Rooms and dialysis machines of HCV patients were separated

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					            DlcLE TIP DERGlsi (JOURNAL OF MEDICAL SCHOOL) C:27 S:3-4                              2000


                SEROPREVALENCE AND RISK FACTORS OF HCV IN
                                            DIALYSIS PATIENTS


                            Mehmet Emin YILMAZ, MD., Assoc. Prof.                       1

      ismail H. KARA, MD., Assist. Prof.                        2   Yasin SARI, MD., Resident.             3


        Suzan DOZEN, MD., Resident.4                            Yasemin Usul, MD., Resident.5

                                   Bunyamin I~IKOGLU, MD., Prof.                    6




        ABSTRACT

         Nowadays, increased seroprevalence of hepatitis C virus (HCV) in hemodialysis
 (HO) patients is an important problem. In this study, it was aimed to investigate the
 seroprevalence and risk factors leads to spread of HCV in HO and continuous
 ambulatory peritoneal dialysis (CAPO) patients. 67 HO and 35 CAPO patients were
.enrolled in the study, 44 (43.1%) of them were female and 58 (56.9%) were male. Any
 risk factor for HCV infection was questioned. Third generation EL/SA reagent was used
 in the study. In our HO Center, all precautions have been taken for the prevention of
 spreading of HCV. Rooms and dialysis machines of HCV patients were separated from
 others. Mean age of cases was 41.6%15.3(range 19-75)year. All cases except two had
 blood transfusion and all cases had at least one surgical intervention (central venous
 catheter and/or arterio-venous shunting operation). Eight (7.8%) cases had dental
 interventions including conservative .tooth treatment or tooth extractions. There was not
 relation between low socioeconomic status, duration time of dialysis and higher
 prevalence of HCV in dialysis patients (p>O.05).In general, anti HCV seropositivity in our
 center was 41% and these cases were generally asymptomatic, but had elevated liver
 enzyme levels and slightly decreased albumin levels and at least all cases had one risk
 factor. Seroconversion ratelyear of our anti HCV (-) patients were O.148lpatients year in
 HO patients and O.OO2/patients  year in CAPO patients, respectively. The seroconversion
 ratelyear and prevalence of HCV is higher in HO patients than CAPO patients. It should
 be necessary to take additional measures to universal precautions for the prevention of
 spreading of HCV such as separation of dialysis machines, education of nurses and to
 change gloves regularly when moving from patient to patient, etc.
         Key    Words:Hemodialysis, Hepatitis C, Risk factors, Blood Transfusion.
        INTRODUCTION
        Approximately 4 million persons in the United States and probably more
than 100 million persons worldwide are infected with hepatitis C virus (HCV).
The virus has the unique ability to cause persistent infection in susceptible
hosts after parenteral or percutaneous transmission, and its underlying
mechanisms are not well understood. Hepatitis C virus, which before its
identification was labeled "non A, non B hepatitis" is a linear, single-stranded,



   (1,3.4.5.6) Department   01 Nelrology.

   (2) Department   01 Family Medicine,     Dlcte University, School 01 Medicine,           Diyarbaklr,   TURKEY.
  116

 positive-sense. 9500 nucleotide RNA virus. the genome of which is similar in
 organization to that of flaviviruses and pestiviruses; HCV constitutes its own
 genus in the family Flaviviridae. The HCV genome contains a single large open
 reading frame (gene) that codes for a virus polyprotein of approximately 3000
 amino acids (1-3).
                                                                                     =
        The 5' end of the genome consists of an untranslated region adjacent to
 the genes for structural proteins. the nucleocapsid core protein and two
 envelope glycoproteins, E1 and E2/NS1. Nucleotide sequencing has identified
 at least six distinct genotypes, as well as subtypes within genotypes. of HCV.
 The genotypic diversity of HCV results from its high mutation rate. There is no
 specific treatment for HCV and however there are new hopeful studies for that
 (2,4.5).
           Essentially, it is determined that genotype 1. 2 and 3 are seen very
  often in all over the world, genotype 1b is the main genotype in Japan, Eastern
  and Southern Europe and Southeast Asia. It is suggested that the treatment
  and prognosis of that illness changes according to the type of genotypes.
. Especially in the patients with HCV genotype 1b. there is no correlation
  between the amount of viral load and response to interferon treatment. Type 1
  is seen more often after blood transfusion and in sporadic hepatitis (6).
        Initial studies reported on HCV antibody prevalence in hemodialysis (HO)
 patients ranging from 2 to 60%. A number of risk factors account for the
 increased risk of HCV infection in hemodialysis patients. These include blood
 transfusions, immune defects relating to viremia and extracorporal
 hemocirculation that is repeated (7).
       We aimed to determine the risk factors that are important for spreading of
  HCV and HCV seroprevalence in HD and CAPO patients in our HO center.
        SUBJECTS AND METHODS
        PATIENTS AND STUDY DESIGN
        67 HO [38 Male (M), 29 Female (F)) and 35 CAPO [20 M. 15 F] patients
 undergoing dialysis program in HD center, Medical Faculty of Oicle University
 were evaluated according to prospective cohort study from January 1999 to
 December 1999. Our new renal dialysis center started its function since 1998.
 The rooms of HO patients, dialysis machines and personnel were divided in
 three sections such as HBV, HCV and normal groups. Any risk factor for HCV
 infection (blood or blood products transfusion, low socioeconomic status,
 surgical interventions, intrafamilial transmission and hospitalization) was
 questioned. The ethical committee of the university hospital approved the
 protocol of the study. All patients and controls gave written informed consent to
 the study.
        Blood sampling
         The collection of blood samples of controls was performed in early
  morning. In patients undergoing HO, blood samples were drawn just before the
  start of HO and immediately after its end from the arterial line. Freshly drawn
  blood (15 ml) samples obtained and immediately centrifuged at 200 9 (20 min at
                                                                              117

 24°C). Then, centrifuged samples were investigated by Third generation ELlSA
 reagent (Equipar, Sri. -Italy) and Tecan-Minilyser (Austria) apparatus. The
 results were supported immunoComb 11       HCV test (indirect solid phase enzyme
 immunoassay-EIA, Organics-Israel). Cut-off value: After finding mean values of
 both two positive controls and two negative controls, the results were divided by
 three. Cut off: positive control+negative control/3.
         Hemodialysis
        The patients received 5 hour and three times per week HO with a PS
 hollow fiber disposable dialyser (Fresenius Medical Care, Germany) and
 dialysers were never reused. HO was carried out using Braun-Oialog and
 Fresenius-4008S (Germany) dialysis machines and bicarbonate as dialysate.
 All patients were receiving heparin (Iow molecule weight heparin). Machines
 were heat disinfected between treatments and chemically every month.
 Screening of anti-HCV antibodies and monitoring of alanine aminotransferase
 (ALT) and albumin levels were part of HD center routine. Blood samples are
 collected every 2 weeks from anti-HCV negative patients and every 4 weeks
. from   anti-HCV positive ones. Medical records were kept constantly for all
. patients, and these records included data such as symptoms of hepatitis,
 history of liver enzyme abnormalities, medication history, past medical history,
 history of transfusions, dialysis schedule, bleeding episodes, and demographic
 and risk factors.
         Statistical   Analysis
        Statistical analyses were made in SPSS 7.5 PC program. Results were
 expressed as means:tSO. Two different groups were compared by independent
 t test. The one-way ANOVA and post hoc Bonferroni tests were used to
 compare independent-unpaired parametric samples of different groups,
 chi-square test were used to compare categorical samples and the Spearman
 correlation tests were used to determine the correlations. Values of p<O.05
 were considered statistically significant.
         RESULTS

       In table 1, age, duration of hemodialysis and laboratory data of patients in
HO and CAPO group were reported, and in table 2 all of them were compared
according to type of hepatitis. 44 of patients were female and 58 were male.
Mean age of patients was 41.6:t15.3. HCV patients (40.8:t15.9) were younger
than HBV (49.4:t16.0) and normal (44.6:t14.8) groups, but there was statistically
no difference between them (p>O.05).
       There was difference in ALT (p=O.03) and AST (p=O.01) levels between
these groups. There was statistically significant difference in ALT levels
between normal and HCV (+) groups (p=O.03)and that of AST levels between
normal and HbsAg (+) groups (p=O.01). However, duration of hemodialysis,
albumin concentrations and ages of HCV patients weren't statistically different
from other groups (p>O.05). All of the patients had at least one risk factor. All
patients except two had blood transfusion, all patients had at least one surgical
intervention (central venous catheter and/or arterio-venous shunting operation).
 118

Only eight (%7.8) patients had dental interventions including conservative tooth
treatment or tooth extractions. All patients had a social guarantee. However, the
socioeconomic status of patients those were insured by social guarantees and
by government were lower than that of Western societies. There was no relation
between low socioeconomic status, time of dialysis duration and prevalence of
HCV in dialysis patients (p>O.05). In general, anti HCV seropositivity in our
                                                                                                ::-
center was 41% and these patients were generally asymptomatic, but had
elevated liver enzyme levels and decreased albumin levels (Rgure 1 and 2).
    Table 1. Sociodemographic and laboratory data of patients in HD and
CAPD groups.
                                                        GROUPS

                                          HD (n=67)               CAPD (n=35)               p
   Age (Year)                             44.6:t:16.4              4O.3:t:13.8       >0.05
   Dunation time of Dialysis (Month)       15.9:t:9.0              43.8:t:34.9      <0.0001
   Albumin (aIL)                           3.4:t:O.6              3.0:t:0.6          <0.05
   ALT (lUll)                              58:t63                  42:1:73           0<05
   AST (lUll)                                                     31:t:44           <0.05



      Table 2. Sociodemographic and laboratory data of patients according to
type of hepatitis.


                                               GROUPS
                               NORMAL                   HCV            HBV         HCV+HBV
                                11=69                   0=39         n=11           0=3
   Age (Year)                  44.6:t:14.8          4O.8:t:15.9      49.4:t:16.0   33.7:t:7.6
   Dunat. time of Dialy. (Mnh) 28.3:t23.9           23.1 :t27.3      28.2:t28.3    16.3:t6.7

   Albumin (9IL)                       8
                                3.3:t:O.            3.3:t:O.5          3.0:t:O.5    3.0:t:O.6
   ALT (lUll)                   21:t:11             69:t:82            68:t65       51:t:38
   AST (lUll)                   18:t:11             4O:t:42             61:t:52      29:t:15
                                                                                            119




                    300




                    200




             ~ 'ro1

                     oJ     ~
                            . .
                                       T
                                       Ii
                                       ..

                                       .
                                          .. ~
                                                                                 I!IIAlT
                -100                                                             8AST
                            NORMAl          HCV           HBV       HCV+HBV


                                              HEPATEST




Figure 1a. Liver enzymes levels in patients undergoing HD.



                      400



                      300



                      20C
               g?
               Z
               :J
                      100


                              =r:: -                            ~        LE;::
                                                                                   I!BAlT
                     -100                                                          .AST
                                  NORMAl            HCV               HBV


                                                  HEPATEST




Figure 1b. Liver enzymes levels in patients treated by CAPD.
120



                           HEMODIAL YSIS
         HCV+HBV

         3/4%
         HBV

         7/10%



                                                           NORMAL
                                                           29 / 43%




         HCV

         28/ 42%




      Figure 2a. HCV and HBV Percents in patients undergoing HO.


                                CAPD

        HBV
        4/11%




        HCV
                                                          NORMAL
        11/31 %
                                                          20 / 57%




      Figure 2b. HCV and HBV Percents in patients treated by CAPD.
                                                                              121

      In HD group, in 28 of 67 cases HCV, in three of them HCV + HBV, and in
seven HBV was positive. In CAPD group, in 11 cases HCV and in four cases
HBV was positive. In HD group 28 cases and in CAPD group 20 cases had
negative hepatitis marker. Seroconversion rate/year of our anti HCV (-) patients
were 0.148/patients year in hemodialysis patients and 0.002/patients year in
CAPD patients, respectively.
       DISCUSSION
       In patients with hepatitis C, an episodic pattern of aminotransferase
elevation is common. A specific serologic diagnosis of hepatitis C can be mode
by demonstrating the presence in serum of anti HCV. Because nonspecificity
can confound immunoassays for anti-HCV, a supplementary recombinant
immunoblot assay (RIBA) should be done, especially in persons with tow prior
probability of infection, to establish the specific viral proteins to which anti-HCV
is directed. Assays for HCV RNA are the most sensitive tests for HCV infection
(8,9).
        Elevation of ALT with anti-HCV seropositivity for at least 6 months are the
.laboratory features enough to define chronic hepatitis C. Chronic hepatitis
 follows acute hepatitis C in 50 to 70 percent of patients. Many patients of
 hepatitis C are identified in asymptomatic patients who have no history of acute
 hepatitis, eq., those discovered while attempting to donate blood or as a result
 of routine laboratory screening tests. Among symptomatic persons with
 anti-HCV, even when aminotransferase levels are normal, between a third and
 a half have been reported to have chronic hepatitis on liver biopsy, although
 mild in most patients. In these asymptomatic persons with normal
 aminotransferase levels, the presence of detectable circulating HCV RNA
 appears to distinguish those with chronic hepatitis on biopsy from those with
 normal liver histology (10,11).
       Among the patients with chronic hepatitis B, HCV seroprevalence was
reported ranging from 10 to 20% in the Southern Europe and USA (11,12). HCV
co-infection in patients with inactive chronic hepatitis B increases to 30-35%
levels especially in the Mediterranean Countries (13). In our country, dual
infection ratio was found 9% in a study that HCV co-infection was investigated
among patients with chronic HBV infection (14).
      HCV infection is investigated in two different groups according to the
routes of transmission.
     A-Parenteral: Occupational, Transfusion of blood and blood products,
Nosocomial, Hemodialysis patients, Intravenous drug users,
        B-Non-Parenteral:    Perinatal transmission, Sexuel transmission,
 Intrafamilial transmission. Routine screening of blood donors for anti-HCV
reduced the frequency of transfusion-associated HCV infection. After the
introduction of first generation anti-HCV immunoassays, the infection risk of
transfusion-associated hepatitis reduced 80% in countries such as Japan, USA,
and Spain that HCV genotype 1 is predominant. The introduction of
second-generation       of HCV assays has reduced the frequency of
transfusion-associated hepatitis C to almost imperceptible levels. Rarely, when
 122

donor is at window period during the blood transfusion, it can be transmitted
(15,16). Solvent detergent treatment in screening of plasma for anti-HCV is the
most effective method and is used commonly. Thus, transmission of HCV by
immune globulins preparations and coagulation factor concentrates are
eliminated by this way (17). The mechanism of HCV transmission as a hospital
infection isn't well known. During surgical interventions, it should be necessary
to take additional measures for the prevention of transmission of HCV (18).
Although it is reported that HCV is the most common cause of post-transfusion
or sporadic non A-non B hepatitis in USA, in 40% of the patients there was no
 risk factor for parenteral transmission (19).
        Similarly, also in our country, only 44% of patients whose anti-HCV was
 positive had a transfusion story (20). Since 1989, the prevalence of HCV
 infection in different risk groups and blood donors was investigated by using
 specific tests for HCV. First prevalence study of HCV infection was made in
 volunteer blood donors (21). Anti-HCV prevalence in volunteer blood donors is
 lower than 2% in Northern Europe and larger part of USA, 0.5-0.8% in Australia
 and other parts of USA, 1-1.5% in the Southern Europe and Japan, 5% in
 Chine, higher than 10% in the Northern Africa (22-24). In our country, the
'prevalence of anti-HCV in blood donors is about 1% (25,26).
       The seroprevalence of anti-HCV in intravenous drug users is high in all
over the world (57-86%) and there is a significant parallelism between the
seropositivity and duration of drug using (27,28). The importance of sexual
transmission in the epidemiology of HCV infection is not clear. It ranges from 0
to 27% (29). The hospitalization story is an epidemiological risk in patients with
HCV infection (30). Transmission from a patient to another one can be seen. It
is reported that this type of transmission can cause outbreak of HCV infection in
hematologyand pediatric oncology clinics (31).
      The risk of HCV infection is increased in organ transplant recipients and
in hemodialysis patients (7,27,32-37). The HCV prevalence changes from
country to country. In our country, according to European Dialysis and
Transplant Association (EDTA) data, HCV prevalence was 17.7% in 1993.
However, according to Turkish Nephrology Associations' (TNA) data, HCV
seroprevalence was reported as 38% in 1996, it increased to 52.6% in 1997
and finally to 63.2% in 1998 (32,33).
        In these studies, the relationship between HCV seropositivity and blood
transfusion and duration of hemodialysis were demonstrated. Previous HD story
is an important risk factor for HCV seropositivity of CAPD patients. Some of
these studies were tests that made by using first generation ELlSA and had
significant risk of false negativism (34-36). A number of factors account for the
risk of HCV infection in hemodialysis patients. These include blood transfusions
and duration of hemodialysis. Moreover, the presence of anti-HCV has been
often documented in non-transfused hemodialysis patients suggesting
nosocomial transmission of HCV. Seroconversion rate/year of 129 anti-HCV (-)
patients undergoing HD was reported as 0.15/year (9,37).
       The patients that are enrolled in our study had a hospitalization story at
least one time. At the beginning of 1999 (first six months), when there was 16
                                                                             123

 patients in HCV room, liver enzymes of 16 patients that undergoing dialysis in
 normal room began to increase. All these patients had blood transfusions
 or/and surgical intervention during 1999. In 11 of these patients anti-HCV
 antibody became detectable in 6-12th months. On the other hand, in CAPD
 group, only one anti-HCV seropositivity was demonstrated. In only one case,
 intrafamilial transmission was identified. Only eight (7.8%) patients had dental
 interventions including conservative tooth treatment or tooth extractions.
        It is reported that in France anti-HCV seroprevalence was 23.6% in renal
 transplant recipients (35). When 27 patients were followed prospectively, it was
 seen that ten (37%) patients were seropositive during the transplantation and
 other patients became seropositive in following days, in 11 (41%) patients
 antibodies become detectable after 95 months and in 6 (22.2%) patients who
 were seropositive at the beginnings, antibodies became undetectable after 111
 months (35).
           Hemodialysis patients are at high risk of infection by hepatitis C virus
  and this is also an important problem that is met in our country's hemodialysis
. units. It is suggested the separation of the hemodialysis machines and rooms of
  anti-HCV positive patients, couldn't prevent the outbreak of HCV infection in a
  HD Unit. However, in a recent study of Katsoulidou and his colleagues (37),
  molecular and epidemiological analysis suggested that horizontal nosocomial
  patient to patient transmission was the most likely explanation for the virus
  spread within the HD Unit and other recognized rates had less importance.
       In our country, there are many studies that HCV seroprevalence in HD
 units was investigated (38). In the study of Ozdemir et al. (39) anti-HCV
 seropositivity was found in 145 (34.7%) patients by using 2nd generation ELlSA
 reagent. YOcel et al. (40) found anti-HCV seropositivity in 33 (32.6%) of 101
 patients by using 2nd generation ELlSA reagent in Bursa Hospital HD Unit.
 Olmez et al. (41) found anti-HCV seropositivity in 36 (24.6%) patients, HbsAg
 seropositivity in 20 (%13) patients and anti-HCV plus HbsAg seropositivity in six
 (%4.1) patients in Dicle University HD Center by using 2nd generation ELlSA
 reagent (In 1996, dialysis machines, rooms and personnel weren't yet
 separated).
       Nowadays, in our center, the rooms, dialysis machines and personnel of
 HD patients are separated according to HCV, HBV and HCV plus HBV and
 normal patients groups. When 67 HD and 35 CAPD patients that are
 undergoing dialysis program at presently in our HD center as from 1999, are
 evaluated by using 3rd generation ELlSA reagent, it is seen that anti-HCV
 seropositivity is 41%. In general, these patients were generally asymptomatic.
 but had elevated liver enzyme levels and decreased albumin levels. In our
 study, total 102 patients were enrolled. In 39 of them, anti-HCV seropositivity
 and in 11 of them, HbsAg seropositivity was demonstrated.
       CONCLUSION
       In conclusion, our observation that seroconversion rate/year of our
 anti-HCV patients were 0.148/patients years in HD patients and 0.002/patients
 years in CAPD patients, respectively. The seroconversion rate/year and
 124

prevalence of HCV is higher in HO patients than CAPO patients. In HO patients,
it should be necessary to take additional measures to universal precautions for
the prevention of outbreak of HCV such as separation of dialysis machines,
education of nurses and changing gloves regularly when moving from patients
to patient, etc.
                                    OZET
    DivALiz HASTALARINDA HEPATiT C SEROPREVALANSI VE RisK
                                FAKTORLERi

       Hemodiyaliz hastalannda hepatit C virOsO (HCV) seroprevelansmm
yOksekligi anemli bir problemdir. Bundan dolaYI HCV'nin bula~ma yollan da
gOnOmOzdeanem kazanml~tlr. Bu ~all~mada, Oicle Universitesi Hemodiyaliz
Merkezinde, hemodiyaliz (HO) ve sOrekli ayaktan periton diyalizi (SAPO)
hastalarmda HC seroprevelansl ve virOsOnyaYllmasml saglayan risk faktarleri
ara~tlnldl.
      Qah~maya 67 HO ve 35 SAPO hastasl ahndl. Hastalann 44 ( % 43.1)'i
kadm, 58 (% 56.9)'u erkekti. Hastalar, HCV infeksiyonu i<;in risk saYllan
herhangi bir faktare sahip olma (kan veya kan OrOnleritransfOzyonu, dO~Ok
sosyoekonomik statO, cerrahi mOdahale ve hastahanede yatma) aylsmdan
sorgulandl. Qah~mada 3. ku~ak ELisA kiti kullanlldl. Merkezimizde HCV
yaYllmasln1engelleyici tOm anlemler almml~tlr. HCV'li hastalarm oda ve diyaliz
makinalan digerlerinden aynlml~tlr.
         Olgulann ortalama ya~141.6:t:15.3 (19-75) Ylldlr. Olgulann ikisi dl~mda
hepsine kan transfOzyonu ve tOmOneen az bir cerrahi giri~im (santral venaz
katater ve/veyaarteriyo-venaz ~ant operasyonu) yapJlml~tlr. Yalnlz sekiz olgu
/%7.8) difl <;ekimiveya konservatif difl tedavisi garmO~tOr.Oiyaliz hasatalannda
dOflOksosyo ekonomik statOve diyaliz sOresiile HCV seropozitifligi % 41'dir ve
bu olgulann tOmO genelde asemptomatik olmakla birlikte, karaciger enzim
seviyelerinde yOkselme, albumin seviyelerinde yOkselme, albumin seviyesinde
ise hafifye dOflme bulunuyordu ve hastalann hepsi en az bir risk faktarOne
sahipti. Anti-HCV(-) hastalanmlzda Yllllk serokonversiyon oranl, HO
hastalannda O.148/hasta Ylh iken; SAPO hastalannda bu oran O.OO2/hasta
Yllldlr.
       HO merkezimizde, HO hastalarmda HCV prevalansl ve Yllllk
serokonversiyon oranl SAPO hastalarmdan daha yOksektir. HO hastalannda,
HCV yaYlhmlnl anlemek iyin, diyaliz makinalannln aYlrlml, hemflire egitimi ve
bir hastadan ba~ka bir hastaya geyildiginde eldiven degi~tirilmesi vb. genel
anlemlerin allnmasl gerekli olabilir.
       Anahtar Kelimeler:    Hemodiyaliz, Hepatit C, Risk Faktarleri, Kan
TransfOzyonu.
                                                                              125

      REFERENCES

1. Rehermann B. Immunopathogenesis of hepatitis C. In: Liang TJ, moderator.
   Pathogenesis, natural history, treatment, and prevention of hepatitis C. Ann
   Intern Med 2000;132:296-305.
2. Purcell RH. Pathogenesis of hepatitis C virus. Presented at the 37th Annual
   Meeting of the Infectious Diseases Society of America; Philadelphia, Pa;
   November 18-21, 1999. Session 70, S110.
3. Choo aL, Kuo G, Weiner AJ, Overby LR, Bradley DW, Houghton M. Isolation
   of a cDNA clone derived from a blood-borne non-A, non-B hepatitis genome.
   Science 1989; 244: 359-62.
4. Von Doom U. Molecular biology of the hepatitis C virus. J Med Viro11994; 43:
   345-56.
5. Simmonds P. Variability of hepatitis C virus. Hepatology 1995; 21: 570-83.
6. Pawlotsky JM, Tsakiris L, Roudot-Thoraval F, Pellet C, Stuyver L, Duval J, et
   al. Relationship between hepatitis C virus genotypes and sources of
   infection in patients with chronic hepatitis C. J Infect Dis 1995;171
   (6):1607-10
7. Fabrizi F, Lunghi G, Guarnori I, Raffaele L, Crepaldi M, Pagano A, Locate11i
   F. Incidence of seroconversion for hepatitis C virus chronic HD patients: a
   prospective study. Nephrol Dial Transplant 1994; 9: 1611-5.
8. Pillot J, Dubreuil P. Are blotting tests (Riba, western-blot) still useful as
   markers of hepatitis C virus infection? Hepatol1995; 23:103-5.
9. Arynsoy T. HCV (+) hastalar ayry hemodiyaliz makineleri ve/veya odalarynda
   tedavi edilmemelidir [Turkish). Diyaliz ve Nefroloji BOlteni 1998; 2(3):
    108-112.
10. Poynard T, Bedossa P, Opolon P. Natural history of liver fibrosis
   progression in patients with chronic hepatitis C. The OBSVIRC, METAVIR,
   CLlNIVIR, and DOSVIRC groups. Lancet 1997;349:825-32.
11. Hopf U, Moller B, Kuther D, Stemerowicz R, Lobeck H, Ludtke-Handjery A,
   et al. Long-term follow-up of posttransfusion and sporadic chronic hepatitis
   non-A, non-B and circulating antibodies to hepatitis C virus (HCV). J Hepatol
   1990; 10: 69-76.
12. Sanchez-Tapias JM, Barrera JM, Costa J, Ercilla MG, Pares A, Comalrrena
   L, et al. Hepatitis C virus infection in patients with nonalcoholic chronic liver
   disease. Ann Intern Med 1990; 112: 921-4.
13. Fong TL, Di Bisceglie AM, Waggoner JG, Banks SM, Hoofnagle JH. The
   significance antibody to hepatitis C virus in patients with chronic hepatitis B.
   Hepatology 1991 ;14: 64-7.
14. Ozen H, Kocak N, Yuce A, Gurakan F. Low prevalence of hepatitis C virus
   antibody in Turkish children with chronic hepatitis B infection [Letter). J
   HepatoI1995;23(4):480
 126


15. Brechot C. Hepatitis C virus 1b, cirrhosis and hepatocellular carcinoma.
   Hepatology 1997; 25: 772-4.
16. Wang YJ, Lee SD, Hwang SJ, Chan CY, Chow MP, Lai ST, et al. Incidence
   of posttransfusion hepatitis before and after screening for hepatitis C virus
   antibody. Vox Sang 1994, 67:187-90.
17. Horowitz B, Prince AM, Horowitz MS, Watklevicz C. Viral safety of solvent
   detergent treated blood products. Dev Bioi Stand 1993; 81:147-61.
18. Gerberding JL. Incidence and prevalence of human immunodefiency virus,
   hepatitis B virus, hepatitis C virus and cytomegalovirus among health care
   personnel at risk for blood exposure: Final report from a longitudinal study. J
   Infect Dis 1994; 170:1410-7.
19. Alter MJ, Hadler SC, Judson FN, Mares A, Alexander WJ, Hu PY, et al. Risk
   factors for acute non-A, non-B hepatitis in the United States and association
   with hepatitis C virus infection. JAMA 1990; 264:2231-35.
20. Cakaloglu Y, Okten A, Kaymakoglu S. Prevalence of antibody to hepatitis C
   virus in cryptogenic, hepatitis related and alcoholic chronic liver disease and
   in blood donors in Turkey. Turk J Med Bioi Res 1992; 3: 53-7.
21. Esteban JI, Lopez-Talavera JC, Genesca J, Madoz P, Viladomiu L, Muniz
   E, et al. High rate of infectivity and liver disease in blood donors with
   antibodies to hepatitis C virus. Ann Intern Med 1991; 115: 443-9.
22. Dawson GJ, Lesniewski RR, Stewart JL. Boardway KM, Gutierrez RA,
   Pendy L. et al. Detection of antibodies to hepatitis C virus in U.S blood
   donors. J Clin Microbiol1991; 29:551-6.
23. Di Bisceglie AM. Hepatitis C. Lancet 1998; 251:351-5.
24. Patino-Sarcinelli F, Hyman J, Camacho LA, Linhares DB, Azevedo JG.
   Prevalence and risk factors for hepatitis C antibodies in volunteer blood
   donors in Brazil. Transfusion 1994; 34:138-40.
25. Cakaloglu Y. Hepatit C Virus infeksiyonu epidemiyolojisi [Turkish]. Viral
   hepatitis 1994: 191-235.
26. Yenen OS, Badur S. Prevalence of antibodies to hepatitis C virus in blood
   donors and risk groups in Istanbul, Turkey [Letter]. Eur J Clin Microbiollnfect
   Dis 1991;10(2):93-4.
27. Esteban JI, Esteban R, Viladomiu L, Lopez-Talavera JC, Gonzalez A,
   Hernandez, et al. Hepatitis C virus antibodies among risk group in Spain.
   Lancet 1989; 5:2(8658) 294-297.
28. Bell J, Batey RG. Farrell GC, Crewe EB, Cunningham AL, Byth K. Hepatitis
   C virus intravenous drug users. Med J Aust 1990:153:274-6.
29. Akahane Y, Aikawa T, Sugai Y, Tsuda F, Okamoto H. Mishiro S.
   Transmission of HCV between spouses [Letter]. Lancet 1992; 339:1059-60.
                                                                             127

30. Chiaramonte M, StroffoliniT, Lorenzoni U, MinnitiF, Conti S, Floreani A, et
   al. Risk factors in community-acquired chronic hepatitis C virus infections: A
   patient control study in Italy.J Hepatol 1996; 24: 129-34.
31. AllanderT, Gruber A, Naghavi M,Beyene A, Soderstrom T, BjorkholmM,et
   al. Frequent patient-to-patient transmission of hepatitis C virus in a
   Hematology ward. Lancet 1995; 345: 601-07.
32. Erek E, SOleymanlar G, Serdengeyti K. TOrkiye de nefroloji-diyaliz ve
   transplantasyon      (Turkish-Registry of Nephrology, Dialysis and
   transplantation). 1998:10-11.
33. Erek E, SOleymanlar G, Serdengeyti K. TOrkiye de nefroloji-diyaliz ve
   transplantasyon     (Turkish-Registry of Nephrology, Dialysis and
   transplantation). 1999:10.
34. Canero-Velasco MC, MuttiJE, Gonzalez JE, Alonso A, Otegui L, Adragna
   M, et al. HCV and HBV prevalence in Hemodialysed pediatric patients.
   Multicenterstudy. Acta Gastroenterol Latinoam 1998; 28(3): 265-8.
35. Pol S, Legendre C, Saltiel C, Carnot F, Brechot C, Berthelot P, et al.
   Hepatitis C virus in kidney recipients. Epidemiology and impact on renal
   transplantation. J Hepatol1992; 15:202-6.
36. Katsoulidou A, Paraskevis D, Kalapothaki V, Arvanitis D, Karayiannis P,
   Hadjiconstantiou V, et al. Molecular epidemiology of a hepatitis C virus
   outbreak in a hemodialysis unit. Nephrol Dial transplant 1999; 14(5):
   1188-94.
37. Sampietro M, Badalamenti S, Salvadori S, Corbetta N, Graziani G, Como G,
   et al. High prevalence of rare hepatitis C virus in patients treated in the same
   hemodialysis unit, evidence for nosocomial transmission of HCV. Kidney Int
   1995; 47: 911-917.
38. Akpolat T, Arik N, Gunaydin M, Utas C, Dilek K, Caglar S, et al. Prevalence
   of anti-HCV among hemodialysis patients in Turkey: a multicentre study.
   Nephrol Dial Transplant 1995; 10(4): 479-80.
39. Ozdemir FN, Arslan H, GOz G, Erten Y, Kayata~ M, Hyzel N, et al. Kronik
   hemodiyaliz hastalannda HCV enfeksiyonu prevalansl ve risk faktorleri
   [Turkish]. Poster Sunumu., XIII. Ulusal Bobrek Hastallklan, Diyaliz ve
   Transplantasyon Kongresi, Istanbul, 22-26 Ekim 1996:147.
40. YOcel Y, TOrksoz N, Ye~il N, Ediz B. SSK Bursa Hastanesi hemodiyaliz
   hastalarynda HCV enfeksiyonu gorOlme slkllgl [Turkish]. Poster Sunumu,
   XIII. Ulusal Bobrek Hastallklan, Diyaliz ve Transplantasyon Kongresi,
   Ystanbul, 22-26 Ekim 1996:85.
41. Olmez N, Erta~ B, GOI F, Sary A, Koy S, Egilmez L, et al. Hemodiyaliz
   hastalarmda hepatit B virusu ve hepatit C virusu birlikteligi [Turkish]. Poster
   Sunumu, XIII. Ulusal Bobrek Hastallklan, Diyaliz ve Transplantasyon
   Kongresi, istanbul, 22-26 Ekim 1996:192.