The pig, it is believed, can be a host for viruses that infect such birds as chickens and ducks. But it can also be the host for other viruses that infect humans.
Tiek uzskatīts, ka cūkas var pārnēsāt vīrusus, ar kuriem inficējas tādi putni kā vistas un pīles, taču tās var pārnēsāt arī citus vīrusus, ar kuriem inficējas cilvēki.