CDC Watching for Next Worrisome Outbreak

Monday, May 17th 2004, 1:21 pm

By: News On 6

ATLANTA (AP) _ SARS. West Nile. HIV. Bird flu. Once-obscure and unknown diseases have caused some of the most worrisome outbreaks in recent years, and health officials can only guess what disease will strike next.

Despite having the best medical and science know-how in history, today's health experts are struggling to predict the next outbreak as even the rarest diseases can be easily and quickly spread around the globe because of air travel and international commerce.

Some of last year's outbreaks _ including SARS worldwide and monkeypox's first presence in the United States _ emerged with little warning.

``We know we need to continue to expect the unexpected,'' said Dr. James Hughes, director of the National Center for Infectious Diseases at the Centers for Disease Control and Prevention based in Atlanta.

While health officials _ including those at the CDC _ say it's impossible to determine exactly what disease will appear next, they are constantly preparing for the world's next outbreak.

``We always say that the most important disease is the next one _ unfortunately there is no crystal ball to look into,'' said Dr. Corrie Brown, a University of Georgia professor and member of the Secretary of Agriculture's advisory committee for animal and poultry diseases.

Health officials say there's no evidence yet of any new outbreaks threatening humans, but they are closely watching a few likely suspects.

At the top of the list is influenza. Up to 50 million people died in the flu pandemic of 1918-1919, the worst flu outbreak in recent history. Because flu strains mutate and swap genes with other flu viruses, health officials fear that another powerful strain could strike at any time.

``Most of us in infectious diseases are waiting for an influenza pandemic,'' said Dr. Mark Smolinski, a former CDC official who helped investigate hantavirus when that disease first appeared in 1993 in the United States.

The avian influenza outbreak earlier this year in Asia scared health officials, as it hit eight Asian countries, killing 24 people in Vietnam and Thailand. About 100 million chickens in Asia either died from the illness or were slaughtered to prevent its spread.

``It's the first time we've ever had an avian flu epidemic in multiple countries at one time of a highly pathogenic strain,'' said Smolinski, now acting vice president of biological programs at the nonprofit Nuclear Threat Institute.

Another concern are diseases transmitted by insects. The mosquito-borne West Nile virus came to the United States in 1999 and has spread across the continental United States.

That experience has made health officials wary of Rift Valley fever, another mosquito-borne disease, but one that is much deadlier than West Nile. Rift Valley fever has a mortality rate of up to 26 percent, compared to West Nile, which kills up to 10 percent of those it infects.

``If we get Rift Valley fever in the United States, it would make West Nile look like a hiccup,'' Brown said. ``It was heavily investigated during the Cold War as a good way to immobilize troops.''

Once confined to Africa, Rift Valley fever entered the Arabian peninsula for the first time four years ago. It's believed to have spread through exported livestock. About 95 people died from it in Saudi Arabia in 2000.

The concern in the United States over the Rift Valley fever is that about 25 different kinds of domestic mosquitoes could carry the virus if it reaches North America.

The pig-borne Nipah virus, discovered in 1998 in Malaysia, ``has surfaced periodically in the swine populations,'' said Dr. Nina Marano, acting associate director for veterinary medicine and public health for the CDC. Nearly 900,000 hogs were killed and 265 people died before the Malaysian outbreak was controlled.

Both of these viruses have manmade dangers: Federal officials warn that terrorists could try to spread them both as bioweapons.

Those new threats come on top of long-standing diseases that have been difficult to contain. About a quarter of the 57 million deaths in the world in 2002 were from infectious diseases. About 2.8 million people died that year from HIV and AIDS, the globe's leading killers, Hughes said.

``Malaria, tuberculosis and HIV still are wiping out large portions of the population,'' Smolinski said. ``We're very concerned about the global pandemic of HIV _ the horse is out of the barn on that _ it's just starting to be seen in some of these very heavily populated countries like India, China, Thailand.''

Avian influenza and SARS have led to unprecedented collaboration between international medical and veterinary experts. The U.N. Food and Agriculture Organization, the World Health Organization and the Paris-based World Organization for Animal Health have been working on ways to better trade information and expertise on dangerous animal diseases that can harm humans.

In the United States, human and animal health experts are combining their talents to fight emerging diseases. The CDC is working to merge surveillance systems of state diagnostic labs, veterinary labs, wildlife health agencies and zoos. Travel medicine clinics also can provide early warning for U.S. health officials, as doctors spot cases in Americans who travel abroad.

``People have said for a long time 'It's a global village' and it really, very much is,'' said Dr. Phyllis Kozarsky, director of the Travel Clinic of Emory University School of Medicine. ``As people travel, so do microbes.''