In the first part (episode 2.20) Foreman contracted the patient's illness after visiting his apartment. Since it was immediately apparent that Foreman and the patient had the same disease, the two cases were combined here and treated as one diagnosis.

Initial Symptoms: Man with euphoria + shot in the head
Diagnosis: Legionnaire's disease (House) + primary amoebic meningoencephalitis from Naegleria (House+Cameron)

Contributions by Team
House (6): Diagnosis for Legionnaire's disease, idea to biopsy Foreman's brain, idea to biopsy an infected animal, suggests that disease might be an amoeba, realizes that Legionnaire's disease was fighting amoeba, diagnosis for Naegleria
Chase (1): Points out that bullet may be magnetic so a MRI cannot be done
Cameron (2): Idea to perform angiogram, diagnosis for Naegleria
Foreman (2): Knowledge about bullets and police vests, idea to perform white matter biopsy

Notes: After some internal debate, I've decided to call Cameron's biopsy of Foreman a diagnosis. On the show this was represented as the last option if the team failed to diagnose Foreman in any other way, but it was indeed a diagnosis. Foreman was diagnosed by two separate methods at the same time.
Chase was correct in his suggestion that the initial patient had elevated carbon monoxide concentrations in his blood, but it appears this was unrelated to his symptoms and infections so Chase was not awarded credit for it.
House was given an error for destroying the MRI when he already knew the bullet was magnetic.

Labels: Season 2