Overview of Outbreak
Photo Credit: Baltimore City Health Department
Surge in International Cases: Since November 2023, the Democratic Republic of Congo (DRC) has seen a significant increase in mpox clade 1, with continued significant spread to neighboring countries (22 African Union members as of February 2025). Imported cases of clade 1 have been seen in numerous countries, including within the EU, UK, and North America. The first case of clade I mpox in the United States was detected in November 2024; there have now four cases of Clade 1b reported (CA, GA, NH, NY). All four individuals traveled from areas experiencing clade 1 mpox transmission.
Transmission: Mpox spreads through close or intimate contact with a person with mpox, direct contact with an infected animal, or contact with contaminated objects.
Geographic Spread: Clade 1a has spread beyond the DRC to neighboring Clade 1b has spread more widely to several other African countries. Clade 1b cases have also been seen in travelers to Sweden and Thailand.
Spread to US: There have been four reported cases of clade 1 mpox in the United States in people who had recently traveled to affected areas in Central and Eastern Africa as off February 2025.
Clinical Concerns: The case fatality rate of the current Clade 1 outbreak is just over 3%, which is much higher than the recent worldwide Clade 2 outbreak (<0.1%). Recent studies that could perhaps be linked that discuss epidemiology of this outbreak:
Infection Control: See CDC guidance for general and pediatric-specific.
NEJM Jan. 2025: Evolving Epidemiology of Mpox in Africa 2024
Transmission
Common routes of transmission to children
- Zoonotic Transmission: Traditional route via infected animals, which would only be expected to occur in areas outside of the US where mpox is commonly seen.
- Direct Contact: Skin-to-skin exposure to lesions or body fluids, which is more likely to occur among household contacts. Adolescents are at risk from direct contact occurring during sexual activity with someone with mpox.
Uncommon routes of transmission to children
- Fomites: Contact with contaminated objects or surfaces.
- Respiratory Droplets: Possible transmission through close, prolonged exposure.
- Nosocomial Transmission: Rare but reported in healthcare workers. Personal protective equipment is effective.
- Vertical Transmission: Documented but limited data.
- Breastfeeding: Unconfirmed, but caution is advised due to risk of close contact.
Symptoms and Complications
- Incubation period: 3-17 Illness lasts 2-4 weeks.
- Classic Symptoms: Characteristic rash often preceded by fever, chills, myalgias, malaise, headaches, lymphadenopathy.
- Atypical Presentations (Clade 2): Limited rash spread with more mild or absence of systemic symptoms.
- Complications: Potential for abscess formation, secondary bacterial infections, airway disease (e.g., pneumonia, epiglottitis), encephalitis, corneal infection, and gastrointestinal issues.
Diagnosis
- Testing: PCR testing is recommended, with samples taken from at least two.
Contact state/local health departments before specimen collection. Commercial laboratory testing is available. Results are typically available within a few days.
- Differential Diagnosis: Consider chickenpox, molluscum contagiosum, measles, rickettsial infections, HSV, bacterial skin infections (e.g., impetigo), cutaneous anthrax, scabies, syphilis, or cutaneous drug reactions.
Treatment
CDC: Treatment
- Supportive Care: Includes hydration, complication management, and pain relief.
- Information for skin, lesion and wound care is available through the American Academy of Dermatology Association.
- Tecovirimat: Trials of tecovirimat (STOMP and PALM007) demonstrated safety, but lack of efficacy for treatment of mpox. However, tecovirimat from the Strategic National Stockpile (SNS) will remain available for treatment of mpox in patients who have or are at high risk for severe illness as defined in the CDC-held expanded access IND protocol. Those at high risk include people who:
- Are severely immunocompromised patients (e.g., those with HIV with CD4 <200, or solid organ transplant recipients)
- Have atopic dermatitis and other conditions affecting skin integrity
- Are children
- Are pregnant or breastfeeding
Vaccination
CDC: Vaccination
- JYNNEOS Vaccine: Administered to high-risk individuals in two subcutaneous doses, 28 days Intradermal administration is not recommended for those under 18.
- Post-Exposure Prophylaxis: Ideally given within 4-14 days post-exposure. Available under EUA for children and adolescents younger than 18.
- Vaccinia immune globulin intravenous should be considered for children younger than 6 months.
- Pre-Exposure Prophylaxis: Recommended for at-risk adolescents, including those younger than 18 years with the risk factors described by the CDC.
- Countries experiencing person-to-person clade I mpox spread. CDC has vaccination recommendations for people traveling to countries with clade I outbreaks. As of February 14, 2025, these countries include Burundi, Central African Republic, Democratic Republic of the Congo, Kenya, Republic of the Congo, Rwanda, Uganda, and Zambia (*NEW)
Active Items for Providers
- Stay up-to-date with current situation to know risk of mpox in travelers and in the community in the US.
- Work with your hospital to understand steps to obtain tecovirimat by EA-IND if needed for a pediatric patient.
- Promote vaccine use in high-risk adolescents age 18 years and up.
Additional Resources/References
- World Health Organization (WHO). “Mpox (Monkeypox) Outbreak – Democratic Republic of ” Available at: WHO Mpox Updates
- Centers for Disease Control and Prevention (CDC). “Clinical Guidance for Mpox Treatment and ” Available at: CDC Mpox Guidelines
- European Centre for Disease Prevention and Control (ECDC). “Mpox (Monkeypox): Epidemiological ” Available at: ECDC Mpox Report
- National Emerging Special Pathogens Training and Education Center (NETEC).“Mpox (Monkeypox) Laboratory Resources.” Available at: NETEC Laboratory Resources for Mpox
- Food and Drug Administration (FDA). “Emergency Use Authorization (EUA) for JYNNEOS Vaccine.” Available at: FDA JYNNEOS Vaccine
- Tecovirimat “Tecovirimat (TPOXX): Usage and Guidelines.” Available at: CDC Tecovirimat Information