozeki K, Kashima T, Irie Y. Mode of nosocomial HCV infection among chronic hemodialysis patients and its prevention. Hepatology 1994;19:293.  Back to cited text no. 6    
7.Calabrese G, Vagelli G, Guaschino R, Gonella M. Transmission of anti-HCV within the household of haemodialysis patients. Lancet 1991;338:1466.  Back to cited text no. 7  [PUBMED]  [FULLTEXT]
8.Teruel JX, Pascual J, Liano F, Ortuno J.Importance of nosocomial transmission of hepatitis C virus infection in dialysis units. Clin Nephrol 1992;38:232-3.  Back to cited text no. 8    
9.Da-Porto A, Adami A, Susanna F, et al. Hepatitis C virus in dialysis units: a multicenter study. Nephron 1992;61:309-10.  Back to cited text no. 9    
10.Mariani G, Di-Paolantonio T, Baklaya R, Morfini M, Mannucci PM. Prospective study of the evaluation of hepatitis C virus infectivity in a high­purity, solvent/detergent-treated factor VIII concentrate: parallel evaluation of other markers for lipid-enveloped and non-lipid-enveloped viruses, the Ad Hoc Study Group of the Fondazione dell'Emofilia. Transfusion 1993;33(10):814-8.  Back to cited text no. 10    
11.Jadoul M, Cornu C, van-Ypersele-de­Strihou C. Incidence and risk factors for hepatitis C seroconversion in hemodialysis: a prospective study. The UCL Collaborative Group. Kidney Int 1993;44(6):1322-6.  Back to cited text no. 11    
12.Nordenfelt E, Lofgren B, Widell A, et al. Hepatitis C virus infection in hemodialysis patients in southern Sweden: epidemiological, clinical, and diagnostic aspects. J Med Virol 1993;40(4):266-70.  Back to cited text no. 12    
13.Allander T, Medin C, Jacobson SH, Grillner L, Persson MA. Hepatitis C transmission in a hemodialysis unit: molecular evidence for spread of virus among patients not sharing equipment. J Med Virol 1994;43(4):415-9.  Back to cited text no. 13    

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Correspondence Address:
Hassan Abu-Aisha
Department of Medicine King, Khalid University Hospital P.O., Box 2925, Riyadh 11461
Saudi Arabia
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