ap ill oma - associ ated ▁t urt le ▁her pes vir us ▁( FP TH V ), ▁and ▁now ▁called ▁Ch el on id ▁al ph ah er pes vir us ▁ 5 , ▁is ▁believed ▁to ▁be ▁the ▁caus ative ▁agent ▁of ▁the ▁disease . ▁The ▁reason ▁for ▁this ▁belief ▁is ▁because ▁nearly ▁all ▁t issue ▁samples ▁tested ▁from ▁t urt les ▁with ▁les ions ▁carry ▁gen etic ▁material ▁of ▁this ▁her pes vir us , ▁varying ▁between ▁ 9 5 ▁and ▁ 1 0 0 % ▁depending ▁on ▁different ▁studies ▁and ▁locations . ▁The ▁DNA ▁loads ▁of ▁the ▁her pes vir us ▁in ▁tum our ▁t issue ▁are ▁ 2 . 5 – 4 . 5 ▁log arith ms ▁higher ▁than ▁in ▁un in fect ed ▁t issue . ▁The ▁F P TH V ▁her pes vir us ▁has ▁been ▁found ▁in ▁t urt les ▁free ▁from ▁F P ▁and ▁this ▁suggest ▁that ▁the ▁F P ▁pro gression ▁is ▁mult ifact orial ▁and ▁might ▁even ▁involve ▁some ▁sort ▁of ▁tum our - prom oting ▁phase . ▁The ▁global ▁pre val ence ▁of ▁the ▁disease ▁also ▁suggests ▁a ▁mult ifact orial ▁cause , ▁rather ▁than ▁single ▁factors ▁or ▁agents . ▁Possible ▁factors ▁include ▁some ▁par as ites , ▁b acter ia , ▁environmental ▁poll ut ants , ▁U V - light , ▁changing ▁water ▁temper atures ▁and ▁bi ot ox ins . ▁Even ▁phys i ological ▁factors ▁such ▁as ▁stress ▁and ▁imm un olog ic ▁status ▁appear ▁to ▁be ▁associated ▁with