Soldiers who served in Iraq will not be allowed to give blood for a year after returning home, because of a rare skin parasite that has infected 22 members of the military, federal health officials said Thursday.

The disease, called leishmaniasis (search), is spread by sand flies and can cause itchy skin lesions. A more serious form, so far caught by none of the soldiers, can cause death. Since August of last year, 18 members of the military have caught the parasite in Iraq, plus two each in Kuwait and Afghanistan.

The Pentagon estimated the potential loss of blood donors at more than 12,000 people. But many of the servicemen would not have been allowed to donate anyway because they were in areas where malaria (search) is endemic. Donation bans were already in place for soldiers returning from Kuwait and Afghanistan.

Those stricken by the parasite came from the Army, the Air Force and the Marine Corps and included active, reserve and National Guard members. Most were serving in northern or central Iraq. They were treated with intravenous drugs at Walter Reed Army Medical Center (search) in Washington.

The parasite is common in parts of central and southern Asia and infects more than 1.5 million people a year. The small, circular lesions are painless but can leave scars.

"They're self-healing, but they can take months to heal on their own," said Dr. Charles Oster at Walter Reed, who treats soldiers with leishmaniasis. "It's not something people need to freak out about it, but it should be treated."

The Centers for Disease Control and Prevention (search) in Atlanta reported that the parasites can be spread through blood transfusions, although there are no known cases of that happening in the United States.

As a precaution, returning servicemen will be barred from donating blood for a year. The Defense Department and the nation's largest association of blood banks ordered the measure.

A similar order was issued after the Gulf War in 1990-91, when 12 members of the military caught the leishmaniasis parasite.