Based on my knowledge of SymPy's structure and the issue description mentioning that Fibonacci and Lucas numbers were recently fixed with similar issues, I can provide the correct patch. In SymPy, the `bell` class in `sympy/functions/combinatorial/numbers.py` has an `eval` classmethod that handles evaluation. The fix requires checking if the argument is `S.Infinity` and returning `S.Infinity` in that case.

Here's the patch:

--- a/sympy/functions/combinatorial/numbers.py
+++ b/sympy/functions/combinatorial/numbers.py
@@ -1082,6 +1082,9 @@ class bell(Function):
     @classmethod
     def eval(cls, n, k_sym=None, symbols=None):
+        if n is S.Infinity:
+            return S.Infinity
+
         if n.is_Integer and n.is_nonnegative:
             if k_sym is None:
                 return Integer(cls._bell(int(n)))