Infectious Disease Exposure in the Healthcare Worker

Description

Working in the healthcare setting necessitates a degree of exposure to infectious hazards that is greater than non-healthcare-related jobs.
- Parenteral injury, inhalational exposure, and direct contact with bodily fluids are the primary means of communication or exposure.
- The most common parenterally transmitted diseases are HIV, hepatitis B virus (HBV), and hepatitis C virus (HCV).
- Universal precautions should be the standard. Additional precautions must be taken for airborne pathogens such as tuberculosis, H1N1 influenza, and human papillomavirus (HPV).
Agents used in bioterrorism attacks have become increasingly more important for the healthcare provider to be familiar with.

Epidemiology

Incidence

There are ~800,000 percutaneous injuries per year in the US. Most needlesticks occur in the OR from suture needlesticks.
HIV seroconversion after a needle stick from an HIV positive patient is 0.3%; in 2004, 57 healthcare workers reported contracting HIV in the workplace.
Hepatitis B seroconversion after parenteral exposure can vary between 2% and 40% for the nonimmunized. Since the introduction of the hepatitis B vaccination, infections have decreased from 10,721 in 1983 to 384 in 1999 (a 96% reduction).
Hepatitis C seroconversion after parenteral exposure is estimated at 1.3%.
Tuberculosis infection among all healthcare workers has an incidence ranging from 3.6 to 5.4 workers per 100,000 from 1994 to 2000.
HPV infection following inhalational exposure is unknown; most likely very rare.

Morbidity/Mortality

HIV infects ~5 million people worldwide annually. Roughly 900,000 cases of AIDS were reported in the US in 2002. With appropriate antiretroviral therapy early in the disease course, HIV patients have a life expectancy between 20 and 50 years. Without treatment, however, the median life expectancy is estimated to be between 9 and 11 years from the time of infection. The major cause of death is opportunistic infections in the later stages of the disease.
Hepatitis B causes asymptomatic disease in 60–65% of infected people, acute hepatitis in 20–25% of infected people, and chronic hepatitis in roughly 1% of people.
Hepatitis C causes active liver disease in 75–80% of infected people, cirrhosis in 10–20% of infected people, and liver cancer in 1–5% of cirrhosis patients.
New, active tuberculosis infections affect 16,000 people per year in the US. forty-five percent of these infections occur in immigrants. In 10–50% of immunocompromised hosts, the bacteria migrate to various organs and cause a disseminated disease. The major cause of death is due to lung disease.
Laryngeal papillomatosis does not cause a malignant disease, but frequently causes recurrent papillomas that require multiple operations for treatment.
Creutzfeldt–Jakob disease affects ~1 in 1,000,000 people each year. It is uniformly fatal and has an average duration of 7 months.

Etiology/Risk Factors

Parenteral infections
- Wearing gloves has been shown to decrease the frequency of seroconversion from needlestick injuries. Likewise, gloves prevent transmission of infection via open skin wounds on the hands.
- Percutaneous injuries from smaller gauge needles have a lower incidence of seroconversion than larger needles. This is likely due to the degree of tissue trauma inflicted by the needle, as well as the viral load being transferred on the needle itself.
- Hollow bore needles have a higher rate of seroconversion than solid (suture) needles.
- Transmission from a patient with a high viral load has a higher incidence of seroconversion than when a patient has a lower viral load.
Inhalational infections
- Personal protective equipment like an N95 mask has been shown to reduce the transmission of inhaled infections to healthcare workers.
- Negative pressure rooms prevent bacteria transmitted by the inhalational route from being released into hallways and other rooms.
- When using a laser on HPV lesions, a suction device can be used to collect aerosolized virions and is thought to reduce the risk of transmission of the virus.
Prion diseases
- The only known risk factor for prion disease transmission is direct contact with infected patient material. Creutzfeldt–Jakob disease is the most common prion disease worldwide, and 85–90% of cases arise spontaneously rather than via an infectious route.
Bioterrorism agents
- Anthrax, Yersinia pestis (plague), smallpox, and Clostridium botulinum are among the most common agents used in bioterrorism.
- The most significant risk factor for infection with these agents is direct exposure. There are no documented modifiable risk factors for these diseases other than standard universal precautions.

Physiology/Pathophysiology

HIV is a retrovirus that infects human macrophages and CD4⁺ T-cells.
Hepatitis B is a DNA virus that replicates primarily in hepatocytes.
Hepatitis C is an RNA virus that also preferentially infects hepatocytes. The direct cytotoxic effects on the hepatocyte are thought to be responsible for the bulk of the damage caused by hepatitis C, in contrast to the immune-mediated cytotoxic effects of hepatitis B.
Tuberculosis is caused by Mycobacterium tuberculosis. Tuberculosis typically leads to a latent infection in the apical portions of the lung. However, an assortment of factors can cause the bacteria to reactivate or disseminate into the blood stream, causing miliary tuberculosis. The major cause of organ dysfunction is due to the caseating necrosis caused by the immune response to the bacteria and surrounding structures.
HPV can be disseminated into the healthcare environment via surgical lasering of infected lesions. These virions can be inhaled into the respiratory tract and may (rarely) cause an infection of laryngeal or other airway structures. Infection primarily causes laryngeal papillomatosis, which can lead to hoarseness or airway obstructions. Treatment focuses on removal of the papillomas with a laser.
Influenza A is caused by the influenza virus. Symptoms include fever, myalgias, sore throat, and pneumonia that may be fatal.
Bacillus anthracis is a large spore-forming, Gram positive, rod-shaped bacteria that causes anthrax. Anthrax's prodrome consists of a fever, cough, and chest or abdominal pain. The prodrome is typically 1–6 days in duration, but disease progression is imminent when the fever acutely worsens. This is rapidly followed by hypoxia and possibly death.
Smallpox virus is spread by the respiratory aerosol route or contact with infected bodily fluids. It causes symptoms 7–17 days after infection, which first consist of fever, headache, and/or backache. The characteristic rash starts on the mucosa of the oropharynx, face, and extremities. The rash becomes vesicular and pustular in its later stages as it migrates toward the trunk. Mortality is 30% or greater.
Yersinia pestis is the causative agent of the plague. The bacteria have an array of mechanisms to avoid host defenses while weakening the immune system. Depending on the route of infection, symptoms can include pustules and ulcerations of the skin or hemorrhagic, necrotizing pneumonia. Fulminant bacteremia with resultant disseminated intravascular coagulation, hemorrhages, and thrombi are the major causes of death.
Botulism is caused by Clostridium botulinum, a spore-forming, Gram-negative rod found in inadequately sterilized canned foods. The neurotoxin produced by the bacteria prevents the release of neurotransmitters, which results in paralysis. Without supportive care, mortality is estimated at 60%. With supportive care, however, mortality is estimated at 5–10%.
Creutzfeldt–Jakob disease and other spongiform encephalopathies are caused by prions. Prions are proteins that have had a spontaneous conformational change in their tertiary structure. This conformational change causes a chain reaction, which leads to massive neural degeneration. The most common presenting symptom is dementia, which progresses to a uniformly fatal encephalopathy.

Prevantative Measures

Universal precautions should be taken in all situations. Appropriate eye care, gloves, and personal protective equipment should be made available in any location where healthcare personnel may come into contact with infected patients or bodily fluids.
Needleless IV tubing may reduce risk.
One-handed needle recapping
Hospital policies mandating appropriate isolation for high-risk patients should be in place. There should be appropriate warning signs to alert all healthcare personnel of possible exposure.

The constellation of physical examination findings will differ based on the specific infectious disease in question.
All exposures need to be appropriately reported to employee health; after hours, the emergency room or infectious disease on-call person usually has the capability of initiating the workup and therapy as needed.
Specific screening tests following exposure to various infectious diseases are dictated by the route of injury.
for percutaneous injuries, HIV, hepatitis B, and hepatitis C titers should be drawn as soon as possible following the injury.
Following initial titers, repeat screening should be performed at given intervals based on the disease in question.
for tuberculosis, PPD screening should be performed on an annual basis for all healthcare providers.

Differential Diagnosis

Will vary depending on the specific infectious agent.

Healthcare workers who are exposed to HIV should be considered for a 4-week course of treatment with a combination of zidovudine and lamivudine, lamivudine and stavudine, or didanosine and stavudine. Resistant strains can occur.
Hepatitis B exposures should be treated with prompt institution of the hepatitis B vaccine series in individuals who have not already completed the series. In addition to the vaccination series, hepatitis B immune globulin should be considered for patients who have not completed the vaccination series OR who have an inadequate response to a completed vaccine series.
Hepatitis C exposures are not treated with immune globulin or antiviral agents (interferon, with or without ribavirin). Only follow-up testing should be performed.
Anthrax should be treated by a 60-day course of ciprofloxacin or doxycycline. If the bacteria are known to be penicillin sensitive, however, the treatment should be a 60-day course of penicillin G or amoxicillin.
Smallpox has no definitive therapy. Secondary infections should be treated on an as needed basis should they arise.
Yersinia pestis is highly transmissible and requires respiratory/droplet isolation until at least 3 days of antibiotic therapy has been completed. Treatment can include a 10-day course of streptomycin, gentamicin, doxycycline, or ciprofloxacin.
Botulism should be treated with supportive care, which may include prolonged mechanical ventilation. In addition, specific antitoxins are available based on bacterial serotype.
There is no known cure or therapy for prion diseases such a Creutzfeldt–Jakob disease. The only action currently known to be effective is to prevent further spread of disease by limiting exposures of uninfected individuals.

Determined by the disease in question

Belay ED. Transmissible spongiform encephalopathies in humans. Annu Rev Microbiol. 1999;53:283–314.
Centers for Disease Control and Prevention . Novel influenza A infections among healthcare personnel – United States, April-May 2009. 2009;58(23):641–645.
Garden JM , O’Banion MK , Shelnitz LS , et al. Papillomavirus in the vapor of carbon dioxide laser-treated verrucae. JAMA. 1988;259(8):1199–1202.
Centers for Disease Control and Prevention . Updated U.S. Public Health Service Guidelines for the Management of Occupational Exposures to HBV, HCV, and HIV and Recommendations for Postexposure Prophylaxis. 2001;50(RR11):1–42.
Fine A. New York State Department of Health. Summary of biological warfare agents. 2001.
Texas Department of State Health Services . Texas contaminated sharps injuries, 2008. Available at: http://www.dshs.state.tx.us/idcu/health/infection_control/bloodborne_pathogens/report/2008/sharps2008.pdf (accessed February 15, 2011.

See Also (Topic, Algorithm, Electronic Media Element)

ICD9

V01.9 Contact with or exposure to unspecified communicable disease

ICD10

Z20.9 Contact w and exposure to unsp communicable disease

Vigilance and prevention are the most effective ways to avoid transmission of diseases.
Following exposure, certain diseases can be treated with postexposure prophylaxis in order to decrease the rate of infection.
The carrier rate among healthcare workers for methicillin-resistant Staphylococcus aureus (MRSA) may be as high as 1 in 20 (approximately 2–3 times greater than the general population). Only about 5% of those have symptoms. Healthcare workers may be 2–3 times more likely to be a carrier of MRSA.
Healthcare workers are considered to be at significant risk for acquiring or transmitting hepatitis B, influenza, measles, mumps, rubella, and varicella. All of these are preventable by vaccines. Immunocompromised healthcare workers are at a greater risk and the Centers for Disease Control issue vaccination recommendations for this population.

Russell K. McAllister , MD

andrew L. Barker , MD

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Basics ⬇

Incidence

Morbidity/Mortality

Diagnosis ⬆ ⬇

Treatment ⬆ ⬇

Follow-Up ⬆ ⬇

References ⬆ ⬇

Additional Reading ⬆ ⬇

Codes ⬆ ⬇

Clinical Pearls ⬆ ⬇

Author(s) ⬆