Washington ? The number of troops with new cases of post-traumatic stress disorder jumped by roughly 50 percent in 2007 amid the military buildup in Iraq and increased violence there and in Afghanistan.

Records show roughly 40,000 troops have been diagnosed with the illness, also known as PTSD, since 2003. Officials believe many more are likely keeping their illness a secret.

“I don’t think right now we … have good numbers,” Army Surgeon General Eric Schoomaker said Tuesday.

Defense officials had not previously disclosed the number of PTSD cases from Iraq and Afghanistan.

Army statistics showed there were nearly 14,000 newly diagnosed cases across the services in 2007 compared with more than 9,500 new cases the previous year and 1,632 in 2003.

Schoomaker attributed the big rise partly to the fact that officials started an electronic record system in 2004 that captures more information, and to the fact that as time goes on the people keeping records are more knowledgeable about the illness.

He also blamed increased exposure of troops to combat in 2007, including President Bush’s troop buildup and the fact that 2007 was the most violent year in both conflicts.

More troops also were serving their second, third or fourth tours of duty – a factor mental health experts say dramatically increases stress. And to supply enough forces for the buildup, officials extended tours to 15 months from 12, another emotional strain.

Officials have been encouraging troops to get help even if it means they go to civilian therapists and don’t report it to the military.

“We’re trying very hard to encourage soldiers and families to seek care and to not have them feel in any way, shape or form that we’re looking over their shoulder or that we’re invading their privacy,” Schoomaker said.