Aging populations on Japan's northeast coast are struggling to recover from last month's devastating earthquake and tsunami, and health officials fear they could be hit by a potentially deadly new wave of disease, The Wall Street Journal reported Monday.

Hospitals serving the region said they are seeing a surge in elderly patients with pneumonia, which doctors attribute largely to living conditions in crowded emergency shelters that now house tens of thousands of displaced people.

Public health officials also said they are worried about flu outbreaks, respiratory illnesses caused by dust-borne pathogens and a high incidence of blood clots in the legs of now less-active older residents.

About 20 percent of Japan's population is over 65 years old; that proportion is even higher in parts of the disaster-stricken northeast, a fact that stands to complicate recovery efforts and pose unexpected challenges for public health authorities.

In Ishinomaki, a fishing port city about 210 miles north of Tokyo, the Red Cross Hospital has been treating pneumonia patients at roughly five times the normal rate since the March 11 disaster, said Dr. Masaru Yanai, head of respiratory medicine.

Of the roughly 150 patients with tsunami-related pneumonia admitted to the hospital, Yanai said, 80 percent are elderly and two-thirds had been living in shelters in school gymnasiums and other public buildings.

For older people with weakened immune systems, the stress of temporary housing arrangements, along with often poor nutrition in the shelters, can make them more prone to illness, Yanai said.

Many patients have "aspiration pneumonia," a lung infection that starts when people breathe in bacteria-laced saliva -- a situation exacerbated by poor oral hygiene because of shortages of water and supplies in shelters, he said.

Up the coast in the city of Ofunato, the main hospital is also experiencing an increase in pneumonia cases to between five and 10 times the average before the tsunami.

In response, public health officials have been encouraging people in shelters to brush their teeth more often and rinse their mouths. In nearby Rikuzentakata, dentists have set up shop in one of the main evacuation centers to help.

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