A Rare Case of Rickettsia and Herpes Simplex Virus 1 Co-infection in a Male Patient with Meningoencephalitis

Herpes simplex viruses (HSVs) belong to the Herpesviridae family. Close contact is the primary mode of transmission for both HSV-1 and HSV-2, leading to a persistent lifelong infection. HSVs are widely recognized as causative agents of viral infections affecting the central nervous system, capable of presenting as both meningitis and encephalitis. Herpes simplex virus type 1 (HSV-1) is the predominant viral cause of encephalitis, accounting for the majority of cases. Here, a rare co-infection case of meningoencephalitis, associated with HSV-1 and rickettsia is described. A 42-year-old man presenting with non-remitting headache for 6 days, fever, sweating, and muscle aches was admitted to the Emergency Department. His Weil-Felix test was positive for Proteus OX2 indicating rickettsial infection. Therapy started promptly however patient’s condition deteriorated. Cerebrospinal fluid (CSF) analysis revealed lymphocytic pleocytosis, and elevated protein concentration. CSF molecular analysis was positive for HSV-1. His cranial MRI indicated cytotoxic edema and gyral enhancement at the right temporal lobe. He was administered acyclovir for 14 days during hospital stay and was successfully discharged. This case report highlights that HSV-1 meningoencephalitis can co-occur with rickettsia infection in immunocompetent individuals, and co-infection with other agents should always be considered to avoid the progression of the disease.