(CNN) -- Ten medical aid volunteers were killed in one Afghanistan attack in August. In July, a 78-year-old French humanitarian worker was executed along the Mali-Mauritanian border after some three months in captivity.
In Darfur, Sudan, two kidnapped German relief personnel were held captive for more than a month before their release in July. Another aid worker, an American woman, was taken three months ago in Darfur and is still being held hostage.
Aid workers have been ambushed, bombed, assassinated or taken hostage in growing numbers worldwide. Attacks and killings from attacks have risen over the last several years.
The majority of victims are local employees of aid organizations, who work to help their own people, U.N. and humanitarian officials say.
According to the U.N. Office for the Coordination of Humanitarian Affairs, 102 relief workers were killed in 2009, up from 30 a decade earlier. The year 2008 was a grim milestone -- 122 aid workers were killed, the most in one year.
Dr. Abby Stoddard, a partner at Humanitarian Outcomes, which monitors security issues in the world's relief community, told CNN: "There have been more aid worker attacks, but there have been more aid workers deployed, too.
"We have documented a 60 percent rise in such attacks between 2005 and 2009 per every 10,000 aid workers."
Another reason aid groups are vulnerable is that they often do not use armed escorts. The point is to be perceived -- without question -- as a non-combatant. But sometimes that doesn't matter.
On August 19, 2003, the U.N. headquarters in Baghdad was destroyed by a truck bomb, leaving 22 dead, including Secretary-General Kofi Annan's chief envoy in Iraq at the time, Sergio Vieira de Mello. Scores more were injured.
The U.N. designated August 19 as World Humanitarian Day in 2008 to honor those who perished in the Baghdad bombing and for the continuing sacrifice of the global aid community.
Learn more about World Humanitarian Day
"It seems that the blue flag of the U.N. is no longer the shield of protection it used to be," Michael Bociurkiw, with the U.N. Children's Fund (UNICEF), said via cell phone from Maseru, Lesotho, where UNICEF is fighting malnutrition, poverty, HIV/AIDS and other diseases.
"It's as if the Baghdad bombing marked our loss of innocence -- that it was the start of a kind of open season on aid workers," the 46-year-old Canadian said. "The recent killing of the aid workers in northern Afghanistan was really horrific and shocked the entire aid community to the core."
No one understands that better than Dirk Frans, the Dutch national who leads the International Assistance Mission in Afghanistan -- the group that had 10 of its own slain on August 5 in the northern province of Badakhshan. That group included six Americans, a Briton, a German and two Afghans.
"It was an isolated, opportunistic attack," he told CNN from Kabul, Afghanistan's capital. "This group was in the wrong place at the wrong time."
Frans, 56, added: "Unfortunately, we are reducing our exposure in Badakhshan by not working in that area for now."
This hit on a point brought up by Stoddard: "When there is violence against aid workers, those who need the aid don't get it."
Stories like these don't deter Lisa Browne, an American project coordinator with the Johanniter-International Assistance medical group in Darfur, Sudan -- her third aid posting in Africa.
For more than two years she has lived and worked in Ed al Fursan, a remote section of South Darfur.
"I generally enjoy it here. I'm basically comfortable," Browne, 29, told CNN from Nyala, Darfur. "Staff safety and security is a general concern for all humanitarian actors in South Darfur, including (Sudanese) governmental partners."
She added: "If I was asked to take another position here, I would do it again, no questions asked."
Another aid worker, Marcus Prior, 41, with the U.N.'s World Food Programme (WFP), spoke to CNN via phone from WFP's offices in Islamabad, Pakistan's capital, where he was getting a quick break from working in the flooded Swat Valley.
The WFP offices in Islamabad were breached in October 2009 when a suicide bomber detonated a device inside the building, killing five.
"Places like Somalia and (the Democratic Republic of the) Congo have been particularly dicey at times," he said. "I remember on one of my very first aid missions to Somalia, being rushed into our office because there was an unidentified gunman in the vicinity.
"And then crossing the front lines outside Goma in eastern Congo, with flak jacket and helmet on, was also nerve racking. It felt like old-fashioned warfare, with two sides peering at each other from trenches across a no-man's land."
A Somali working with WFP in Somalia, who asked to remain anonymous, said via email: "For many people, including my family, the thought of working in Somalia, and Mogadishu in particular, is extraordinarily dangerous.
"Everyone who cares about me knows of a humanitarian worker killed, injured or abducted in the line of duty in Somalia."
He added: "The scale of disaster and human suffering I see daily and the value of my work gives me more reasons to stay than to leave."
John Holmes, the U.N. under-secretary-general for humanitarian affairs and emergency relief coordinator, told CNN he thinks there is a "particular brand of ideology" proliferating in the world that identifies "all foreigners" as enemies.
"We are perceived as having some sort of political agenda, which is not true," he said from New York. "We are solely there to help people in need. We are operating purely on the basis of that need."
And that perception can sometimes be misperceived, especially in the case of Afghanistan, where U.S. military personnel comprise much of what are known as provincial reconstruction teams, or PRTs -- effectively working as an outreach unit to help develop areas outside Kabul. And while their purpose is to help locals, they are dressed in military uniforms and often carry weapons.
Stoddard said that in countries where the U.S. is one of the "belligerents" involved in conflict, such as in Afghanistan, a confusing message can go out to locals about aid workers.
"The PRTs have been a difficult aspect for the aid community to deal with ... much of the aid community feels this blurs the lines of aid work and military action, and further endangers the aid community."
Holmes said aid groups had to maintain strict neutrality and added a plea to captors of humanitarians worldwide currently holding them hostage.
"I would very strongly appeal to these armed groups -- whether they are Taliban or al Shabaab or whatever -- to release them immediately," he said.
But in reality, little can be done to keep combatants from targeting aid workers. According to Stoddard, a total of 45 aid workers have been killed so far in 2010, another 47 have been kidnapped.
