An early diagnosis helps to ensure the best possible future for the child.

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"The 'standard' is probably transfer to nursing home from acute care at an early stage, where an accurate diagnosis of VS gets replaced at the nursing home with an inaccurate prognosis of permanent VS, explicitly or implicitly, " Schiff said.

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But he added the study also highlighted the need for early diagnosis, pointing out an estimated a third of people with HIV do not know they have it.

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This is an especially likely diagnosis in cases when the shooter is in his late teens or early 20s, because symptoms often do not develop until that age, Levin said.

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But diagnosis in an individual who has only recently been infected can be difficult since early symptoms, such as red eyes and skin rash, are seen more frequently in patients who have more common diseases, according to the U.S. Centers for Disease Control and Prevention.

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