From Perplexity: HIV viral load as biomedical optical illusion.
Rebecca Culshaw and Kary Mullis’s critique of HIV “viral load” can be summarized as considering it a biomedical optical illusion because they fundamentally challenge whether viral load tests truly measure the presence of active HIV virus in the body, asserting the results may reflect something quite different or misleading rather than actual viral particles.
Core Critiques of Viral Load
Both Culshaw and Mullis argue that viral load tests—for HIV, typically based on PCR or RT-PCR—do not detect whole, infectious viruses but instead amplify fragments of genetic material that could originate from multiple sources, including non-infectious viral remnants, cellular debris, or artifacts produced during laboratory processing. Mullis, the inventor of PCR, repeatedly emphasized that this technique is highly sensitive but cannot by itself distinguish between active infectious viruses and unrelated genetic sequences. Culshaw builds on this critique, noting that the correlation between “viral load” numbers and actual patient health outcomes is inconsistent and may reflect technical or conceptual errors in test interpretation.
The “Optical Illusion” Analogy
They liken viral load measurement to an optical illusion: something that seems to show more than is actually present. For Mullis, the tremendous amplification inherent in PCR can make a trivial genetic sequence appear abundant, producing a result that can be visually persuasive on a graph or report but is not biologically meaningful. Culshaw adds that faith in such metrics can lead scientists and doctors to misinterpret the course of infection, the effect of drugs, and the patient’s prognosis. Just as an optical illusion visually misleads by exploiting perception, viral load numbers can “biomedically” mislead by representing amplified noise rather than meaningful viral activity.
Implications of Their Critique
PCR methodology can amplify negligible fragments into apparently large quantities, which are then called “viral load” but do not directly represent live, replicating virus.
Clinical decisions based largely on viral load results may be guided by a misinterpretation of laboratory artifacts, rather than objective biological reality.
Both consider reliance on viral load dangerous, saying it could result in unnecessary, harmful treatment, and a distorted scientific understanding of HIV.
Their critique focuses on the gap between biomedical appearance and biological reality, making “optical illusion” a fitting metaphor
