MPOX (formerly known as monkeypox) is a disease caused by infection with a virus. This virus is part of the same family as the virus that causes smallpox. People with mpox often get a rash, along with other symptoms. The rash will go through several stages, including scabs, before healing. Mpox is not related to chickenpox.

Mpox is a zoonotic disease, meaning it can be spread between animals and people. It is endemic, or found regularly, in parts of Central and West Africa. The first human case of mpox was recorded in 1970, in what is now the Democratic Republic of the Congo. In 2022, mpox spread around the world. Before that, cases of mpox in other places were rare and usually linked to travel or to animals being imported from regions where mpox is endemic.

The mean incubation time is 7 days with initial symptoms of a flu-like illness with fever, malaise, headache, and fatigue often accompanied by swelling of lymph nodes.

Shortly after a rash can appear with lesions before scabbing. The lesions are the infectious component and usually occur at the site of contact eg throat/mouth for receptive oral sex. Most persons have fewer than 10 lesions and almost 10% present with only a single genital lesion. Hospitalisation is uncommon and the major reason for admission is usually for pain control, typically for anorectal or oral pain. Complications can occur if there is a secondary infection of the lesion. The symptoms usually resolve by themselves within a few weeks, but you are considered infectious while you have symptoms.

MPOX is transmitted through intimate skin-to-skin contact with the skin lesions. Contaminated objects such as bedding, clothing, or sex toys can also carry the virus but have much lower risk.

It is not classified as a sexually transmitted infection, but sex can make its transmission easy and is considered to be a common driver of transmission in the current outbreaks.

A recent study (The Lancet), found that MPOX transmits most efficiently when lesions come into contact with mucus membranes in the anus, rectum, genitals, mouth and throat. MPOX is more likely to transmit through oral or anal sex than through contact with external skin, which would need some sort of defect, such as a wound, to allow entry of the virus.

For most patients, treatment for MPOX is mainly supportive, such as pain medication. Most people with MPOX recover fully within 2 to 4 weeks without the need for medical treatment.

There are no treatments specifically for MPOX virus infections. However, MPOX and smallpox viruses are genetically similar, which means that antiviral drugs and vaccines developed to protect against smallpox may be used to prevent and treat MPOX virus infections. New Zealand has secured 504 doses of Tecovirimat, also called Tpoxx which is reserved for severe cases who need to be hospitalised.

Tecovirimat is an antiviral medication approved by the FDA for treatment of smallpox in adults and children but not for MPOX because data are not available on the effectiveness of Tecovirimat in treating MPOX in humans.

The Jynneos vaccine is a 2 dose vaccine that is being used for MPOX. This requires two shots 4 weeks apart with maximum effectiveness attained 2 weeks after the second shot. Jynneos has been specifically evaluated in people with HIV and shown to be safe.

If you have been vaccinated for smallpox in the past this shows limited protection as the efficacy wanes over time and cases have still occurred. Research from the Spanish outbreak showed 18% of cases were amongst people that had previously been vaccinated as children.