Doctor explains how Bella, Yolanda and Anwar Hadid all contracted same disease as new photos spark concern

A doctor has explained how Bella Hadid, her brother Anwar, and their mother Yolanda all contracted the same illness that's common among celebrities.

It comes as Bella shared a series of worrying photos from her hospital bed yesterday (Thursday 18 September), sparking concern among fans.

For those who aren't familiar with her health struggles, the American model, 28, suffers from a bacterial infection that's also affected not only her other family members, but a slew of other A-listers too.

Shania Twain, Alec Baldwin, Avril Lavigne, and Justin Timberlake are just a few on the long list of famous faces who have also publicly spoken out about battling the illness.

The disease is said to impact around 400,000 people in the US every year, while in the UK there are around 3,000 to 4,000 new cases yearly. However, the figures are thought to be much higher in reality, as according to GOV.uk, many cases are treated without formal laboratory confirmation.

We're talking about Lyme disease - a bacterial infection that can be spread to humans by infected ticks.

It's typically easier to treat if it's diagnosed early with one of the main symptoms being a 'circular or oval shape rash' forming around the tick bite.

Bella has been candid about her struggles with the disease since being diagnosed in 2012, saying that the 'excruciating pain' leaves her struggling to carry out simple tasks.

She previously told Vogue: "It’s hard to take a shower most days, which I promise guys, if you’re reading this, I shower every day. But sometimes, if I have one day off, if I can get in the shower and make myself breakfast, I see that as an accomplishment."

And the model isn't the only member of her family who suffers from Lyme disease - her brother Anwar and mother Yolanda also contracted it around the same time.

However, while suffering herself, Yolanda said in her own heartbreaking Instagram update this week that her 'pain cannot compare' to watching her daughter suffer.

She wrote: “As you will understand, watching my Bella struggle in silence has cut the deepest core of hopelessness inside me. The invisible disability of chronic neurological Lyme disease is hard to explain or understand for anyone.

"I try to lead by example on our Lyme journey but my own pain cannot compare to watching my baby suffer.”

Yolanda continued: "After many years I stopped sharing my personal story because I needed an energetic shift, time to focus on my healing rather than absorb other people’s opinions about my journey."

And now, a doctor has delved into how something as shocking as three family members getting Lyme disease can happen, including how rare it is.

Speaking to PEOPLE, Dr. Raphael Kellman, the founder of the Kellman Center for Integrative and Functional Medicine, explained that it's actually 'not uncommon that a few members of a family have Lyme disease'.

He told the publication: "But it’s not genetic, it’s because they share the same environment.

"A major cause could be imbalances in the billions of gut bacteria that we call the microbiome, those bacteria that are inside of our gut that outnumber us 10 to one and keep us healthy."

The doctor continued: "It’s not uncommon for the microbiome to be unhealthy, and if the microbiome is unhealthy in one member of the family, it’s likely that it’s unhealthy in another member of the family."

He added that if someone suffers from chronic Lyme disease, other underlying illnesses that weren't picked up on often contribute to the problem. And they could potentially be genetic, for example, low thyroid.