As the H5N1 bird flu virus continues to spread among animals, the discovery of infected rats in Riverside County provides another example of the virus' penchant for surprise.

Before future studies would uncover a link between Nipah outbreaks and the felling of native forests for the purposes of fruit plantations, more than 1 million pigs are culled to quell an outbreak that leads to the deaths of 105 people.

H5N1 bird flu is branching out. New data from the Centers for Disease Control and Prevention indicates that a second type of H5N1 has likely spread from dairy cows to humans.