BAGHDAD, Iraq (CNN) -- Cholera deaths at a Baghdad orphanage and deteriorating water and sewage systems are spurring fears of a larger outbreak of the killer disease, the United Nations children's agency said.
An Iraqi boy washes Thursday from a drainage pipe on the outskirts of Baghdad's Sadr City neighborhood.
As the rainy season begins, waterway pollution from raw sewage "is perhaps the greatest environmental and public health hazard facing Iraqis -- particularly children," said UNICEF spokeswoman Claire Hajaj in an e-mail to CNN on Wednesday. "Waterborne diarrheal diseases kill and sicken more Iraqi children than anything except pneumonia."
Cholera has claimed 24 lives nationwide since August, according to the Iraqi government, including two children at the city's Al Hanan orphanage.
"While national caseloads are declining, we are increasingly concerned about a possible outbreak in Baghdad," Hajaj said. "The capital accounts for 79 percent all new cases and is now up to 101 cases, the vast majority reported in the past three weeks."
Cholera can kill in a matter of hours if left untreated, according to MayoClinic.com. Most people who are exposed to the disease show no signs of the illness, making them unknowing carriers, the Web site said. Those who do get sick usually experience symptoms such as mild or moderate diarrhea, nausea, cramps, dehydration or shock.
Discovery of the illness at the orphanage "raises concerns for all children in institutions and schools Baghdad," said Hajaj. We estimate that only one in three Iraqi children can rely on a safe water source -- with Baghdad and southern cities most affected," she said.
Areas of the capital hardest hit by cholera include Sadr City, Mada'in, Baladiyat, and the Rusafa-Karkh, said Hajaj.
To fight the outbreak, UNICEF is providing water purification tablets and rehydration salts for families and safe water to the most affected areas. And the group is asking Iraq's government to clean water storage tanks.
The current cholera wave was first detected in the northern city of Kirkuk in August, according to the World Health Organization, and many cases have been reported in the Kirkuk and Sulaimaniya region.
Of the 24 cholera deaths reported by the Iraqi Health Ministry, 14 occurred in Sulaimaniya, five in Tameem where Kirkuk is located, three in Baghdad, one in Anbar and one in Nineveh.
U.S. and Iraqi officials are hoping that recent gains by the military gains impose some stability that will enable authorities to address water and sewage infrastructure problems.
UNICEF is urgently asking Iraq's government to clean water storage tanks in all institutions as one preventive measure. UNICEF also is supporting a public information campaign in Baghdad. A WHO clinic has now been established in Al Hanan and patients are being provided bottled water.
Meanwhile, fighting continued Thursday as coalition troops targeted a Shiite extremist, killing two armed men, the U.S. military said in a statement. Troops detained five other suspected criminals, the statement said.
"The target was described as a "a significant explosively formed penetrator facilitator and trainer within Special Group criminal elements in the Khan Bani Saad area and Baghdad, who have not honored [Islamic cleric] Muqtada al-Sadr's pledge for a cease-fire." Khan Bani Saad is north of Baghdad in Diyala province.
"Special Groups" is the term used by the U.S. military to describe Shiite extremists. Muqtada al-Sadr is the anti-American Shiite cleric with great influence in Iraq's Shiite heartland. Over the summer, he imposed a cease-fire on his militia, the Mehdi Army. Many observers believe that move is one of the factors that has led to a recent decrease in violence in Iraq.
As for the incident, the military says the target was a cohort of "other senior-level criminal element leaders" linked to attacks on coalition troops.
The "two armed men" were killed when they left a building targeted by troops. They were "displaying hostile intent with assault rifles aimed toward coalition forces." The troops traded fired with the men and killed them. The five were detained without incident, the military said.
"We will continue to show restraint towards those who honor Muqtada al-Sadr's pledge to stop attacks," said Maj. Winfield Danielson, Multi-National Forces-Iraq spokesman. "While Iraqi and coalition forces are making progress against criminals who are not honoring this pledge, their networks remain a dangerous enemy of Iraq that must be removed."
• Small arms fire killed a U.S. soldier Wednesday in a western section of Baghdad, according to a U.S. military statement released Thursday. The soldier was a member of the Army's Multi-National Division - Baghdad. Since the start of the war, 3,879 U.S. troops have died in Iraq, including 35 in November.
• The U.S. military said its operations targeted al Qaeda in Iraq on Thursday. Troops detained 12 people in Tarmiya, north of Samarra, Hawija, and Baiji.
• Iraq's Interior Ministry reported two roadside bombs on Thursday. One in southeastern Baghdad exploded near Shaab stadium, killing a civilian and wounding six others. Another detonated on Palestine Street in eastern Baghdad and wounded six civilians.
• The military on Thursday said a team of U.S. Apache helicopters fired 30 mm cannon and Hellfire missiles at a house from which insurgents attacked a coalition convoy on Tuesday. Three insurgents were killed in the incident southeast of Baghdad -- a region that has been a major battleground during this year's U.S. troop increase.
• A U.S. Air Force unmanned MQ-1 Predator reconnaissance aircraft crashed on Thursday in an unpopulated Iraqi area, the U.S. military said. An investigation into the crash is under way, according to a military statement. E-mail to a friend
CNN's Mohammed Tawfeeq in Baghdad and Joe Sterling in Atlanta contributed to this report.