Doctors were puzzled when an outbreak of a little-known virus was reported among a group of 10 people living in London. They were non-drug users, had never received a blood transfusion, and showed no other identifiable risk factors for bloodborne viruses

The case was somewhat of a mystery, but then one of the doctors noticed unusual scars across one of the patient’s back. This led them to identify a common thread between all of the infected men: they were all Muslims who had taken part in a bloody blade-sharing religious ritual.

Reporting in the journal Emerging Infectious Diseases, scientists from Imperial College London and St Mary’s Hospital in London documented the spread of Human T-cell lymphotropic virus type 1 (HTLV-1) by self-flagellation.

All of the men appeared to have acquired the blood-borne virus separately through a religious ritual that involves inflicting wounds on oneself using rods or whipping blades as an expression of faith in some Shia Islamic and Catholic communities.

One of the men even recalled the blades being soaked in a bucket of an antiseptic solution along with the blades used by other men. While you might assume this would be enough to sterilize the equipment, the virus was still active and was passed on to other men who proceeded to open wounds with the blade

“It is likely that either sharing blood-stained blades, reusing personal equipment after inadequate cleaning with a shared disinfectant, contact of infected blood with open wounds, or contact with infected medical equipment resulted in HTLV-1 transmission,” the study authors write.

HTLV-1 is actually a distant relative of HIV. The vast majority of people with HTLV-1 never display any symptoms, however, between 2 to 5 percent of infected people will develop a cancer of the T-cells, a type of white blood cell. Less than 2 percent of people with HTLV-1 will develop HAM/TSP, a chronic disease of the nervous system. Unfortunately, there is no known cure yet.

The most common cause of transmission is breastfeeding, sharing needles, and sexual transmission. The doctors on the case now argue that self-flagellation should be added to the list of ways to spread a dangerous viral blood infection. They note that one of the men also had contracted hepatitis C, a blood-borne virus that can eventually result in life-threatening damage to the liver. Although fairly common in some parts of the world, this religious ritual has never been officially described as a risk factor, until now. 

"Our message is not 'Don't do it.' Our message is 'If you do it, don't share equipment," Dr Divya Dhasmana of St. Mary's Hospital in London told The Associated Press.