Mpox: What nurses need to know

What is mpox (monkeypox)?

Human mpox is a zoonotic viral disease caused by the mpox virus, which belongs to the same family of viruses as smallpox. The first human case was identified in 1970.¹ Mpox is considered a re-emerging disease that has caused multiple localized outbreaks since 2017. In 2022, mpox began spreading rapidly in many countries that have not historically had cases. While cases have declined in some countries since then, the current mpox outbreak in the United States is not over.

On November 28, 2022, the World Health Organization officially renamed the monkeypox virus disease as mpox² in an effort to avoid racist, stigmatizing and othering of certain populations.

About the virus:

• Incubation period ranges from 5 to 21 days.
• Illness typically lasts for 2 to 4 weeks.
• Infectious period lasts until all scabs or crusts have fallen off, though may extend longer for some individuals.
• Transmission modes include airborne/aerosol, droplet, and contact.

What are the symptoms and complications of mpox?

Mpox can have wide-ranging clinical manifestations, including:

• Rash or skin lesion on the face, inside of the mouth, hands, feet, chest, and other parts of the body. Skin lesions may vary in size and range from a few to several thousand and may look like pimples or blisters. NOTE: many people in the current outbreak present with only one single lesion.³
• Fever
• Headache
• Chills
• Cough  
• Sore throat
• Exhaustion
• Swollen lymph nodes
• Myalgia (muscle and backaches)
• Asthenia (profound weakness)

While mpox is usually self-limiting and typically spontaneously resolves within a few weeks, some individuals (e.g., children, pregnant women, and immunocompromised persons) may experience serious health complications including:⁴

• Sepsis
• Encephalitis
• Secondary infections
• Bronchopneumonia  
• Abscess and airway obstruction
• Corneal infection and vision loss
• Myocarditis
• Acute kidney injury

How is mpox transmitted?

Human-to-human mpox transmission, including nosocomial and household transmission, has been well documented. Mpox can be transmitted through close contact with an infected animal (e.g., rodents) or human, or fomites (e.g., contaminated clothing or bedding) and through infectious aerosols emitted by patients in the infectious period. The virus can enter the body through the respiratory tract, broken skin (even if not visible, via contact with bodily fluids), or mucous membranes (eyes, nose, or mouth).

Prolonged upper respiratory tract viral shedding from patients with mpox has been documented even after skin lesion resolution.⁵ Transmission from viral shedding may also begin prior to the onset of rash.⁶

Asymptomatic cases have been documented both prior to and during the 2022 outbreak.⁷ The World Health Organization reported that nearly 10 percent of cases detected were asymptomatic.⁸

What protections do nurses and other health care workers need to care for a patient with confirmed or suspected mpox?

Mpox requires airborne, contact, and droplet precautions.

• Suspected or confirmed mpox cases must immediately be placed in airborne infection isolation rooms (also called a negative pressure room).
• Nurses and other health care workers should have the highest level of personal protective equipment (PPE) when caring for patients with suspected or confirmed mpox.
  • Highest level of PPE for mpox: powered air-purifying respirator (PAPR), coveralls impermeable to viral penetration that incorporate head and shoe covering, and gloves.
  • Minimum level of PPE for mpox: fit-tested, single-use N95 respirator, isolation gown, goggles, and gloves.
• Infectious mpox virus can be resuspended in aerosols when contaminated objects (e.g., bedding, clothing, or PPE) are shaken or moved. Mpox virus particles have been found to retain infectivity in aerosols from 18 to 90 hours.⁹
  • Strict procedures for donning and doffing PPE upon entry and exit from the patient’s isolation room must be followed.
  • Cleaning protocols must be observed after each doffing for PPE designed to be reused (e.g., PAPRs).
  • Tight control of patient transport and health care worker movement through the facility must also be implemented to prevent transmission or contamination of mpox.

NOTE: For nurses who work in California, the Cal/OSHA Aerosol Transmissible Diseases Standard requires that health care facilities implement airborne precautions for mpox cases, including:

• Placement of patients with suspected or confirmed mpox in a negative pressure room.
• Use of an N95 or more protective respirator, in combination with other required PPE (gown, gloves, eye protection) for any encounter with a patient with suspected or confirmed mpox.
• Use of a PAPR for aerosol-generating procedures performed on patients with suspected or confirmed mpox.

1. Ježek et al., “Human Monkeypox: Clinical Features of 282 Patients,” The Journal of Infectious Diseases, August 1987
2. CDC Changes Monkeypox Terminology to Mpox, November 28, 2022
3. Thornhill, J.P., S. Barkati, et al., “Monkeypox Virus Infection in Humans across 16 Countries — April–June 2022,” NEJM, July 21, 2022
4. World Health Organization, “Monkeypox,” last updated May 2022
5. Adler et al., “Clinical features and management of human monkeypox: a retrospective observational study in the UK,” The Lancet Infectious Diseases, May 2022
6. Nolen et al., “Extended Human-to-Human Transmission during a Monkeypox Outbreak in the Democratic Republic of the Congo,” Emerging Infectious Diseases, June 2016
7. Hammurland et al., “Multiple diagnostic techniques identify previously vaccinated individuals with protective immunity against monkeypox,” Nature Medicine, August 2005
8. World Health Organization, “Multi-country outbreak of monkeypox, External situation report #2 – 25 July 2022”
9. Verreault, Daniel et al. “Susceptibility of monkeypox virus aerosol suspensions in a rotating chamber,” Journal of Virological Methods vol. 187,2 (2013): 333-7. doi:10.1016/
j.jviromet.2012.10.009.