How could you tell this has happened?

How could you tell this has happened?



This is exactly the kind of nightmare that is keeping scientists awake at night in different research laboratories around the world.

Take bird flu: we keep seeing small numbers of human beings get infected and die, and sometimes we see clusters of cases, especially in families, which could indicate that the virus is learning how to spread between people. Of course clusters can also occur where several family members have been exposed to the same sick animal, which makes these things even harder to monitor.

We saw a similar process happen with SARS - a highly infectious virus managed to jump from animals to humans, and was only contained with huge health control efforts. We were very fortunate that SARS did not spread to countries like Burundi in Africa, which would not have had the resources to trace contacts and impose strict isolation. If it had, we would still have a dangerous SARS epidemic in Africa today.