5
votes
2answers
65 views

Viruses: Adaptation to a new host through repeated host jumps

A friend told me, during a 3 minute discussion, that viruses that are endemic in host $A$ and make repeated jumps to host $B$ but can't be transmitted between individuals of species $B$, may slowly ...
14
votes
3answers
655 views

What causes a 'stuffy' or 'runny' nose when you have a cold?

When humans get the common cold, a common symptom is a stuffy or runny nose. Is that the body's immune response or is that the virus's doing?