101 RISKS OF BLOODBORNE DISEASE
Caesar M. Ursic M.D., Doru I. E. Georgescu M.D.

1. What infectious diseases are transmissible via blood transfusion?

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In developed nations with mature blood banking systems, by far the most common transfusion-acquired infections are hepatitis from the hepatitis B (HBV) and C (HCV) viruses. Other less commonly transmitted agents include the human immunodeficiency virus (HIV) and cytomegalovirus (CMV). Even rarer but still occasionally reported bloodborne infections are parasitic diseases such as malaria (genus, Plasmodium), babesiosis (genus, Babesium), Chagas disease (Trypanasoma cruzi), toxoplasmosis (Toxoplasma gondii), the lymphomas and leukemias caused by the human T-cell lymphotropic virus (HTLV-I), and infectious mononucleosis (Epstein-Barr virus). Bacterial contaminations are also rare but possible, especially in platelet preparations that are stored at room temperature. This may result in a toxic shock-like syndrome, the risk of which has been estimated as equivalent to the risk of HIV transmission.

2. What are the estimated risks of HBV, HCV, and HIV transmission by blood transfusion in the United States?

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3. Which bloodborne pathogens pose a risk to surgeons?

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Although the epidemic of HIV has increased general concern about bloodborne pathogens, the prevalence of hepatitis C virus (HCV) throughout North America has led to a shift of emphasis from HIV to hepatitis. Hepatitis B is an occupational risk in surgery, but vaccinations and a relatively efficient post-exposure protocol have reduced the consequences of contamination with HBV. Surgeons in the United States care for more patients with chronic hepatitis C than with chronic hepatitis B, and no vaccine is available for HCV infection. Although the rate of seroconversion for hepatitis C is 10% versus 30% for hepatitis B, when acute infection occurs, there is a much higher chance of developing chronic hepatitis (50% versus 10%) after HCV infection. Thus, HCV infection is the greatest threat to surgeons.

4. What is the risk to health care workers of exposure to HBV?

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The number of new infections in 2001 has dropped to approximately 78,000 from the estimated yearly incidence of 260,000 in the 1980s. At present, 1.25 million U.S. residents have chronic hepatitis B, with the highest prevalence occurring among 20-49-year-old individuals. Thirty percent of percutaneous hollow needle exposures are followed by acute infection. Thirty percent of hepatitis B cases are clinically occult, and ≤ 10% of infected people remain viral carriers for life. Many carriers are asymptomatic and suffer no active liver disease, although they are potentially infectious to others. Twenty-five percent of HBV-infected individuals eventually die from hepatic diseases.

5. What is the risk to health care workers of exposure to HCV?

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The number of new infections in 2001 was 25,000, down from 240,000 per year in the 1980s. Currently, 3.9 million (1.8%) U.S. residents have HCV infection, of whom 2.7 million are infected chronically. The risk of seroconversion from a percutaneous hollow needle injury is 10%, but 90% of acute infections result in the chronic carrier state, which is typically asymptomatic. Although these data are still controversial, 50% of HCV infected patients will develop cirrhosis, and 50% of these patients will develop a hepatoma.

6. What is the risk to health care workers of exposure to HIV?

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The risk of HIV seroconversion after percutaneous inoculation with HIV-contaminated blood is approximately 0.3%. Risk of infection also appears to be greater when the source of the blood is a terminally or severely ill patient. The U.S. Centers for Disease Control and Prevention (CDC) reports that 57 health care workers in the U.S. have been documented as seroconverting to HIV as a result of an occupational exposure to the virus. The majority of these individuals were either nurses (n = 24) or laboratory workers (n = 19); physicians accounted for only six of these cases. The routes of infection were percutaneous (puncture or cutting wounds) in 84% of the cases. Thus, the risk appears small relative to the large number of exposures that have probably occurred since the onset of the epidemic in the early 1980s. The CDC also reports that as of January 1, 1998, there has been no documented transmission of HIV infection from a patient to a surgeon secondary to occupational exposure.

7. How well does hepatitis B vaccination protect against the disease?

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Effective protection against hepatitis B correlates positively with post-immunization anti-hepatitis B surface antibody (anti-HBs) serum titers of ≥ 10 mIU/mL. These titers are achieved in 95% of young, healthy recipients of the standard three-dose immunization regimen, and the actual protective efficacy (i.e., ability of the vaccine to prevent the disease) is estimated to approach 100% in these individuals. Although about 50% of successfully vaccinated adults demonstrate a decrease in their anti-HBs levels to nondetectable levels by 10 years, continued immunologic protection is thought to persist via the amnestic humoral response. Because of the persistence of this “immune memory” to the viral antigen, healthy individuals appear to enjoy lifelong protection after vaccination and do not require booster doses. A bivalent vaccine immunizing against both hepatitis A and B was approved in 2001 by the U.S. Food and Drug Administration for individuals 18 years of age and older, and it is as successful as the monovalent vaccine in conferring protection from the HBV infection with the added benefit of protecting against hepatitis A viral infection.

8. Are patients at risk of infection from surgeons who are infected with HBV?

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Transmission of hepatitis B infection from surgeons to patients has been documented. Surgeons who are at risk for transmitting infection to patients are generally positive for the e-antigen of hepatitis B. The e-antigen is a degradation product of the nucleocapsid of the virus and represents active viral replication within the liver. People who test positive for the e-antigen have high viral titers and are quite infectious. The large number of documented transmissions of HBV to patients by surgical providers is particularly troublesome and may require restriction of clinical privileges. Furthermore, a recent report from England documented transmission of HBV infection from surgeons to patients even when the surgeon was negative for the e-antigen.

9. What is the proper response after percutaneous exposure to a patient with known hepatitis B?

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This depends on the provider’s vaccination status. Older individuals show a tendency to mount a weaker or delayed immunologic response as measured by peak serum titers of anti-HBs. If the provider has been vaccinated and has a positive antibody titer, no additional response is necessary. If the provider has not been vaccinated and is negative for antibodies to HBV or if the provider completed the series of vaccinations but exhibited a weak or absent antibody titer, then he or she should receive a dose of hepatitis B immunoglobulin and begin the hepatitis B vaccination series. For surgeons who were successfully immunized against HBV in the past, neither routine booster doses nor routine immunity status surveillance is recommended.

10. What are the recommendations for hepatitis C immunization?

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There is currently no effective vaccine available against HCV. Immunoglobulin for HCV does not confer protection. Using universal barrier precautions remains the best strategy.

11. Does laparoscopic surgery minimize the risk of HIV contamination?

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The laparoscopic technique reduces exposure to blood products and sharp instruments; however, the risks are different. The evacuation of the pneumoperitoneum during laparoscopic procedures releases aerosolized HIV-infected blood and peritoneal fluid into the operative suite. Evacuation of the pneumoperitoneum into a closed system diminishes this exposure.

12. Is double gloving an effective method of protection?

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Although double gloving may not prevent percutaneous injury, it clearly reduces blood exposure. The contact rates between blood and the surgeon’s skin are decreased by 70% when the surgeon wears two pairs of gloves. Whereas outer glove perforation occurs in 25% of cases, inner glove perforation occurs in only 10% of cases (surgeons, 8.7%; assistants, 3.7%). The longer the procedure, the more frequent are inner glove perforations. The nondominant index finger is the most common target.

13. Are eye splash injuries a major threat to surgeons?

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A CDC study demonstrated that approximately 13% of documented HIV transmissions occurred by mucocutaneous contact. Eye splash injuries during surgery are often underestimated, although they are the easiest type of contact to prevent. A recent study examined 160 eye shields used by surgeons and assistants. All operations lasted ≥ 30 minutes. The shields were inspected for macroscopic splashes and then tested for microscopic splashes. Forty-four percent of the shields tested positive for blood. The surgeon was aware of a spray in only 8% of cases. The splashes were macroscopically visible in only 16% of cases. The risk of eye splashes was higher for surgeons than for assistants and increased with the length of the operation. The type of operation also proved to be a determining factor; vascular surgery and orthopedic surgery had the higher risks for eye splash injuries. Eye protection should be mandatory.

14. What is the surgeons’ rate of exposure to blood and body fluids?

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Percutaneous blood exposure occurs in 1.2-5.6% of surgical cases and mucocutaneous blood contact in 6.4-50.4%. The discrepancy among reported rates reflects differences in data collection, procedures performed, surgical technique, and degree of precautions. No health care worker has ever been infected through exposure of intact skin to blood and body fluids. However, transmission of HIV after mucocutaneous contact with HIV-infected blood has been reported. The risk of contamination is real for all personnel in the operating room, but it is much higher for surgeons and first assistants, who account for 80% of all body contamination and 65% of injuries.

15. Again, what are the seroconversion rates for HIV and HBV exposure?

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Seroconversion rates from a hollow needle stick are 0.3% for HIV and 30% for HBV.

16. What is the lifetime occupational risk of HIV infection for surgeons?

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The risk of HIV infection for a surgeon can be calculated by obtaining the product of HIV seroprevalence in surgical patients (0.32-50.00%), percutaneous injury rate (1.2-6.0%), and seroconversion rate (0.29-0.50%). The calculated risk per case of acquiring HIV ranges from 0.11 per million to 66 per million. Assuming that a surgeon performs 350 operations per year over a 30-year career, the estimated lifetime cumulative risk ranges from 0.12% to 50.0%, depending on the variables. Several assumptions are inherent in this calculation:

* The formula assumes a constant HIV prevalence, but it is estimated that the prevalence increases by 4.0-8.6% annually in the United States.
* The formula assumes that exposure to HIV-infected blood occurs only through percutaneous injuries, disregarding the risk caused by mucocutaneous exposure.
* The formula assumes that whereas every operation carries the same risk, the risk varies with the length of procedure and amount of blood loss.
* The formula assumes that the risk per case is the same for a trauma surgeon in center city Detroit and a plastic surgeon in Beverly Hills.

Clearly, these assumptions are imprecise.

17. Are there effective methods to reduce the risk of transmission of bloodborne diseases to surgeons?

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For HBV infection, in addition to universal precautions, a highly effective vaccine is available, but it is not used as much as it should be. Most surgeons who are 45 years or older have not been vaccinated. A precisely defined postexposure protocol is also available. For HCV and HIV infections, the most pragmatic approach is to lower the rate of percutaneous and mucocutaneous injuries by observing barrier precautions and using safe surgical technique.
Finally, prompt response to blood exposure is required. Contamination of the hands or arms is best dealt with by immediate rescrubbing. If this is not practical, the area should be irrigated with povidone iodine, and rescrubbing should be accomplished soon thereafter.

References
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