A 36-year-old healthy man developed an acute febrile illness associated with a vesicular rash. He presented to an urgent care clinic where he was diagnosed with varicella infection ("chicken pox"). The patient did not recall a sick contact or exposure to varicella, but he did report working in an emergency department (ED). He was initially treated with oral acyclovir, but the progression of his lesions eventually required a brief hospitalization for dehydration and acute renal failure. His condition ultimately improved and his symptoms resolved.

The ED worker later learned from his supervisor that a patient had presented to the ED with chicken pox during one of his shifts, and his exposure likely occurred at that time. He raised concern that his illness could have been prevented had proper procedures been in place. His case prompted extensive discussion of infection control procedures among the ED leadership, given that many ED providers were exposed to this highly communicable disease.

by Richard Rothman, MD, PhD; Sahael Stapleton, MD

The case presented provides an opportunity to discuss infectious threats and strategies for protecting health care workers (HCWs) from diseases obtained through workplace exposure. ED personnel interact with large numbers of patients who may have occult, subtle, or clinically apparent infectious diseases. Effective prevention strategies are available that can significantly reduce the risk of HCWs contracting communicable diseases. However, as this case points out, managing even known pathogens can be challenging.

One reality that is difficult to avoid is the ED patient–provider interaction, which is critical to patient care but leaves providers vulnerable to infectious disease exposures. Patients' histories may be incomplete or unknown, and interventions are often immediate—requiring close contact between the patient and HCW (e.g., emergent endotracheal intubation). The 24/7 access provided by EDs makes them a likely location for early contact with dangerous foreign pathogens. Nevertheless, hospitals need to respond, adapt, and evolve their care delivery systems, particularly to address emerging agents.

Types of Infectious Threats

Potential infectious pathogens can be grouped into three categories: known and common endemic infectious diseases (e.g., influenza, human immunodeficiency virus (HIV), hepatitis, varicella, malaria); emerging infectious diseases (e.g., H1N1 influenza, severe acute respiratory syndrome (SARS), extensively drug resistant tuberculosis [XDR-TB]); and biothreats (e.g., smallpox, anthrax, botulism). Pathogens can be transmitted through direct contact with infected individuals or contaminated objects, airborne exposure, fecal-oral, or blood routes.(1) Infection can occur through incidental exposure, such as contact with infected respiratory secretions (2), or iatrogenic exposure, such as a blood-borne pathogen contracted via a needle stick injury.

Common Pathogens

An infectious threat prevalent in many ED populations is HIV.(3) As this pathogen emerged, the Centers for Disease Control and Prevention (CDC) created a series of universal precautions for HCWs to follow with all patients, regardless of HIV status.(4) These include handwashing; use of gloves, gowns, and face masks for encounters involving potential exposure to body fluid; and safe needle disposal.(4)

In this case, an ED provider contracted varicella after being exposed during one of his shifts. Varicella zoster virus (VZV) transmission does not require direct patient contact and can occur by direct contact with blister fluid or aerosolized particles.(1,5) Accordingly, CDC guidelines for controlling risk of VZV transmission include standard, "contact," and "airborne" precautions for patients with known or suspected VZV.(1) Contact precautions include single patient rooms and a 3 feet minimum distance between all patients; airborne precautions include airborne infection isolation rooms and use of N95 respirators by HCWs. If a HCW is exposed, VZV serology testing is indicated to ensure the presence of antibody. If seronegative, HCWs can be monitored for symptoms or given vaccine.(1) Additionally, pregnant or immunocompromised HCWs with known exposure should receive varicella zoster immunoglobulin.(1) It's unclear exactly what happened in the case presented, but these prevention steps along with the HCW's knowledge of his history and past exposures may help mitigate such situations.

Emerging Threats

Respiratory infections such as H1N1 influenza, SARS, and XDR-TB have emerged as global health threats.(6) Outbreaks are frequently unavoidable and unpredictable. Early on, the cause and extent of disease, including the transmission potential, are often unknown. In suspected outbreaks, triage nurses are provided with detailed protocols for assessing severity and stratifying patients based on risks of exposure. Risk factors may include travel history, sick contacts, occupation, and results from diagnostic testing.(2) CDC guides for evaluating patients suspected of having such infectious diseases are updated regularly during an emerging outbreak. However, there is often a gap between publication and adoption in the ED. Educating HCWs is a time-consuming process, which can lag behind the emergence of a threat.

Biothreats

Biothreats carry the potential for significant morbidity and mortality and require a pandemic response plan. In the case of a suspected biothreat, the CDC partners with EDs and other frontline sites to conduct rapid epidemiologic assessments to confirm or refute existence of cases and determine whether they are isolated or part of a true outbreak.(7) Most bioterrorism agents are not transmitted person-to-person, and the CDC recommends only standard precautions when caring for patients.(7) Some agents carry significant person-to-person transmission threats. For example, the most common type of smallpox virus, variola major, is highly contagious, readily transmitted person-to-person, and fatal in up to 30% of cases.(7) Known or suspected cases of smallpox should adhere to standard, airborne, and contact precautions.(7,10) A vaccine is available and effective for high-risk individuals, though pre-exposure vaccination is not currently recommended for individuals who do not work directly with the virus.(11)

During infectious outbreaks or biothreats, EDs may become overcrowded, requiring alternative operational measures. For example, if all isolation rooms become occupied, patient cohorting and alternative sites of care may be required.(7) Certain aspects of recommended disaster plans, such as ensuring available critical care space and allocating mechanical ventilators, may fall short during outbreaks leaving EDs and hospitals overtaxed.(8,9) Improved information technology can assist with rapidly disseminating information to providers while allowing EDs and infection control experts to implement new safety practices that protect patients and HCWs.

Prevention Strategies

In addition to disease-specific strategies, HCW screening and ongoing guidance from federal agencies can further minimize the impact of infectious exposures. Although ED employees are not required to undergo more rigorous health screening than other hospital workers, one could argue for enhanced screening—particularly during an outbreak—as a disaster center can potentially limit exposure of disease-naive employees. However, infectious etiology is often unknown and manpower unavailable to allow avoiding particular patients, nor is it reasonable to expect every worker to consider every potential exposure at all times.

The CDC provides guidance for infection control practices, based on transmission mechanisms and infection control principles.(1) Individual hospitals also provide HCWs with institution-specific guidance through dedicated departments and teams, such as Hospital Epidemiology and Infection Control or Occupational Safety and Health. Key infection control program components include HCW immunization verification, periodic immunity testing, and boosters for diseases such as hepatitis B, varicella, influenza, MMR (measles, mumps, and rubella), diphtheria, and tuberculosis. Additionally, these programs deliver postexposure prophylaxis (1) and provide preventive educational and operational programs aimed at improving patient safety measures for daily infectious exposures (e.g., handwashing) as well as unanticipated infectious threats (e.g., outbreak triage protocols).(2)

Summary

EDs will remain on the frontline of many infectious threats. Continued efforts must be made to provide HCWs with a safe environment, while allowing for accurate and well-planned responses to infectious disease agents. Additional planning, regular drills, and leveraging new technology (to help identify potential outbreaks early and disseminate information rapidly) will be important to help protect ED HCWs and the populations they serve.

Take-Home Points

• EDs are on the frontlines of exposure for any infectious threat, including common pathogens, emerging agents, and biothreats.
  
• Exposure cannot be eliminated, but careful planning can contain the impact.
• Prevention strategies focus on appropriate health screening of HCWs, standard precautions to limit transmission of many communicable diseases, and guidance from key organizations (e.g., CDC and Association for Professionals in Infection Control and Epidemiology) on disaster planning.

Richard Rothman, MD, PhD
Associate Professor
Department of Emergency Medicine
Johns Hopkins University School of Medicine

Sahael Stapleton, MD
Resident Physician
University of California, San Francisco

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