The 10 most common symptoms of bird flu to look out for as state of emergency declared in USA

California has declared a state of emergency after 34 people cases of bird flu were detected.

Governor Gavin Newsom took action on Wednesday (December 18) as cases of the avian influenza A (H5N1) subtype snowballed.

According to Cleveland Clinic, bird flu is spread to humans via an infected animal's bodily fluid.

This could be its spit, milk, poop or even 'respiratory droplets.'

You can 'breathe it in' from small dust particles in animal habitats, or get it into your eyes, nose of mouth after touching bodily fluids.

The H5N1 bird flu virus (Smith Collection/Gado/Getty Images)

It can cause some common cold and flu symptoms, but serious cases can quickly become fatal.

Outbreak explained

Bird flu has been detected in some 645 dairy cows in California since late August, but half these cases were only just identified in the last month alone.

The majority of the 34 humans infected are believed to be farmworkers who worked closely with infected cattle.

It comes as the first person to ever contract 'severe' bird flu in the US was hospitalized in critical condition.

Infected dairy cows are thought to be responsible for the outbreak (Michael M. Santiago/Getty Images)

It's suspected the person, who is over 65 and has underlying health issues, came into contact with an infected flock of birds in their backyard.

The CDC said: "While an investigation into the source of the infection in Louisiana is ongoing, it has been determined that the patient had exposure to sick and dead birds in backyard flocks.

"This is the first case of H5N1 bird flu in the US that has been linked to exposure to a backyard flock."

There have been a total of 61 bird flu cases throughout the country this year alone, although the CDC did confirm 'no person-to-person spread of H5 bird flu has been detected.'

What are the symptoms of bird flu?

A high fever can be a sign of bird flu (Tom Merton/Getty Images)

There are 10 key signs of bird flu to be mindful of, although Cleveland Clinic claims some of the most recent cases in the US have caused pink eye and 'mild respiratory symptoms.'

Main symtoms include:

• Pink eye (conjunctivitis)
• Fever
• Fatigue
• Cough
• Muscle aches
• Sore throat
• Nausea and vomiting
• Diarrhea
• Stuffy or runny nose
• Shortness of breath

These symptoms can be mild or severe.

In some cases, bird flu can cause serious complications, including pneumonia, sepsis, brain swelling and respiratory failure.

How to treat bird flu

If detected early enough, bird flu can be treated with antiviral medication.

A sore throat, fever and muscle aches can be treated with over-the-counter medicine as usual.

You should get plenty of rest and stay hydrated, too.