Trend in seroprevalence of HTLV-1/2 in Taiwanese blood donors-A 10-year follow-up.

OBJECTIVES: This study evaluated the Human T-lymphotropic virus (HTLV) screening policy impact on the HTLV seroprevalence from 2009 to 2018 as well as the differences between administrative districts in terms of prevalence distribution in Taiwan. BACKGROUND: Since February 1996, the Taiwan Blood Services Foundation (TBSF) had conducted HTLV screening of blood donors. The HTLV seroprevalence was 0.032% in 1999. MATERIALS AND METHODS: This cross-sectional study included donors' data collected from blood donation centres across Taiwan from 2009 to 2018. Enzyme immunoassay and Western blot assay were used for screening and confirmation of HTLV infections. In this study, the researchers calculated the trends in the HTLV rates of first-time and repeat donors across time as well as the HTLV prevalence distribution across the 22 administrative districts of Taiwan. RESULTS: Amongst 17 977 429 employed blood donations, 739 HTLV-seropositive donations (4.11 per 100 000 donations) were identified. The HTLV-positive donors were aged between 17 and 64 years, with a median age of 49 years. The overall seropositivity rates of first-time and repeat donors were 34.36/100 000 and 1.27/100 000. HTLV seroprevalence in first-time blood donors significantly decreased by 57% (crude odds ratio [95% confidence interval] (crude OR [95% CI]) = 0.43 [0.28-0.64]) within 10 years. A slight decline was also identified in repeat donors (crude OR [95% CI] = 0.73 [0.4-1.32]). Donors from different districts showed significantly varied prevalence. Most districts with high prevalence are situated in eastern Taiwan, for both donation types. Older blood donors were more likely to be infected with HTLV than younger ones in first time and repeat donors. Middle age donors (50-65 years) had an 18.47-39.65 greater risk than those aged <20 years. Significant higher risk of female was observed in both donation types. Amongst different age groups, first-time female donors increase 1.31-1.88 times infection risk and female in repeat donor group had 1.55-3.43 times greater risk. CONCLUSION: Over years of implementation of the HTLV blood donor screening policy by the TBSF, the HTLV seroprevalence of first-time donors has decreased consistently. Moreover, the HTLV seroprevalence of repeat donors has dropped considerably. This implies that the screening policy provides continued benefit. Females and older blood donors were more likely infected with HTLV than males and younger blood donors. The influence of age on infection was greater amongst first-time donors than amongst repeat donors. Therefore, appropriate measures should be taken to ensure public safety.

Dengue Virus Ribonucleic Acid Detection Rates in Blood Donors Correlate With Local Infection Incidences During a Dengue Outbreak in Taiwan.

BACKGROUND: Evidence for mitigation of transfusion-transmitted dengue informed by surveillance data is lacking. In this study, we evaluated the risk of positive dengue viral (DENV) ribonucleic acid (RNA) from blood transfusions during a large outbreak in Taiwan. METHODS: Serum collected from blood donors living in districts experiencing the dengue epidemic were tested for DENV RNA using a qualitative transcription-mediated nucleic acid amplification assay (TMA). The TMA-reactive specimens were further tested for immunoglobulin (Ig)M and IgG antibodies, nonstructural protein 1 (NS1) antigen, and viral RNA by reverse-transcription polymerase chain reaction. We estimated DENV RNA prevalence and the number of DENV infections among blood donors. RESULTS: A total of 4976 specimens were tested for DENV RNA, and 21 were TMA-reactive. The detection rate was 0.84 (95% confidence interval [CI], 0.15-4.73), 3.36 (95% CI, 1.31-8.60), and 6.19 (95% CI, 3.14-12.17) per 1000 donors in districts where the weekly dengue incidence was 5-50, 50-200, and 200 or more per 100 000 residents, respectively. Alanine aminotransferase screening only detected 4.4% of TMA-reactive donations. A total of 143 transfusion-transmitted DENV infections probably occurred during this outbreak, accounting for 9.2 in 10 000 dengue infections. CONCLUSIONS: Approximately 0.5%-1% of blood donations were DENV RNA positive in epidemic districts. The correlation of DENV RNA rates with dengue incidence may inform the design of effective control measures.