Answered by Shaykh Yusuf Weltch
Suppose a young Muslim girl killed lice on several pages of the Quran while reciting the Quran. She remembers it being before puberty but could have done it after she started menstruating.
She has repented after realizing it was disbelief, but what about the Quranic pages with blood stains? What should she do to right the wrongs? Should she go through the pages of the Quran, and how should she clean that as well? Is she a non-believer, and if so, how will she repent?
In the Name of Allah, the Most Merciful and Compassionate
It is not disbelief to kill lice on the Quran, even though one must abstain from doing so. This is even more true of a young child who has yet to reach legal maturity (puberty). Disbelief is to reject tenets of faith that one is required to believe in order to be a Muslim. [Tahawi, al-Aqida al-Tahawiyya]
The Messenger of Allah (may Allah bless him and give him peace) said, “The pen (i.e., of the book of deeds) has been raised (i.e., does not write the sins) for three: for the one sleeping till they awake, from the child till they reach puberty, and from the mentally challenge till they gain full sanity.” [Tirmidhi]
As for the time you killed lice after reaching puberty, you must repent from this action by being remorseful and resolving never to do it again.
Cleaning Lice Blood
The blood that comes from lice is not impure because it is not flowing blood. In the Hanafi school, blood is only impure if and when it is actually or potentially flowing. The blood in lice is not enough to be considered flowing. [Maydani, al-Lubab fi Sharh al-Kitab]
For this reason, even though it is considered unclean, it is not impure and does not have to be purified.
If you are able to remove the blood stains without further damaging the Quranic text, do so. If not, you may continue to use it despite the stains.
Hope this helps
Allah knows best
[Shaykh] Yusuf Weltch
Checked and Approved by Shaykh Faraz Rabbani