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HIV Transmission in a Dialysis Center -- Colombia, 1991-1993

Although never reported in the United States, previous reports of possible patient-to-patient transmission of human immunodeficiency virus (HIV) associated with hemodialysis (1,2) indicate the potential for this problem and the importance of infection-control measures in dialysis centers. In May 1994, CDC received a report of a cluster of HIV seroconversions among patients undergoing treatment at a dialysis center in Colombia. This report summarizes the findings of the epidemiologic and laboratory investigations of this cluster by the National Institute of Health in Colombia and CDC (3), which underscore the need for strict adherence to infection-control practices during dialysis (4,5).

In May 1993, blood specimens from three patients of the dialysis center in Colombia were HIV-antibody-positive. This finding prompted the subsequent testing of blood specimens from all dialysis center patients that had been stored during January 1988-December 1993 transplant program. An epidemiologic investigation was initiated after these specimens were tested for HIV antibody by enzyme immunosorbent assay and confirmatory Western blot.

A retrospective cohort study was conducted among all patients who were dialyzed in the dialysis center from January 1992 (approximately 6 months before the first seroconversion) through December 1993 (epidemic period). An HIV seroconverter was defined as any patient with a documented seroconversion from HIV-antibody-negative to positive during the epidemic period. An HIV seronegative patient was a patient whose most recent serum sample was HIV negative. To determine potential risk factors for HIV seroconversion, HIV seroconverters were compared with HIV seronegative patients. Medical, blood bank, and dialysis center records were reviewed, and confidential interviews were conducted with available patients or family members. Any potential exposures to HIV (e.g., surgical or dental procedures or behavioral risk factors) were included in the analysis if they had occurred less than or equal to 1 year before HIV seroconversion for seroconverters or less than or equal to 1 year before the epidemic period for HIV seronegative patients. In addition to the dialysis center, the endoscopy suite and dental clinic located within the hospital containing the dialysis center were inspected; infection-control practices in these settings were observed. Three isolates of HIV were analyzed from four seroconverters and four controls (controls included two HIV-infected persons from the same city but who had not been dialyzed at the dialysis center and two from a different city). Polymerase chain reaction was used to amplify a 480 nucleotide sequence of the HIV-1 gag gene, which encodes for p24 and p7; in addition, three isolates were analyzed for each HIV-infected person.

Of the 84 dialysis center patients dialyzed during the study period (January 1988-December 1993), blood specimens were available for 59 patients. Of these, 13 (22%) were HIV seropositive, including 10 who were HIV seroconverters (nine of whom seroconverted during the epidemic period {January 1992-December 1993}). All HIV seroconverters had undergone greater than or equal to 10 dialysis sessions. Of the nine who seroconverted during the epidemic period, seven were male, two had a history of paying for sex, and five had received blood products (screened for HIV) less than or equal to 6 months before seroconversion; none reported intravenous or illicit drug use or receiving unscreened blood products, and none of the males reported having had sex with other men. None met clinical criteria for acquired immunodeficiency syndrome; four died following seroconversion, but none died because of HIV-related illness.

The first HIV seropositive patient dialyzed during the epidemic period (patient A) tested positive 20 days after beginning care at the dialysis center in May 1992. The risk for seroconversion among patients who received dialysis during the 4-month period (May-August 1992) when patient A was dialyzed was significantly higher than for those who were dialyzed only during other months (i.e., nine of 10 versus none of nine; relative risk=infinity; exact 95% confidence interval=3.0-infinity). The only patient who received dialysis during the same period as patient A but who did not seroconvert was recorded to have always used separate patient-care equipment designated for patients known to be infected with hepatitis B virus (HBV); all other patients dialyzed during this period were recorded to have used common equipment. Risk for HIV seroconversion was not associated with other factors, including history of transfusions less than or equal to 6 months before seroconversion, a kidney transplant, or dental or endoscopic procedures.

Nucleotide sequence comparison of HIV deoxyribonucleic acid indicated that isolates obtained from the four dialysis center seroconverters were genetically closer to each other (0.02%-0.05% variation) than to the four controls (0.06%-0.08% variation), suggesting a common source for infection in patients in the dialysis center (6). An HIV isolate from patient A, who died 4 months after beginning dialysis at the dialysis center, was not available for testing. Isolates from three of the four dialysis center seroconverters were 100% homologous at the amino acid level. This amino acid homology was not found for isolates from seroconverters compared with controls.

The dialysis center had no written policies about reprocessing patient access needles, dialyzers, or blood lines. Interviews with staff nurses indicated that all dialyzers and blood lines were labeled appropriately and individually reprocessed with 5% formaldehyde while still attached to the machine, placed in separate labeled containers, and stored for reuse only on the same patient. In contrast, patient access needles were reprocessed through the use of a 0.16% solution of benzalkonium chloride; in this procedure, the pairs of access needles for two to four patients were placed unlabeled in a common soaking pan for disinfection, and the disinfectant was changed every 7 days.

As a result of the investigation, changes in procedures implemented at the dialysis center included cessation of reprocessing patient-care equipment and providing HIV counseling to all infected patients. National surveillance was initiated for HIV infection among patients undergoing dialysis, and the Ministry of Health has banned the use of quaternary ammonium compounds for disinfecting intravascular devices. Reported by: M Velandia, MD, J Boshell, MD, A Iglesias, MD, G Ramirez, MD, National Institute of Health, Advanced Training Program in Applied Epidemiology, Ministry of Health, Bogata, Colombia. B Rengifo, MD, M Essex, DVM, Dept of Cancer Biology, Harvard School of Public Health, Boston, Massachusetts. V Cardenas, MD, Field Epidemiology Training Program, International Br, Div of Field Epidemiology, Epidemiology Program Office; Hospital Infections Program, National Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: The epidemiologic and laboratory findings from the investigation described in this report indicate that transmission of HIV in the dialysis center was associated with a common exposure or patient-to-patient transmission. In particular, the investigation implicated receipt of dialysis after an HIV-seropositive patient began dialysis as the most likely risk exposure for infection and suggested that cross-contaminated, inadequately disinfected patient access needles may have been inadvertently shared among HIV-infected and noninfected patients. Benzalkonium chloride, the disinfectant used for reprocessing the needles, is a chemical germicide with low-level activity and is not recommended in the United States for disinfection of intravascular devices (e.g., dialysis access needles) (7).

Previous reports of possible patient-to-patient transmission indicate that potential routes for transmission of HIV in other health-care settings include inadequate reprocessing or inadvertent reuse of hypodermic needles and breaks in universal precautions (8,9). The outbreak in Colombia suggests that, in dialysis centers worldwide, reprocessing of patient-care equipment must conform to established infection-control practices (4,5,7).

The global implementation of dialysis and other advanced medical technologies must be accompanied by rigorous adherence to infection-control practices. Standards and recommendations outlined by the Association for the Advancement of Medical Instrumentation (10) and CDC (4,5,7), including sterilization before reuse of all intravascular patient-care items (i.e., intravascular access devices), are essential for preventing transmission of bloodborne pathogens such as HBV and HIV.


  1. Dyer E. Argentinian doctors accused of spreading AIDS. Br Med J 1993;307:584.

  2. Marcus R, Favero MS, Banerjee S, et al. Prevalence and incidence of human immunodeficiency virus among patients undergoing long-term hemodialysis. Am J Med 1991;90:614-9.

  3. Velandia M, Fridkin SK, V Cardenas, et al. Transmission of HIV in a dialysis centre. Lancet 1995;345:1417-22.

  4. Favero MS. Precautions for dialyzing human immunodeficiency virus-infected patients. In: Monkhouse PM, ed. Aspects of renal care. London: Balliere Tindall, 1989:55-61.

  5. CDC. Recommendations for prevention of HIV transmission in health care settings. MMWR 1987;36 (no. 2S).

  6. Myers G. Molecular investigation of HIV transmission {Editorial}. Ann Intern Med 1994; 121:889-90.

  7. CDC. Guidelines for handwashing and hospital environmental control. Atlanta: US Department of Health and Human Services, Public Health Service, 1985.

  8. Hersh BS, Popovici F, Apetrei RC, et al. Acquired immunodeficiency syndrome in Romania. Lancet 1991;338:645-9.

  9. Chant K, Lowe D, Rubin G, et al. Patient-to-patient transmission of HIV in private surgical consulting rooms. Lancet 1994;342:1548-9.

  10. Association for the Advancement of Medical Instrumentation, ed. Recommended practice for reuse of hemodialyzers. Arlington, Virginia: Association for the Advancement of Medical Instrumentation, 1993.

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