Measles at Lowest Level Ever in US

WASHINGTON (Reuters) - Measles cases hit an all-time low in the United States last year, but a few cases are still imported from countries with lower vaccination rates and still occur domestically as well, health officials reported on Thursday.

Only 37 cases of measles were reported to the federal Centers for Disease Control and Prevention in 2004, down from the 44 cases reported in 2002 and a huge drop from the 4 million or so cases seen every year before routine vaccination began in 1963.

"Confirmed measles cases occurred predominantly among preschool-aged children (aged 1 to 4 years)," the CDC said in its weekly report on death and disease.

Nearly three-quarters of the cases, or 27, came from abroad, imported by travelers from China, India, Bangladesh and several other countries.

Measles was long considered a normal childhood disease, but the virus can cause severe complications in otherwise healthy children and adults, including sometimes fatal encephalitis, pneumonia and diarrhea.

Most developed countries routinely vaccinate children against measles but the virus still killed 500,000 people, mostly children, around the world in 2003, according to the World Health Organization.

It is one of the most infectious diseases known and before routine vaccination began in the United States in 1963, almost everyone got measles. There were 3 to 4 million cases and an average of 450 deaths a year in the United States.

In the past, most U.S. measles cases were either imported or occurred among groups that refuse to be vaccinated, including some religious groups. In 2004, nearly all the cases were imported or linked to imported cases but four of them could not be traced to any one cause, the CDC said.

"Of the 27 persons with imported measles cases, 13 (48 percent) were infectious during aircraft flights," the report reads. The virus is very infectious so CDC officers have to painstakingly track down everyone who may have sat near a measles patient on an airplane.