Mpox on the Move: What the Spread of Clade I Means for Healthcare Workers

On November 16, 2024, the California Department of Public Health (CDPH) confirmed the first known case of mpox clade I in the United States (U.S.).¹

Mpox has two main types: clade I and clade II. Clade II has been in the U.S. since 2022, but clade I has not been reported prior to the case identified last month. A large outbreak of clade I began in Sept 2023 in the DRC spreading to other African countries. Beginning in August 2024, there have been travel-related cases of clade I in countries like Germany, India, Kenya, Sweden, Thailand, Zimbabwe, and the UK. In the past, clade I was known to cause more severe illness and had higher death rates (between 3% and 11%).¹

However, new information shows that the current cases might not be as serious, with death rates dropping to about 1% when patients get good medical care.¹

In countries with strong healthcare systems, like the U.S., these rates are expected to be even lower. Clade I has a death rate of less than 1% both in and outside of Africa. The recent cases of clade I mpox outside Africa are all linked to clade I, and there have been no deaths reported. Most of these cases have shown mild symptoms.¹

What to Know About Mpox Symptoms and Risks

People with mpox often develop a rash that can appear on the hands, feet, chest, face, mouth, and near the genitals. The incubation period for mpox is between 3 to 17 days, during which a person may feel fine and show no symptoms.²

Currently, the overall risk of clade I mpox to the general population in the United States from the outbreak in Central and Eastern Africa is considered low.¹

Earlier this year, the CDC conducted a risk assessment using data from Africa, the ongoing clade II outbreak in the U.S., and historical information on clade I outbreaks in the Democratic Republic of the Congo (DRC) and other countries. Their simulations suggest that close-contact transmission within households is unlikely to lead to many cases of clade I mpox in the U.S.¹

In countries like Sweden, Thailand, Germany, and India, there has been no significant spread of the virus, and in the UK, any spread has been limited to close household contacts.¹

Infection Prevention Guidelines for Healthcare Settings

As Infection Prevention Fellow Doe Kley highlighted in her mpox update earlier this year, treatment and prevention measures are the same for both mpox clades.3 At-risk individuals should get vaccinated and seek medical attention if they experience symptoms of mpox. The virus spreads through direct contact with mpox lesions, respiratory secretions, and droplets, as well as contaminated materials like bedding and clothing.²

The following guidelines outline essential practices for managing patients with suspected or confirmed mpox infection:

Patient Management

• • Isolation: Place suspected or confirmed mpox patients in a single-person room. Ensure the door remains closed and provide a dedicated bathroom. Limit patient movement outside the room to essential medical purposes. If transport is necessary, the patient should wear a medical mask and cover any exposed lesions.

Infection Control Precautions

• • Personal Protective Equipment (PPE): Ensure that all healthcare personnel entering the patient’s room are equipped with:
  1. o Gown
  2. o Gloves
  3. o Eye protection (i.e., goggles or a face shield that covers the front and sides of the face)
  4. o NIOSH-approved particulate respirator equipped with N95 filters or higher
• • Perform frequent hand hygiene
• • Handle waste according to U.S. Department of Transportation regulations. Waste contaminated with mpox is classified as Category B infectious substances, except for specific laboratory cultures.
• • Avoid activities that could aerosolize viral particles, such as dry dusting, sweeping, or vacuuming. Use wet cleaning methods whenever possible.2
• • Use EPA-registered hospital-grade disinfectants with emerging viral pathogen claims. Products with Emerging Viral Pathogens claims may be found on EPA's List Q. The EPA has extended the use for List Q disinfectants for mpox through August 2026. Learn more here about navigating List Q as it relates to Mpox.
• • Soiled laundry (e.g., bedding, towels, personal clothing) should be handled with carefully and in accordance with recommended standard practices, avoiding contact with lesion material that may be present on the laundry. Never shake or handle soiled linens in a manner that may disperse infectious materials.

By adhering to these guidelines, you can help minimize the risk of mpox transmission in healthcare settings and protect both patients and staff. For more information, see our Mpox Pathogen Education Sheet.