Mpox

Overview

Mpox is an infectious disease caused by the monkeypox virus (MPXV), which is in the same family of viruses that causes smallpox. Known primarily for its characteristic rash with lesions that scab over, the mpox rash can occur on hands (palms), feet (soles), chest, face, and on/near the genitals or anus. Mpox has routinely occurred in countries of central and west Africa since it was first described in 1950, with limited travel-related spread. There are two distinct clades of MPXV: clade I (typically in central Africa) and clade II (seen more commonly in west Africa). Each clade also has two subclades (Ia, Ib, IIa, IIb).

In May 2022, a large-scale, international outbreak of clade IIb mpox led the World Health Organization (WHO) to declare a Public Health Emergency of International Concern (PHEIC). It spread rapidly around the globe, almost exclusively through sexual networks of men who have sex with men. In May 2023, the PHEIC declaration was ended, although clade IIb mpox continues to circulate globally at a lower level.

Until 2024, clade I mpox had remained limited to central Africa. In Aug 2024, the WHO declared a new PHEIC to clade Ib mpox due to unprecedented spread both within the Democratic Republic of Congo (DRC) and into surrounding countries. Unlike clade II mpox, clade I has demonstrated spread through familial networks and among healthcare workers, as well through sexual networks. While the PHEIC was lifted in Sept 2025, clade Ib mpox has also continued to spread. Most cases are still in the Central African region, although very low levels of clade I mpox have also appeared globally, mostly associated with travel to affected areas or epidemiologically linked to these travelers.

Mpox is a zoonotic disease, with cases often found close to tropical rainforests where there are animals that carry the virus. The disease can spread among humans through contact with bodily fluids, lesions on the skin or on internal mucosal surfaces, such as in the mouth or throat, respiratory droplets, and contaminated objects. The 2022 worldwide clade II outbreak resulted in tens of thousands of cases in the U.S., and DoD reported over a thousand cases among active-duty military members.

Importantly, all known clades of mpox are spread through close or intimate contact with a person with mpox, direct contact with an infected animal or contact with contaminated objects (e.g. clothes or linens used by an infected person).

The public health control measures established in 2022 for mpox control remain effective. The JYNNEOS vaccine, available and recommended for personnel at high risk, is also effective. NMCFHPC modeling of shipboard spread, along with observation of recent shipboard cases, suggests the threat of mpox to Navy operations remains low; spread on a ship or operational unit is anticipated to be limited, and large outbreaks are not expected.

Web Resources

Clinicians

Clinical guidance, including recognition, management and clinical isolation guidance are generally covered by CDC: CDC Clinical Overview
Clinical management for Fleet medical personnel can be found in the NMCFHPC Fleet Mpox Medical Guidance 15Oct24 file: Mpox Medical Guidance
Quick Reference Sheet for Fleet medical personnel: NMCFHPC Fleet Mpox Case Quick Reference 10Oct24 file: NMCFHPC Fleet Mpox Case Quick Reference
Clinical guidance for MTFs can be found in the DHA Mpox Guidance Update_5 Sep2024 file: DHA Mpox Guidance Update 5

Currently, neither mpox testing nor treatment are readily available in a forward deployed operational setting. Units should identify suspected cases, isolate them, and move them for care at an MTF when operationally feasible

Preventive Medicine

Prevention

General risk reduction strategies:

Avoid close contact with people who are sick with signs and symptoms of mpox, including those with skin or genital lesions.   
Avoid contact with wild animals (alive or dead) especially small mammals, including rodents (rats, squirrels) and non-human primates (monkeys, apes).   
Avoid contact with contaminated materials used by people who are sick (such as clothing, bedding, or materials used in healthcare settings) or that came into contact with wild animals.   
Avoid eating or preparing meat from wild animals (bushmeat) or using products (creams, lotions, powders) derived from wild animals.

The clade II mpox outbreak that began in 2022 was primarily transmitted through sexual networks, and there is evidence that a large proportion of clade Ib mpox is also being spread through sexual contact. More information about sexual transmission may be found at:

NMCFHPC Mpox and Sexual Health Fact Sheet

CDC recommends two doses of the JYNNEOS vaccine, administered 28 days apart, for populations who, based on their occupational, sexual and travel history are at higher risk for exposure to mpox virus. Mpox vaccine is NOT recommended for the general public. Pre-travel mpox immunizations may be considered for travelers/deployers to areas experiencing transmission who have an increased risk of personal or occupational exposure. This may include animal handlers, veterinary personnel with animal contact, laboratory personnel, security personnel, medical personnel, civil engineers, special operations, and civil affairs personnel. Additionally, immunization should be considered for travelers to areas experiencing transmission who anticipate sexual contact with local populations or close physical contact with animals. DoD information on the JYNNEOS vaccine can be found here: DHA-IHD Mpox Vaccine Info Paper (*CAC Required*)

Isolation

In operational environments, patients who are suspected mpox cases (see CDC mpox case definitions below) should be isolated and treated as probable or confirmed cases. When operationally feasible, isolate patients ashore. If a rash has not developed 5 days after prodromal symptoms, alternate diagnoses should be considered. Clinicians should seek assistance from the nearest MTF or cognizant NEPMU for support with isolation guidance as well as follow-on testing, prophylaxis, and treatment indications.

Home isolation is most often recommended during recovery from mpox, and should be continued until symptoms resolve, the scabs have fallen off, and a fresh layer of intact skin has formed. This could take 2-4 weeks. CDC Home isolation recommendations

Contact Tracing

As soon as a suspected case is identified (using current mpox case definition for a suspected case), contact tracing should be initiated.  This is particularly relevant for shipboard populations where lab testing may not be as easily accessible.  Mpox case definitions (including a case definition for clade I) are available from CDC:  Mpox Case Definitions | Mpox | CDC

Conduct a public health interview to elicit names and contact information for all high and intermediate risk contacts going back 4 days prior to illness onset and ending with the resolution of the illness (or the time of the interview if illness is not resolved). The CDC recommends using your state or county/local health department reporting form or CDC’s Case Investigation Tool for collecting information during patient interviews for probable and confirmed cases. The CDC Short Case Report Form may also be used.

Management of Contacts

Exposure in both community and healthcare settings should be assessed to determine the risk of transmission and if post-exposure prophylaxis (PEP) is indicated. Assess exposure risk based on CDC’s risk assessment standards:

For community exposures, CDC risk assessment and recommendations can be found at Monitoring and Risk Assessment for Persons Exposed in the Community | Mpox | Poxvirus | CDC.
For healthcare setting exposures, CDC risk assessment and recommendations for healthcare settings can be found at Infection Control: Healthcare Settings | Mpox | Poxvirus | CDC.

Mpox vaccine is recommended as PEP to contacts with higher risk exposure to monkeypox virus and may be recommended for intermediate risk exposures. PEP vaccine is most effective if received within 4 days of exposure and should be administered as soon as possible up to 14 days after exposure. Mpox vaccine is also recommended for people with ongoing risk of mpox exposure. More information on Mpox vaccine indications can be found here: CDC Mpox Vaccination Guidelines

All contacts, regardless of level of exposure risk or vaccination status, should monitor for symptoms for 21 days after their last exposure. Symptom monitoring can be active (e.g., medical evaluates an exposed individual daily) or passive (e.g., exposed individual self-monitors and reports symptoms to preidentified medical contact). Monitoring should include assessment of temperature and skin examination for rash, including inside the mouth and in the genital and anal areas. Examination can be performed by the person themselves, a caregiver, or a healthcare provider.

Asymptomatic close contacts may return to work per Commander’s operational needs and risk tolerance.

Cleaning, Disinfection, and Laundry

Use disinfectant products that are registered by the EPA for Emerging Viral Pathogens, tier 1 (https://www.epa.gov/pesticide-registration/disinfectants-emerging-viral-pathogens-evps-list-q). Follow CDC guidance for home infection control and laundry handling CDC Guidance for Cleaning and Disinfection, including proper use of personal protective equipment.

Routinely clean and disinfect commonly touched surfaces and items such as counters, tables/furniture, handrails, and light switches. Persons with mpox should use separate bathrooms and toilets if possible; surfaces should be cleaned and disinfected after use in shared bathroom/toilet spaces. Infected persons should do their own laundry if possible. If Navy issued mesh laundry bags are used, bags should be washed along with clothing/bedding.

Fact Sheets

⛓ Links

Surveillance and Reporting

Routine surveillance is one of the best ways to identify disease clusters or outbreaks. Monitor disease and injury surveillance for clusters of rashes, and investigate increased cases of rash for infectious causes. If an mpox case is suspected, enhance surveillance to identify other potential mpox cases through clinical record queries for other local patients presenting with rash.
Although mpox is currently not on the Armed Forces Reportable Medical Events list, the CDC recommends reporting of probable and confirmed cases within 24 hours to enable timely implementation of prevention measures and contact tracing. Mpox is a reportable event in DRSi.
Mpox CDC case definitions are updated here: Mpox Case Definitions | Mpox | CDC

Suspected, probable, or confirmed cases should be evaluated by local Preventive Medicine personnel, who can assist with reporting through DRSi and to local/state public health authorities. Cases in operational or training settings should also be referred to the cognizant Navy Environmental and Preventive Medicine Unit (NEPMU).
Additional information on DRSi can be found at https://www.med.navy.mil/Navy-Marine-Corps-Public-Health-Center/Preventive-Medicine/Program-and-Policy-Support/Disease-Surveillance/
Operational units without adequate internet access can seek assistance with reporting from the nearest Navy Environmental Preventive Medicine Unit: https://www.med.navy.mil/Navy-Marine-Corps-Public-Health-Center/Field-Activities/.

Consultation

NEPMUs can provide consultative assistance with contact tracing, mitigation, isolation measures, education, reporting and messaging. Contact information is available at NMCFHPC Field Activities

MTF infectious disease specialists and the DHA Immunization Healthcare Division (through a 24/7 answering service at 877-438-8222) can assist with clinical consultation, vaccine access, and treatment.

DoD Epidemiology and Selected Publications

McGee, Sasha A., Jamaal A. Russell, and Maura Metcalf-Kelly. "Enhanced mpox outbreak case detection among MHS beneficiaries through use of ESSENCE." MSMR 30.5 (2023): 4-8.

Metcalf-Kelly, Maura, Matthew Garrison, and Ralph Stidham. "Characteristics of Mpox Cases Diagnosed in Military Health System Beneficiaries, May 2022–April 2024." Medical Surveillance Monthly Report 31.9 (2024): 7.

Titanji BK, Eick-Cost A, Partan ES, Epstein L, Wells N, Stahlman SL, Devineni P, Munyoki B, Pyarajan S, Balajee A, Smith J, Woods CW, Holodniy M, Davey VJ, Bonomo RA, Young-Xu Y, Marconi VC. Effectiveness of Smallpox Vaccination to Prevent Mpox in Military Personnel. NEJM 2023 Sept 21; 389(12): 1147-1148

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