At least 20 people have been diagnosed with anthrax since the infection was detected last week, governor of Yamalo-Nenetsky region Dmitry Kobylkin said on Tuesday. A 12-year-old boy has died of the disease.

All of the infected are nomads indigenous to the remote Siberian region Yamal, some 2,000 kilometers (1,250 miles) northeast of Moscow. The authorities moved at least 90 people to a hospital in the regional capital, Salekhard, for additional tests. Half of the group children.

The outbreak also killed 2,300 reindeer, which the locals use as farm animals. The patients included a family that "ate reindeer meat raw and drank the blood," governor's spokeswoman Natalya Khlopunova said, adding that "the nomads do have this custom."

No 'epidemic'

Scientists believe the outbreak could have been caused by a recent heat wave that saw temperatures reaching 35 degrees Celsius (95 degrees Fahrenheit) in the subarctic region. The heat likely thawed a long-frozen reindeer carcass that had been trapped in permafrost.

The last recorded anthrax outbreak in the region was in 1941.

On Tuesday, governor Kobylkin said all reindeer in the area have now been vaccinated and the deaths have stopped.

"There is no epidemic in Yamal," Kobylkin said. "Only a small area was quarantined. The overwhelming majority of the nomads from the quarantined territory are healthy, but Yamal doctors are providing them with preventive treatment."

The government also sent dozens of military experts to analyze the area and destroy the diseased animals.

Anthrax spreads through spores in the soil, infecting livestock through grazing. It cannot spread directly between animals or humans, but humans can become ill after handling diseased animals or eating infected meat. The infection can also be cured by antibiotics.

dj/kms (dpa, AP, AFP, Interfax)