Nearly a week after a 6.3 magnitude earthquake ripped through Central Java, health officials are concerned about possible outbreaks of diseases such as dysentery and tetanus. Aid agencies and local officials have improved their response, and employed lessons learned after the Indian Ocean tsunami in 2004 to prevent epidemics.

Survivors in the devastated region of Klaten pick through the remains of their houses to salvage belongings and building materials. The sites are treacherous, with parts of concrete walls poised to collapse, and the ground bristling with dirty, sharp pieces of hardware.

The World Health Organization has expressed concern about a possible outbreak of tetanus, which plagued Banda Aceh after the 2004 tsunami. More than 70 people died from the disease there during the recovery. Tetanus is a common bacteria that attacks the nervous system and thrives in open wounds. Hospitals earlier in the week reported shortages of tetanus vaccine.

The WHO's Indonesia representative, Georg Petersen, says overflowing hospitals and poor sanitation aggravate the problem.

"There's been clearly a lack of latrines, so water sanitation issues in the hospital grounds has been an infectious disease risk. It seems to be easing, but it's still there," he said. "And with so many people, more than 200,000 people homeless in the area, and water and sanitation again difficult, there is a risk of infectious diseases."

WHO Regional Advisor Luis Jorge Perez says aid workers and local physicians are monitoring hospitals, having learned some hard lessons during the tsunami relief efforts. More than 160,000 people died or were injured in Indonesia's Aceh province when the tsunami hit in December 2004.

"The disease surveillance plan which was implemented in Banda Aceh is the one that's being used right here," he said. "So they're looking out for all the possible diseases that could appear after natural event like this one."

Perez adds that Indonesia's response time and coordination following the quake is far better than efforts after the tsunami. He says vaccination programs for aid workers and a tracking system for medical supplies will help to prevent life-threatening outbreaks.

Thursday night, representatives of more than 40 local and international groups met for the first time to jump-start coordination among health agencies.

More than 6,000 people died in the earthquake, which struck last Saturday morning.

The WHO estimates that more than 22,000 patients have been treated in hospitals here over the last week, most of them for open fractures and wounds caused when they were crushed by debris. Health organizations are asking for donations of orthopedic supplies to aid in the huge number of reconstructive surgeries that must be done.

United Nations officials say 22 countries have contributed to the relief effort so far, with food, supplies, medicine, and 10 mobile field hospitals.