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Occupationally Acquired Infections in Health Care Workers

http://www.annals.org/cgi/content/full/125/11/917

Kent A. Sepkowitz, MD
 

1 December 1996 | Volume 125 Issue 11 | Pages 917-928

Background: Health care workers are at occupational risk for a vast array of infections that cause substantial illness and occasional deaths. Despite this, few studies have examined the incidence, prevalence, or exposure-associated rates of infection or have considered infection-specific interventions recommended to maintain worker safety.

Objective: To characterize the type and frequency of infections, the recommended interventions, and the costs of protecting health care workers. Part II of this two-part review focuses on infections caused by bloodborne organisms, organisms spread through the oral-fecal route, and organisms spread through direct contact. It also reviews established interventions for controlling transmission.

Data Sources: A MEDLINE search and examination of infectious disease and infection control journals.

Data Selection: All English-language articles and meeting abstracts published from January 1983 to February 1996 related to occupationally acquired infections among health care workers were reviewed. Outbreak- and non-outbreak-associated incidence and prevalence rates were derived, as were costs to prevent, control, and treat infections in health care workers.

Data Synthesis: Occupational transmission to health care workers was identified for numerous diseases, including infections caused by bloodborne organisms (human immunodeficiency virus, hepatitis B virus, hepatitis C virus, Ebola virus), organisms spread through the oral-fecal route (salmonella, hepatitis A virus), and organisms spread through direct contact (herpes simplex virus, Sarcoptes scabiei). Most outbreak-associated attack rates range from 15% to 40%. Occupational transmission is usually associated with violation of one or more of three basic principles of infection control: handwashing, vaccination of health care workers, and prompt placement of infectious patients into appropriate isolation.

Conclusions: The risk for occupationally acquired infections is an unavoidable part of daily patient care. Occupationally acquired infections cause substantial illness and occasional deaths among health care workers. Further studies are needed to enhance compliance with established infection control approaches. As health care is being reformed, the risk for and costs of occupationally acquired infection must be considered.

Ann Intern Med. 1996;125:917-928.

More than 10 years have elapsed since the last major consideration of occupationally acquired infections in health care workers [1,2]. Since then, much has changed--new infections have been identified, diagnostic tests for previously recognized diseases have been improved, the use of molecular epidemiologic techniques in outbreak investigations has increasingly become routine, and outpatient and home care have become more common.

The topic of occupationally acquired airborne infections in health care workers was addressed in part I of this two-part review [3]. Infections such as occupationally acquired tuberculosis, varicella-zoster, measles, and respiratory syncytial virus infections were considered, as were ethical and historical concerns. Part II of this review discusses infections caused by bloodborne organisms (such as human immunodeficiency virus [HIV], hepatitis B virus [HBV], hepatitis C virus [HCV], cytomegalovirus [CMV], and Ebola virus), organisms spread through the oral-fecal route (such as salmonella and hepatitis A virus [HAV]), and organisms spread through direct contact (such as herpes simplex virus and Sarcoptes scabiei). It then summarizes known interventions, including handwashing, vaccination, and prompt placement of potentially infectious patients into appropriate isolation. The risks to health care workers inherent in health care delivery should be considered by planners of health care for the next century.

Bloodborne transmission Table 1 has received increased attention with the advent of the acquired immunodeficiency syndrome epidemic and, more recently, the outbreak of Ebola virus infection. Although many nonmedical occupational groups are at risk for diseases caused by organisms transmitted through the airborne or oral-fecal route, health care workers are one of the few groups at risk for the transmission of bloodborne pathogens. In addition to blood-to-blood transmission, some of these pathogens may be transmitted in saliva, as occurs with CMV and B virus infection.

Table 1. Occupationally Acquired Infections Resulting from Bloodborne Transmission*

HIV Infection

The occupational risk for transmission of HIV has been the subject of numerous thorough reviews [9,34-40] and is not considered in detail here. The rate of seroconversion after exposure ranges from 0.1% to 0.4% [4,5,35]. In general, a large inoculum--including that from a source case with more advanced disease, a stick with a large-bore blood-containing needle, or a more severe injury--is associated with a higher rate of transmission [41].

Occupational transmission has been confirmed in 49 health care workers and may have occurred in 102 others [6] Table 2. Percutaneous exposure alone was the source of transmission for most confirmed cases of infection (42 persons). The optimal management of health care workers after exposure remains unknown. A recent retrospective, case-control study examined risks associated with transmission in 31 case-patients and 679 controls [41]. In this analysis, the use of zidovudine was associated with a 79% risk reduction, although zidovudine failure has occurred [42]. Provisional Public Health Service recommendations include three antiretroviral drugs (zidovudine, lamivudine, and indinivir) for high-risk exposures [7,43].

Table 2. Health Care Workers with Documented and Possible Cases of Occupationally Acquired HIV Infection in the United States, through 1995*

Hepatitis B

Hepatitis B virus was one of the first bloodborne pathogens to be recognized as an occupational risk among health care workers [44-46]. An early review [46] found a preponderance of cases of hepatitis B among pathologists, laboratory workers, and blood bank workers, alerting investigators to the risks of exposure to blood. Subsequent studies confirmed these early observations [47-63]. In general, the seroprevalence of HBV in health care workers is twofold to fourfold higher than that of blood donor controls [47,61]; the highest rates are seen among dentists [8,47]; physicians [8,47,61,63]; laboratory workers [8,47,63,64]; dialysis workers [63]; cleaning service employees [51,62]; and nurses [8], including emergency department nurses [56]. Widespread transmission may occur from a single surgical procedure [65]. Many infections in health care workers are asymptomatic [48].

In prevaccine surveys, the annual incidence of hepatitis B was 5 to 10 times higher among physicians and dentists than among blood donors and more than 10 times higher among surgeons, dialysis workers, persons caring for the mentally handicapped, and laboratory workers exposed to blood [47,61,66].

The risk for transmission from a single needlestick varies according to E antigen status: 1% to 6% for E antigen-negative blood compared with 22% to 40% with E antigen-positive blood [8-10,67]. However, transmission of E antigen-negative blood has caused fulminant hepatitis requiring liver transplantation [68]. Hepatitis delta virus has been transmitted to a surgeon [69]. The quality-adjusted loss in life expectancy is similar for persons who receive needlesticks involving a source patient who has HBV infection and for persons who receive needlesticks involving a source patient with HIV infection [70,71]. Not all cases of HBV transmission are explained by needlesticks, suggesting that other modes of spread may be possible [8,9,72].

Infection control interventions, such as the segregation of dialysis recipients according to surface antigen status [73,74] and vaccination [74,75], have effectively reduced occupational acquisition of HBV. However, the Centers for Disease Control and Prevention (CDC) calculate that 6500 to 9000 new HBV infections occurred among health care workers in 1990 [8]. Given the natural history of HBV infection, 300 to 950 of these health care workers (5% to 10%) will eventually develop chronic HBV infection that will lead to death from cirrhosis in 100 to 150 persons and to fatal hepatocellular carcinoma in 25 to 40 persons [8]. Despite this, HBV vaccination of health care workers remains incomplete. In one study, 23% of health care workers were unvaccinated [52], a rate similar to that of anesthesiologists in the United Kingdom [76]. A three-vaccine series is 88% effective [77,78]; decreased response is seen among recipients who are older, who smoke, or who are obese [77,78].

Hepatitis C

The 1990 introduction of a test for HCV infection has dramatically improved our understanding of disease epidemiology. Because HBV and HCV have similar modes of transmission, it was assumed that groups of health care workers at increased risk for hepatitis B also would be at risk for hepatitis C [19,52,60]. This, however, has not proven to be true for many groups, including dialysis workers [79-82], laboratory workers [83], persons who work with the mentally impaired [84], and surgical staff [83]. Indeed, although "occupational exposure" accounts for about 2% of all cases of hepatitis C [19], the seroprevalence of HCV among health care workers is roughly similar to that of the general population (about 1%) [83,85-89]. Dentists do have increased risk [16,17]: In one serosurvey [16], significantly more dentists (1.7%) than blood donors (0.13%) were seropositive for HCV; the highest rate of seroprevalence was seen among oral surgeons (9%).

Seroconversion occurs in 1.2% to 10% of nonimmune health care workers who receive needlesticks from a source patient with hepatitis C [11-15]. Variation among control populations [90-92], variation in employee populations [18,93,94], and variation in the sensitivity of tests for HCV [19] have contributed to the lack of consensus about risk [14,18,94]. Optimal management of a needlestick is unknown, but the administration of immune globulin is not recommended [18,40].

Cytomegalovirus Infection

The prevalence of CMV infection in the United States varies according to geography, patient age, and group studied and ranges from 40% to 95%. The annual community incidence among adults is about 2% [21]. Transmission of CMV may occur through sexual contact or through contact with infectious blood. Respiratory secretions, saliva, and urine may also transmit CMV, as shown by increased rates of CMV infection among day care workers (8% to 10% per year) [95,96]. Early incidence [97-99] and prevalence studies [100], as well as meta-analyses [101,102] and reviews [103,104], suggested that pediatric health care workers had elevated risk, similar to that of day care workers. Subsequent reports [20,21,35,105,106], however, have not shown this risk, perhaps because many recent studies were done in the era of universal precautions. Similarly, no increase in CMV infection among dialysis workers [107] or renal transplantation workers [108] has been found.

Studies using molecular epidemiologic techniques have also shown that health care workers are at low risk for occupational transmission of CMV [109,110]. No transmission was documented among 188 health care workers at a pediatric chronic care or neonatal unit in which many of the patients were heavy CMV shedders [110]. Molecular analysis of CMV recovered from one of two nurses who seroconverted showed discordance with CMV taken from a known occupational contact and concordance with CMV from a family member with new disease.

Ebola Virus Infection and Other Viral Hemorrhagic Fevers

The recent outbreak of Ebola virus infection in Zaire involved 296 cases and was associated with a 79% mortality rate [22-24]. At least 90 persons (32%) were health care workers [24,25], a fact that led the CDC to issue recommendations for the management of persons with suspected viral hemorrhagic fevers [26]. Among the recommended practices were use of universal precautions, use of strict barrier protection, restriction of workers and visitors, and use of negative-pressure ventilation in the presence of respiratory symptoms.

In a 1979 outbreak of Ebola virus infection in Sudan, persons who provided nursing care were five times more likely to develop disease than were those who provided no care [111]. In all, 34 cases of infection occurred and 22 persons died. Similar outbreaks involving health care workers have been reported with Crimean hemorrhagic fever-Congo virus infection in Pakistan, where 10 of 17 exposed workers developed disease and 2 died [112]; Lassa fever virus infection on an obstetrics ward, where 7 of 26 exposed workers developed disease and at least 1 died [113]; and Marburg virus infection [114,115]. Ribavirin was effective as therapy for 3 health care workers with Crimean hemorrhagic fever-Congo virus [116].

B Virus Infection

Fatal, occupationally acquired infection with B virus (Herpesvirus simiae) was described in 1932, when a physician died of encephalomyelitis 3 days after being bitten by a clinically well rhesus monkey [117,118]. Since that time, more than 24 infections with B virus have occurred in humans, and 18 persons have died [119]. The peak incidence of B virus infection occurred in 1957-1958, in conjunction with the production and testing of poliomyelitis vaccines [119]. In the 1980s, a cluster of four cases (two of which were fatal) occurred in a research facility in Pensacola, Florida [27], leading to the development of new recommendations for monkey handlers [28]. Treatment with acyclovir may be effective [27,29], but the optimal duration of therapy is unknown and may extend years.

Other Infections

Creutzfeldt-Jakob disease is a uniformly fatal neurodegenerative disorder that has been the subject of extensive epidemiologic investigation [31,32]. Health care workers are not considered to be a group at risk [31], but cases have been reported in two neurosurgeons [31,32], two histopathology technicians [120,121], and one pathologist [122]. In none of these cases could a specific incident that may have led to transmission be recalled. Recent recommendations stress sterilization of equipment to minimize the risk [30].

Outbreaks of Epstein-Barr virus infection have seldom been reported. Transmission of Epstein-Barr virus to 9 of 29 medical staff (31%) in an obstetrics and gynecology clinic was never explained [123]. Investigators at a hospital that treated hundreds of cases of nasopharyngeal carcinoma suggested that nosocomial spread was a major source of Epstein-Barr virus infection among health care workers at their institution [124]. Occupationally acquired cases of syphilis [125], malaria [126], and yellow fever [127] have been reported.

Enteric pathogens spread in various ways, including through the ingestion of contaminated food; through direct person-to-person contact; and through contact with infectious waste, usually feces Table 3. Insufficient handwashing by health care workers probably contributes more to the transmission of these pathogens than to the transmission of bloodborne or airborne pathogens.

Table 3. Occupationally Acquired Infections Resulting from Oral-Fecal Transmission*

Salmonellosis

The number of cases of salmonellosis has increased steadily since the 1950s, and food-related outbreaks continue to occur. The effect of contaminated food was vividly shown by a recent outbreak that was traced to ice cream and that caused more than 200 000 cases of salmonellosis across 41 states [153]. In general, institutional disease accounts for 10% to 30% of all cases [138,154,155]. Hospitals, nursing homes, psychiatric facilities, pediatric wards, and nurseries are common sites [138,154-157].

Massive contamination of mashed potatoes was responsible for a large outbreak at a hospital in Jordan [128], where 183 of 619 persons (19.6%) (including 150 hospital employees) developed disease. Investigation showed that 11 of 61 kitchen workers (18%) were infected with salmonella; all had been negative on cultures taken 3 months earlier, suggesting that routine surveillance cultures may not be useful.

Person-to-person transmission of salmonella occurred in a hospital in Maine [158], where several workers who drank tainted eggnog developed salmonellosis. As the outbreak progressed, at least eight additional workers who had not drunk eggnog also developed disease. Person-to-person spread has been suggested by other studies [159,160], including the report of an outbreak that involved fasting patients who had recently had gastrectomy and infants who were not receiving hospital food. In a nursing home in Tennessee, 8 of 160 employees (5%) developed salmonellosis; the highest attack rate was seen in laundry workers [129]. Several laundry workers had no direct contact with infected patients, suggesting that transmission occurred through contaminated linen.

Interrupting an identified outbreak may be difficult. In Cincinnati, Ohio, 24 of 52 kitchen workers were found to have Salmonella drypool, which accounted for at least 11 cases of salmonellosis among staff who ate food that had been prepared at the hospital [161]. The epidemic was stopped only after 50 of 52 kitchen workers were treated with trimethoprim-sulfamethoxazole. Because 32% of treated employees developed reactions to drug treatment, this approach may not be advisable for routine outbreaks. In one study [162], the cost of identifying and treating one salmonella-infected health care worker, including cultures, antibiotic therapy, and lost work time, was $3500.

Hepatitis A

The number of cases of hepatitis A gradually increased in the United States in the 1980s; incidence peaked in 1989 [163]. Common risk factors for the acquisition of HAV include contact with an infected person (26%), employment in or attendance at a day care center (14%), and use of injection drugs (11%) [163]. The overall prevalence rate of HAV infection in the United States is about 38%, similar to rates described in health care workers (35% to 54%) [164-166]. In one report [165], the rates of antibodies to HAV were significantly higher in nurses older than 30 years of age than in office workers; in another study, charwomen had the highest rate [166].

Many outbreaks have been reported in pediatric or neonatal intensive care units [130,133-136] and orphanages [167]. A neonate who acquired HAV through a transfusion spread the organism to 10 of 61 susceptible nurses (16%) [136]. An infected child who had an immune defect that resulted in an inability to seroconvert to HAV remained undiagnosed for a protracted period, leading to transmission of HAV to 15 of 102 staff [131]. Adults with diarrhea have also transmitted the virus to health care workers [168,169].

An outbreak of HAV infection in a burn unit occurred despite the use of appropriate infection control measures, and HAV was spread to 11 of 59 susceptible nurses (18.6%) [132]. Eating on the hospital ward was the most important risk factor for infection. Other nosocomial outbreaks have resulted from the consumption of contaminated food, including orange juice [170] and sandwiches [171]. One outbreak resulted in 66 cases of clinical or subclinical disease [171].

The intramuscular administration of immune globulin to persons who have contact with HAV-infected patients has been used effectively for many years to prevent secondary cases. Defining which, if any, health care workers should routinely be vaccinated for HAV is currently being discussed [137,172].

Shigellosis

Given the small inoculum size required for transmission of shigella [173], the reason for the relative infrequency of nosocomial shigella infection has been the subject of speculation but remains obscure [138]. Outbreaks in day care centers have been reported [153,174]. At a teaching hospital in Kenya [175], salmonella accounted for 10% and shigella accounted for 2.5% of 360 cases of nosocomial diarrhea. In another report [139], 3 of 32 workers in a newborn nursery developed shigellosis. All were chronic nail-biters. The cost of controlling the outbreak was $5000.

Cryptosporidiosis

Cryptosporidia have been spread to a medical intern and possibly other staff [176], a nurse [177], and a laboratory researcher [178]. Proper infection control techniques failed to control an outbreak in Wales, where 5 of 16 nurses developed disease [140]. This outbreak was perpetuated by severe environmental contamination; replacement of sinks and hand basin taps with leg-operated machinery proved to be an effective intervention. Veterinarians and animal handlers also have an increased risk for cryptosporidiosis. In one outbreak [141], cryptosporidiosis developed in 10 of 20 veterinary students who worked with calves that had died of the disease. This outbreak was similar to another calf-related outbreak, in which 12 of 18 animal handlers became infected [142].

Helicobacter pylori Infection

Several recent reports have examined the seroprevalence of antibodies to Helicobacter pylori among health care workers [143-147]. One found that seroprevalence was higher among endoscopists (69%) than among internists (40%) [145]. Two other studies [143,147] found that about 52% of endoscopists and only about 14% to 21% of blood donors were seropositive for H. pylori [143,147]. Dentists have no increased seroprevalence despite contact with saliva [144]. These findings suggest that contact with contaminated equipment, rather than routine patient care or contact with saliva [144], is an important mode of transmission.

Other Infections

Clostridium difficile has emerged as an important cause of hospital-acquired diarrhea and has been cultured from the hands of 14% to 59% of asymptomatic health care workers during outbreaks [179,180]. However, controversy exists about the potential role of C. difficile as an occupationally acquired organism [181-183]. Possible nosocomial transmission of fatal C. difficile infection to an otherwise healthy worker has recently been reported [184]. Several nursing home outbreaks of infection with the Norwalk virus (a small, round-structure virus) have resulted in rates of transmission to staff that range from 30% to 50% [148-152]. In one outbreak, "care attendants" had an incidence rate of 92% [149]. In an outbreak of Escherichia coli O157: H7-associated hemorrhagic colitis in a nursing home [185], 18 of 137 staff members (13%) developed symptoms; 5 of the 18 had bloody diarrhea. No health care worker developed the hemolytic-uremic syndrome. Cholera has spread to staff [186], but studies done before vaccination found no risk to personnel on a polio ward [187].

Eating hospital food and drinking hospital beverages expose health care workers to the same risks faced by patients and visitors, as shown by hospital food-related outbreaks of salmonellosis [128,158,161], hepatitis A [170,171], yersiniosis [188], campylobacteriosis [189], cyclospora infection [190], and typhoid fever [191].

Infection may spread to health care workers as a result of direct contact. Outbreaks of scabies, particularly among nurses and laundry workers, have been reported from several hospitals [192-195]. In one hospital [193], almost 300 health care workers were affected, including 45 of 200 laundry workers (22.5%), 126 of 1448 nurses (8.7%), and 32 of 87 health care workers (36.8%) who had direct contact with patients. The outbreak cost about $50 000 for days of work missed and for treatment. In another outbreak [194], secondary spread to the spouses of health care workers was seen. A large, sustained outbreak at an extended-care facility [195] resulted in the infection of 26% of the staff, including half of all nurses.

Cutaneous herpes (herpetic whitlow) is an occupational hazard for dentists; anesthesiologists; dialysis technicians; physiotherapists; physicians; and nurses [196,197], particularly nurses in intensive care units [196,198,199]. That dermatologists face risk associated with laser treatment of warts with lasers has been suggested [200,201], including a recent study [202] in which molecular epidemiologic techniques were used. Tinea corporis may spread to staff [203,204], further thwarting control efforts.

Laboratory personnel, veterinarians and animal handlers, pathologists, surgeons, dentists, anesthesiologists, and laundry workers are at risk for an array of specific infections Table 4. In addition, the concerns of pregnant health care workers are considerable and unique because certain otherwise mild infections may affect fetal development.

Table 4. Occupationally Acquired Infections Encountered in Specific Groups of Health Care Workers*

Laboratory-acquired infections have been extensively studied [205-207]. Collins [205] identified 2168 infections and 48 deaths from diseases ranging from brucellosis and Q fever (the most common) to rabies and the plauge. The potential danger of working in laboratories is dramatically illustrated by the fate of Ricketts (for whom Rickettsia was named), who died of laboratory-acquired rickettsiosis [205]. Neisseria meningitidis has fatally infected laboratory workers [208]. Although many clinical health care workers receive prophylaxis after exposure to N. meningitidis, studies have not documented the spread of this organism to health care workers in the clinical setting [209].

Despite the seemingly limitless number of infections that health care workers can acquire on the job, the interventions to prevent transmission are simple, well known, and effective. Compliance with three practices--handwashing, vaccination, and appropriate isolation of infected patients--can control transmission dramatically and cost-effectively.

Handwashing

Handwashing is the oldest, simplest, and cheapest way to control the nosocomial spread of infectious organisms. In the 1840s, Semmelweis introduced the practice of "hygienic hand disinfection" on obstetric wards in Vienna, decreasing the maternal mortality rate from 13.7% to 1.3% [241-243]. Since that time, handwashing has become routine for all persons doing any surgical procedures; however, workers involved in medical care have notoriously low rates of handwashing--usually less than 50% [244-248].

Numerous studies have examined the specific aspects of handwashing, including type of soap [249,250], type of sink [251], drying method [252], and method of scrubbing [243,253-255]. One study showed that chlorhexidine was both significantly more effective and more often used than alcohol and soap [249]. Additional strategies to improve compliance [244,247,251] are necessary because compliance, not brand of soap or type of sink, remains the major obstacle to preventing transmission. In addition to preventing patient-to-patient spread, handwashing may prevent the acquisition by health care workers of such infections as those caused by rhinovirus, respiratory syncytial virus, HAV, adenovirus, and salmonella. Emphasis of this might promote compliance and lead to an overall reduction of transmission.

Vaccination

Recommendations about vaccines are updated frequently [256], but vaccination of health care workers remains incomplete [257-259]. Indeed, compliance with HBV vaccination remains appalling: In a recent survey in an inner-city hospital, 23% of workers were unvaccinated [52]. Health care workers are often the source of outbreaks of measles and rubella [257] and, less commonly, HBV infection [260], further emphasizing the need for improved compliance with vaccination. A demonstration of evidence of antibodies to vaccine-preventable diseases, including measles, mumps, rubella, and hepatitis B, is required of employees at many hospitals. The varicella-zoster virus has recently been recommended [261], whereas the role of the HAV vaccine is being determined.

Isolation

Appropriate isolation of infected patients is another time-honored practice [262]. It is the most complicated and potentially expensive of the three standard interventions. Difficulties arise when trying to balance the need to protect health care workers against the realities of cost, as shown by the recent debate surrounding tuberculosis control [263]. A common sense approach may find an acceptable middle ground [264,265]. In general, universal precautions for infections with bloodborne organisms, respiratory and droplet isolation precautions for infections with airborne organisms, and contact isolation precautions (or enteric precautions) for infections caused by organisms spread by the oral-fecal route are effective and widely used [33]. Updated guidelines for isolation precautions have recently been published [33].

Public attention has recently focused on the risk to patients posed by infectious health care workers. Transmission of HIV from an infected dentist to four patients [266] stirred a national debate in the United States about mandatory HIV testing of health care workers. Workers have been the source of many infections other than HIV infections, including tuberculosis [267], hepatitis B [260], measles, and rubella [257]. Little public concern or awareness, however, has been directed toward the risk to health care workers of caring for contagious persons, despite the continuing illness and occasional death that result from occupationally acquired diseases.

Several recent developments have changed many aspects of occupational risk. Old diseases that may be spread to health care workers, such as tuberculosis and diphtheria, have reemerged, forcing the reexamination of existing infection control policies [268]. New technology has identified old infections, such as hepatitis C. This, in turn, has been followed by numerous studies delineating the natural history and transmission rates of disease, including risk to health care workers [11-19,79-94]. Seemingly new diseases with undefined risks, such as HIV and Ebola virus infection, have become evident, leading to appreciation of risks to health care workers and recommendations for worker safety [7,26].

Recognition and confirmation of outbreaks, as well as improved understanding of transmission [269,270], rely increasingly on molecular epidemiologic techniques. These techniques have been applied to investigations of many diseases, including CMV infection [109], adenovirus infection [271,272], hepatitis B [260], hepatitis C [273], HIV infection [274], and tuberculosis [275,276]. Molecular analysis may identify previously undiscerned outbreaks [275] or rule out others [276].

The recent trend toward an increase in the use of outpatient care has also changed the risk for occupationally acquired infection, as well as the groups of health care workers at risk [64,277,278]. In 1867, Simpson expressed his hope that, given the high concentrations of sick patients, "hospitals should not become pesthouses, and do more harm than good" [279]. Since that time, the risk posed to patients and staff by nosocomial infection has been repeatedly shown. In this regard, the result of shorter hospitalizations may well be salutary, although the risk for undetected infection may increase as patients receive more care away from diagnostic centers.

In summary, daily patient care presents the health care worker with a real, although small, risk for infection. Indeed, the cost to prevent, control, and treat occupationally acquired infections is considerable, in terms of both dollars spent and lives affected. This does not imply that working with contagious persons is a heroic endeavor. Rather, incurring the risk for occupationally acquired infection is necessary for daily health care delivery. Indeed, the willingness of health care workers to accept this risk is, in many ways, as important to health care as their professional skills. This should be considered in the coming years as health care delivery in the United States continues to be reformed.

Acknowledgment: The author thanks Bruce Artim, JD, for research assistance.

Requests for Reprints: Kent A. Sepkowitz, MD, Infectious Disease Service, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, Box 288, New York, NY 10021.

From Memorial Sloan-Kettering Cancer Center and New York Hospital-Cornell Medical Center, New York, New York. For the current author address, see end of text.

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