For the past 200 years homoeopathic remedies known to cure and prevent threadworm infestations are:

Acon, Alum, Ambr, ASAR. CALC, CHIN, CINA, Colch, Croc, Dig, FERR, Graph, hyos, IGN, Kali-c, Mag-c, MAR, Merc, Nat-c, Nux-m, NUX-V, Petr, Phos, PLAT, Rhus, Sabad, Sabin, SCILL. Sep, SIL, SPIG, SPONG, SULPH, Valer, Zinc.

Rubrics like this one are not intended to be used as specifics for getting rid of a worm or any specific kind of parasite. The selection of the remedy is still based on the distinguishing features in the person who has (had) the worm. The infestation affects their whole constitution, not just their bum. Therefore, the most important symptoms on which to base a prescription will be qualifying modalities found in areas such as joint pains; abdominal discomfort; odour, frequency and consistency of stool; changes in appetite, thirst; sweats; itching; disruption in sleep patterns; and mood alterations. Concomitant symptoms may be found anywhere in the case which lead to the correct prescription. This will result in eradicating the worm infestation, restoring health, and most importantly, reducing the risk for future infections. It is not simply a matter of killing off the worm and larvae. It is the child who is ill because of the effects of infestation, treat the symptoms as the child expresses them. Not simply Teucrium = threadworms. If Teucrium does address the symptom similarity as expressed by the child then the child's whole constitution needs Teucrium, and Teucrium will be their constitutional remedy until at some later stage a new symptom picture emerges.
The worm can go find somewhere else to live or complete its life cycle. RIP.