If untreated, the illness can become severe.

若不加以治疗，病情就可能会变得很严重。

《牛津词典》

This can lead to death if untreated.

如不经治疗，可导致死亡。

youdao

If untreated early in the disease course, deformities may occur.

如果在发病的早期没有治疗，极有可能会造成畸形。

youdao

Lupus can be life threatening if left untreated.

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If left untreated,fistula can cause other health problems.

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If left untreated, sleeping sickness kills.

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Both diseases are manageable but not curable, and both can be deadly if untreated.

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Carried by contaminated water or food, it causes severe dehydration through diarrhoea and can prove fatal if untreated.

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If untreated, the person could experience nausea, hypertension, vomiting, coma, seizure and then death due to cardio-respiratory arrest.

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