(For full coverage, click on [nHAITI])

* Main risk is bacterial infections from wounds

* Diarrhea, kidney failure could be threats

* Children at special risk

By Maggie Fox, Health and Science Editor

WASHINGTON, Jan 18 (Reuters) - An earthquake killing up to 200,000 people would have been bad enough anywhere, but in Haiti, where AIDS, tuberculosis and malaria are rampant, children are malnourished and hygiene is already a challenge, it may create one of the worst medical disasters ever.

Medical teams pouring in to set up mobile hospitals say they are already overwhelmed by the casualties and fear the worst is yet to come as infection and disease take hold.

"The number one risk is always bacterial infections where they have open wounds," said Josh Ruxin, a Columbia University public health expert living and working in Rwanda.

Haitian government officials said the death toll from Tuesday's magnitude 7 quake was likely to be between 100,000 and 200,000, and no one has even begun to get a count of injuries, which include crushed or amputated limbs, compound fractures and lacerations.

Without quick treatment, these wounds will become infected. "Things are going to get much much worse before they are going to get better," Ruxin said.

Water is at a premium and diarrhea is likely. Children, the weak and elderly will die unnecessarily from diarrheal disease that would be easily treated with water and rehydration salts under more normal conditions, doctors said.

Frustrated medical teams have flown in mobile hospitals and tons of supplies, but have been largely unable to get them set up because roads are destroyed and security lacking.

The U.S. Centers for Disease Control and Prevention sent a team of 267 medical experts, including surgeons, who arrived on Friday but had to wait until Sunday night for military escorts to take them through the chaos.

"Because of the amount of time that has gone by, they'll probably have a lot of diabetes that is out of control," Dr Steven Harris, CDC's senior medical director in Haiti, said in a telephone interview. "There will be kidney failure because of dehydration."

The CDC is anticipating outbreaks of infectious diseases such as measles and malaria. "They are the typical kinds of diseases we have here anyway but they certainly would be worse following a disaster like this," Harris said.

SMALLEST VICTIMS

"This could turn into a children's disaster of unprecedented proportions," said Dr Irwin Redlener of Columbia University's National Center for Disaster Preparedness.

He said 40 percent of Haiti's population is made up of children under the age of 14, far more than in most countries.

"They are more susceptible to infections, dehydration and shock. And of course there is a tremendous emotional impact," Redlener said.

Ruxin sees one spark of hope.

"While this is a terrible tragedy, there is an opportunity to do something which decades of aid hasn't and that is build up a public health infrastructure that is stable," Ruxin said.

A Commonwealth Fund report released on Friday found that in New Orleans, devastated by Hurricane Katrina in 2005, healthcare had improved.

It found that a program that set up a network of local clinics funded by federal and local government was providing care to more patients than were getting care before the disaster.

(Editing by Eric Beech)

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