RESEARCHES said they have identified a particularly severe form of mpox in people with advanced HIV which had a death rate of 15 percent among patients with AIDS.

Mpox, previously known as monkeypox, has long been endemic in several African countries but started spreading across the world last May, overwhelmingly affecting men who have sex with men.

More than 85,800 mpox cases, including 93 deaths, have since been reported across 110 countries, according to the World Health Organization.

Between 38-50 percent of the global mpox patients were also living with HIV, according to a new study published in the Lancet journal.

For the study, an international team of clinicians looked at 382 people with both HIV and mpox from 19 countries. That number included 27 people who died of the disease -- more than a quarter of the total toll during the global outbreak.

The clinicians identified a particularly extreme form of the disease, which they called "fulminant mpox", that affected people with advanced HIV or AIDS. Symptoms include massive, necrotising lesions on the skin, genitals, and sometimes even lungs.

The worst lesions and other symptoms were often seen in the patients with the lowest count of a type of white blood cell called CD4 cells.

HIV destroys CD4 cells, which are used as an indicator for the health of a patient's immune system.

A healthy person without HIV should have a CD4 count above 500 cells per cubic millimetre of blood.

People are diagnosed with AIDS when their CD4 count drops below 200, according to the US Centers for Disease Control and Prevention.

The severe form of mpox resulted in the death of 15 percent of patients with a CD4 count below 200, which included all 27 fatalities, the study said, emphasising that the sample size was small.

- 'Significant threat' -

People using antiretroviral therapy for their HIV often have a higher CD4 count than 200, suggesting that people most at risk of this severe form of mpox were unlikely to be receiving treatment.

The study's first author, Oriol Mitja of Spain's Germans Trias i Pujol University Hospital, said in a statement that health authorities should prioritise mpox vaccines for "people living with HIV, particularly in countries with low levels of diagnosis or without universal free access to antiretroviral treatment".

The researchers also called for this severe form of mpox to be added to the list of "AIDS-defining conditions" maintained by international public health agencies, which helps doctors identify which infections could be most dangerous for people living with HIV.

Matthew Hodson, executive director of UK-based charity NAM Aidsmap, said the study showed that despite a drop-off in mpox numbers across much of the globe, the disease remains a "significant threat" for people with advanced HIV.