Do you need to use definite article ("the") with &

[pink_08]

I saw this sentence in OG where they stress the use of "the". My question is - do you really need it when a restrictive pronoun
"that" is used.

Schistomiasis, a disease cause by parasitic worm, is prevalent in xyz, and it has become more widespread as irrigation projects have enlarged the habitat of freshwater snails that are the parasite;s hosts for part of its life cycle

[pink_08]

Correction ::

I saw this sentence in OG where they stress the use of "the". My question is - do you really need it when a restrictive pronoun
"that" is used.

Schistomiasis, a disease cause by parasitic worm, is prevalent in xyz, and it has become more widespread as irrigation projects have enlarged the habitat of the freshwater snails that are the parasite;s hosts for part of its life cycle