Please solve the programming task below using a self-contained code snippet in a markdown code block.

A substring is a contiguous (non-empty) sequence of characters within a string.
A vowel substring is a substring that only consists of vowels ('a', 'e', 'i', 'o', and 'u') and has all five vowels present in it.
Given a string word, return the number of vowel substrings in word.
 
Please complete the following python code precisely:
```python
class Solution:
    def countVowelSubstrings(self, word: str) -> int:
```