By Gary Evans, Medical Writer
Although the overall risk of transmission is low, at least two healthcare workers have been occupationally infected with monkeypox virus (MPXV) in the United States. In an unusual case, two caregivers were infected by environmental fomites in the home of a patient in Brazil.
Although rare, healthcare workers have been infected in previous outbreaks, and there likely are a fair number of unreported cases, given the stigma associated with MPXV. The 2022 global outbreak has emerged primarily in men who have sex with men (MSM) and it is the first time the virus — endemic to regions of Africa — has appeared in so many non-endemic countries.
As usual in epidemics, the number of healthcare workers infected is hard to pin down. As of Aug. 22, 2022, the World Health Organization (WHO) reported 256 monkeypox cases in healthcare workers globally. “However, most were infected outside of the working place or are currently under investigation to determine infection source,” the WHO reported.1 A review of subsequent reports suggested the WHO had not updated the healthcare infection situation through mid-October 2022. In addition, at a Sept. 15 news conference on one of the U.S. cases, Rita Singhal, MD, chief medical officer for Los Angeles County, said about eight healthcare workers worldwide have contracted monkeypox via needlesticks.2
However, some of these are not traditional needlestick blood exposures, but occurred after workers tried to remove the top — or “roof” — of a monkeypox pustule or lesion with a needle or sharp to obtain a sample of infectious fluid for testing.
“You don’t need to try to unroof the lesion,” says William Schaffner, MD, a CDC advisor and medical professor at Vanderbilt University. “You just swab it thoroughly and you will be able to get an adequate specimen. I think we need to get this information out to the rank and file so the safety of healthcare workers will be protected.”
The CDC emphasizes that “MPXV PCR testing cycle threshold values from swabbed skin and mucosal lesion specimens have been very low, indicating that surface swabbing collects sufficient amounts of viral material without a need to unroof lesions.”3
In a separate report, the CDC noted “there have been two documented cases of healthcare workers infected through a skin-penetrating injury from a non-bloody sharp used to sample a skin lesion. In both cases, the healthcare worker’s first or only lesion after infection appeared at the inoculation site. The sharp likely was contaminated with monkeypox virus from vesicular or pustular material. However, there was not testing of the sharp for the presence of viral DNA or for replication-competent virus.”4
Of the U.S. cases, one occurred in Los Angeles County and the other in an unidentified county in Florida. Few details were available on the California case as this report was filed, but Singhal said in the news briefing “it was not directly a needlestick injury, but it was an exposure at the work site.”
The CDC recently reported the case in a Florida nurse in detail. “While obtaining swabs from a patient with suspected monkeypox, the nurse used a needle to create an opening in the vesicular lesion to facilitate direct contact of the swab with fluid in the lesion,” the agency explained. “The needlestick occurred when recapping the used needle by hand before disposal. It caused a break in the skin on the index finger through the nurse’s gloved hand, accompanied by a small amount of bleeding.”3
The wound was immediately washed with soap, water, and a chlorohexidine solution, and the nurse received the first dose of a two-dose JYNNEOS vaccination series as post-exposure prophylaxis (PEP) 15 hours after the injury. In accordance with CDC guidance, the nurse continued to work while asymptomatic and was actively monitored by the hospital infectious disease experts.
“The nurse wore a surgical mask, consistent with CDC COVID-19 guidance, and chose to wear medical gloves when interacting with [all] patients,” the CDC reported. “Ten days after the exposure, a single skin lesion formed at the site of the needlestick. The nurse immediately began isolating at home and kept the lesion covered until it had crusted over, the scab had fallen off, and a new layer of skin had formed beneath the lesion 19 days later.”
Investigators in Brazil recently reported traditional monkeypox bloodborne transmission after a healthcare worker was stuck by a needle containing an infected patient’s blood. Including the thumb inoculation site, the nurse developed six other lesions on her hands, face, and left thigh. The lesions were associated with severe pain, particularly at the inoculation site. The monkeypox vaccine is not available in Brazil, so PEP was not an option. The nurse’s blood remained MPXV-positive for 19 days after symptom onset.
“How detectable MPXV DNA corresponds to true viremia is unknown, but persistent DNA suggests bloodborne transmission could be possible through needlesticks, blood transfusions, and organ transplants,” the investigators wrote.5 “Persistent MPXV DNA in the nurse’s oropharyngeal samples aligns with another report,6 but efficiency for droplet or airborne transmission remains unknown.”
A more bizarre case in Brazil included a homebound patient and two nurses, all three of whom were subsequently found to be a 100% genetic match in their infecting MPXV. Apparently, the two nurses were infected by objects or surfaces in the patient’s home environment since they only wore gloves when collecting specimens for culture.
“I think this just really serves to highlight that monkeypox viral infection can be acquired through fomites,” said Daniel Griffin, MD, a clinician and researcher at Columbia University. In a video briefing, Griffin recommended wearing a new pair of gloves to obtain the patient culture, disposing of them properly, washing hands, and donning a new pair of gloves. Although they wore all other personal protective equipment, the nurses did not wear gloves in the patient’s home other than when collecting the specimen.7
On July 29, 2022, the nurses obtained a specimen collection from a suspected monkeypox patient at his home, according to a preprint report by Brazilian investigators. The healthcare workers wore safety glasses, disposable isolation gowns, and N95 respirators. Lesion specimen collection was conducted using dry sterile swab procedure plastic gloves. After collection, the material was stored in a sample transport box and the workers sanitized their hands with 70% ethanol.8
“Gloves were used only during collection; in the remaining time at the patient’s house and during sample box transport, the healthcare workers did not wear gloves, but the remaining personal protective equipment was used until the moment they returned to the workplace to store the collected material,” the investigators wrote. “Work materials such as clipboard, sample transport box, and table were not sanitized. The healthcare workers did not have contact with other suspected/confirmed cases of monkeypox on the same day or in the following days.”
The patient was diagnosed with MPXV. Subsequently, both nurses became infected and developed relatively serious symptoms, with one suffering a progressive spread of lesions to her face and the other one developing lymphangitis.
“The interaction of patients with healthcare workers provides a window of opportunity for MPXV transmission,” the investigators concluded. “The present case report highlights the possibility of fomite transmission route of MPXV, suggesting that [viral] particles are infectious and resistant to environmental conditions. Therefore, extreme caution needs to be taken with general protection equipment and house objects used by suspected cases.”
In addition to these cases, a nurse in France was infected after trying to “harvest a vesicle” on the ankle of a suspected monkeypox patient. She was using a safety needle but failed to activate it, leaving the needle exposed while trying to work with the sample. The nurse incurred a needlestick to her thumb and began bleeding through her glove. She was given subcutaneous PEP with a third-generation smallpox vaccine within three hours of the injury. That may have made all the difference — the nurse only developed a vesicle at the inoculation site and one other lesion.9
While these injuries allow mitigation efforts to prevent transmission to patients and co-workers, there are also cases of employees continuing to work without suspecting they have smallpox. In 2018, a healthcare worker (patient 3) in England was infected with MPXV after shaking or handling bedding of an undiagnosed patient. As a result, upon discovery of infection, the hospital had to perform a thorough follow-up to find potentially exposed patient and colleague contacts.
“A total of 134 possible contacts of patient 3 were identified, including staff and patients on the ward where patient 3 worked, family and community contacts, and staff and patients at the general practitioner’s office where patient 3 had sought care,” the researchers reported. “A total of four contacts of patient 3 became ill within the incubation period and required medical assessment.”10
There also are reports of providers working with MPXV lesions in the current outbreak. Supriya Narasimhan, MD, hospital epidemiologist at Santa Clara Valley (CA) Medical Center, said this happened recently at a hospital in Massachusetts.
“They had a healthcare worker who had worked accidentally without knowing that they had monkeypox, and they had to do a large-scale risk assessment,” Narasimhan said at a recent webinar. “As it turned out, the lesions were in areas of the body that were not in contact with the patients, and this healthcare worker had been diligent about hand hygiene and wearing gloves. [They] didn’t have a large number of patients who have had a high-risk exposure. Post-exposure prophylaxis is recommended for people who might have had that kind of contact.”11
Also speaking at the webinar, Jill Holdsworth, CIC, FAPIC, infection prevention manager at Emory Hospital in Atlanta, discussed the implications of discovering a healthcare worker has contracted MPXV.
“We would work with occupational health on this, and they would do a lot of this type of investigation,” Holdsworth said. “I know this has happened before, and some of the questions that you would want to ask are, ‘First where are the lesions?’ A lot of the time, the lesions are in a place that would have been covered by clothing, so they would have been contained, and the risk level would be very low. If they had lesions on the palms of their hands, obviously that would be a lot higher risk.”
The current isolation guidelines call for placement of MPXV patients in a private room with an unshared toilet, keeping the lesions covered as much as possible. Negative pressure or airborne precaution rooms are unnecessary unless an aerosolizing procedure is performed. Healthcare workers entering the room should wear N95 respirators, gowns, gloves, and eye protection. Transmission can occur through skin-to-skin contact and direct or indirect contact with body fluids, respiratory droplets, and suspended droplet nuclei.
“Also, make sure we have a mask on that patient,” Holdsworth said. “Make sure they’re in a private room with the door closed, cover those lesions whenever possible, and limit movement in and out of the room.”
MPXV patients can be infectious up to five days before onset of rash. “We know that they are infectious until there’s that new skin growth that’s coming up after those lesions have crusted,” Holdsworth said. “That duration of isolation is really important to understand.”
In terms of cleaning environmental surfaces, use a product on the EPA Q list with an “emerging viral pathogens claim,” Holdsworth said. “Follow the manufacturer’s instructions for use and, as always, make sure that you’re using something that is going to be easy to use and to be compliant during use,” she recommended. “You want to avoid things like dry dusting, sweeping, vacuuming. Using wet methods of cleaning is always going to be better for things like this.”
It is important to work closely with environmental services, ensuring they know how to use the product and use appropriate PPE when cleaning. “Everybody was a little scared in the beginning, just to clean these rooms,” Holdsworth said.
Indeed, healthy caution is warranted. A study at the Royal Free Hospital in London revealed MPXV patients repeatedly contaminate the environment in isolation rooms. The healthcare workers who entered the five patient rooms were vaccinated, but the level of contamination was concerning and has clear implications for other settings. The occupied rooms were cleaned every 12 hours, and terminally cleaned upon discharge. The samples were taken while the patients were hospitalized in the isolation rooms.
“We identified widespread surface contamination (56 of 60 samples were positive) in occupied patient rooms, on healthcare worker PPE after use, and in PPE doffing areas,” the authors reported. “Of 20 air samples taken, five (25%) were positive. Three (75%) of four air samples collected before and during a bedding change in one patient’s room were positive. Replication-competent virus was identified in two (50%) of four samples selected for viral isolation, including from air samples collected during bedding change.”12
The researchers also found MPXV DNA in the air collected at distances of greater than 5 feet from the patient’s bed and at a height of about six feet. “Monkeypox virus can be present in either aerosols or suspended skin particles or dust containing virus, and not only in large respiratory droplets that fall to the ground within 1-1.5 meters of an infected individual,” the authors concluded. “After the doffing of PPE by hospital staff, monkeypox virus DNA was detected on the floor of the anteroom where doffing took place. Monkeypox virus DNA was detected in one air sample taken in the corridor before doffing, but not in other air samples taken before and during doffing in anterooms used for doffing.”
With MPXV also detected on PPE, self-contamination during doffing may be a concern. “That’s the one that gives me nightmares,” Griffin said in a separate video briefing. “We’re super careful when we go in that room. We now move back into that anteroom where we don and doff our PPE and we think now we’re safe. We need to take [PPE] off in a careful way and put it in the bin.”13
Given the findings of the Royal Free Hospital study, Griffin said he would support vaccination of healthcare workers. In a related finding, the CDC issued an alert about untreated HIV patients developing severe monkeypox with hundreds of recurring lesions, certainly suggestive of a greater ability to contaminate the patient environment. While the outbreak began primarily in white men, cases in the United States now reflect disproportionate disease in Black and Hispanic men.14
“Concurrent to this shift, there are increasing numbers of severe cases,” said Agam Rao, MD, FIDSA, an epidemiologist with the CDC. “We have seen this in people who are severely immunocompromised, mostly MSM with newly diagnosed HIV that is advanced.”
Schaffner says there is no need for mass vaccinations of healthcare workers, “with the possible exception of some institutions in the country that are dealing with a large number of monkeypox patients. Perhaps in their emergency room or in a clinic they have set up. You could vaccinate a limited number of healthcare workers in those settings who have regular exposure to diagnosed or suspected monkeypox patients.”
REFERENCES
- World Health Organization. Multi-country outbreak of monkeypox, External situation report #4. Aug. 24, 2022.
- Toohey G. Nation’s first MPX case in healthcare worker exposed on the job is reported in L.A. County. Los Angeles Times. Sept. 15, 2022.
- Mendoza R, Petras JK, Jenkins P, et al. Monkeypox virus infection resulting from an occupational needlestick — Florida, 2022. MMWR Morb Mortal Wkly Rep 2022;71: 1348-1349.
- Centers for Disease Control and Prevention. Science brief: Detection and transmission of monkeypox virus. Updated Oct. 18, 2022.
- Bubach L, Casadia LVB, Polly M, et al. Monkeypox virus transmission to healthcare worker through needlestick injury, Brazil. Emerg Infect Dis 2022;28:2334-2336.
- Loeb M, Zando I, Orvidas MC, et al. Laboratory-acquired vaccinia infection. Can Commun Dis Rep 2003;29:134-136.
- Griffin D. TWiV 943: Clinical update with Dr. Daniel Griffin. Oct 8, 2022.
- Salvato RS, Ikeda MLR, Barcellos RB, et al. Healthcare workers occupational infection by monkeypox virus in Brazil. Emerg Infect Dis 2022 Sep 30;28. doi: 10.3201/eid2812.221343. [Online ahead of print].
- Le Pluart D, Ruyer-Thompson M, Ferré VM, et al. A healthcare-associated infection with monkeypox virus of a healthcare worker during the 2022 outbreak. Open Forum Infect Dis 2022;ofac520.
- Vaughan A, Aarons E, Astbury J, et al. Human-to-human transmission of monkeypox virus, United Kingdom, 2018. Emerg Infect Dis 2020;26: 782-785.
- SHEA & APIC Webinar: IPC strategies to reduce the risk for monkeypox outbreaks. Sept. 15, 2022.
- Gould S, Atkinson B, Onianwa O, et al. Air and surface sampling for monkeypox virus in a UK hospital: An observational study. Lancet Microbe 2022;S2666-5247(22)00257-9.
- Griffin D. TWiV 945: Clinical update with Dr. Daniel Griffin. Oct 15, 2022.
- Centers for Disease Control and Prevention. Severe manifestations of monkeypox among people who are immunocompromised due to HIV or other conditions. Sept. 29, 2022.
Although the overall risk of transmission is low, at least two healthcare workers have been occupationally infected with monkeypox virus (MPXV) in the United States. In an unusual case, two caregivers were infected by environmental fomites in the home of a patient in Brazil. Although rare, healthcare workers have been infected in previous outbreaks, and there likely are a fair number of unreported cases, given the stigma associated with MPXV.
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