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Surgical Risk of Blood-Borne Transmissible Disease


This chapter includes an accompanying lecture presentation that has been prepared by the author: .

Key Concepts

  • Blood exposure during the conduct of neurosurgical procedures poses a risk of transmission of known and unknown pathogens that can result in serious occupation-associated infections to the surgeon and surgical team.

  • Hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) are the recognized viral pathogens of greatest concern, but the microbiology of human blood-borne pathogens is continuing to expand and other pathogens are potential risks.

  • The first line of prevention of viral transmission to the surgical team is using appropriate personal protective barriers, avoidance of high-risk surgical techniques that are associated with blood exposure, and prompt responses when an exposure event occurs.

  • All neurosurgeons should know if they have active infection with HBV, HCV, or HIV. Effective antiviral therapies are available to treat each of these infections to effect potential cure (HBV or HCV) or effectively provide long-term treatment of the infection (HIV).

  • All neurosurgeons should be vaccinated against hepatitis B and they should know their response to the vaccination. Positive responders are protected against infection from exposure events, and nonresponders must know their status so that specific hepatitis B immunoglobulin can be administered to provide passive immunity. Postexposure monitoring permits specific treatment of HBV infection should it occur.

  • No effective vaccine exists for HCV, but exposure events need to be monitored for 6 months following exposure, and effective direct-acting antiviral therapy should be given at that time. Because the risk of seroconversion from a percutaneous injury is less than 2%, postexposure prophylaxis is not warranted, but rather effective treatment is begun in the event of seroconversion.

  • Postexposure prophylaxis with effective antiretroviral chemotherapy is recommended for all exposure events from HIV-infected patients. The exposed surgeon should be monitored following exposure. In the unlikely event that seroconversion occurs, effective chemotherapy provides greatly enhanced survival.

  • Avoidance of blood exposure is still the best preventive measure and requires that neurosurgeons have a sense of awareness of sharps in those procedures (i.e., craniotomy, spine surgery) that have the highest risk of exposure events.

The first reports of patient-to-surgeon transmission of blood-borne pathogens occurred nearly 70 years ago. , These early reports of “serum hepatitis” were generally viewed with a detached attitude by surgeons as reflecting something that occasionally happened, and these events did not arouse concern about occupational risks. With the recognition of hepatitis A virus (HAV) and hepatitis B virus (HBV) as distinct viral pathogens, and the development of specific antibody detection methods, the scope of HBV infection among patients and among surgeons was appreciated. Surgeons had a disproportionately higher prevalence of HBV positivity than did the general population, and it was rapidly appreciated that transmission of the infection from patients to surgeons (and other health care providers [HCPs]) was far more common than had been realized. Moreover, a nonserotyped hepatitis was identified, indicating yet another form of transmissible hepatitis that occurred after blood transfusion and other forms of percutaneous blood exposures. This nonserotyped hepatitis was labeled non-A, non-B hepatitis (NANBH). During the 1970s, evidence was mounting that surgeons and other HCPs were exposed to multiple potential hepatitis viruses, but an attitude of indifference persisted with respect to these risks.

Acquired immunodeficiency syndrome (AIDS) was first reported in 1981, and subsequent investigations characterized human immunodeficiency virus (HIV) as the putative agent. HIV infection was associated with sexual contact, but it also became evident that blood transfusion and other mechanisms of percutaneous exposure to contaminated blood were sources of viral transmission. During the 1980s, nearly 1 million people in the United States had HIV infection, and clinical AIDS was a uniformly fatal disease. Furthermore, it became apparent that HIV infection was a latent disease that otherwise healthy-appearing people carried for a number of years before clinical AIDS was evident. It was also recognized that those with latent infections were reservoirs for transmission of the virus to others. Events surrounding the recognition of HIV infection led to great concern and anxiety in the surgical profession about the occupational risks for both HIV and hepatitis infection. Demands for testing of patients before operations surfaced, and denial of care of HIV-infected individuals was feared as part of the aftermath.

Nearly 40 years have passed since the first AIDS cases were reported, and many events have tempered the great fears that surfaced about the occupational risks for this infection in the 1990s. Occupational transmission of HIV infection has been proved to be very uncommon. The development of effective antiretroviral therapy (ART) has not eradicated HIV infection but has provided long-term quality of life for many patients. ART has dramatically reduced circulating viral loads in infected patients and has reduced further the risks for transmission among those receiving treatment. With respect to hepatitis, an effective HBV vaccine has been developed from recombinant technology that has dramatically reduced the risk for occupational HBV infection for surgeons. No vaccine has yet been developed for hepatitis C virus (HCV) infection, but highly effective treatments for both HBV and HCV have been documented to eradicate the chronic infection once a diagnosis is established.

Unfortunately, these many positive developments have now re-created lassitude and indifference about occupational infection in the operating room. Old bad habits are resurfacing, and accepted principles for prevention are being ignored. The objective of this chapter is to emphasize to neurosurgeons that continued vigilance is necessary because both known and, in all likelihood, unknown transmissible agents remain in the surgical environment. This sense of awareness of both known and unknown risks requires a commitment to avoiding blood exposure when providing neurosurgery care.

Hepatitis

The past 40 years have yielded a dramatic expansion in our understanding of hepatitis infection. Currently six distinct hepatitis viruses have been identified ( Table 60.1 ). At the present time, only HBV and HCV appear to be of occupational concern to surgeons. Most of the following discussion is limited to HBV and HCV infection.

TABLE 60.1
Features of Known Hepatitis Viruses as Currently Identified
Type of Hepatitis Route of Genome Viral Family Transmission Occupational Risk
A RNA Picornaviridae Fecal-oral No chronic infection; not considered an occupational risk
B a DNA Hepadnaviridae Blood-borne 850,000 chronically infected patients in the United States; documented vaccination eliminates the risk
C a RNA Flaviviridae Blood-borne About 3–5 million chronically infected patients in the United States; no vaccination; avoiding exposure is the only preventive strategy
D RNA Viroid Blood-borne Not identified as occupational risk; requires coexistent HBV infection; no risk with HBV vaccination
E RNA Caliciviridae Fecal-oral No chronic disease; not common in United States; not considered an occupational risk
Pegivirus (Formerly G) RNA Flaviviridae Blood-borne Commonly called GBV-C; not associated with infection; not considered an occupational risk
GBV-C, GB virus C; HBV, hepatitis B virus.

a Only hepatitis B and hepatitis C are considered occupational pathogens.

HAV is transmitted by the fecal-oral route and is usually acquired after ingestion of contaminated water or food products. It is an RNA virus that causes an acute and frequently severe hepatitis syndrome. Infected individuals with the hepatitis syndrome (jaundice, malaise) are acutely ill, but the disease is seldom lethal except in elderly and infirm patients. Importantly, there is no state of chronic HAV infection in the aftermath of the acute clinical infection. The absence of a chronic state of infection and the infrequently identified transmission of HAV from blood or blood products do not make this a virus of major occupational concern in health care.

Hepatitis E virus (HEV) had been identified primarily in Southeast Asia but is now identified globally. Like HAV, it is transmitted by the fecal-oral route, and there is no chronic infection after resolution of the acute infection. A vaccine for HEV has been developed but is currently only available in China. Occupational blood exposure is not associated with a risk for HEV infection.

Hepatitis D virus (HDV), also known as the delta agent, is an incomplete RNA virus that cannot cause infection or replicate without the coexistence of concurrent acute or chronic HBV infection. HDV infection is not commonly identified in the United States. It is principally seen among the injection drug use population. HDV infection amplifies the severity of the underlying HBV infection. HDV is a blood-borne pathogen and theoretically could be an occupational risk for HCPs if preexistent HBV infection were present. Effective vaccination against HBV infection eliminates this risk.

The virus originally identified as hepatitis G virus is now identified as human pegivirus. It is blood borne and is found commonly in association with HBV and HCV infection. It has genetic homology to HCV. It is present in as many as 1.4% of blood donors and persists in a chronic state for many years. It does not appear to have a role in human infection as an independent pathogen.

Hepatitis B Infection

HBV infection is the most thoroughly studied of the blood-borne hepatitis viruses in humans. HBV is a DNA virus that is very efficiently transmitted with exposure to blood or blood products. Before the era of effective vaccination, HBV infection was the most common and most serious of occupational infections for surgeons. A single hollow percutaneous needlestick injury was associated with a 25% to 30% risk for transmission to the naïve host in the era before vaccination and effective postexposure prophyaxis. Injection drug use with shared needles has been a major source of transmission of the infection. HBV is also a sexually transmitted disease, and a national initiative to vaccinate pediatric and adolescent populations against HBV is underway. Effective screening of the blood supply has virtually eliminated contaminated units of transfused blood as a source of new cases of HBV infection.

Access of HBV to the host results in binding and internalization of the virus within hepatocytes. Viral replication occurs at varying rates after infection. In only about 25% of acute infections is there a clinically discernible hepatitis syndrome. Most cases either are characterized by a mild malaise without jaundice or have a completely indolent character. Among all acute infections, about 5% of cases result in chronic sustained infection that persists indefinitely. The incidence of chronic infection is not related to whether acute infection was identified, meaning that many individuals with chronic disease are unaware of their disease status. This chronic state of infection is associated with sustained damage to the liver, although selected cases may have a persistent viremia without evidence of continued liver damage. Hepatocellular carcinoma, portal hypertension, and end-stage liver disease from hepatic cirrhosis are the consequences for many patients with the chronic disease. The individual with chronic HBV infection is a reservoir for virus that can infect others. It is currently estimated that 850,000 people in the United States have chronic HBV infection, with estimates of 27 million people living with chronic HBV infection in the international community.

HBV infection among surgeons in the era before the availability of the vaccine was common. In a 1996 study, about one-third of surgeons in practice for more than 10 years had serologic evidence of prior HBV infection. About one-third had been vaccinated, but one-third had no antibody on serology and remained vulnerable to acute infection. In the late 1980s, the Centers for Disease Control and Prevention (CDC) estimated that 250 HCPs died annually from the consequences of occupationally acquired chronic HBV infection that had obviously been contracted many years previously. Effective HBV vaccination programs have reduced the incidence of chronic infection to far less than the population in general and have dramatically reduced the risk of death from occupationally acquired infection.

In the 1980s, a highly effective HBV vaccine was developed using attenuated virus from infected patients. Recombinant technology rapidly emerged and resulted in development of an equally effective vaccine that was not derived from human sources. The vaccine is administered in three doses, with the second and third doses given 1 and 6 months after the initial administration. About 95% of individuals have an appropriate antibody response to the surface antigen of HBV. Documentation of the antibody response is essential, and revaccination is necessary for those who do not seroconvert from the initial immunization effort. Revaccination after a failed initial attempt has a 30% to 50% probability of being successful. Nonresponders may also have increased doses of the vaccine, intradermal injection of the vaccine instead of conventional intramuscular delivery, and other methods to improve responsiveness. An HBV vaccine with a novel immune adjuvant has now been approved for use and may be of value in improving the rates of vaccine responsiveness among those individuals who have previously been nonresponders. Vaccination of all surgeons and HCPs is necessary, and not being vaccinated is unacceptable.

Hepatitis C

HCV was identified in 1989 and has for the most part been the virus responsible for NANBH. HCV is an RNA virus with multiple different serotypes. It is a source of occupational infection for surgeons and HCPs but is less efficiently transmitted than HBV. A percutaneous needlestick from a hollow needle has about a 1.8% risk for transmission of the virus. HCV has many of the same epidemiologic characteristics as HBV with respect to high-risk populations of patients and means of infection within society. Screening of the blood supply for antibody to the virus has dramatically reduced the risk for transfusion-associated infection.

The clinical sequelae after infection of the hepatocyte follow patterns similar to HBV. Like HBV, most acute HCV infections are clinically indolent and not associated with a clinical picture of hepatitis. However, unlike HBV, rates of chronic HCV infection are 60% to 80%. The natural history of chronic disease is highly variable, with some patients progressing to end-stage liver disease or hepatocellular carcinoma while others have chronic antigenemia but do not have an evolving pattern of liver damage. Still others may have spontaneous resolution of the infection at a later time. HCV has an unpredictable time course. Individuals who are antigen positive are infectious to others. There are over 40,000 new cases of acute HCV infection annually in the United States, and approximately 3.5 million individuals are living with chronic infection. HCV is the leading cause of chronic liver disease leading to hepatic transplantation.

There is no vaccine for HCV. The HCV infection results in a circulating antibody that is not thought to neutralize the virus. There are multiple different serotypes of the virus, and reinfection can occur with the same viral type in patients who cleared the initial infection. The prospects for a vaccine are challenging when even acute infection does not confer protective immunity for the host against future infection. The antibody response may be delayed up to 6 months after acute infection, which makes HCV detection in the blood supply more difficult among donors with recent acute infection. The impact of effective direct-acting antivirals against HCV may affect the development of an HCV vaccine, as well as influencing postexposure prophylaxis, as is discussed later in the chapter.

Human Immunodeficiency Virus

HIV is a retrovirus. It is an RNA virus and has the enzyme reverse transcriptase that results in production of a complementary DNA (cDNA) from the RNA template after the virus invades the target cell. The incorporation of the viral cDNA into the host cell genome becomes the basis for the synthesis of viral proteins and replication of new viral units. The CD4-positive lymphocyte becomes a major target of the virus, and the lysis and loss of these cells are a fundamental issue in the immunodeficiency state that evolves with subsequent clinical AIDS. The acute infection may be characterized by a modest and nonspecific viral syndrome or by no discernible symptoms. The progression of the natural history of the infection without treatment is 10 years or longer before AIDS emerges.

HIV infection is transmitted by sexual contact and by injection drug use. Vertical transmission from infected mothers to newborns has been dramatically reduced in frequency in the United States by the use of antepartum ART. Transmission secondary to blood transfusion has essentially been eliminated with effective screening procedures in the United States and Western Europe. HIV infection remains an international pandemic, especially in the African continent where preventive strategies have been ineffective and treatment of established infection has been unavailable. About 1.1 million people are living with HIV infection in the United States, and there are about 40,000 new cases reported annually. About 15% of HIV-infected individuals are unaware of their infection. ART has been quite effective in providing long-term survival of these patients, but the development of an effective vaccine and definitive cure of HIV infection have remained elusive.

Considerable effort has been extended into the evaluation and prevention of occupational HIV infection among HCPs. A serologic survey of more than 3000 orthopedic surgeons at a national meeting identified only two cases of HIV infection, both of which were in individuals with nonoccupational risks for infection. Prospective evaluation of mucous membrane and percutaneous exposure events among HCPs has documented 58 cases of occupational infection ( Table 60.2 ). Transmission from a percutaneous exposure is reported at a 0.3% risk among HCPs, but this risk is likely much lower if patients are receiving ART and have low viral titers. Epidemiologic evaluation of HCPs who have developed infection, but who do not have documented specific events related to acquiring the disease, has resulted in the initial identification of 150 cases of possible occupational transmission as of December 2013 (see Table 60.2 ). At this time, no documented infections have been transmitted from patient to surgeon in the United States from percutaneous exposure events in the operating room. Compared with HBV and HCV, the efficiency of transmission in the health care setting is much less with HIV. The changing antigenic presentation of the virus from the constant mutation process has made stable antigen targets for vaccine development quite elusive.

TABLE 60.2
Cases with Documented or Possible Seroconversion to HIV Through December 2013
Modified from Joyce MP, Kuhar D, Brooks JT. Notes from the field: occupationally acquired HIV infection among health care workers—United States, 1985-2013. MMWR Morb Mortal Wkly Rep. 2015;63:1245–1246.
Occupation Documented Cases Possible Cases
Nurse 24 (41.4%) 37 (24.7%)
Clinical Laboratory Technician 16 (27.6%) 21 (14.0%)
Physician: Nonsurgical 6 (10.3%) 13 (8.7%)
Physician: Surgical 0 6 (4.0%)
Nonclinical Laboratory Technician 4 (6.9%) 0
Housekeeping/Maintenance 2 (3.4%) 14 (9.3%)
Surgical Technician 2 (3.4%) 2 (1.3%)
Hospice Care Giver/Attendant 1 (1.7%) 16 (10.7%)
Emergency Medical Technician/Paramedic 0 13 (8.7%)
Embalmer/Morgue Technician 1 (1.7%) 2 (1.3%)
Respiratory Therapist 1 (1.7%) 2 (1.3%)
Dialysis Technician 1 (1.7%) 3 (2.0%)
Dental Workers/Dentists 0 6 (4.0%)
Others 0 15 (10%)
Total 58 150

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