Human T-lymphotropic virus type II in Japan

Area of Science:

• Virology
• Epidemiology
• Public Health

Background:

• Human T-lymphotropic virus type II (HTLV-II) is a retrovirus with a global distribution.
• Previous studies have not confirmed the presence of HTLV-II in Japan.
• Understanding the prevalence and origin of HTLV-II is crucial for public health strategies.

Purpose of the Study:

• To investigate the presence of HTLV-II infection in Japan.
• To identify the specific subtype of HTLV-II if detected.
• To explore the potential origin of HTLV-II in the identified case.

Main Methods:

• Serum specimens from 1,500 individuals with known human T-lymphotropic virus type I (HTLV-I) seropositivity were tested for HTLV-II.
• An additional 30,000 blood donors in Japan were screened for HTLV-II.
• Positive samples were further analyzed to determine the HTLV-II subtype.

Main Results:

• None of the 1,500 HTLV-I positive individuals tested positive for HTLV-II.
• One individual among the 30,000 blood donors screened was clearly seropositive for HTLV-II.
• This individual was confirmed to be positive for the HTLV-IIb subtype.

Conclusions:

• This study reports the first confirmed case of HTLV-II infection in Japan.
• The findings highlight the importance of continued surveillance for HTLV-II, even in regions where it was previously considered absent.
• Further research is needed to understand the transmission dynamics and origin of HTLV-II in Japan.