Wastewater in several Californian cities, including San Francisco and Los Angeles, recently tested positive for bird flu. But understanding disease risk and exposure to humans isn’t so straightforward

H5N1 avian influenza, more commonly known as bird flu, has infected more than 100 million birds in the U.S. and almost 500 dairy cattle herds across 15 states. The virus has popped up in mammals including elephant seals,

A teenager in British Columbia was hospitalized in critical condition with the disease, and officials were working to find out how the person was exposed to the virus.

A Canadian teenager infected with bird flu — that country’s first case involving a locally acquired infection — is in critical condition and experiencing difficulty breathing, health officials said Tuesday.

It's not clear how the British Columbia teenager picked up the virus, which has been detected recently in wild birds and poultry in the province, a health official said.

Bird flu H5N1 has infected dozens of people in the U.S. this year. Could it be the next pandemic? Experts explain the threat and symptoms to watch for.

Canada detected its first human case of the new strain. Sen. Elizabeth Warren (D-Mass.) said Monday that President elect-Trump “and his transition team are already breaking” a law on presidential transition.

In what is believed to be Canada's first human case of bird flu, a teenager is in a British Columbia children's hospital in critical condition with a presumptive case of the virus, the CBC reports. Authorities say the unnamed teen developed symptoms Nov.