Testing for acute HIV infection feasible but impact remains uncertain

Incorporating acute HIV screening into routine HIV testing at sexually transmitted infection clinics and HIV testing and counseling centers in Lilongwe, Malawi.

Rutstein SE, Pettifor AE, Phiri S, Kamanga G, Hoffman IF, Hosseinipour MC, Rosenberg NE, Nsona D, Pasquale D, Tegha G, Powers K, Phiri M, Tembo B, Chege W, Miller WC. J Acquir Immune Defic Syndr. 2015 Sep 29. [Epub ahead of print]

Background and objectives: Integrating acute HIV infection (AHI) testing into clinical settings is critical to prevent transmission and realize potential treatment-as-prevention benefits. We evaluated acceptability of AHI testing and compared AHI prevalence at sexually transmitted infection (STI) and HIV testing and counseling (HTC) clinics in Lilongwe, Malawi.

Methods: We conducted HIV RNA testing for HIV-seronegative patients visiting STI and HTC clinics. AHI was defined as positive RNA and negative/discordant rapid antibody tests. We evaluated demographic, behavioral, and transmission-risk differences between STI and HTC patients and assessed performance of a risk-score for targeted screening.

Results: Nearly two-thirds (62.8%, 9280/14 755) of eligible patients consented to AHI testing. We identified 59 persons with AHI (prevalence=0.64%) - a 0.9% case-identification increase. Prevalence was higher at STI (1.03% (44/4255)) than HTC clinics (0.3% (15/5025), p<0.01), accounting for 2.3% of new diagnoses, vs 0.3% at HTC. Median viral load (VL) was 758 050 copies/ml; 25% (15/59) had VL ≥10 000 000 copies/ml. Median VL was higher at STI (1 000 000 copies/ml) compared to HTC (153 125 copies/ml, p=0.2). Among persons with AHI, those tested at STI clinics were more likely to report genital sores compared to those tested at HTC (54.6% versus 6.7%, p<0.01). The risk score algorithm performed well in identifying persons with AHI at HTC (sensitivity=73%, specificity=89%).

Conclusions: The majority of patients consented to AHI testing. AHI prevalence was substantially higher in STI clinics than HTC. Remarkably high VLs and concomitant genital sores demonstrates the potential for transmission. Universal AHI screening at STI clinics, and targeted screening at HTC centers, should be considered.

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Editor’s notes: Acute HIV infection (AHI) is defined as the time from HIV acquisition to the appearance of detectable antibodies. Individuals with AHI are highly infectious, at least partly due to high viral load. Effective strategies to identify and treat people with AHI could increase the impact of treatment as prevention strategies, although there continues to be debate around the contribution of AHI to HIV transmission at population level.

This study in Malawi was part of a clinical trial evaluating the impact of behavioural and antiretroviral programmes during AHI. The study was done in four high-volume urban facilities. Pooled HIV RNA testing was performed on blood from participants with negative or discordant rapid HIV tests, according to the routine testing algorithm (discordant defined as one positive and two negative tests). Overall participation rates were relatively low, with only one in three individuals with negative or discordant rapid HIV tests included. Most of the loss was due to potentially eligible persons not being screened. The reasons for this are not mentioned, although more than a third that were screened did not consent. Overall, one in 150 participants had AHI. This was higher, at one in 100, at the STI clinics. The proportion with AHI was lower than previous research in Malawi, which could reflect a decline in HIV incidence at population level.

The potential risk of HIV transmission during AHI is highlighted by the characteristics of the people with AHI. Almost half had HIV RNA >6 log10 copies/ml, a similar proportion had genital ulcers, and only one in five reported condom use at last sex. The algorithm for focussing AHI testing, previously developed in the same setting, had suboptimal performance across all sites. 

This study adds to a body of evidence that suggests testing for AHI is feasible and will increase the overall yield of HIV testing by a small amount. We now need more evidence around whether programmatic implementation of AHI testing would have an impact on HIV transmission, and on the cost-effectiveness of different testing strategies. Data from treatment as prevention trials, none of which have included specific strategies to diagnose AHI, will also indirectly inform whether this should become a higher priority for public health programmes. 

Africa
Malawi
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