New Bugs Suspected
In Fatal Illnesses
Lisa M. Krieger
Examiner Medical Writer
Some of the sudden and unexplained illnesses that kill healthy young Americans each year may be the result of unidentified or newly emerging infectious organisms, according to medical sleuths at a new federal research project at the Centers for Disease Control and Prevention.
Of 45 mystery diseases reported to the team between 1995 and 1997, 13 cases were successfully traced back to a known organism. But in 23 cases, no cause could be found.
"Despite extensive testing and an impressive autopsy rate, no causes or putative agents were identified for a substantial number of cases," Dr. Jennifer Flood of the CDC-based Emerging Infections Program said at the annual meeting of the Infectious Disease Society of America, held in San Francisco.
Some illnesses may represent pathogens for which no test has been developed, she said.
It is also likely that some illnesses and deaths resulted from pathogens that are well known but could not be identified because of inadequate samples of infected tissue, blood or spinal fluid. For example, in the sudden death of a young child, overwhelmed parents and emergency room doctors may fail to consider saving enough tissue for later testing.
"In summary, our study finds that severe, unexplained, life-threatening illnesses that are potentially due to infectious agents and affect young healthy individuals are occurring regularly at all sites under our surveillance," Flood said.
The study, called the Unexplained Illnesses and Deaths Surveillance Project, fills a gap in America's disease-reporting system. It offers a way for doctors to report cases of illnesses that don't fit into known syndromes and may not yet have names.
The project comes at a time of growing concern over outbreaks of new infections.
Emerging infectious diseases "are a reflection of our ever-changing, increasingly complex world," said Minnesota state epidemiologist Dr. Michael Osterholm. "A viral infection in Calcutta today may very well surface in Minneapolis tomorrow."
A recent outbreak in Nicaragua of unexplained fever associated with bleeding lungs and many deaths - combined with recent outbreaks of other highly fatal illnesses such as AIDS and hantavirus in the United States and Ebola hemorrhagic fever in the Congo - are reminders that surveillance for emerging infections should be a high priority, experts say.
Since the early 1970s, many pathogens - such as hantavirus and the organisms that cause Lyme disease, Legionnaires' disease, toxic shock syndrome, AIDS, hepatitis C and cryptosporidiosis - have been identified.
Emerging infections from contaminated foods and water have placed entire communities at risk. Early in 1993, hamburgers served at a fast-food chain caused a multistate outbreak of hemorrhagic colitis and serious kidney disease, resulting in the deaths of at least four children. A similar outbreak at the Odwalla juice factory in Half Moon Bay was blamed for the death of a child.
A once-obscure intestinal parasite, Cryptosporidium, caused the largest waterborne disease outbreak ever recognized in this country. The microbe cyclospora was responsible last year for more than 1,000 illnesses in 11 states. It was imported into the country on Guatemalan raspberries. Little is known about cyclospora's life cycle or how it spreads.
The arrival of new diseases may result from genetic changes in existing organisms, permitting infection to spread from animals to humans. The spread may be accelerated by ecological upset in a region. Then, because of the ease of global travel, the bugs quickly spread to new geographic areas or new human populations.
"Today, one of every nine individuals who has ever lived on Earth is currently alive," said Osterholm. "There are billions of humans, each with his own ecosystem of billions of microbes. The human microbial reservoir is now vast and unparalleled."
And not just humans travel. The global economy has created markets for exotic pets and foods, both of which harbor disease. Between January and March, 39 percent of all cantaloupes, 74 percent of onions, 79 percent of cucumbers and 59 percent of tomatoes came into the United States from Mexico, where public health measures are relatively lax, Osterholm said.
Guatemala's first raspberry vine was planted in 1988; last year, one-third of all raspberries eaten in the United States originated in that nation - some carrying cyclospora.
"Today, you don't need to leave home to acquire "travelers' diarrhea,' " Osterholm said.

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