Complex sentence: Soil-transmitted helminthiasis (STH) is a sub-group within the group of helminth infections (helminthiasis) which is caused specifically by those helminths which are transmitted through soil contaminated with faecal matter and are therefore called soil-transmitted helminths.
Split into simpler sentences: Soil-transmitted helminthiasis (STH) is a sub-group within the group of helminth infections (helminthiasis). It is caused specifically by those helminths which are transmitted through soil contaminated with faecal matter and are therefore called soil-transmitted helminths.