Almost four in every 1,000 people in Nunavut may have a rare, incurable yet preventable virus called HTLV-1, a research report prepared for the Nunavut government has found.

Known as the Human T-Cell Lymphotropic Virus Type One, HTLV-1 is transmitted through sexual intercourse, breastfeeding, blood-to-blood contact and needle sharing.

In less than five per cent of those infected, it can cause cancer of the blood and disorders affecting the bladder, legs and nervous system.

The overall prevalance rate of the virus in the territory is still low at 3.7 for every 1,000 people.

But health officials are stressing the importance of safer sex practices and testing, said Dr. Geraldine Osborne, Nunavut's associate medical officer of health

"It's a concern as much as any sexually transmitted disease — as much as hepatitis C, hepatitis B, all these other viruses that are here that are preventable," Osborne told CBC News.

The study, which had its final report published in July, was prepared by the Public Health Agency of Canada and Nunavut Health and Social Services.

Detected in 2005

The virus was discovered in Nunavut when a person died in May 2005 of adult T-cell leukemia/lymphoma stemming from HTLV-1. Two more deaths were connected to that person, followed by an additional 14 infections through their contacts.

The infections dated back to 1994, the report said.

In the territory-wide study, researchers looked at 4,750 anonymous blood serum samples taken between May and October 2006 from Nunavut residents seeking routine medical care in the Baffin, Kivalliq and Kitikmeot regions.

That turned up another 31 people showing positive for HTLV-1, with one in the Kivalliq region and the remaining 30 in the Baffin region.

"We found that people over 45 had the highest rate of infection. Younger people didn't," Osborne said. "We think this is probably because they have had more prolonged sexual exposure."

Not much is known about the virus's prevalance in Canada, the report's authors said.

"HTLV-1 is not reportable at the national level or in most provinces/territories," the report read in part, although it did cite research from Canadian Blood Services in 1999-2000 that found a positive rate of 1.8 per 100,000 among blood donors.

However, the study noted that small infection clusters have been found in aboriginal communities in Alaska and British Columbia. In fact, the first cluster of HTLV-1 infection among Canadian aborignal populations was found along coastal B.C. in 1993.

"It's easier for that agent to be transmitted to other members of a population especially when that population is in a small close-knit community," said Dr. Mel Krajden, the director of hepatitis services and director of public health laboratory services with the B.C. Centre for Disease Control.

Most infected people may not know they have HTLV-1 unless they are among the five per cent who develop cancers or illnesses related to the virus. However, there is no effective cure for the virus.

Osborne said the Nunavut government will continue to offer free testing, counselling and advice to residents. Health officials will also continue with prenatal screening.

In 2005, Uqqummiut MLA James Arreak was upset when it was disclosed that the initial cases of HTLV-1 were found in his community of Clyde River.

In commenting on the latest report, health officials refused to identify any of the affected communities because of the stigma associated with the virus.