Increased viral load in people with tuberculosis (TB) may be coincidental to, rather than a consequence of, TB according to research presented at the XIV International AIDS Conference in Barcelona. If supported by further research this finding would contradict earlier studies that suggested that TB causes an increase in viral load.
The findings are likely to provoke considerable controversy in the field of HIV and TB treatment.
Investigators from the UK, USA and South Africa, examined the CD4 counts and viral loads of 1,400 HIV-positive mineworkers in South Africa over a 20 month period.
Baseline CD4 counts and viral load measurements were obtained. People with active TB or a previous AIDS-defining illness were excluded from the study. People who developed TB were treated with standard anti-TB drug therapy. Nobody in the study was provided with HAART.
The CD4 counts and viral loads of 17 people who developed TB were compared to a control group of 29 in whom no TB was detected. The average baseline CD4 count for both the TB and control groups was approximately 282 cells/mm3.
Although final viral load was higher in the TB group than the control group (91,000 copies/ml against 25,000 copies/ml), after adjustment for age, previous TB and baseline viral load, the difference ceased to be both clinically and statistically significant.
The investigators therefore concluded that an incident of TB was not associated with a significant increase in final viral load, and that a high viral load may be a risk factor for the development of TB. They added that viral load as a predictor of opportunistic infections warranted further investigation.
Day J et al. Does tuberculosis increase HIV viral load? Oral Presentation, XIV International AIDS Conference, Barcelona, 2002.