A patient withactive shingles (herpes zoster)is contagious to individuals who havenever had varicella (chickenpox) or the varicella vaccine.The best roommate selectionis someone who has received thevaricella vaccine, as they are consideredimmune and not at riskfor contracting the virus.

Why the Other Options Are Incorrect?

B. Treatment with acyclovir– Acyclovirtreatsherpes zoster but does notprevent transmissionto others.

C. A history of herpes simplex– Priorherpes simplex virus (HSV) infection does not confer immunity to varicella-zoster virus (VZV).

D. Varicella zoster immunoglobulin (VZIG)–VZIG provides temporary immunitybut does not offerlong-term protectionlike the vaccine.

CBIC Infection Control Reference

APIC guidelines recommendplacing patients with active shingles in a room with individuals immune to varicella, such as those vaccinated​.

Standard Precautionsare sufficient forcongenital cytomegalovirus (CMV), which means thatgloves should be used when handling body fluids. CMV is primarily transmitted viadirect contact with saliva, urine, or blood.

Why the Other Options Are Incorrect?

A. Wear masks and gloves–Masks are not necessary unless performing high-risk aerosol-generating procedures.

C. No barrier precautions are needed–Gloves are required when handling bodily fluidsto prevent transmission.

D. Use gowns, masks, gloves, and a private room– CMV does not requireContact or Airborne Precautions.

CBIC Infection Control Reference

APIC guidelines state thatCMV transmission is prevented using Standard Precautions, primarily with glove use for body fluid contact​.

Among the listed pathogens,Hepatitis Chas thehighest risk of seroconversion following a percutaneous exposure, though it's important to note thatHepatitis Bactually has the highest overall risk. However, since Hepatitis B is not listed among the options, the correct choice from the available ones isHepatitis C.

TheAPIC Textconfirms:

“The average risk of seroconversion after a percutaneous injury involving blood infected with hepatitis C virus is approximately 1.8 percent”.

The other options are not bloodborne pathogens typically associated with high seroconversion risks after needlestick or percutaneous exposure:

A. Shigella– transmitted fecal-orally, not percutaneously.

B. Syphilis– transmitted sexually or via mucous membranes.

C. Hepatitis A– primarily fecal-oral transmission, low occupational seroconversion risk.

The correct answer is B, "1 and 4 only," indicating that the information can best be used to heighten awareness among Emergency Department (ED) staff and review the TB exposure control plan. According to the Certification Board of Infection Control and Epidemiology (CBIC) guidelines, tuberculosis (TB) remains a significant public health concern, particularly with the increasing proportion of cases among foreign-born persons in the United States. The data showing a rise from four to 22 states with over 50% of TB cases among foreign-born individuals highlights an evolving epidemiological trend that warrants targeted infection prevention strategies (CBIC Practice Analysis, 2022, Domain II: Surveillance and Epidemiologic Investigation, Competency 2.1 - Conduct surveillance for healthcare-associated infections and epidemiologically significant organisms).

Heightening awareness among ED staff (option 1) is critical because the ED is often the first point of contact for patients with undiagnosed or active TB, especially those from high-prevalence regions. Increased awareness can improve early identification, isolation, and reporting of potential cases. Reviewing the TB exposure control plan (option 4) is equally important, as it allows the infection preventionist to assess and update protocols—such as ventilation, personal protective equipment (PPE) use, and screening processes—to address the heightened risk posed by the growing number of cases among foreign-born individuals (CBIC Practice Analysis, 2022, Domain III: Infection Prevention and Control, Competency 3.2 - Implement measures to prevent transmission of infectious agents).

Option 2 (inform staff who are foreign-born) is not the best use of this data, as the information pertains to patient demographics rather than staff risk, and targeting staff based on their origin could be inappropriate without specific exposure evidence. Option 3 (educate patients and visitors) is a general education strategy but less directly actionable with this specific epidemiological data, which is more relevant to healthcare worker preparedness and facility protocols. Combining options 1 and 4 aligns with CBIC’s emphasis on using surveillance data to guide prevention and control measures, ensuring a proactive response to the increased TB burden (CBIC Practice Analysis, 2022, Domain II: Surveillance and Epidemiologic Investigation, Competency 2.5 - Use data to guide infection prevention and control strategies).

Theincidence ratemeasuresnew cases of infection in a population over a defined time periodusing the formula:

Why the Other Options Are Incorrect?

B. Disease specific– Refers to infectionscaused by a particular pathogen, not the general rate of new infections.

C. Point prevalence– Measuresexisting cases at a specific point in time, not new cases.

D. Period prevalence– Includesboth old and new cases over a set period, unlike incidence, which only considers new cases.

CBIC Infection Control Reference

APIC definesincidence rate as the number of new infections in a population over a given period​.

The correct answer is C, "Mucormycosis," as it is the infectious disease associated with environmental fungi. According to the Certification Board of Infection Control and Epidemiology (CBIC) guidelines, mucormycosis is caused by fungi belonging to the order Mucorales, which are commonly found in the environment, including soil, decaying organic matter, and contaminated water. These fungi can become opportunistic pathogens, particularly in immunocompromised individuals, leading to severe infections such as rhinocerebral, pulmonary, or cutaneous mucormycosis (CBIC Practice Analysis, 2022, Domain I: Identification of Infectious Disease Processes, Competency 1.1 - Identify infectious disease processes). Environmental exposure, such as inhalation of fungal spores or contact with contaminated materials, is a primary mode of transmission, making it directly linked to environmental fungi.

Option A (Listeriosis) is caused by the bacterium Listeria monocytogenes, typically associated with contaminated food products (e.g., unpasteurized dairy or deli meats) rather than environmental fungi. Option B (Hantavirus) is a viral infection transmitted through contact with rodent excreta, not fungi, and is linked to environmental reservoirs like rodent-infested areas. Option D (Campylobacter) is a bacterial infection caused by Campylobacter species, often associated with undercooked poultry or contaminated water, and is not related to fungi.

The association of mucormycosis with environmental fungi underscores the importance of infection prevention strategies, such as controlling environmental contamination and protecting vulnerable patients, which aligns with CBIC’s focus on identifying and mitigating risks from infectious agents in healthcare settings (CBIC Practice Analysis, 2022, Domain III: Infection Prevention and Control, Competency 3.2 - Implement measures to prevent transmission of infectious agents). This knowledge is critical for infection preventionists to guide environmental cleaning and patient careprotocols.

The correct answer is B, "24 hours," as this is the earliest recommended time that a healthcare personnel with an acute group A streptococcal throat infection may return to work after receiving appropriate antibiotic therapy. According to the Certification Board of Infection Control and Epidemiology (CBIC) guidelines, which align with recommendations from the Centers for Disease Control and Prevention (CDC), healthcare workers with group A Streptococcus (GAS) infections, such as streptococcal pharyngitis, should be treated with antibiotics (e.g., penicillin or a suitable alternative) to eradicate the infection and reduce transmission risk. The CDC and Occupational Safety and Health Administration (OSHA) guidelines specify that healthcare personnel can return to work after at least 24 hours of effective antibiotic therapy, provided they are afebrile and symptoms are improving, as this period is sufficient to significantly reduce the bacterial load and contagiousness (CBIC Practice Analysis, 2022, Domain III: Infection Prevention and Control, Competency 3.2 - Implement measures to prevent transmission of infectious agents).

Option A (8 hours) is too short a duration to ensure the infection is adequately controlled and the individual is no longer contagious. Option C (48 hours) and Option D (72 hours) are longer periods that may apply in some cases (e.g., if symptoms persist or in outbreak settings), but they exceed the minimum recommended time based on current evidence. The 24-hour threshold is supported by studies showing that GAS shedding decreases substantially within this timeframe with appropriate antibiotic treatment, minimizing the risk to patients and colleagues (CDC Guidelines for Infection Control in Healthcare Personnel, 2019).

The infection preventionist’s role includes enforcing return-to-work policies to prevent healthcare-associated infections (HAIs), aligning with CBIC’s emphasis on timely and evidence-based interventions to control infectious disease transmission in healthcare settings (CBIC Practice Analysis, 2022, Domain III: Infection Prevention and Control, Competency 3.1 - Collaborate with organizational leaders). Compliance with this recommendation also supports occupational health protocols to balance staff safety and patient care.