Mpox is a historically rare infection caused by MPox Virus (MPV), first identified in 1958 in a colony of monkeys isolated for research in Denmark. The major reservoir is likely African rodents, but MPV can infect non-human primates as well as humans, with the first human cases reported in 1970.

MPV is in the same group of viruses (Orthopoxvirus) as the variola (smallpox) virus, but compared to smallpox, mpox is typically a milder disease and fatalities have been rare in the current worldwide outbreak. Although it may appear similar to chickenpox, neither mpox nor smallpox are in the same group of viruses as chickenpox (varicella, also known as Human alphaherpesvirus3) which has vaccines and treatment distinctly different from MPV.


MPV can be transmitted through close physical contact such as skin-to-skin (hugging, massaging, sexual contact); saliva (kissing) and respiratory secretions (coughing); and by contact with fabrics (clothing, bedding, towels) and surfaces that have been used by someone with active monkeypox. It can also be spread by handling infected animals, being bitten or scratched by an infected animals, or by preparing or eating meat from an infected animal. Once symptoms begin, an individual may remain infectious for 2-4 weeks.


Skin infections of MPV typically cause itchy and/or painful pimples or blisters at the contact site which may occur anywhere on the body, including inside the mouth and around the anus or vagina.

Other symptoms may include:

  • fever
  • chills
  • swollen lymph nodes
  • fatigue
  • muscle aches, backache, and headaches
  • respiratory symptoms including sore throat, nasal congestion, or cough.

Some individuals only have a rash; others may have flu-like symptoms before the rash appears 1-4 days later; and others may develop a rash then flu-like symptoms.

If someone is exposed to MPV, symptoms typically start with three weeks of exposure, and active infection typically lasts 2-4 weeks. For someone with a known exposure, a vaccine (Jynneos) can be administered (ideally within four days to prevent disease; up to 14 days after exposure will reduce symptom severity but may not prevent illness).

Current supplies of Jynneos are very limited so it must be authorized by, and obtained from, the Gallatin City County Health Department (GCCHD).

How to get help

If you have a new/unexplained rash or other symptoms and believe you may have been exposed to mpox, please seek medical evaluation as soon as possible. It is very important to avoid close contact with other people until a health care provider has evaluated you and ruled out mpox.

  • If you are an MSU student, please call 406-994-2311 to make a same-day appointment for evaluation.
  • If you are not a student, please see your provider or contact the Gallatin City County Health Department (406-582-3100) if you do not have a provider.

At your visit, a rash may be swabbed for samples and and sent to the Montana Public Health Laboratory for initial evaluation, followed by a confirmatory test for MPV by the Centers for Disease Control and Prevention. This process can take several days during which you should quarantine until results are back and shown to be negative for MPV.


For many individuals mpox may be a mild and self-limited disease, but it can be very serious for some people due to their overall health status, other illnesses, and/or immunocompromised status. It can cause permanent scarring, and rarely, it can be fatal. There is a medication (TPOXX, tecovirimat) which can be obtained by a clinican's request to GCCHD or the state public health office if you have risk factors for which treatment is recommended.


Many residents of the USA born in 1972 or earlier have been vaccinated against smallpox, a vaccination which provides significant protection from closely-related monkeypox. However, the CDC recommends that if it has been more than three years since smallpox vaccination, an individual is considered susceptible to mpox.

Therefore, other than those with recent vaccination (primarily U.S. military staff and/or research laboratory staff) most individuals will be considered susceptible and need to follow quarantine, isolation, vaccination and treatment guidelines. Public health authorities are recommending vaccination with Jynneos for those at high risk for exposure to mpox, but Montana State and Gallatin County public health officials are still working on how to establish priorities for the very limited number of doses of Jynneos available. Please check their sites frequently if you are interested in becoming vaccinated against mpox.

Currently, behavioral approaches to reducing risk of contact with an infected person are the most effective measure, especially risk reduction with intimate contact. Please see this CDC website for tips on how to be safer during sex and in close gatherings.

Websites with more detailed information about mpox

Last updated 02-16-22