16th August 2023

A 30-year-old man presents with low-grade fever, a fine pink rash that started on his face and spread down his body, and tender swellings at the back of his neck

A 30-year-old man presents with low-grade fever, a fine pink rash that started on his face and spread down his body, and tender swellings at the back of his neck. He confirms that he was never vaccinated as a child.

What is the most likely cause of the swelling at the back of his neck?