Abstract:

Background: In many resource-limited settings patients on ART are monitored by immunological and clinical criteria because viral local testing in not readily available. This may lead to misclassification of individuals or to a delay in switching to 2nd line regimens. In sub-Saharan Africa factors associated with virological failure have been studied but they differ widely between settings, hence searching for factors relevant to our own setting is important for patient management. A recent study in our schistosome-endemic are showed that schistosomiasis was significantly associated with immunological failure, and it was unclear whether it is associated with virological failure as well.

Objectives: The primary objective was to determine performance of the World Health Organization (WHO) immunological and clinical criteria against the gold standard virological criteria for treatment failure. Another aspect of the study was to determine factors associated with virological failure and impact of schistosomiasis on viral load and virological failure.

Methodology: This was a cross-sectional study that enrolled patients who were diagnosed to have ART treatment failure by WHO immunological and clinical criteria at Bugando Medical Centre and Sekou Toure hospital, Mwanza, Tanzania. The participants were interviewed to obtain demographic, ART and CD4 characteristics, as well behavior and other risk factors for ART treatment failure and schistosomal infection. Each individual was required to provide stool and urine samples for investigating schistosomal eggs. Blood samples were taken for haemoglobin, schistosome circulating anodic antigen (CCA) and HIV viral load.

Results: Among a total of 191 participants, median age was 41 [36-47] years and 63 % were female. Fifty eight percent were below the WHO limit for virological treatment failure and hence could have been misclassified, while 50% had undetectable viral loads. Sensitivity, specificity, PPV and NPV of the various WHO immunological criteria were 30-58%, 33-59%, 10-40% and 33-94% respectively; those participants who had >50% drop from peak CD4 were least likely to have virological failure. Factors significantly associated with virological treatment failure were younger age (<30 years), university education level, lower current CD4 count, anemia (haemoglobin<9g/dl) and recurrent or new pruritic purpura eruptions (PPE), while CD4 drop >50% was negatively associated with virological failure. Schistosomiasis co-infection was identified in 35% of participants by CAA testing, but was not significantly associated with virological failure. However, we did find a significant positive correction between CAA and viral load.

Conclusion: The performance of WHO immunological failure criteria is poor to detect and predict virological failure. Continuing the use of these criteria for ART monitoring will lead to high rate of misclassification and delay switching to 2nd line factors associated with virological failure were younger age, university education, low peak and current CD4, and as well clinically those patients with having PPE and anemia. Active schistosome infection was not associated with virological failure. The main limitation of this cross-sectional study was that viral load testing was only done once hence some elevated viral load measurement may not have represented true virological failure. But y linear regression there was a significant positive correlation between CAA and viral load values, suggesting that schistosome infection could increase HIV transmission and speed the progression of disease.