The virus responsible for the Avian flu . has been contained
can be passed from human to human
has renewed fears about a future global pandemic
can be passed from birds to humans

D. can be passed from birds to humans.

Explanation:

Pathogens are organisms such as virus, fungi, bacteria, protozoa, worms that causes diseases to its host.

Avian flu is a strain or variant of the Influenza virus which is predominantly causes a disease in birds such as chickens. The virus responsible for the Avian flu can be passed from birds to humans; when anyone comes in contact with a bird that is carrying the virus i.e a sick bird with Avian flu.

Homeostasis can be defined as a process through which a living organism maintains a steady or stable physical, internal and chemical environment ideal to enhance life and proper functionality.

If a person becomes infected with a pathogen, such as a virus. The internal stimulus that mainly takes place in order for their body to maintain homeostasis is that their core temperature increases. This is because pathogens such as a virus do not thrive or survive in a hot environment; they're naturally allergic to high temperature (heat).

warfare was the primary means of cultural transmission in both regions.