Despite advances in technology, one of the biggest threats to human survival comes from primitive life forms.
Infectious deseases are caused by microorganisms, such as bacteria, viruses and parasites.
These organisms have no access to eduction or technology, but they present a huge challenge to humanity.
That's because they are adaptable.
Just as adaptability has helped humans survive, it makes it more difficult to control infectious diseases.
There are several kinds of infectious diseases.
Bacterial infections, such as pneumonia, are caused by bacteria.
These infections can be treated by antibiotics, which kill the bacteria.
Viral infections are cause by viruses, such as the influenza virus.
These can sometimes be prevented by vaccines, such as the flu vaccine.
An example of a parasitic infection is malaria.
Malaria is caused by parasites transmitted to humans by infected mosquitoes.
Once inside the body, the parasites can be difficult to kill or control.
And of course these parasites are also adaptable.
How serious are infectious diseases?
Consider what happened in 1918, the influenze pandemic.
It started in the fall of 1918 with what seemed to be something no more serious than the common cold.
In the next two years however, it infected a fifth of the world's population.
In fact, it turned out to be the most deadly epidemic in history, killing between 20 and 40 million people.
People wore masks to prevent transmission of the virus through the air.
Now, a century later, we have flu vaccines that have reduced the severity of epidemics.
These vaccines need to be updated every year because the virus changes and new strains emerge.
What researchers fear is that a new strain of the virus will develop and cause another pandemic.
Once an outbreak occurs, transmission of the disease will be evem faster than before.
An unintended consequence of our improved transportation system will be the speed at which an epidemic can spread.
Experts predict that public health systems will be overwhelmed and unable to react quickly enough.
So the best defense will be to prevent an outbreak from occuring.
This will require global cooperation and the sharing of data.
It may also require changes in how human interact with animals.
Animals such as bird and pigs carry viruses that may mutate into a strain that can infect humans.
Such a new strain could lead to another pandemic well before a new vaccine could be developed.
Since diseases and epidemics don't stop at national borders, this is a global issue requiring global action.
The threat of a global epidemic is another example of why we must learn to live together.