The prevalence of human T‐lymphotropic virus type 1 & 2 (HTLV‐1/2) in South African blood donors

Abstract

Background and objectives Donated blood is not currently screened for human T‐cell lymphotropic virus (HTLV) in South Africa. Several small studies have detected HTLV‐1 in South Africa, but prevalence by geographic region or population group is unavailable. Materials and Methods We performed a large seroprevalence study of South African blood donors during 3 months in 2013. All geographic regions except the Western Cape were included, and Black and Coloured (local term for mixed race) donors were oversampled. Identity‐unlinked plasma samples were screened with the Abbott Prism HTLV‐1/2 assay, and repeatedly reactive samples were tested by the Inno‐LIA HTLV‐1/2 Score confirmatory assay. Odds ratios were calculated with multivariable logistic regression. Results Of 46 752 donors tested, 133 (0·28%) were initially reactive, 111 (0·24%) repeatedly reactive and 57 (0·12%) confirmed positive for HTLV‐1; none were HTLV‐2 positive. Prevalence was 0·062% weighted to annual blood donations but highly concentrated in the Black population group (OR = 20·24 CI: 2·77–147·88); higher in females than males (OR = 1·81 CI: 1·06–3·08); and in donors aged >50 years compared to ages 16–19 (OR = 6·4 CI: 2·95‐13·86). After controlling for age, sex and population group, there was no difference in prevalence between new and repeat blood donors or among geographic regions within South Africa. Conclusions We conclude that HTLV‐1 infection is widespread among the Black population of South Africa and its epidemiology is similar to other endemic areas. Because South Africa is increasing its recruitment of Black blood donors, the implications for blood screening require further consideration.

Health economic implications of testing blood donors in South Africa for HTLV 1 & 2 infection

“…The results of the HTLV seroprevalence study 12, intervention and treatment costs and TT efficiency data were used to estimate the economic implications of the four different strategies. We conducted a budget impact and cost‐consequence analysis in terms of infections and disease prevented in recipients, but did not conduct a cost‐utility analysis because health state preference weights (utilities) for HTLV infection are not available for South Africa or similar countries.…”

“…In a seroprevalence study 12, we evaluated interventions where donation screening is conducted using a chemiluminescent immunoassay (ChLIA) (Abbott, Pleasanton, CA, USA), with confirmation testing performed using InnoLIA (Innogenetics, Ghent, Belgium). Confirmed positive donors are assumed to be notified, counselled and referred for clinical management.…”

“…These decision drivers lead to the development of a risk assessment question “What HTLV screening strategy should be adopted by SANBS to mitigate the risk of TT‐HTLV to patients, achieve the best use of finite health funds in the country and limit psychological impact to blood donors?” The Blood safety, Health economics, Budget impact and simplified cost‐effectiveness, Operational risk and Ethical and Social concern/trust assessments were applied. The latter two are presented in the supplement and the HTLV seroprevalence study results are reported separately 12. Briefly, in the seroprevalence study an overall South African donor HTLV‐1/2 prevalence of 0·062% was found.…”

Multiple recombinant events in human T-cell Leukemia virus Type 1: complete sequences of recombinant African strains

“…From each sample, 250 ng of DNA was amplified under the following conditions: 98°C, 1 min; 40X (98°C, 5 s; 72°C, 20 s); 72°C, 1 min. Reaction tubes were prepared in a dedicated room outside the laboratory with a final volume of 50μl (DNA matrix, 250 ng); dNTP mix (Roche, Basel, Switzerland), 40 mM; 5X Phire II reaction buffer which contains 1.5 mM MgCl2 at final reaction concentration (Ozyme, Saint Quentin-en-Yvelines, France), 10 μl; Phire II hot start DNA polymerase (Ozyme), 2 U and 0.5 mM of each oligonucleotide primer (Eurofins MWG, Ebersberg, Germany) [17].…”

Molecular epidemiology, genetic variability and evolution of HTLV-1 with special emphasis on African genotypes

“…The proportion of the different HTLV-1 genotypes and subgroups is presented for each African country. This figure incorporates the information from papers of molecular epidemiology available on PubMed [20, 21, 23–27, 30, 41, 44–46, 55, 68, 135–144]. It also incorporates results from two manuscripts in preparation (Cassar et al and Filippone et al), notably concerning the situation in Benin, Sierra Leone, Western Sahara, and Madagascar, where no data were available to our knowledge.…”