Search for human T-lymphotropic virus type I carriers among northeastern Chinese

Genetic typing and intrafamilial transmission of human T-lymphotropic virus type 1 in non-endemic areas of China

The origin and intrafamilial transmission of Human T-Lymphotropic Virus Type 1 (HTLV-1) in non-endemic populations such as China is still unknown. In this study, donors from blood banks/centers in China (including 28 provinces and Shenzhen city) during 2019 and 2021 were screened for HTLV-1/2 antibody, and all the reactive samples were tested using a line immunoassay (LIA) and quantitative polymerase chain reaction (qPCR). Samples that can be detected using qPCR were amplified and sequenced for the long terminal repeat (LTR) region. The positive donors were contacted to identify their relatives. As a result, 4,451,883 blood donors were totally tested, and 50 of them were confirmed to be HTLV-1/2 positive. Viral LTR sequences genotyped from 26 HTLV-1 carriers demonstrated that all had the HTLV-1a genotype, of which Transcontinental and Japanese subgroups accounted for half each. There were 17 family members of 11 index donors detected, and the HTLV-1 infection rate in the spouses of male index donors (83.3%, 5/6) was significantly higher than that in the husbands of female index donors (0.0%, 0/4). However, 7 children of HTLV-1 positive women were tested and found negative. Therefore, our findings indicated that HTLV-1 is spreading silently from high-endemic to low-endemic areas in China. To prevent further HTLV-1/2 transmission, an efficient HTLV-1/2 screening strategy and counseling of the virus carriers are essential.

Prevalence of human T-cell lymphotropic virus type-1 infection among blood donors in mainland China: a systematic review and meta-analysis of the last 20 years

Background: The southeastern coastal area of China has a high prevalence of HTLV-1 infection among blood donors. However, the estimation of HTLV-1 prevalence on a national and regional level is little known. The aim of this study is to understand and explore the estimation of HTLV-1 infection prevalence among blood donors on a national and regional level in mainland China by using a systematic review and meta-analysis. Study design and methods: All relevant publications of the past two decades (1998-2017), which were reported in both English and Chinese languages, were adopted and systematically assessed. The estimation of prevalence and its 95% confidence interval (CI) at the level of provinces/municipalities and overall were estimated using meta-analysis method. Results: From the 327 studies searched, 60 met the inclusion criteria. These were from 18 provinces and four municipalities and included 1,420,079 blood donors. The overall estimation of the HTLV-1 prevalence in blood donors was 0.169‰, and its 95% CI was 0.121‰-0.240‰. Conclusion: A disproportionate distribution of HTLV-1 infection among blood donors in different provinces/municipalities regarding its prevalence has been reported. This study recommends developing appropriate HTLV-1 screening strategies of blood donors in various regions of China considering regional prevalence, and cost-effectiveness.

History and update of HTLV infection in China

Human T-lymphotropic virus (HTLV) infection is a high risk factor for lymphoproliferative, inflammatory, and infectious disorders. The epidemiology of HTLV-I, II in industrialized countries has been intensively investigated, and mandatory screening of blood supplies for HTLV-I/II was implemented in mid-1980s in most developed and several developing countries, yet no expanding investigation has been executed in China so far and also been considered as a non-endemic region. However, Gessain et al. reported that the current number of HTLV carriers in the highly populated China is very probably much higher. Therefore, gaining insight into the epidemiology of HTLV infections is essential for avoiding HTLV-induced risk. To introduce the history and renew the HTLV infection in China, we reviewed literatures and conducted an investigation among blood donors in 9 provinces in China. Concluded from the historical and renewed data, the HTLV screen in China can be divided into three stages.

Prevalence of human T-lymphotropic virus type 1 infection among blood donors in mainland China: a meta-analysis

BACKGROUND

Human T-lymphotropic virus type 1 (HTLV-1) is considered to be the etiological agent of adult T-cell leukemia/lymphoma (ATL) and HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Blood transfusion is a common transmission pathway for HTLV-1. However, no surveys to determine the overall prevalence of HTLV-1 infection and HTLV-1 genotypes among blood donors on the Chinese mainland have yet been conducted.

METHODS

A systematic review and meta-analysis of the peer-reviewed literature on this topic was carried out. Data manipulation and statistical analyses were performed using the Comprehensive Meta Analysis Version 2.0 program.

RESULTS

Forty-four eligible articles involving 458525 blood donors were selected. Analysis revealed the pooled prevalences of HTLV-1 infection among blood donors in Fujian and Guangdong provinces to be 9.9/10000 (95% confidence interval (CI) 4.4/10000-22.2/10000) and 2.9/10000 (95% CI 1.7/10000-4.8/10000), respectively; there were only two cases of HTLV-1 infection among 204763 donors in other areas of the Chinese mainland. In addition, 40 of 42 (95.2%) HTLV-1 isolates belonged to the Transcontinental subgroup A of the HTLV-1 subtype A (Cosmopolitan subtype).

CONCLUSIONS

The prevalence of HTLV-1 infection among blood donors is low and restricted mainly to the provinces of Fujian and Guangdong. Most isolates belong to the Transcontinental subgroup within HTLV-1 subtype A.