A mum is organising a day of wearing purple to raise awareness of a form of childhood arthritis which affects her daughter.

Letitia Hirsch, three, has polyarticular juvenile idiopathic arthritis, or JIA – a disorder which causes joint problems and is thought to affect one child in every 1,000.

Extreme heat or cold as well as humidity can trigger pain and swelling and it also affects her autoimmune system, meaning chicken pox or similar illnesses pose a much bigger threat.

Her mum Sarah Evans, of Harris Road, Sheerness, said: “She’s generally quite happy. She seems to be a normal three-year-old.

She loves running around and playing with the other children but when it’s time to stop, some time she’ll be in tears because of the pain in her joints.

“So she has ice packs and wheat bags. She also has a bath spa.”

Other problems caused by the youngster’s JIA included soiling her nappies up to 10 times a day when she was younger and there is a chance it could lead to bowel disease later in life.

It may also cause uveitis, an illness which affects the eyes and can lead to glaucoma and blindness in some cases.

Letitia was recently cleared of this but she has to have regular checks with an ophthalmologist.

Miss Evans, 36, said: “It was very difficult at first but it’s something you adjust to, as I suppose you would with any child with an illness.

“She has to have medication every morning and evening and sometimes when she’s in pain. She used to have intensive physio but now it’s more like three times a week.”

The mum of five is alerted by Letitia’s nursery if any of the other children have contagious diseases or infections.

Miss Evans has joined forces with a mother from Corby, Northamptonshire, Lynette Haselip, whose daughter also has JIA in an attempt to spread awareness.

They are urging people to post selfies of themselves wearing the colour purple on Facebook and Twitter with the hash tag #wearpurpleforjia on Friday, June 19, to coincide with the end of Rheumatoid Arthritis Week.

Miss Evans added they are hoping the social media campaign will go viral in the same way as the initiative for ALS did last year, “without people having to pour buckets of water on their heads”.

People are also asked to donate to the Children’s Arthritis Trust, either directly or by going to www.justgiving.com/Lynette-Haselip.