How could this happen? 15- year-old has 15 maggots removed from her mouth

A schoolgirl who went to the dentist with swollen gums was horrified when 15 maggots were removed from her mouth.
Ana Cardoso, 10, was taken to the clinic after complaining about feeling a tingling sensation in her gums and things "moving around".
Stunned mum Adriana, 35, said: "She had been saying for a few days that she felt something moving around in her mouth and at first I thought she was joking.
Maggots in girl's teethCEN
Horror: The girl 'felt something moving around' in her teeth
"I couldn’t see anything and she didn’t seem to be in pain

But then it started getting worse and no matter how much we brushed her teeth she said she still felt something.
"I know my daughter and she is not one to make up stories or lie so eventually I took her to see a dentist.
"I couldn’t believe it when they said she had a disease and then started pulling the maggots out. I thought I was going to be sick."
Ana was diagnosed with a rare form of Oral Myiasis, a fly lava maggot infection that grows in humans and animals.
A spokesman for the dental surgery in the Brazilian capital Brasilia said: "There were 15 maggots in her mouth so we videoed the removal for our records as it is a fairly rare occurrence.
"We also wanted to show the girl's family what had happened and warn others."
The 2.43 minute video shows Ana’s reaction as a surgeon in white gloves takes out one maggot at a time with a pair of tweezers.
Mum Adriana added: "She was actually very calm throughout the whole process but I suspect that was more out of helplessness - I mean where could she run to?"