Background & aim: Human lymphotropic retrovirus type 1( HTLV1) is the first known virus which could cause serious diseases such as adult leukemia- lymphoma T-cell lymphoma (ATL) and Tropical Spastic (TSP). On the other hand, due to the HTLV1 similarity symptoms in patients with multiple sclerosis symptoms in Khorasan as the region's endemic, knowledge and understanding of the virus and the disease is necessary in other areas as well. The aim of the present case report study was to investigate the HTLV1 infected virus with similar multiple sclerosis symptoms in a Non-endemic area.

Case presentation: The patient in the present case report study was a 56 years old women which her illness was early diagnosed as MS (multiple sclerosis).  No sign of improvement in therapy period was observed. Therefore, due to limited symptoms in lower extremities and sphincter dysfunction, her serum and cerebrospinal fluid for the presence of antibodies anti HTLV1 was evaluated. The presence of Abs with clinical symptoms, cause diagnosis of the virus in the patient.

Conclusion: This patient was referred with symptoms of progressive paraparesis spatic and at first her disease was mistakenly diagnosed as MS.  Due to lack of response to treatment and atypical clinical symptoms related to MS and Khorasan province after two years the patient was diagnosis as HTLV1. It is recommended to apply differential diagnosis of MS in specific geographic regions, such infection  as HTLV1 especially in endemic areas should be considered.