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The importance of extended high viremics in models of HIV spread in South Africa

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Abstract

Recent studies found a substantial fraction of ‘extended high viremics’ among HIV-1 subtype C, the most common subtype in southern Africa. Extended high viremics are HIV infected individuals who maintain a high viral load for a longer time period than usual after the initial infection. They are more infectious during this period, and their infection progresses to full-blown AIDS and death much faster than usual. This study investigates the impact of extended high viremics on the spread of the HIV epidemic in South Africa. We develop a simple deterministic compartmental model for HIV infection that includes extended high viremics. As the available data on extended high viremics are limited, we parameterize this model using only the fraction of extended high viremics among new infections and the reduced life-span of extended high viremics. We find that without extended high viremics, the HIV prevalence in South Africa would have remained close to its 1990 level, instead of increasing to the current epidemic levels. We also find that the greater the fraction of extended high viremics among susceptibles, the greater the steady-state HIV prevalence and the more sensitive the steady-state prevalence is to the HIV transmission probability. These results suggest that extended high viremics have an impact on the HIV epidemic in South Africa; justify the need for comprehensive epidemiological studies since the current data is limited; and suggest that future models of HIV for southern Africa should explicitly model extended high viremics.

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Notes

  1. We thank a reviewer for suggesting that this can be proven.

Abbreviations

HIV:

Human immunodeficiency syndrome

RNA:

Ribonucleic acid

CHAVI:

Center for HIV Vaccine Immunology

ART:

Antiretroviral therapy

AIDS:

Acquired immunodeficiency syndrome

MSM:

Men who have sex with men

PrEP:

Preexposure prophylaxis

IDU:

Injection drug user

HAART:

Highly active antiretroviral therapy

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Acknowledgments

Ekkehard Beck was supported by a Northwestern Industrial Engineering and Management Science Graduate Fellowship. Mustafa Waheed was supported by a Northwestern University Summer Internship Grant.

The authors thank two anonymous reviewers for their constructive and helpful comments and ideas. We also thank Stephane Helleringer for the initial motivation and many helpful comments. Ekkehard Beck is supported by a Northwestern Industrial Engineering and Management Science Graduate Fellowship. Mustafa Waheed was supported by a Northwestern University Summer Internship Grant. We have no conflicts of interest to declare.

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  1. Department of Industrial Engineering and Management Sciences, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA

    Benjamin Armbruster, Ekkehard C. Beck & Mustafa Waheed

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  1. Benjamin Armbruster
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  2. Ekkehard C. Beck
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Correspondence to Ekkehard C. Beck.

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Armbruster, B., Beck, E.C. & Waheed, M. The importance of extended high viremics in models of HIV spread in South Africa. Health Care Manag Sci 17, 182–193 (2014). https://doi.org/10.1007/s10729-013-9245-z

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  • DOI: https://doi.org/10.1007/s10729-013-9245-z

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