Kenneth Allen, a 70-year-old truck driver from Georgia whose convoy was ambushed in Iraq, says he endures mood swings, jittery nerves and is often awake all night. And Nathaniel Anderson, a Texan whose truck was hit by rockets while hauling jet fuel, lost a contractor friend to suicide. Though suffering from stress-related symptoms himself, he has yet to see a doctor.

The toll of the war on contractors has largely been hidden from public view. About 1,000 have died since the conflict began, and nearly 13,000 have been injured. While some are well compensated, many more collect modest wages for providing support services that are vital to the military.

The federal government, which has paid billions of dollars to corporations for services in Iraq since the war began, has not examined the issue of mental health problems among private workers, according to Pentagon and Veterans Affairs officials. “To my knowledge, it has not been looked at systematically,” said Dr. Matthew Friedman, a Veterans Affairs official who heads the national center for post-traumatic stress syndrome.

Contract workers who are wounded or disabled in the war zone are treated in military hospitals in Iraq and Germany, but once home, they are not eligible for care in the military or Veteran’s Affairs system. And unlike troops, they are not routinely evaluated for mental or stress disorders after their tours. When soldiers and veterans complained in recent months of lapses in their care, top officials in Washington promised improvements, but the plight of troubled civilian workers has not captured such attention.

Many companies conduct pre-deployment psychological screening and offer limited counseling but provide few resources when their workers return home and often go off the payroll.

Employers are required by federal law to provide medical insurance for workers in a war zone. Workers have filed about 205 claims for treatment of post-traumatic stress disorder, or PTSD, according to the Department of Labor, which monitors the data. Industry officials say that number significantly underrepresents the problem because many troubled people do not file claims.

Of those who do, many have been denied coverage and filed lawsuits. Gary Pitts, a Houston-based lawyer, says insurers have challenged almost every claim filed by about 50 clients, even though the insurance companies paid for medical care involving their physical injuries.