Background

In 2022, during the global outbreak of mpox clade IIb, New York City (NYC) recorded 3,821 confirmed cases. ¹ Most cases occurred through community transmission, while healthcare-associated transmission was uncommon. However, because mpox had not previously been seen in NYC, healthcare staff may have had difficulty recognizing suspected cases, leading to delays in the implementation of infection prevention and control measures. The risk of transmission from unrecognized mpox is particularly concerning in inpatient psychiatric units, where direct physical contact and exposure to contaminated fomites may be more common in shared spaces. In July 2022, a patient was admitted to an NYC Health + Hospitals/Bellevue (Bellevue) inpatient psychiatry unit with mpox that went unrecognized for 4 days, delaying the implementation of isolation precautions. This report describes the investigation of staff and patients potentially exposed to mpox and outlines lessons learned.

Case

A man in his 30s with a history of depression and substance use disorder presented to the Bellevue Emergency Department (ED) with suicidal ideation. At ED triage, the patient also reported 2 days of rectal pain, hematochezia, and constipation. He disclosed a history of sexual intercourse with both men and women. Two days prior, he had been presumptively diagnosed as having HSV proctitis at an urgent care clinic but had not taken the prescribed antiviral medication. Physical examination revealed a 0.3 cm scarred, non-tender, non-purulent lesion near the anus and a tender prostate on the rectal exam. Nucleic acid amplification tests for gonorrhea, chlamydia, herpes simplex virus 1 and 2, and varicella-zoster virus, which were negative. He was treated empirically for bacterial prostatitis with doxycycline and ceftriaxone before being admitted to a 28-bed psychiatry unit, where he shared a room with 2 other patients.

On hospital day 2, a computed tomography scan of the abdomen and pelvis revealed no acute pathology. Internal medicine was consulted on day 4 and found 2 tender, ulcerated perianal lesions, along with 2 small scabbing lesions on his trunk and arm. The patient was transferred to a medical unit and placed on airborne and contact isolation for suspected mpox. Swabs of the perianal lesions tested positive for non-variola Orthopoxvirus DNA.

Investigation

The psychiatry unit where the patient was initially admitted had regular group therapy and mealtimes in common areas, with patients free to interact outside their assigned rooms, though physical contact is prohibited.

Following the patient’s transfer to an isolation room on a medical unit, the psychiatry service collaborated with the hospital epidemiologist to investigate and mitigate any potential healthcare-associated transmission of mpox. Through patient interviews and chart reviews, exposed individuals were categorized according to exposure risk level as defined by the Centers for Disease Control and Prevention (CDC) in July 2022 (Table 1). Exposed patients were restricted from group activities and asked to eat meals in their rooms. Individual therapy and essential medical services were continued. Environmental services performed cleaning and disinfection of all common areas and the index mpox patient’s previous room using bleach-based disinfection products. For 21 days post-exposure, exposed patients were quarantined on the unit, separated from new admissions, and monitored daily for the development of mpox symptoms. Those discharged early were given instructions on community quarantine. For patients who needed transfer to other congregate settings, prior to transfer, we checked if the receiving unit was able to maintain quarantine and symptom monitoring for the remainder of the 21-day period.

Table 1.

CDC mpox exposure risk criteria

Note. CDC, Centers for Disease Control and Prevention.These criteria were used in July 2022 by the CDC but have since been updated here: https://www.cdc.gov/mpox/hcp/infection-control/healthcare-settings.html#cdc_generic_section_11-assessing-risk-of-mpxv-exposures-in-healthcare-settings-to-guide-monitoring-and-recommendations-for-postexposure-prophylaxis

Occupational health services assessed all staff members who were on the unit concurrently with the index patient. Staff members were categorized by exposure risk (Table 1), and those exposed were required to report daily temperatures and symptoms for 21 days after the last exposure. None were furloughed from work.