TT virus infection in French hemodialysis patients: study of prevalence and risk factors.

The TT virus (TTV) is a recently discovered DNA virus which was first identified in patients with non-A to -G hepatitis following blood transfusion. In this study, we tested 150 attendees of two hemodialysis (HD) units of the public hospitals of Marseilles, France, for the presence of TTV genome by using a PCR-based methodology. The overall prevalence of TTV viremia was 28% (compared to 5.3% in blood donors from the same region). We demonstrated the existence of chronic infections and superinfections by strains belonging to different genotypes. The prevalence of infection was higher in patients originating from Africa, in patients with previous blood transfusion or organ transplantation, in patients with antibody to hepatitis B core antigen, and in those with diabetes mellitus. A high prevalence of TTV infection (50%) was also observed in a population of patients with diabetes mellitus but without renal disease. No significant relationship was found between TTV viremia and hepatitis C virus or GB virus C, transaminases, age, sex, and duration of HD treatment. The PCR amplification products (located in open reading frame 1 of the TTV genome) were sequenced. These genomic sequences were submitted to phylogenetic analysis by using the Jukes-Cantor algorithm for distance determination and the neighbor-joining method for tree building. In several instances, sequences from viruses isolated in a HD unit were grouped in the same phylogenetic cluster. These results together with the different distribution of cases in the two HD units suggest there is viral transmission within each.

A new approach to evaluate vascular access in hemodialysis patients.

We evaluated the importance of vascular access in hemodialysis patients using noninvasive methods with the Transonic Systems monitor in 108 patients. Most of these patients (84%) had native vein fistulas. We found that a blood flow rate of below 500 ml/min suggested the occurrence of vascular stenosis and justified confirmation by angiography. Increased recirculation could be evaluated readily and was detected in only 10% of patients. Finally, employing the evaluation of the Kt/V index, we found a good correlation between low flux through the fistula and a low Kt/V value.

Transmission of the hepatitis C virus in an hemodialysis unit: evidence for nosocomial infection.

Hepatitis C virus (HCV) infection is a frequent feature in hemodialysis (HD) patients. The way of viral transmission is difficult to establish, but in previous studies the role of blood transfusions and of HD treatment duration, and the possibility of nosocomial transmission of the virus have been suggested. We present here the results of a virological follow-up of HCV infection in our HD unit in 1993-1994, and a molecular study of viral strains that led to a possible reconstruction of viral spreading. All patients in our unit were regularly tested for alanine aminotransferase, HCV antibodies and HCV RNA in serum. Seven seroconversions were detected during follow-up, and a high proportion of type 1b HCV strains was found in infected patients. Nucleotide sequences located in the envelope 1 (E1) viral coding region of type 1b strains were compared in our patients and numerous controls infected with the same HCV genotype. A high proportion of patients with antibodies to HCV were detected in our unit (32.5%). Blood transfusions and duration of HD treatment were risk factors for HCV infection. Seroconversions in patients never transfused and predominance of type 1b HCV strains suggested that infection had occurred via the nosocomial pathway in our unit. Similar sequences in the E1 region were found in four patients treated, forming a distinct cluster in a phylogenetic tree. Of these four patients, two had been infected before 1991, and the others made a seroconversion for HCV at the same period in 1994. In all other patients, including a nurse who had been in charge of some infected patients, distinct strains were found. Duration of HD treatment seems to be a major factor of risk for HCF infection in HD units. Contamination could occur during blood transfusion or via the nosocomial pathway through a crossinfection mechanism from patients already infected. The latter mechanism was formally demonstrated in this study.

Preliminary evidence for a role of apolipoprotein E alleles in identifying haemodialysis patients at high vascular risk.

Conventional risk factors have very low predictive power in identifying haemodialysis patients at high risk of vascular accidents. A role for apolipoprotein E isotypes was looked for in a small, but rigorously defined, cohort of longterm haemodialysis patients. In individuals with high vascular risk, as identified by higher common carotid intima/media thickness, we found an excess of apolipoprotein E4 alleles. This preliminary result requires confirmation in large patient cohorts.

Nosocomial transmission of hepatitis C virus in haemodialysis patients.

A systematic virological follow-up of 114 haemodialysis patients treated in the same unit showed that 37, including 17 PCR positive patients, were seropositive for hepatitis C virus (HCV). Type 1b HCV was detected in 10 patients and was much more frequent in this population than in the whole population of patients treated in the hepatogastroenterology departments in southeastern France. The E1/E2 genomic region of seven type 1b HCV strains was sequenced. In four patients, a similar strain was detected in both the E1 variable region and the E2 hypervariable region (HVR1). In addition, two of these four patients were seronegative and PCR negative at the beginning of the study and had not been transfused or transplanted during this period. A phylogenetic tree was drawn which confirmed that these strains were very similar and showed that HCV was transmitted via the nosocomial pathway in this haemodialysis unit.

Leishmaniasis: a rare cause of unexplained fever in a renal graft recipient.

We report a case of visceral leishmaniasis in a 38-year-old renal transplant recipient living in an endemic country. Antimonial derivatives induced a rapid remission. A review of the literature disclosed 8 cases of this association with a fatal fulminant outcome in 5 cases. We suggest that the specific immunosuppression used in renal transplant patients might facilitate the development of a dormant infection and in these patients the misleading presentation may delay the diagnosis. Moreover special caution with treatment of leishmaniasis must be taken in renal transplant because of possible interactions between antimony compounds and ciclosporin metabolites. In renal transplant patients living in endemic countries, visceral leishmaniasis should be kept in mind as a potential cause of unexplained long-standing fever and considered as an opportunistic infection.