September: In a remote Colombian peninsula, thousands of Indians fall ill. As family members watch helplessly, some of the victims become delirious, go into convulsions and die.

October: Hundreds of people, stricken with fevers and body aches, crowd a village clinic in Nicaragua. Autopsies on those who succumb discover their lungs are filled with blood.Specialists scrambled in recent weeks to deal with these outbreaks of rare diseases. But while they are dangerous and alarming, epidemics of more common diseases like cholera and dengue fever have quietly spread through Latin America and are claiming thousands of lives each year.

Health experts say minor outbreaks of diseases imported from Latin America can be expected in the United States. But they say there is little risk of epidemics because the United States has adequate insecticide spraying and proper sanitary systems.

In the 1950s and 1960s, Latin American nations tried to eradicate the mosquito that carries dengue. Insecticide-spraying pushed the mosquito, Aedes aegypti, back to a few pockets in the jungle and almost wiped it out. But the effort was dropped because of high costs.

This past week the Pan American Health Organization announced that Aedes aegypti has regained the territory it formerly occupied. It said dengue is raging in Latin America, sickening 200,000 people and killing 76 this year alone.

An international conference to be held in Brazil on Nov. 30 is aimed at renewing the mosquito-eradication efforts. Doctors are also busy fighting new diseases.

One of the first missions of the Epidemic Strike Force, created on Oct. 1, was in northwestern Nicaragua, where a killer disease baffled doctors until early November.

"People were dying left and right," said Dan Epstein, spokesman for the Pan American Health Organization, who recently returned from Nicaragua to his Washington office. "They were suffocating in their own blood."

The disease, first thought to be a form of Ebola, an incurable disease that causes massive hemorrhaging, was later found to be leptospirosis, which infects humans when waste matter from diseased rodents mixes with drinking water or is absorbed through breaks in the skin.