Dangerous viruses in the wild

In a previous Dispatch, I reported that nearly two-thirds of the world’s infectious diseases in humans come from animals. In fact, nearly two million people die each year from infections spread from animals worldwide.

In the past, the biggest danger came from domesticated animals.

In fact, close human contact with domesticated animals over ten thousand years resulted in human diseases such as tuberculosis and anthrax. Thankfully, there have been many advances in the last 50 years in veterinary science and public health. Human infections from domesticated animals, while still quite serious in some groups, now cause relatively little trouble.

Fifty years ago, scientists paid less attention to animals in the wild. Today, however, most of the danger comes from the wild.

One example is the Nipah virus. It comes from South Asia and originates from flying foxes. These animals actually belong to a species of fruit bat, Pteropus vampyrus.

When a flying fox gets the Nipah virus, it’s like getting a cold.

To humans, the Nipah virus can be deadly.

How do humans get it?

Well, flying foxes are messy eaters. Since they are actually bats, they hang upside down and drop masticated fruit into human food supplies. This introduces the virus into human saliva. The infection becomes lethal in humans who enter the forest. 

In recent years, we’ve seen dozens of outbreaks of the Nipah virus. Hundreds of people have died with each outbreak. There have been similar problems with bats encountering people in newly populated areas in Australia. 

Living in the U.S. doesn’t make you immune to lethal infections from animals in the wild. Take a look at this list of infectious diseases that now endanger the U.S.:

Swine Flu (H1N1 influenza)

The Swine Flu came from Mexico. It emerged in San Diego in 2009, from pigs and poultry that encountered wild waterfowl. It infected millions and killed thousands of people. Humans then spread the virus back to pigs, triggering a pandemic in livestock.

Bird Flu (H5NI avian influenza strain)

The Bird Flu came from Hong Kong in 1997. It re-emerged globally between 2003 and 2004 from wild waterfowl. Then, it spread to humans via wild or dead poultry, due to global expansion of intensive poultry farming encroaching on wildlife habitats.

SARS (severe viral respiratory infection)

SARS came from Guangdong (Canton) Province, China, adjacent to Honk Kong, in 2003. It originated from horseshoe bats. Then, it spread to humans via contact with civet cats, originating from wildlife markets and global trade. So far, this virus has stayed in China. No new cases have emerged since 2004.

West Nile Virus (mosquito-borne) 

The first case of this virus appeared in the West Nile District of Uganda in 1937. The first U.S. case did not appear until 1999 in Queens, New York. Various wild birds–especially robins in the U.S.–carried the virus. It spread by international air travel to humans, horses, and other birds, especially crows.

You may wonder what’s happening to stop the onslaught…

First of all, teams of biologists, physicians, and veterinarians now work on something called Project Predict. It’s a global effort to understand the ecology of emerging infectious diseases. The U.S. Agency for International Development funds it.

Scientists with Project Predict gather blood and other samples from wildlife to create a “library” of infectious agents. If one suddenly emerges as an infection in humans, scientists will understand something about the source and biology of these organisms. 

Ultimately, you can protect yourself by using good basic sanitation and hygiene.

What won’t help you are the legions of “anti-bacterial” products flooding the marketplace. As I’ve said before, watch out especially for those containing Triclosan. This agent has a number of negative health effects. 

Also: It looks like 2013 will be the worst flu season in at least 10 years. The flu vaccine, however, may be a waste of time and money. Don’t despair. Tomorrow, you’ll learn about what you can do naturally to prevent and treat the flu.