A 40-year-old German man with severe monkeypox has tested positive for HIV after his condition was initially dismissed as sunburn.

The unidentified patient approached doctors after a painful red spot appeared on his nose, but the medics assumed it was a case of sunburn. However, his condition soon deteriorated as he developed a lesion on the nose and it began to rot.

The patient was diagnosed with monkeypox after he developed pus-filled sores all over his body, which were severe around his penis and mouth, NY Post reported citing Medical Journal Infection.

The man, who was hospitalized, was then administered antivirals to combat the virus. During further tests, he was diagnosed with sexually transmitted diseases including syphilis and HIV.

The man was not previously diagnosed with sexually transmitted diseases and by the time they were detected, syphilis had already spread to multiple organs, reports said. The tests also indicated the HIV infection had developed into AIDS.

The medics administered the man antiretroviral pills twice a day to reduce the amount of HIV infection in his bloodstream. To treat the syphilis infection, the patient was given ceftriaxone through an IV drip for ten days, 7 News.com.au reported.

Although the antiviral drugs helped dry out the sores from monkeypox, the condition of his nose only partially improved as it had already started to die and had turned black.

According to the doctors, the man's monkeypox infection became severe as HIV left him immunocompromised and susceptible to necrosis.

Necrosis is the death of body tissue, which occurs when too little blood flows to the area. The irreversible condition is often caused by injury, radiation or chemicals.

"Most cases of (monkeypox) infection so far have been reported as mild, and controlled HIV infection does not appear to be a risk factor for severe courses. However, this case illustrates the potential severity of (monkeypox) infection in the setting of severe immunosuppression and untreated HIV infection," doctors said in the medical journal.

The medical journal did not mention the current condition of the patient or the details of his recovery.