What happens in Las Vegas stays in Las Vegas, publicists say. But that "stay-put" concept doesn't apply to the outbreaks of emerging and re-emerging diseases that spring up in the nooks, crannies and corners of the world.

Ancient and newly discovered diseases can spread steadily, sometimes at alarming rates, agreed speakers at the eighth annual Northern California International Health Conference, "Global Health Challenges of Emerging Diseases," held recently on the University of California, Davis campus.

One example is the mosquito-borne disease, West Nile virus (WNV), first isolated in 1937 in the West Nile district of Uganda, said UC Davis medical entomologist Gregory Lanzaro, director of the UC Mosquito Research Program and director of the UC Davis Center for Vectorborne Diseases.

WNV spread to New York in 1999 and reached California in 2002. Last year the disease killed 18 people in California and infected more than 900 others throughout the state, according to the Centers for Disease Control and Prevention (CDC). WNV is now a permanent part of the Western hemisphere.

"Vectorborne diseases have the propensity to spread very rapidly," said Lanzaro, adding that last year's WNV activity in California "could have been far worse" had it not been for the state's mosquito abatement districts. "California," he said, "has the most sophisticated mosquito abatement program in the world, the best in the world."

Conference coordinator and physician Marc Schenker, professor and chair of the Department of Public Health Sciences at the UC Davis School of Medicine, said malaria, tuberculosis and AIDS kill millions of people throughout the world each year, but many more diseases, from avian flu to West Nile, threaten us.

"In the final analysis, it is you--you are the ones who are going to have to make the differences," Schenker told the 500 health professionals and students attending the conference.

Stressing the global threat of diseases--that diseases in other parts of the world affect us all--executive associate dean Thomas Nesbitt of the UC Davis School of Medicine said the United States must get more involved in global health challenges. "And it's the right thing to do," he said. "We as a country have the financial and intellectual resources to help others."

Keynote speaker and UC Davis provost Virginia Hinshaw, who researched influenza viruses in humans, mammals and birds for more than 25 years, warned that the H5N1 avian flu poses a "significant threat to public health."

The influenza pandemic of 1918, also known as "The Spanish flu," killed between 20 and 40 million people globally, she said. "In World War I, more soldiers died of the flu than of wounds."

It's not a matter of "if" but "when" the H5N1 avian flu strikes the United States, she said. Since 2003, it has spread to more than 50 countries on three continents via migratory or wild birds and poultry.

"The power of the flu" is that it is able to change, to mutate, said Hinshaw, defining an influenza pandemic as a "global outbreak of disease that occurs when a new influenza virus appears or emerges in the human population, causes serious illness, and spreads easily from person to person worldwide."

Hinshaw said a "medium-level pandemic of avian flu in the United States" could result in 207,000 deaths, 734,000 hospitalizations, 18 to 20 million outpatient visits, and 20 to 37 million people "being sick." It could affect 15 to 35 percent of the population, she said, and create an economic burden of $166 billion.

To combat the threat, Hinshaw advocated three "pre" steps: global surveillance and assistance, stockpiling of vaccines and antivirals, and research on new vaccines; and three "post" steps: quarantine of infected people, ring vaccination, and antiviral treatment of infected and exposed humans.

Urging global cooperation, Hinshaw said: "We're only as healthy as our neighbors; we're all connected."

Physician Phillip Hopewell of San Francisco General Hospital and a professor at UC Francisco, said tuberculosis is not an "emerging" disease, but what's emerging is the "recognition" of TB as a global health problem. "It's been well emerged for centuries," he said. Nine million new cases of TB surface every year, and now "India and China make up 40 percent of them."

Veterinarian Nina Marano of the CDC's National Center for Infectious Diseases, called for "Integrated human and animal health surveillance at state, national and global levels."

"Most companies fail to create the future not because they fail to predict it, but because they fail to imagine it," she said, quoting management strategist
Gary Hamel, author of Leading the Revolution.

Other speakers touched on some of the 1,415 species of infectious agents that are known to cause disease in humans and "are ready to pounce." These include virus, prions, bacteria, rickettsia, fungi, protozoa and helminthes. CDC classifies 61 percent or 868 as zoonotic, meaning a disease that can be transferred between humans and animals. In the last 25 years, 38 new pathogens have moved from animals to humans, CDC statistics show.

Lanzaro zeroed in on infected insects that can transmit parasitic, bacterial and viral pathogens. Parasitic diseases include malaria, spread by Anopheles mosquitoes, and leishmaniasis, spread by sandflies. "Malaria is responsible for 1 to 3 million deaths per year and 300 to 500 million clinical cases," he said. "Visceral leishmaniasis is almost 100 percent fatal if not treated."

Bacterial diseases include lyme disease, vectored by blacklegged ticks, and plague, spread by rodent fleas.

Mosquito-borne viral diseases include dengue and yellow fever, both vectored by Aedes aegypti mosquitoes, and West Nile, spread by Culex mosquitoes. "Dengue is expanding throughout the world, with 2.5 to 3 billion at risk and there is no vaccine," Lanzaro said.

"Malaria, is one of the oldest infectious diseases and is expanding its range. Forty percent of the world's population now lives in malaria endemic areas. Malaria has been on the increase in areas that include central and southern China, Mexico and Central America."

Lanzaro listed eight roadblocks to controlling vectorborne diseases:

. Displacement of people by war, civil strife and natural disease
. Breakdown of public health programs
. Poverty
. Drug resistance by pathogens
. Insecticide resistance in vectors
. Bad policies, for example, the ban on DDT in Africa
. No silver bullet; yellow fever's silver bullet is a vaccine
. Global warming

UC Davis physician Christian Sandrock said many factors play a role in infectious disease outbreaks following a natural disaster, such as a flood, hurricane or earthquake. For example, if mosquito abatement procedures cease after flooding, this can lead to mosquito-borne diseases. "But if the disease is not present before the disaster, it's unlikely to be there afterwards."

During the breakout sessions, speakers expressed concern about anthrax, cholera, E. coli "superbugs," Ebola virus, hepatitis A and B, hendra virus, hydatid, lyme, mad cow, measles, meningitis, monkeypox, Nipah virus, polio, rabies, Rift Valley fever, rinderpest, salmonella, smallpox, SARS (severe acute respiratory syndrome), tetanus, typhoid and whooping cough.

Smallpox, caused by the variola virus, has been eliminated throughout the world, but stockpiles of the virus pose a bioterrism threat, said physician Mark Edward Stinson of the Contra Costa Regional Medical Center and an associate clinical professor, UC Davis School of Medicine. The last case of smallpox occurred in 1977 in Somalia.

"Anthrax," Stinson said, "is an old disease but it's an emerging cause of man's malevolence."

Factors that can play major roles in disease outbreaks include poverty, famine, poor sanitation practices, wars, political instability, human overcrowding, drug abuse, migration, sex industry, world travel, agro-terrorism, bioterrism, global commerce, changing land use and agricultural practices (including deforestation and loss of natural wetlands), changing climates (drought, rainfall) and natural disasters (such as earthquakes, volcanic eruptions, floods and hurricanes).

Stinson said that even "airline air" plays a more major role. "The airlines have cut back on the air turnover," he said. "That's why airline personnel stand at the back of the plane where the air is fresher."


Sidebar

Barriers to Successful Technology Transfers

Barriers to successful technology transfers between developed and undeveloped nations on global health issues include the high cost of technology, poor infrastructure, level of education, lack of funding capital and lack of an enabling environment, physicians and veterinarians said at the 8th annual Northern California International Health Conference at UC Davis.

Anvar Velji, chief of infectious disease at Kaiser Permanente, South Sacramento, and a clinical professor of medicine at UC Davis School of Medicine, said that globally, 1.2 billion people, or one in six, live on under $1 per day, and that 842 million adults are illiterate.

"Eighty-seven percent of the $12 trillion global pie is spent on 16 percent of the world's population," Velji said.

He advocates that nations work together, following the "Swiss guidelines: decide objectives together, build up mutual trust, share information and responsibilities, develop a network, and create transparency."

Enlightened leaders or politicians are also crucial, he agreed.

Veterinarian Tilahun Yilma, professor at the UC Davis School of Veterinary Medicine, said university researchers need to promote the culture of science in developing countries, "not to publish for promotion but to advance knowledge."

We need to tear down the internal and external barriers, Yilma said, recommending as "required reading" Graham Hancock's book, Lords of Poverty, which chronicles "the power, prestige and corruption in international business."

Physician Evaleen Jones, assistant clinical professor at Stanford University School of Medicine and president, founder and medical director of Child Family Health International, said the outerspace pathogens in Michael Creighton's science-fiction book, Andromeda Strain, published in 1969, "thoroughly scared us but we have our own here, too."

In the United States, the top health-related killers are heart attack, cancer and stroke, she said, a far cry from the top killers in Africa: AIDS, malaria and respiratory infections.