The identification and distinction of the pathological conditions underlying acute psychosis are often challenging. We present the case of a 35-year-old ranger who had no history of acute or chronic infectious disease or any previous neuropsychiatric symptoms. He arrived at the Psychiatry Clinic and was admitted as an emergency case, displaying bizarre behavior, hallucinations, paranoid ideation, and delusional faults. These symptoms had first appeared 7 days earlier. An objective examination revealed abnormalities of behavior, anxiety, visual hallucinations, choreiform, and tic-like facial movements. After the administration of neuroleptic and antidepressant treatment, he showed an initial improvement, but on day 10 entered into a severe catatonic state with signs of meningeal irritation and was transferred to the intensive care unit. An electroencephalogram showed diffuse irritative changes, raising the possibility of encephalitis. Taking into consideration the overt occupational risk, Borrelia antibody tests were prescribed and highly positive immunoglobulin (Ig)M and IgG titers were obtained from serum, along with IgG and antibody index positivity in cerebrospinal fluid. In parallel, anti-N-methyl-D-aspartate receptor antibodies and a whole battery of other autoimmune encephalitis markers showed negative. A complex program of treatment was applied, including antibiotics, beginning with ceftazidime and ciprofloxacin - for suspected aspiration bronchopneumonia - and thereafter with ceftriaxone. A gradual improvement was noticed and the treatment continued at the Infectious Disease Clinic. Finally, the patient was discharged with a doxycycline, antidepressant, and anxiolytic maintenance treatment. On his first and second control (days 44 and 122 from the disease onset), the patient was stable with no major complaints, Borrelia seropositivity was confirmed both for IgM and IgG while the cerebrospinal fluid also showed reactivity for IgG on immunoblot. On the basis of the putative occupational risk, acute psychotic episode, and the success of antibiotic therapy, we registered this case as a late neuroborreliosis with atypical appearance.