Centers for Disease Control
Outbreaks of hepatitis B virus infection among hemodialysis patients -
- California, Nebraska, and Texas, 1994
Morb Mortal Weekly Rep
(Apr) 45:No. 14 1996
The full text article follow below (Reports from the MMWR
are in the public domain)
From April through August 1994, outbreaks of hepatitis B virus
(HBV) infection occurred in five chronic hemodialysis centers in
California, Nebraska, and Texas. This report summarizes
investigations by state and local public health officials and CDC,
which suggest that transmission of HBV from hemodialysis patients
with chronic HBV infection to susceptible patients resulted from
failure to identify and isolate HBV-infected patients during
hemodialysis; sharing of staff, equipment, and supplies among
patients; and failure to vaccinate susceptible patients against
In these investigations, a case of acute HBV infection was
defined as seroconversion from hepatitis B surface antigen
(HBsAg)-negative to HBsAg-positive in a hemodialysis patient during
the exposure period defined in each investigation. A susceptible
patient was defined as a hemodialysis patient who was negative for
HBsAg, antibody to HBsAg (anti-HBs), and antibody to hepatitis B
core antigen (anti-HBc). An immune patient was defined as a patient
who was positive for anti-HBs as a result of vaccination or
positive for anti-HBc and/or anti-HBs as a result of natural
infection. A patient with chronic HBV infection was defined as any
patient who was positive for HBsAg for greater than 6 months or was
positive for both HBsAg and anti-HBc (immunoglobulin M negative).
Hemodialysis Center A, Texas
From April 1 through May 18, 1994, cases of acute HBV
infection were identified through routine seroscreening in 14 (70%)
of 20 patients at center A, which opened in January 1994. In
addition, a case of previously unrecognized chronic HBV infection
was identified in a patient who had received hemodialysis nine
times at center A from January 26 through February 9, but had not
been isolated from other patients during these treatments. All
case-patients had shared at least one shift with the patient with
chronic infection; however, no single event, day, or shift was
associated with transmission to all cases. The source-patient had
been transferred from another center where he was known to have
chronic infection, but his serologic status had not been reviewed
on admission to center A. In addition, although all patients at
center A were screened monthly for HBsAg, results were not reviewed
routinely. The investigation also indicated that staff frequently
handled blood-contaminated items without changing gloves or washing
hands and that clean and contaminated supply areas were adjacent to
each other. Less than 20% of the patients at center A had been
vaccinated against hepatitis B; no cases were detected among those
who had been vaccinated.
Hemodialysis Center B, California
From April 1 through June 1, 1994, cases of acute HBV
infection were identified in seven (5.3%) of 131 susceptible
patients in center B. Of the two patients with chronic infections,
one was identified as the source of the transmission through
genetic sequencing of virus isolates from all infected patients.
Staff frequently were assigned to provide simultaneous care
for the source-patient with chronic infection and for susceptible
patients. Common medication/supply carts were moved between
stations, and medications and supplies were shared among infected
and susceptible patients. Staff had been shared among the
implicated source-patient, who received heparin, and two
susceptible patients, of whom one received heparin and became
infected; the other susceptible patient did not receive heparin and
was uninfected. Partially used heparin vials routinely were
returned to a common medication cart. A cohort study indicated that
HBV infection was associated with a single shift (relative risk
[RR]=7.0; 95% confidence interval [CI]=1.5-42.8)--the shift
following that during which staff had been shared among susceptible
patients and the source-patient. In addition, all of the infected
patients on that shift had been at stations clustered in one area
of the unit. Because one heparin vial probably had been shared
among these patients, contamination of a shared multiple-dose vial
was considered the most likely route of HBV transmission among
patients in this outbreak. Of all patients in center B, none had
been vaccinated against hepatitis B.
Hemodialysis Center C, California
Center C opened on April 6, 1994. Based on routine serologic
screening during June 13-August 15, seroconversion to HBsAg
positivity occurred in four (9.5%) of 42 susceptible patients,
including two in June, one in July, and one in August. One patient
known to have chronic infection had been dialyzed in an isolated
area since the center opened. Although this patient had the same
HBsAg subtype as the cases, he was hepatitis B e antigen
(HBeAg)-negative, suggesting he had not been the source. Two
patients with chronic infection had been admitted to center C on
June 20 and 27 (following seroconversion in the first two cases).
Risk for infection was not associated with a single event, day,
shift, or geographic clustering, and infection-control practices
were considered appropriate. All staff were negative for HBsAg, and
no patients had been vaccinated against hepatitis B. Based on a
cohort study, risk for acute infection was associated only with
receipt of hemodialysis as a patient at a community hospital any
time during April 1-21 (RR=9.0; 95% CI=1.1-76.0). Limited results
of HBV testing of all patients receiving hemodialysis at that
hospital precluded determining a source of infection in the
hospital hemodialysis setting.
Hemodialysis Center D, California
From June through August 1994, cases of acute HBV infection
were identified in 11 (14%) of 77 susceptible patients at center D.
Monoclonal antibody subtyping of HBV isolates from two of three
patients with chronic infections and seven of the 11 cases
identified two distinct antigen subtypes (adw2 and adw4). Isolates
from four cases were subtype adw2; stations at which these patients
were treated were clustered geographically, and equipment,
supplies, and hemodialysis staff had been shared among these
patients and the two patients with chronic infections who also had
subtype adw2 infections. The three other cases were infected with
subtype adw4; although these patients were not treated at clustered
stations, their care entailed shared equipment, supplies, and
staff. One of these patients seroconverted 1-2 months before the
others; however, the source of this patient's infection was
unknown. No patients had been vaccinated against hepatitis B.
Hemodialysis Center E, Nebraska
From March through June 1994, cases of acute HBV infection
were identified in two (0.7%) of 303 patients at center E. A
patient known to have a chronic HBV infection had been admitted to
center E in December 1993. The first case became HBsAg-positive in
March 1994; this patient had been hemodialyzed on the same shift
and shared staff with the patient with chronic infection on two
occasions before seroconversion. The second case became
HBsAg-positive in June 1994; this patient had been hemodialyzed on
the same shift and had shared staff with the first case-patient on
two occasions before seroconversion. The same HBsAg subtype (adw2)
was present in the patient with chronic infection and two cases.
None of the patients had been vaccinated against hepatitis B.
Reported by: K Hendricks, MD, L Sehulster, PhD, Infectious Disease
Epidemiology and Surveillance Div; RL Bell, PhD, J Cousins, W
MacNeeley, A Payne, M des Vignes Kendrick, MD, City of Houston Dept
of Health and Human Svcs; D Simpson, MD, State Epidemiologist,
Texas Dept of Health. M Tormey, MPH, A Itano, MSPH, L Mascola, MD,
Los Angeles County Health Dept, Los Angeles; D Vugia, MD, J
Rosenberg, MD, Div of Communicable Disease Control, S Waterman, MD,
State Epidemiologist, California Dept of Health Svcs. TJ Safranek,
MD, State Epidemiologist, Nebraska Dept of Health. Hospital
Infections Program and Hepatitis Br, Div of Viral and Rickettsial
Diseases, National Center for Infectious Diseases , CDC.
Editorial Note: HBV is present in extraordinarily high titers in
blood and other body fluids of infected patients ( greater than or
equal to 109 virus particles per milliliter). Because the virus
survives well in the environment, blood-contaminated surfaces that
are not routinely cleaned and disinfected represent a reservoir for
transmission of HBV (1). Dialysis staff can transfer virus to
patients from contaminated surfaces by their hands or through use
of contaminated equipment and supplies.
All five outbreaks of HBV infection in chronic hemodialysis
centers described in this report were associated with failure of
the facilities to adhere to one or more of the recommended
infection-control practices for preventing the transmission of HBV
and other bloodborne pathogens in such settings. Previous reports
consistently have indicated that risk factors associated with HBV
transmission among patients in hemodialysis centers include the
presence of a patient with chronic HBV infection and failure to
isolate such patients by room, machine, and staff (2-4). These
reports also have documented that physical separation of
HBV-infected patients from susceptible patients substantially
reduces the risk for HBV transmission.
Recommendations for infection-control practices were published
and disseminated initially in 1977 (5); hepatitis B vaccination has
been recommended for susceptible patients since 1982. In 1977, the
national incidence of HBV infection among hemodialysis patients was
3.0%; by 1980, the national incidence had declined to 1.0%, and by
1989, to 0.1% (2).
To prevent transmission of bloodborne pathogens in general
health-care settings, universal precautions were initially
recommended in 1985 and updated in 1988 (6); the recommendations
emphasized the use of barriers (e.g., gowns, gloves, and eyewear)
and adherence to routine hand washing, appropriate disposal of
needles and other sharp instruments, and disinfection and
sterilization procedures. To prevent transmission of bloodborne
pathogens in hemodialysis settings, both universal precautions and
the following hemodialysis-specific infection-control practices
recommended in 1977 should be used:
1) Serum specimens from all
susceptible patients should be tested monthly for HBsAg, and these
results should be reviewed promptly.
2) HBsAg-positive patients
should be isolated by room, machine, instruments, medications,
supplies, and staff.
3) Instruments, medications, and supplies
should not be shared between any patients. When sharing of
multidose medication vials is necessary, medications must be
prepared in a clean centralized area separate from areas used for
patient care, laboratory work, or refuse disposal.
cleaning and disinfection procedures should be followed, including
clear separation of areas established to handle clean and
contaminated items. Blood specimens should be handled with gloved
hands and stored in designated areas away from medication
preparation or central supply areas.
Hepatitis B vaccine has been recommended for all susceptible
hemodialysis patients since it became available in 1982 (7).
However, by 1993 only 29% of hemodialysis patients in the United
States had been vaccinated (2). In 1993, vaccination coverage among
patients in the southern California region was 13%, lower than in
northern California or any other state in the United States (2).
Among immunocompetent persons, a protective antibody response
develops in 90%-95% of vaccine recipients, protection against HBV
infection persists even when antibody titers subsequently decline,
and booster doses are unnecessary (7). In contrast, the proportion
of vaccinated hemodialysis patients who develop a protective
antibody response is lower (50%-60%), and booster doses are
necessary to maintain protection against hepatitis B when antibody
titers decline below protective levels (7,8). However, greater than
or equal to 50% of hemodialysis patients can be protected from
hepatitis B by vaccination, and maintaining immunity among these
patients will reduce the frequency and costs of serologic screening
1. Favero MS, Maynard JE, Peterson NJ, et al. Hepatitis B antigen
on environmental surfaces. Lancet 1973;2:1455.
2. Tokars JI, Alter MJ, Favero MS, Moyer LA, Miller E, Bland LA.
National surveillance of dialysis-associated diseases in the United
States, 1993. Am Soc Artif Intern Organs J 1996 (in press).
3. Niu MT, Penberthy LT, Alter MJ, Armstrong CW, Miller GB, Hadler
SC. Hemodialysis-associated hepatitis B: report of an outbreak.
Dialysis & Transplantation 1989;18:542-6,555.
4. Alter MJ, Ahtone J, Maynard JE. Hepatitis B virus transmission
associated with a multiple-dose vial in a hemodialysis unit. Ann
Intern Med 1983;99:330-3.
5. CDC. Hepatitis-control measures for hepatitis B in dialysis
centers. In: Hepatitis surveillance report no. 41. Atlanta,
Georgia: US Department of Health and Human Services, Public Health
Service, CDC, 1977:12-7.
6. CDC. Update: universal precautions for prevention of
transmission of human immunodeficiency virus, hepatitis B virus,
and other bloodborne pathogens in health-care settings. MMWR
7. CDC. Hepatitis B virus: a comprehensive strategy for eliminating
transmission in the United States through universal childhood
vaccination--recommendations of the Immunization Practices Advisory
Committee (ACIP). MMWR 1991;40(no. RR-13).
8. Stevens CE, Alter HJ, Taylor PE, et al. Hepatitis B vaccine in
patients receiving hemodialysis: immunogenicity and efficacy. N
Engl J Med 1984;311:496-501.
9. Moyer LA, Alter MJ, Favero MS. Hemodialysis-associated hepatitis
B: revised recommendations for serologic screening. Seminars in
10. Alter MJ, Favero MS, Francis DP. Cost benefit of vaccination
for hepatitis B in hemodialysis centers. J Infect Dis 1983;148:770-1.