Public health officials in England have announced that they have identified a new combined type of mpox in a person who recently traveled to Asia. No information has been released about the patient or his condition, but tests show the virus was a unique mixture of the two known types of mpox. Experts worry about what this means for the future spread of the virus.
Mpox virus
Mpox is related to the smallpox virus. The first symptoms are usually fever, headache, muscle aches and back pain. The infection can also cause the lymph nodes to become swollen and runny. A few days after these first symptoms, a rash or sores may appear on the face and then spread to other parts of the body.
Contact with these sores, or fluid from these sores left on clothing or sheets, can spread the disease. The mpox virus can also be spread through saliva and respiratory secretions (droplets in your breath). This means it can be passed on through kisses and extended intimate contact.
Types of Mpox
The researchers identified two types of the virus that are currently circulating in different parts of the world – Clade IIb and Clade Ib.
Clade IIb Mpox
Clade IIb mpox is the type of virus that spread rapidly worldwide in 2022. This outbreak infected 114,000 and caused 220 deaths worldwide. In the United States, the outbreak peaked in the summer of 2022 with 11,000 cases each month.
Although all mpox are of animal origin, Clade IIb mpox is known to pass from person to person. During this global epidemic, the virus spread primarily through sexual behavior between men who have sex with men. Clade IIb mpox is less severe. It usually causes mild symptoms and has a 1% mortality rate.
Clade Ib Mpox
Clade Ib mpox causes more severe disease and has a mortality rate of about 10%. This type of virus has been found in the Democratic Republic of Congo (DRC) for many years. Until recently, most cases passed directly from animals to humans through butchery and food. A new outbreak that started in the DPRK in 2023, however, is spreading from person to person. In some parts of Africa, this clade Ib virus is transmitted between family members through daily household activities. It is also spread in patient care areas when proper protective equipment is not available. In these areas many cases have been reported in children under 15 years of age. In other areas, sexual transmission is more common.
This is the first time clade I mpox has been sexually transmitted. Most cases are transmitted through heterosexual sex. Many cases have been seen in sex workers, truck drivers and other transient workers.
Between January and November 2025, over 48,000 cases of clade Ib mpox were reported in Central and East Africa. There have also been about 43 cases of this type of virus in other countries. Just under half of these cases involved people who had recently traveled to Africa, but 24 of them involved people who had not traveled.
World Health Organization officials now believe that Clade Ib mpox is spreading locally from person to person in Italy, Malaysia, the Netherlands, Portugal, Spain and the United States.
New Discovery in England
Genomic testing revealed that the patient in England has a type of mpox that includes Clade IIb and Clade Ib elements. This is referred to as a recombinant virus because it is formed by combining genetic materials. Experts say it’s no surprise they discovered this recombinant version because viruses are always evolving and both types of the virus are currently circulating.
The concern is that when viruses evolve it may be more difficult to prevent further spread. Dr. Boghuma Titanji, assistant professor of medicine at Emory University, he told the BBC that’s exactly what public health feared, “The more mpox we allow to circulate, the more opportunities the virus has to recombine and adapt, further cementing mpox as a human pathogen that won’t go away.”
There is an Mpox vaccine
There is a vaccine called JYNNEOS that can protect against mpox and smallpox infections. The vaccine is given in two doses, four weeks apart. Vaccination makes mpox less likely to occur and spread and helps reduce symptoms if a person is infected.
The Centers for Disease Control and Prevention (CDC) recommends the mpox vaccine for gay, bisexual, transgender, or other men who have sex with men who have (in the past six months) or expect to:
- One or more sexually transmitted infections
- More than one sexual partner
- Anonymous sexual or intimate contact
- Sex in a sex shop
- Sex in conjunction with a large public event in a geographic area where mpox transmission occurs
A vaccination campaign for people who met these criteria is one way the United States was able to stop the spread of mpox in 2022.
Anyone who meets the criteria and has not been vaccinated should do so as soon as possible. While this new recombinant type of mpox has not yet appeared in the United States, both clade IIb and clade Ib continue to spread here at low rates.
