However, such method was limited by the availability of samples, technologies and resources, and could only broadly distinguish between recent and non-recent infections. Other studies have used biological approaches such as tests for recent infection (TRIs), recent infection testing algorithm (RITA) and BED HIV-1 Capture Enzyme Immunoassay to determine whether a diagnosed individual was recently infected. While a few studies have introduced modified back-calculation method that incorporated diagnosed HIV cases, the estimation of new infections was often made at aggregate level. The widespread use of HAART since the mid-1990s has however distorted the natural history of HIV/AIDS.
In the past, HIV incidence back-calculated by computing the number of diagnosed AIDS cases and distribution of incubation period between HIV infection and AIDS diagnosis was a reasonable approach. Quantification of the undiagnosed intervals is, therefore instrumental for reconstructing epidemic curves for supporting the effective monitoring of the epidemic and evaluating interventions introduced. Epidemiologically, the lag time between infection and diagnosis is an obstacle for proper interpretation of epidemic curves plotted by annual numbers of new HIV diagnoses, as recent and past infections could not be differentiated. Therefore, the status of being undiagnosed, the first stage of the care continuum cascade, constitutes a major gap for achieving effective interventions through HAART.
Moreover, good coverage of highly active antiretroviral treatment (HAART) could reduce the population viral burden, thereby minimizing the transmission risk, as concluded in the HPTN052 study. After HIV diagnosis, transmission risk may fall as a result of self-initiated reduction of risk behaviours and/or interventions. Their transmission risk can be substantial in the presence of a high partner exchange rate and the practice of unprotected sex. Within this undiagnosed period, infected individuals are not aware of their HIV status. An HIV-infected individual remains undiagnosed, unless he/she receives an HIV test for different reasons.
First author NSW is supported by Guangdong Provincial Centers for Skin Diseases and STI Control, the UNC-South China STD Research Training Center (FIC1D43TW009532-01) and the Fogarty International Center.Ĭompeting interests: The authors have declared that no competing interests exist.īefore progression to AIDS, HIV infection is largely asymptomatic in the period since seroconversion, the duration of which can be as long as 7 years or more in the absence of treatment. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.ĭata Availability: All data used in the study have been included in the paper and its Supporting Information files.įunding: This study was supported by a grant approved by the Council for the AIDS Trust Fund, Hong Kong Special Administrative Region Government (project code: MSS229R). Received: MaAccepted: JPublished: July 12, 2016Ĭopyright: © 2016 Wong et al. PLoS ONE 11(7):Įditor: Kok Keng Tee, University of Malaya, MALAYSIA Citation: Wong NS, Wong KH, Lee MP, Tsang OTY, Chan DPC, Lee SS (2016) Estimation of the Undiagnosed Intervals of HIV-Infected Individuals by a Modified Back-Calculation Method for Reconstructing the Epidemic Curves.