Epidemiologic Notes and Reports Nosocomial Transmission of Hepatitis B Virus Associated with a Spring-Loaded Fingerstick Device -- California

In March 1990, staff in a hospital in California noted an increase in the number of patients diagnosed with acute hepatitis B (HB). From June 1989 through March 1990, 20 patients with HB were identified; in comparison, from June 1988 through May 1989, four such patients had been identified. All cases were serologically confirmed as recently positive for hepatitis B surface antigen (HBsAg) or positive for IgM antibody to hepatitis B core antigen (IgM anti-HBc). Review of medical records of the 20 patients indicated that 1) all had been admitted to one medical ward during the 6 months before becoming HBsAg-positive; 2) 18 had diabetes mellitus; 3) during hospitalization, capillary blood samples were obtained from 19 patients to measure blood glucose levels using a spring-loaded device to prick the finger; and 4) one patient with diabetes who had been admitted March 15, 1989, was a hepatitis B virus (HBV) carrier and may have been the source of the outbreak.

To assess the extent of HBV transmission, all patients hospitalized on the medical ward from January through December 1989 were requested to provide blood samples for HBV serologic testing. Samples were obtained from 401 (59%) of 676 patients hospitalized; seven additional cases were identified--five patients with and two without diabetes. Seventy-one (18%) patients were immune (positive for total anti-HBc, IgM class negative). Thus, a total of 27 persons with acute HB--seven (26%) of whom were symptomatic--were identified in persons admitted after the HBV carrier patient (Figure 1). Twenty-six were men. Nineteen were white, four were black, and four were Hispanic. The mean age was 65 years (range: 42-79 years).

Retrospective cohort and case-control studies were conducted to determine risk factors for acquiring HB in patients with diabetes who were hospitalized on the medical ward from March 15 to December 31, 1989. In addition, a case-control study of patients without diabetes who had acute HB was conducted using a stratified random sample of patients without diabetes as controls. Persons immune for HBV infection were excluded from the analyses. Medical charts were reviewed and patients interviewed to determine potential risk factors for HBV infection; dates and reasons for hospitalization; bed location on the ward; underlying illness; surgery and percutaneous exposures during hospitalization, including number of fingersticks, intramuscular injections, transfusions, insulin injections, subcutaneous heparin injections, or intravenous catheter placement or other invasive procedures.

Among patients with diabetes, HB occurred in 23 (42%) of 55 who had fingersticks by the spring-loaded device compared with none of five who did not have fingersticks (p=0.08). A comparison of case- and noncase-patients with diabetes indicated that case-patients had a higher mean number of fingersticks (42 vs. 17; p=0.002, Kruskal-Wallis H (KWH) test), a higher mean number of insulin injections (18 vs. five; p=0.002, KWH test), and a longer mean length of hospital stay (13.8 days vs. 5.6 days; p=0.002, KWH test). Among patients with diabetes, no other exposures were associated with risk of acquiring HBV infection. The case-control study of patients without diabetes indicated that three of four case-patients had capillary blood sampling by fingerstick with the spring-loaded device, compared with none of 20 of the controls (p=0.002). No other risk factors for HBV infection were identified in the case-patients without diabetes.

The hospital indicated that only one type of spring-loaded capillary blood sampling device was used in its inpatient services; this device employs a disposable lancet to prick the skin and a disposable platform to stabilize the device on the finger and control the depth of the puncture. Interviews with the nursing staff indicated that although the nurses always changed the lancets between uses, they did not routinely change the platform after each use or clean the device between uses on different patients.

A possible source of the outbreak, the patient with diabetes who was an HBV carrier, had been admitted to the ward in March 1989 and required multiple fingersticks. The index patient was a woman with diabetes who had onset of HB in June 1989; she had been hospitalized continuously for 11 years with amyotrophic lateral sclerosis and had no risk factors for HB other than fingersticks with the spring-loaded blood sampling device. Because she was hospitalized for a prolonged period and became an HBV carrier, she served as a long-term reservoir for HBV on the medical ward.

Each of the 13 case-patients on whom HBsAg subtyping was performed had subtype ayw3, including the HBV carrier and the index patient. Subtype ayw3 is relatively rare: of HBsAg-positive carriers in the general population, 10%-20% are ayw3 (P. Smith, M.D., personal communication).

The epidemiologic investigation and HBsAg subtyping implicated the spring-loaded blood sampling device as the mode of transmission in this outbreak. The hospital discontinued use of the spring-loaded device on April 1, 1990, and instituted the use of singly packaged spring-loaded disposable lancets for obtaining capillary blood for glucose monitoring. Since this change, no new cases of HB have been identified. Reported by: FW Bauer, MD, PM Klotz, P Ginier, MD, California; RR Roberto, MD, GW Ruther ford, III, MD, State Epidemiologist, California Dept of Health Svcs. G Wesley, MD, A Graham, MD, D Winship, MD, District of Columbia. Center for Devices and Radiological Health, Food and Drug Administration. Hospital Infections Program and Hepatitis Br, Div of Viral and Rickettsial Diseases, Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: This is the first reported outbreak of HB associated with the use of fingerstick devices in the United States. An HB outbreak in which a similar fingerstick device was implicated was recently reported in France (1). These fingerstick devices are used specifically for obtaining capillary blood samples. When the finger is pricked, the device is stabilized on the patient's finger with a platform containing a hole through which the lancet punctures the skin. The investigation in France found that the platform had visible blood contamination in 20 (24%) of 85 finger-sticking tests (1), suggesting that the platform may be easily contaminated with blood from the skin puncture. Contamination of the platform with blood from an HBV-infected patient could enable percutaneous transmission to other patients.

Because HBV circulates in the blood at high titers and can remain viable for at least 1 week in blood samples that have dried on surfaces (2), lancets and platforms should be changed after every use of the spring-loaded device. Other surfaces on the device may also become contaminated with patients' blood during use of the device. In addition, because platforms may not be routinely changed after each use, fingerstick devices with disposable platforms optimally should be used only on individual patients. However, if used on multiple patients, after disposal of the lancet and platform, the device should be cleaned and disinfected at the end of the day and more frequently if visibly contaminated with blood.

Some spring-loaded fingerstick devices do not employ disposable platforms. Use of these devices also optimally should be restricted to one patient, but if used on multiple patients, the lancet should be discarded and the device disinfected between patients. The Food and Drug Administration recommends that the manufacturers' guidelines for disinfection be followed. When no instructions for disinfection are provided, the device should be discarded. Some fingerstick devices do not have disposable lancets; use of these devices should be restricted to use in only one patient and, because they cannot be disinfected, should be discarded when no longer needed by that patient. The Food and Drug Administration is issuing a safety alert concerning the use of all spring-loaded fingerstick devices.

References

1. Douvin C, Simon D, Zinelabidine H, Wirquin V, Perlemuter L, Dhumeaux D. An outbreak of hepatitis B in an endocrinology unit traced to a capillary-blood-sampling device. N Engl J Med 1990;322:57-8

2. Bond WW, Favero MS, Peterson NJ, Gravelle CR, Ebert JW, Maynard JE. Survival of hepatitis B after drying and storage for one week. Lancet 1981;1:550-1.

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