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Chickenpox outbreak among the staff of a large, urban adult hospital: Costs of monitoring and control
BRIEF REPORT
Chickenpox outbreak among the staff of a large, urban adult hospital: Costs of monitoring and control J. L. Faoagali, MBchB, DCP, FRCPA, DHA, FASM D. Darcy, RN Brisbane, Queensland, Australia
Chickenpox is a highly infectious disease of childhood, but there are increasing reports of occurrence in adults. A recent community epidemic of chickenpox resulted in 20 documented cases of adult chickenpox in a large metropolitan hospital. Nine of these cases resulted from direct exposure to an index patient and four were in tertiary contacts of the three index patients associated with the nosocomial outbreak. A total of 165.6 person-days of work were lost (estimated $18,000 cost) as a result of this outbreak, and 70 infection control unit person-hours were required during the investigation and control. This article reports a nosocomial epidemic and reviews guidelines for identification and control of adult chickenpox in a large hospital complex. (AJIC AM J INFECT CONTROL 1995;23:247-50)
A history of chickenpox is usually a reliable indicator of immunity to this infection. 1-3 Increasing numbers of adults who were never infected with the varicella zoster virus (VZV) during childhood are acquiring chickenpox. 4 When these nonimmune adults are among the patients and staff at an adult hospital, the economic impact of such outbreaks can be significant, s' 6 particularly if standard recommendations for excusing exposed nonimmune staff members from duty for days 10 through 21 of their exposure are followed, v' 8 At our institution, determination of the VZV immune status of staff is not currently required before employment. Staff members in contact with patients with chickenpox are questioned regarding their history of infection. Those who do not know their immune status are offered testing. This report documents 20 cases of chickenpox occurring among adult hospital staff members during a 3-month period. It also traces the
From the Royal Brisbane Hospital, Brisbane, Queensland, Australia. Reprint requests: J. L. Faoagali, Director of Medical Microbiology, Royal Brisbane Hospital, Herston Rd., Herston, Brisbane, Queensland, Australia. Copyright © 1995 by the Association for Professionals in Infection Control and Epidemiology, Inc. 0196-6553/95 $3.00 + 0 17/47/62034
infection control unit person-hours of contact tracing and staff person-days of work lost during this epidemic. METHODS
All cases of chickenpox identified in the hospital were followed up by the infection control unit staff to determine the numbers of contacts at risk (nonimmune to chickenpox) and to educate them regarding the symptoms of chickenpox so that they would not continue working while unwell, placing others at risk and continuing the epidemic. The epidemic c o m m e n c e d with a fatal case, which initially was undiagnosed and then was not recognized as infectious while the patient was receiving antiviral therapy. Case 1
On Saturday, September 29, 1992, an immunesuppressed, steroid-dependent patient was admitted to the intensive care unit through the department of emergency medicine with disseminated varicella (chickenpox). The patient, who had been seen at the emergency department twice in the previous week (as well as at a local private hospital), was admitted because of the florid nature of his disease and general collapse. Intravenous acyclovir at a dose of 10 mg/kg every 8 hours was started immediately, and the patient was placed in the open 10-bed intensive care unit 247
248
Faoagaliand Darcy
because he was considered infectious while being treated with acyclovir. The infection control unit was not informed of the admission, which was only detected during the routine semiweekly ward round (3 days after admission). It was decided not to move the patient at that time because he had been treated with intravenous acyclovir for 3 days. He was severely thrombocytopenic, comatose, and in respiratory failure, receiving mechanical ventilation. Despite full care, the patient died on day 5 of his admission. Four secondary cases and one tertiary case of chickenpox were attributed to this patient. These infections developed 12 to 15 days after contact with this index patient. Case 2
The second index patient had thoracic zoster and was being treated in a private ward. He was not reported to the infection control unit until the secondary cases occurred. Case 3
The third index case occurred in a visiting hospital auditor, who contacted the infection control unit on the advice of his local physician on the day of diagnosis. Investigation confirmed that 2 to 3 weeks before development of chickenpox he was auditing the adjacent children's hospital, where he was assumed to have contracted his infection. Three days before development of the rash, he was auditing the occupational and physiotherapy departments of the adult hospital. Two days before appearance of his rash, the auditor spent a considerable time in the operating theater tea room, waiting for theater access. Most of the theater staff on duty were exposed. On the day before the rash developed, he visited most of the air-conditioned wards and services in one hospital block. Other cases
Four other isolated staff members and one immunocompromised patient are known to have acquired chickenpox during this period. None had any direct contact with the three index patients, and these cases were presumed to be part of the ongoing community epidemic. Contact tracing
Notices were sent to all the sections that had been visited by each index patient during the 4 days before their clinical detection, to inform all
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AJIC August 1995
nonimmune staff methbers of their risk of exposure to chickenpox. Nonimmune staff members were requested to contact the occupational health department for advice regarding the prodromal symptoms of infection, to ensure that they did not unnecessarily expose other nonimmune staff members or patients. Laboratory tests
Direct fluorescent antibody testing is performed on vesicular lesions of persons with suspected herpesvirus infection. Antigens specific to VZV, herpes simplex virus 1, and herpes simplex virus 2 are available, but not all are tested on each specimen. The results are available on the day of collection. VZV immunoglobulin G is determined with an enzyme-linked immunosorbent assay technique. This reliably reflects previous exposure (and immunity) to this virus. An enzyme-linked immunosorbent assay test for VZV immunoglobulin G costs approximately $10 (U.S. dollars). The cost of screening a staff of more than 4000 with a high turnover rate (approximately 1000 per year) would be $10,000. This could be reduced by approximately half if only staff members with no documented history or recollection of chickenpox were included. Table 1 sets out the number of direct fluorescent antibody and VZV immunoglobulin G tests performed and positive results during the outbreak period. Costs
Costs were determined by estimating days of work lost while staff members were infected and also hours spent by the infection control unit staff organizing contact tracing and follow-up counseling of nonimmune staff members (Table 2). RESULTS
Four secondary cases and one tertiary case of chickenpox were attributed to the first index patient. These infections developed 12 to 15 days after contact with that index patient. The first index patient was in contact with emergency department, intensive care unit, radiology, and physiotherapy staff of all categories as well as wardsmen, cleaners, mortuary staff, and mortician. Contacts of the secondary patients associated with the first index patient involved several specialist units, the department of anesthetics, theater staff, and patients undergoing anesthetic procedures. One (a physician anesthetist) anesthetized patients all day before his rash appeared. One (a student nurse) was in a class of 40 peers the day
AJIC
Faoagali and Darcy 2 4 9
Volume23, Number4 Table
1. Immune status of staff
September
HSV 1 HSV 2 VZV DFA VZV immunoglobulin G Nonimmune rate (% of patients tested for VZV immunoglobin G)
October
November
December
January
PR
Tests
PR
Tests
PR
Tests
PR
Tests
PR
Tests
8 1 2 17
41 41 11 24 28
1 1 3 53
51 51 17 73 27.3
7 1 1 18
51 51 6 50 64
8 1 0 33
40 40 9 42 22.5
5 2 2 15
61 61 11 34 57
PR, Positiveresults; HSV, herpes simplexvirus; DFA,direct fluorescentantibody; ELISA,enzyme-linkedimmunosorbentassay.
the rash appeared. The tertiary patient associated with the first index patient attended the hospital child care unit on a regular basis. Attendance records confirmed that this child had not been present for the 5 days before development of the rash. No secondary or tertiary cases developed among the contacts of the second index patient, although some staff members did attend work while infectious, necessitating further intensive contact tracing and counseling. Three secondary and three tertiary cases of staff chickenpox were attributed to the third index patient. DISCUSSION
During the spring and summer of 1992, a chickenpox outbreak in southeast Queensland affected many schoolchildren. Exact details are not available because this infectious disease is not notifiable in that area. Patients are probably infectious 3 to 4 days before the development of vesicles and for 5 days after their appearance. VZV culturable from vesicle scabs. These properties of VZV infection were elegantly investigated and reported in 1914 by Thomson and Price, 9 and further described by Thomson in 1916 l° and 1919.11 Our institution's approach to managing hospital employees with exposure to chickenpox or zoster is straightforward ~2 and can be summarized as follows: 1. Verify the suspect case by urgent direct fluorescent antibody testing of vesicular fluid, Tzanck smear of the base of a fresh vesicle, or other appropriate testing. 2. Attempt to determine whether the disease is chickenpox, disseminated zoster (also highly infectious), or dermatomal zoster (less infectious). 3. Urgently collect a list of exposed persons ensuring that all staff are included-wards-
T a b l e 2, Person-days of work lost by staff members infected with VZV during nosocomial outbreak in adult hospital
Staff category
Person-days lost
Medical Physiotherapy Nursing Clerical
20 40 95 10.6
men, ancillary staff, mortuary, cleaners, phlebotomists, and kitchen and catering staff, as well as the nursing and medical staff. Persondays of work lost for all staff members are shown in Table 2. A total of 165.6 person-days of hospital work were lost by staff members nosocomially infected during this epidemic. Infection control unit staff required 70 hours to contact trace, follow up, and counsel all staff members involved in this outbreak. Removing nonimmune contacts from duty for a 12-day period (from days 10 to 21) would result in 96 working hours lost per nonimmune staff member exposed. The need to replace many of these staff members with relief workers doubles the cost of the stand down period to 192 hours (24 days' wages) for each exposed staff member. . Evaluate exposed staff members to determine their past history or serological VZV immune status. Enzyme-linked immunoassay tests reliably detect VZV immunoglobulin G. 2 . Seronegative staff members with no history of chickenpox should be counseled regarding the symptoms of chickenpox and warned not to work if vesicles develop, although there is a risk that nonimmune contacts will be infected and the epidemic will continue. Consideration should be given to removing exposed, nonimmune staff members from duty 10 days after the first day of possible exposure. 7, 8 If chickenpox
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Faoagali and Darcy
has not developed by day 21, the staff members should be allowed to return to work. This loss of work is expensive, and it has recently been suggested that the wearing of a mask by nonimmune staff members enables them to keep working, avoids cross-infection, and keeps costs down. 13 6. Each case of chickenpox in a staff member requires individual evaluation. Centers for Disease Control and Prevention7 recommends that employees remain at home until all lesions are crusted and dry. Thomson 941 showed that nonimmunocompromised persons are unlikely to be infectious by day 5 after vesicle eruption. Full and timely contact tracing could not be carried out for the first index patient because of the wide number of staff exposures, late recognition of the infectious state, and serious and ultimately fatal nature of the disease. Attempts to detect nonimmune contacts of all the infected persons were often frustrated by the lack of awareness of staff members of the infectivity of this disease and the lack of emphasis on the importance of this disease as a cause of nosocomial infection in staff members. A "leak" to the local newspaper ensured headlines on page 3, and this publicity further educated hospital staff members about the epidemic in the community and the need for nonimmune staff members to be aware of the symptoms and signs of chickenpox. This helped ensure that they did not continue working, placing other nonimmune staff members and patients at risk. The dollar costs of our outbreak were similar to those previously reported, s'6 $19,000 and $20,000. Our costs are probably underestimated because some cases may have been missed, the unofficial time involved in contact tracing and counseling has not been included, and excuse from duty of nonimmune staff contacts often was late or was not undertaken because of staff shortages. CONCLUSIONS
Chickenpox in nonimmune adult hospital employees is costly for the hospital and poses a danger for nonimmune immunocompromised patients. Immunocompromised patients with disseminated chickenpox are highly infectious, with or without acyclovir treatment, and nonimmune staff members must be excluded from contact with these patients or excluded from duty from days 10
through 21 after contact, to avoid the risk of tertiary spread. 14 The place of VZV vaccine in management of the nonimmune health care staff needs to be evaluated, and appropriate submissions should be developed regarding the use of this vaccine in the prevention of chickenpox in nonimmune adult health care workers, as well as nonimmune immunocompromised patients. The VZV immune status of health care staff should be determined, and nonimmune staff members should be educated regarding the prodromal symptoms and signs and the potential infectivity of this disease, to minimize the unwitting exposure of other nonimmune persons. References 1. Hyams P J, Vernon S, Eckert D. Susceptibility to varicella virus of certain adults in the south eastern United States. AM J INFECTCONTROL 1984; 12:6-9. 2. Steele RW, Coleman MA, Fiser M, Bradsher RW. Varicellazoster in hospital personnel: skin test reactivity to monitor susceptibility. Pediatrics 1982;70:604-8. 3. Shehab ZM, Brunell PA. Susceptibility of hospital personnel to varicella-zoster virus [Letter]. J Infect Dis 1984; 150: 786. 4. Miller E, Vurdien J, Farrington P. Shift in age in chickenpox. Lancet 1993;341:308-9. 5. Hyams PH, Stuewe MCS, Heitzer V. Herpes zoster causing varicella (chickenpox) in hospital employees: cost of a causal attitude. AM J INFECTCONTROL1984; 12:2-5. 6. Boyce JM, Spruill EY, White RL. Outbreak of nosocomial varicella among personnel exposed to herpes zoster [Abstract L27]. In: Program and abstracts of the 83rd Annual meeting of the American Society for Microbiology, New Orleans. Washington, DC: American Society for Microbiology, 1983. 7. Williams WW. Guideline for infection control in hospital personnel. Infect Control 1983;4:326-9. 8. Bennett JV, Brachman PS, eds. Hospital infections. 3rd ed. Boston: Little Brown, 1992. 9. Thomson FH, Price C. The aerial conveyance of infection. Lancet 1914;1:1669-73. 10. Thomson FH. The aerial conveyance of infection with a note on the contact infection of chickenpox. Lancet 1916; 1:341-4. 11. Thomson FH. Contact infection of chickenpox [Letter]. Lancet 1919;1:397. 12. Wenzel RP, ed. Prevention and control of nosocomial infections. 2nd ed. Baltimore: Williams and Wilkins, 1993. 13. Haiduven D J, Hench CP, Stevens DA. Post exposure varicella management of non-immune personnel: an alternative approach. Infect Control Hosp Epidemiol 1994; 15:332-6. 14. Brunell PA. Varicella zoster vinas. In: Mandell GL, Douglas RG, Bennett JE, eds. Principles and practice of infectious diseases. New York: John Wiley and Sons, 1985:952.
Chickenpox outbreak among the staff of a large, urban adult hospital: Costs of monitoring and control J. L. Faoagali, MBchB, DCP, FRCPA, DHA, FASM D. Darcy, RN Brisbane, Queensland, Australia
Chickenpox is a highly infectious disease of childhood, but there are increasing reports of occurrence in adults. A recent community epidemic of chickenpox resulted in 20 documented cases of adult chickenpox in a large metropolitan hospital. Nine of these cases resulted from direct exposure to an index patient and four were in tertiary contacts of the three index patients associated with the nosocomial outbreak. A total of 165.6 person-days of work were lost (estimated $18,000 cost) as a result of this outbreak, and 70 infection control unit person-hours were required during the investigation and control. This article reports a nosocomial epidemic and reviews guidelines for identification and control of adult chickenpox in a large hospital complex. (AJIC AM J INFECT CONTROL 1995;23:247-50)
A history of chickenpox is usually a reliable indicator of immunity to this infection. 1-3 Increasing numbers of adults who were never infected with the varicella zoster virus (VZV) during childhood are acquiring chickenpox. 4 When these nonimmune adults are among the patients and staff at an adult hospital, the economic impact of such outbreaks can be significant, s' 6 particularly if standard recommendations for excusing exposed nonimmune staff members from duty for days 10 through 21 of their exposure are followed, v' 8 At our institution, determination of the VZV immune status of staff is not currently required before employment. Staff members in contact with patients with chickenpox are questioned regarding their history of infection. Those who do not know their immune status are offered testing. This report documents 20 cases of chickenpox occurring among adult hospital staff members during a 3-month period. It also traces the
From the Royal Brisbane Hospital, Brisbane, Queensland, Australia. Reprint requests: J. L. Faoagali, Director of Medical Microbiology, Royal Brisbane Hospital, Herston Rd., Herston, Brisbane, Queensland, Australia. Copyright © 1995 by the Association for Professionals in Infection Control and Epidemiology, Inc. 0196-6553/95 $3.00 + 0 17/47/62034
infection control unit person-hours of contact tracing and staff person-days of work lost during this epidemic. METHODS
All cases of chickenpox identified in the hospital were followed up by the infection control unit staff to determine the numbers of contacts at risk (nonimmune to chickenpox) and to educate them regarding the symptoms of chickenpox so that they would not continue working while unwell, placing others at risk and continuing the epidemic. The epidemic c o m m e n c e d with a fatal case, which initially was undiagnosed and then was not recognized as infectious while the patient was receiving antiviral therapy. Case 1
On Saturday, September 29, 1992, an immunesuppressed, steroid-dependent patient was admitted to the intensive care unit through the department of emergency medicine with disseminated varicella (chickenpox). The patient, who had been seen at the emergency department twice in the previous week (as well as at a local private hospital), was admitted because of the florid nature of his disease and general collapse. Intravenous acyclovir at a dose of 10 mg/kg every 8 hours was started immediately, and the patient was placed in the open 10-bed intensive care unit 247
248
Faoagaliand Darcy
because he was considered infectious while being treated with acyclovir. The infection control unit was not informed of the admission, which was only detected during the routine semiweekly ward round (3 days after admission). It was decided not to move the patient at that time because he had been treated with intravenous acyclovir for 3 days. He was severely thrombocytopenic, comatose, and in respiratory failure, receiving mechanical ventilation. Despite full care, the patient died on day 5 of his admission. Four secondary cases and one tertiary case of chickenpox were attributed to this patient. These infections developed 12 to 15 days after contact with this index patient. Case 2
The second index patient had thoracic zoster and was being treated in a private ward. He was not reported to the infection control unit until the secondary cases occurred. Case 3
The third index case occurred in a visiting hospital auditor, who contacted the infection control unit on the advice of his local physician on the day of diagnosis. Investigation confirmed that 2 to 3 weeks before development of chickenpox he was auditing the adjacent children's hospital, where he was assumed to have contracted his infection. Three days before development of the rash, he was auditing the occupational and physiotherapy departments of the adult hospital. Two days before appearance of his rash, the auditor spent a considerable time in the operating theater tea room, waiting for theater access. Most of the theater staff on duty were exposed. On the day before the rash developed, he visited most of the air-conditioned wards and services in one hospital block. Other cases
Four other isolated staff members and one immunocompromised patient are known to have acquired chickenpox during this period. None had any direct contact with the three index patients, and these cases were presumed to be part of the ongoing community epidemic. Contact tracing
Notices were sent to all the sections that had been visited by each index patient during the 4 days before their clinical detection, to inform all
/
AJIC August 1995
nonimmune staff methbers of their risk of exposure to chickenpox. Nonimmune staff members were requested to contact the occupational health department for advice regarding the prodromal symptoms of infection, to ensure that they did not unnecessarily expose other nonimmune staff members or patients. Laboratory tests
Direct fluorescent antibody testing is performed on vesicular lesions of persons with suspected herpesvirus infection. Antigens specific to VZV, herpes simplex virus 1, and herpes simplex virus 2 are available, but not all are tested on each specimen. The results are available on the day of collection. VZV immunoglobulin G is determined with an enzyme-linked immunosorbent assay technique. This reliably reflects previous exposure (and immunity) to this virus. An enzyme-linked immunosorbent assay test for VZV immunoglobulin G costs approximately $10 (U.S. dollars). The cost of screening a staff of more than 4000 with a high turnover rate (approximately 1000 per year) would be $10,000. This could be reduced by approximately half if only staff members with no documented history or recollection of chickenpox were included. Table 1 sets out the number of direct fluorescent antibody and VZV immunoglobulin G tests performed and positive results during the outbreak period. Costs
Costs were determined by estimating days of work lost while staff members were infected and also hours spent by the infection control unit staff organizing contact tracing and follow-up counseling of nonimmune staff members (Table 2). RESULTS
Four secondary cases and one tertiary case of chickenpox were attributed to the first index patient. These infections developed 12 to 15 days after contact with that index patient. The first index patient was in contact with emergency department, intensive care unit, radiology, and physiotherapy staff of all categories as well as wardsmen, cleaners, mortuary staff, and mortician. Contacts of the secondary patients associated with the first index patient involved several specialist units, the department of anesthetics, theater staff, and patients undergoing anesthetic procedures. One (a physician anesthetist) anesthetized patients all day before his rash appeared. One (a student nurse) was in a class of 40 peers the day
AJIC
Faoagali and Darcy 2 4 9
Volume23, Number4 Table
1. Immune status of staff
September
HSV 1 HSV 2 VZV DFA VZV immunoglobulin G Nonimmune rate (% of patients tested for VZV immunoglobin G)
October
November
December
January
PR
Tests
PR
Tests
PR
Tests
PR
Tests
PR
Tests
8 1 2 17
41 41 11 24 28
1 1 3 53
51 51 17 73 27.3
7 1 1 18
51 51 6 50 64
8 1 0 33
40 40 9 42 22.5
5 2 2 15
61 61 11 34 57
PR, Positiveresults; HSV, herpes simplexvirus; DFA,direct fluorescentantibody; ELISA,enzyme-linkedimmunosorbentassay.
the rash appeared. The tertiary patient associated with the first index patient attended the hospital child care unit on a regular basis. Attendance records confirmed that this child had not been present for the 5 days before development of the rash. No secondary or tertiary cases developed among the contacts of the second index patient, although some staff members did attend work while infectious, necessitating further intensive contact tracing and counseling. Three secondary and three tertiary cases of staff chickenpox were attributed to the third index patient. DISCUSSION
During the spring and summer of 1992, a chickenpox outbreak in southeast Queensland affected many schoolchildren. Exact details are not available because this infectious disease is not notifiable in that area. Patients are probably infectious 3 to 4 days before the development of vesicles and for 5 days after their appearance. VZV culturable from vesicle scabs. These properties of VZV infection were elegantly investigated and reported in 1914 by Thomson and Price, 9 and further described by Thomson in 1916 l° and 1919.11 Our institution's approach to managing hospital employees with exposure to chickenpox or zoster is straightforward ~2 and can be summarized as follows: 1. Verify the suspect case by urgent direct fluorescent antibody testing of vesicular fluid, Tzanck smear of the base of a fresh vesicle, or other appropriate testing. 2. Attempt to determine whether the disease is chickenpox, disseminated zoster (also highly infectious), or dermatomal zoster (less infectious). 3. Urgently collect a list of exposed persons ensuring that all staff are included-wards-
T a b l e 2, Person-days of work lost by staff members infected with VZV during nosocomial outbreak in adult hospital
Staff category
Person-days lost
Medical Physiotherapy Nursing Clerical
20 40 95 10.6
men, ancillary staff, mortuary, cleaners, phlebotomists, and kitchen and catering staff, as well as the nursing and medical staff. Persondays of work lost for all staff members are shown in Table 2. A total of 165.6 person-days of hospital work were lost by staff members nosocomially infected during this epidemic. Infection control unit staff required 70 hours to contact trace, follow up, and counsel all staff members involved in this outbreak. Removing nonimmune contacts from duty for a 12-day period (from days 10 to 21) would result in 96 working hours lost per nonimmune staff member exposed. The need to replace many of these staff members with relief workers doubles the cost of the stand down period to 192 hours (24 days' wages) for each exposed staff member. . Evaluate exposed staff members to determine their past history or serological VZV immune status. Enzyme-linked immunoassay tests reliably detect VZV immunoglobulin G. 2 . Seronegative staff members with no history of chickenpox should be counseled regarding the symptoms of chickenpox and warned not to work if vesicles develop, although there is a risk that nonimmune contacts will be infected and the epidemic will continue. Consideration should be given to removing exposed, nonimmune staff members from duty 10 days after the first day of possible exposure. 7, 8 If chickenpox
250
AJIC August 1995
Faoagali and Darcy
has not developed by day 21, the staff members should be allowed to return to work. This loss of work is expensive, and it has recently been suggested that the wearing of a mask by nonimmune staff members enables them to keep working, avoids cross-infection, and keeps costs down. 13 6. Each case of chickenpox in a staff member requires individual evaluation. Centers for Disease Control and Prevention7 recommends that employees remain at home until all lesions are crusted and dry. Thomson 941 showed that nonimmunocompromised persons are unlikely to be infectious by day 5 after vesicle eruption. Full and timely contact tracing could not be carried out for the first index patient because of the wide number of staff exposures, late recognition of the infectious state, and serious and ultimately fatal nature of the disease. Attempts to detect nonimmune contacts of all the infected persons were often frustrated by the lack of awareness of staff members of the infectivity of this disease and the lack of emphasis on the importance of this disease as a cause of nosocomial infection in staff members. A "leak" to the local newspaper ensured headlines on page 3, and this publicity further educated hospital staff members about the epidemic in the community and the need for nonimmune staff members to be aware of the symptoms and signs of chickenpox. This helped ensure that they did not continue working, placing other nonimmune staff members and patients at risk. The dollar costs of our outbreak were similar to those previously reported, s'6 $19,000 and $20,000. Our costs are probably underestimated because some cases may have been missed, the unofficial time involved in contact tracing and counseling has not been included, and excuse from duty of nonimmune staff contacts often was late or was not undertaken because of staff shortages. CONCLUSIONS
Chickenpox in nonimmune adult hospital employees is costly for the hospital and poses a danger for nonimmune immunocompromised patients. Immunocompromised patients with disseminated chickenpox are highly infectious, with or without acyclovir treatment, and nonimmune staff members must be excluded from contact with these patients or excluded from duty from days 10
through 21 after contact, to avoid the risk of tertiary spread. 14 The place of VZV vaccine in management of the nonimmune health care staff needs to be evaluated, and appropriate submissions should be developed regarding the use of this vaccine in the prevention of chickenpox in nonimmune adult health care workers, as well as nonimmune immunocompromised patients. The VZV immune status of health care staff should be determined, and nonimmune staff members should be educated regarding the prodromal symptoms and signs and the potential infectivity of this disease, to minimize the unwitting exposure of other nonimmune persons. References 1. Hyams P J, Vernon S, Eckert D. Susceptibility to varicella virus of certain adults in the south eastern United States. AM J INFECTCONTROL 1984; 12:6-9. 2. Steele RW, Coleman MA, Fiser M, Bradsher RW. Varicellazoster in hospital personnel: skin test reactivity to monitor susceptibility. Pediatrics 1982;70:604-8. 3. Shehab ZM, Brunell PA. Susceptibility of hospital personnel to varicella-zoster virus [Letter]. J Infect Dis 1984; 150: 786. 4. Miller E, Vurdien J, Farrington P. Shift in age in chickenpox. Lancet 1993;341:308-9. 5. Hyams PH, Stuewe MCS, Heitzer V. Herpes zoster causing varicella (chickenpox) in hospital employees: cost of a causal attitude. AM J INFECTCONTROL1984; 12:2-5. 6. Boyce JM, Spruill EY, White RL. Outbreak of nosocomial varicella among personnel exposed to herpes zoster [Abstract L27]. In: Program and abstracts of the 83rd Annual meeting of the American Society for Microbiology, New Orleans. Washington, DC: American Society for Microbiology, 1983. 7. Williams WW. Guideline for infection control in hospital personnel. Infect Control 1983;4:326-9. 8. Bennett JV, Brachman PS, eds. Hospital infections. 3rd ed. Boston: Little Brown, 1992. 9. Thomson FH, Price C. The aerial conveyance of infection. Lancet 1914;1:1669-73. 10. Thomson FH. The aerial conveyance of infection with a note on the contact infection of chickenpox. Lancet 1916; 1:341-4. 11. Thomson FH. Contact infection of chickenpox [Letter]. Lancet 1919;1:397. 12. Wenzel RP, ed. Prevention and control of nosocomial infections. 2nd ed. Baltimore: Williams and Wilkins, 1993. 13. Haiduven D J, Hench CP, Stevens DA. Post exposure varicella management of non-immune personnel: an alternative approach. Infect Control Hosp Epidemiol 1994; 15:332-6. 14. Brunell PA. Varicella zoster vinas. In: Mandell GL, Douglas RG, Bennett JE, eds. Principles and practice of infectious diseases. New York: John Wiley and Sons, 1985:952.