。
Just thinking about it gives me the chills.
Literal
Thought [just-with-だけで] pinworm [subject-が] runs-[feminine-わ].
虫唾が走る is a colorful idiom literally 'pinworms run (through one's body),' meaning 'to feel physical revulsion, get the chills, be disgusted.' 虫唾 was originally a folk term for something like stomach acid or pinworms — the sensation of it 'running' gives the disgusted feeling. 考えただけで ('just from thinking') is the minimal condition construction. Feminine わ at the end.