A tick bite on a US man’s scrotum led doctors down a diagnostic rabbit hole that eventually resulted in the second human diagnosis of babesiosis in Australia.

Doctors checked back through his extensive travel history to finally isolate the cause of his illness, a hitchhiking deer tick from a camping expedition in Maine, just before he had headed to the NT.

The 62-year-old presented to the ED at Royal Darwin Hospital after six days of febrile illness including headache, fatigue, malaise and anorexia.

He had previously presented to a GP, who diagnosed flu-like syndrome and advised simple analgesia, but his illness did not improve.