Human T-Cell leukaemia virus type 1(HTLV):A prospectus sero-epidemiological study, Lusaka, Zambia

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Kasolo, Chisaka Francis
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HTLV-1 is a retro-virus responsible for pathological disorders such as Tropical Spastic Paraparesis (TSP) and Adult T cell Leukaemia/Lymphoma (ATL). The main characteristic of HTLV-1 infection is its long period of latency and the age related sero-prelavence, especially in endemic areas. A sero-prevalence study of HTLV-1 at the University Teaching Hospital (UTH), Lusaka, Zambia, was done. Two populations namely healthy blood donors and Patients admitted to UTH with pathology thought to be related to HTLV-1 infection were included in this study. The objectives of this study were: 1. To establish the seroprevalence of HTLV-l among blood donors and patients admitted to UTH. 2. To find out whether the presence of HTLV-1 specific antibodies has any relationship with age, sex, HIV infection, Hepatitis B infection or with any particular pathology. Collected sera were tested for HTLV-l specific antibodies by using Particle agglutination test (PA) and Enzyme immuno-sorbent assay (ELISA). Serum positive on at least one test was subjected to a confirmatory Western Blot test, (Fijirebio) A total of 339 Blood donor and 107 patient sera were tested. A total of 26 sera were positive on PA test, 2 were positive on ELISA, and none on Western Blot. Of the sera testing positive on PA, 23 were from the blood donor sera and 3 were from patient sera. On ELISA test one sample each from the blood donor and patient sera was positive. When the 26 PA positive sera were subjected to Western Blot test, 15 were clear negative, 11 were indeterminants and none were positive. The commonest Protein band seen on Western Blot was the gag encoded protein P19. There was no significant relationship between HTLV-1 Indeterminants and HIV positive sera or between HTLV-1 indeterminants and Hepatitis B surface Antigen positive sera. The test method used showed varied specificity and sensitivity. The difference may have been due to a false positive result, arising possibly from high levels of circulating immune complexes commonly associated with frequent parasitic, bacterial and viral infections which are prevalent among populations in the tropics. The absence of specific anti-HTLV-1 antibodies following the use of confirmatory test, may be related to sampling technique employed in this study. On the other hand this could suggest a low prevalence of HTLV-l infection in Zambia as opposed to reports from other African studies. The indeterminant results obtained on Western Blot may support the long latency associated with HTLV-l infection. The indeterminants may be in the process of seroconverting and thus will need to be followed up over a period in order to establish their true status. Cross reactivity with other retroviruses could also be a likely cause of indeterminant results