Screening for Acute HIV Infection in Fortaleza,Brazil: What Would Be the Best Strategy?

Introduction

The last two decades have been marked by a global reduction in morbidity and mortality related to human immunodeficiency virus (HIV) infection, although there have been significant regional differences.1–3 The evolution of epidemiological indicators in Brazil has also shown similar regional differences. In the last decade, the annual detection rate of new HIV cases in Brazil has been relatively stable, with a 17% reduction in acquired immunodeficiency syndrome (AIDS) detection per population of 100,000.4,5 In the same period, it was observed that in the more economically favored South and Southeast regions, there was a reduction of 34% and 30%, respectively. On the other hand, the North and Northeast regions, which are less economically favored, showed an increase in the detection rates of new AIDS cases, with respective increases of 24% and 11%.4 Moreover, in the North and Northeast, late diagnosis is still common, often associated with the occurrence of opportunistic diseases, resulting in increased HIV-related mortality indicators. Thus, national data report that mortality related to HIV/AIDS was reduced by 9.5% between the years 2000 and 2014. In the same period, there was an increase in 47.8% of this indicator in the state of Ceará and of 83.3% in the country’s Northeast region.6

It is believed that such indicators are strongly influenced by the delay of the timely diagnosis of HIV infection. Studies have shown a disproportionate participation of acute HIV infection (AHI) cases in community transmission,7–10 which may contribute to 10–50% of new infections.11–13 Estimates suggest that the HIV transmission rate follows a U-shaped curve pattern, which is higher in the acute and late phases.13 The phenomenon seems to be related to higher viral load levels and immune response characteristics, especially the delayed maturation of the response mediated by neutralizing antibodies, in addition to behavioral and virologic aspects (viral fitness).14,15 Furthermore, the probability of transmission of viruses with antiretroviral resistance mutations has also been shown to be higher in the context of acute or recent infection.16 Recent studies have concluded that the failure to timely diagnose AHI may have been one of the main causes of the disappointing results obtained by the universal test-and-treat strategy, considered fundamental for achieving the UNAIDS 90-90-90 target.17–22 For these reasons, the diagnosis of HIV infection in the acute phase and followed by the quick introduction of antiretroviral therapy emerge as critical public health interventions in the pursuit of reducing community transmission, preserving the integrity of the immune system, and reducing morbidity and mortality associated with the disease.23–26

Rapid tests for HIV have facilitated and expanded the access to diagnosis, with the third-generation modality being the most used in Brazilian voluntary counseling and testing centers (VCT). Despite having a high sensitivity, such tests are not able to identify AHI.27–29 In this sense, the decision to incorporate nucleic acid amplification tests (NAATs) in screening algorithms has been progressively considered in an attempt to enable the diagnosis of AHI.30 The use of sample pools and the development of targeted testing algorithms have been considered as an alternative approach to increase the yield and reduce the costs of this strategy. Few studies have been developed in low- and middle-income countries. Fortaleza is the fifth most populous city in Brazil, with an estimated 2,686,612 inhabitants.31 It is located in the Northeast region, characterized by lower socioeconomic development indicators, and has only one VCT. The objective of our study was to evaluate the effectiveness of universal screening for AHI in users of VCT, using NAAT investigation and to determine factors associated with the diagnosis of acute or chronic HIV infection.

Materials and Methods

From July 2017 to July 2018, we conducted a prospective cross-sectional study of participants recruited soon after they were given the results of their serological screening conducted at the sexually transmitted infections (STI)/AIDS VCT in Fortaleza-CE, Brazil. We also performed a retrospective evaluation of the users of the service in the same period.

The inclusion criteria for the prospective study were as follows: (1) at least 18 years old and (2) with nonreactive or indeterminate results in the third-generation rapid test for HIV. Individuals who had contraindications to blood sampling or were unable to understand the informed consent form were excluded. Candidates were sequentially invited only during the three shifts of the week when venous blood collection was available. In the retrospective study, all users who underwent rapid HIV testing during the study period were included.

Data from the prospective study participants were obtained through interviews using a structured questionnaire. Retrospective data on service users were obtained by consulting the standard care forms of the Information System of the VCT, a tool standardized by the Brazilian Ministry of Health.

In the service routine, blood samples were obtained by digital puncture and submitted to the HIV Tri Line test (Bioclin^®, Quibasa, Belo Horizonte, Minas Gerais, Brazil), which consists of a third-generation immunochromatographic method that detects immunoglobulin (Ig)M and IgG antibodies to HIV-1 and HIV-2. Reactive results were confirmed by Bioeasy-Alere^® (Alere Inc., Waltham, MA, USA) or TR DPP^® HIV-1/2 tests (Bio-Manguinhos, Rio de Janeiro, State of Rio de Janeiro, Brazil). The serological screening was also performed with tests for hepatitis B (HBV; VIKIA^® HBsAg, Biomerieux, Marcy-l’Étoile, France), hepatitis C (HCV; Bioeasy-Alere^® [Alere Inc., Waltham, MA, USA]), and syphilis (Bioeasy-Alere^® [Alere Inc., Waltham, MA, USA]). Some individuals were not tested due to temporary lack of supplies or prior knowledge of their serological status.

The participants of the prospective study had venous blood drawn soon after recruitment. Five mL of blood from each patient was collected in a plastic tube containing dipotassium ethylenediaminetetraacetic acid anticoagulant and polyester gel. Samples were centrifuged at 2700 rpm for 10 minutes and stored at 2–8°C for later analysis by NAAT HIV/HCV/HBV (Bio-Manguinhos, Rio de Janeiro, State of Rio de Janeiro, Brazil). The AHI was defined as the participant obtaining viral detection in the NAAT after a nonreactive or indeterminate result in the rapid test.

Data were collected using a standardized form and later entered into the Epi Info^® version 7.0 database (Centers for Disease Control and Prevention, Atlanta, GA, USA). For the bivariate analysis, the Chi-square or Fisher’s exact test was used for categorical variables, and the Mann–Whitney U test for continuous variables. The magnitude of the association was expressed through crude prevalence ratios (PRs) with 95% confidence intervals (CIs). A significance level of 5% was considered for all statistical tests. The multivariate analysis was performed using the Poisson regression model, and only those with a significant association (p < 0.05) were included in the final model. The variables “number of partners (male/female)” and “types of partnership (male/female)” were excluded from the model because they presented collinearity with other variables. The average number of years of study was estimated from the table of data grouped according to classes. Statistical analysis was performed using the Statistical Package for Social Science (SPSS Statistics®) software, version 23.0 (IBM Corp., Armonk, NY, USA), and Microsoft Excel^® 2018 spreadsheets (Microsoft, Redmond, WA, USA) were used to format the results into graphs and tables.

The project was submitted and approved by the Ethics Committee on Human Research, an Internal Review Board of the University of Fortaleza on November 30, 2016 (registration number [CAAE] 05703513.4.0000.5052). The participants were informed about the study objectives and invited to participate after reading and signing the informed consent form.

Results

During the study period, 7,345 consultations were performed for serological screening, and 7,166 forms were filled out. A total of 6,943 users were tested for HIV, with positive results in 344 (5%) cases. Of the 6,142 rapid tests performed for HCV, 24 (0.4%) were reactive. For HBV, 5,573 tests were performed, with 22 (0.4%) reactive results. For syphilis, 5,550 exams were performed, with reactive results in 904 (16.3%) ( Figure 1). The difference observed between the cases attended and the tests performed was due to a temporary lack of supplies or prior knowledge of the serological status.

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Figure 1.

Flowchart of the retrospective study group, including VCT users during the study period, presenting the distribution of rapid test (RT) results for human immunodeficiency virus (HIV), syphilis, and hepatitis B and C (HBV and HCV), in addition to the group selected for the prospective study (NAAT screening). VTC, voluntary counseling and testing center; NAAT, nucleic acid amplification test.

Discussion

Our study evaluated the annual registry of the only VCT of the fifth most populous city in Brazil and noted a prevalence of 5% HIV infection among its users. We identified the following to be factors associated with HIV infection: MSM, first visit to the service, number of partners (>two per year), recent STIs, and a positive rapid reactive test for syphilis. Random screening for AHI using a molecular test (NAAT) was performed in individuals with nonreactive or indeterminate results for HIV, and no case of AHI was detected.

Service users were predominantly young adults, male, single, and brown-skinned, seeking the service for the first time; this represents the general population profile and people living with HIV in our country. Comparing the male to female ratio of service users (1:2.2) and individuals diagnosed with HIV infection (1:8.8) showed a significant predominance of males. The proportion of individuals who identified as homo- or bisexual (70.7%) was almost entirely represented by male individuals. National data for the year 2018 reported a lower sex ratio (1:2.6) and a lower proportion (39.5%) of infections related to the homosexual and bisexual exposure category.4 Such findings are compatible with local epidemiological data, characterized by less relevance of parenteral transmission and a predominance of sexual transmission, especially in the MSM population. In addition, the study population had several risk factors for HIV infection, such as multiple partners, low adherence to condom use, and practice of anal sex.

Another peculiarity that drew attention was the high proportion of users with higher educational attainment, which had no significant difference with that of the group diagnosed with HIV infection. The average years of schooling in our sample were estimated to be 10.4 years, while in Brazil, among individuals over 25 years of age, it was 9.3 years. The Northeast region has an even lower average (7.9 years). The proportions of individuals with no schooling or with a higher educational attainment (incomplete or completed) in our study are 1.1% and 38.5%, respectively, while the national data revealed 6.9% and 20.2%, respectively.32 This finding suggests that the passive surveillance strategy may not offer universal coverage, having difficulty reaching the population with greater vulnerability.

Our study could not identify cases of AHI among 336 individuals. This sample represented 5.1% of users with negative or indeterminate results in serological screening. These were tested by the universal screening strategy in individual samples, suggesting the low effectiveness of this approach in our reality. According to the local epidemiological reality and criteria used, the studies available in the literature present variable results. One of the first studies to perform universal screening, using pools of samples from users of VCTs, identified four cases of AHI among 8,155 individuals tested (ratio 1:2039).33 Another study from the same group tested 108,642, identifying 23 cases (ratio 1:4724) and subsequently tested 2,127 individuals, identifying four cases of AHI (ratio 1:532).34,35 On the other hand, a study in a high-prevalence area in South Africa (48%) identified 11 (1.1%) cases of AHI among 994 individuals with negative or indeterminate serology (1:90 ratio).36 Like many Western countries, the epidemiological situation in Brazil is characterized by its essential concentration in certain populations of high vulnerability. The prevalence in the Brazilian population is estimated to be 0.6% at the time of writing. However, much higher proportions were observed in specific subpopulations, such as female sex workers (6.2%), MSM (13.6%), and intravenous drug users (23.1%).37 Such characteristics may explain the low effectiveness of the strategy used, suggesting greater effectiveness of the targeted screening strategy.

Our study identified as factors associated with HIV infection to belong to the MSM category, first visit to the service, number of partners (>2 per year), recent STI, and rapid reagent test for syphilis. Many more recent studies have sought to develop targeted screening strategies for AHI, seeking to increase the efficiency and effectiveness of this approach. Most of them have directed such an approach to the MSM population. A recent systematic review with meta-analysis evaluated different AHI screening strategies in MSM individuals, observing an overall yield of 6.3%, which is significantly higher when the targeted strategy was used (11.1%) and lower with the universal strategy (1.6%).38 The risk scores studied were usually based on epidemiological criteria (age, number of sexual partners, unprotected receptive anal intercourse, exposure to HIV-infected partner, STIs, and illicit substance use) or on the presence of symptoms suggestive of AHI (fever, diarrhea, and fatigue), with symptom-based scores appearing to have greater accuracy in estimating the risks for AHI.38 However, it is likely that selection criteria for targeted screening should be established and/or validated in specific regions and countries and according to their individual epidemiological characteristics.

In this sense, we believe that the epidemiological or behavioral variables identified in our study as associated with the serological diagnosis of HIV infection should be considered a starting point for elaborating scores for local use. On the other hand, more than half (56.9%) of our sample of patients reported clinical manifestations that could be attributed to ARS, and none of them effectively had AHI. Studies conducted in countries with a higher prevalence of undifferentiated acute febrile illnesses, such as malaria, dengue, or other arboviruses, demonstrated that ARS cases can be easily confused with more common etiologies.39–45 It is possible that in this reality, criteria based on clinical manifestations have different accuracy in identifying priority cases for AHI screening.

We believe that our study is a significant contribution because of the scarcity of information related to AHI screening in our environment, representing the reality of a less favored region of a middle-income country where epidemiological indicators of new infections and mortality persist with an upward trend and at odds with the national and regional trend.6 Our research site consists of the only VCT in the fifth most populous city in Brazil, providing good representativeness of the information. On the other hand, the main limitation of our study is its retrospective design when related to serological screening for HIV. This feature resulted in the limited availability of records for some variables requested in the VCT form. We also included only a limited number of individuals in the prospective study that underwent molecular screening. Our limitations resulted from the restricted size of the research team and the availability of venous blood collection in the service during only three morning shifts each week. Irregularity of the supplies to the service resulted in the restricted provision of the four rapid tests to some users.

Finally, our study suggests the possibility that the passive surveillance strategy, which was performed in the VCT, may not be able to reach the entire population with low schooling. This suggests that the creation of new centers or the structuring of active surveillance system could increase the capacity of the health system in the earlier and more timely identification of cases of AHI or recent HIV infection, thus favoring better results in the control of new infections and morbidity and mortality indicators. We also concluded that the strategy of universal screening for AHI by molecular methods proved to be ineffective in our clinical settings. We suggest that new studies be conducted for the development and validation of targeted screening systems. Finally, screening should be prioritized for those in the MSM population, with the presence of the following criteria: first-time visit to the service, number of partners (>two per year), recent STIs, and rapid reagent test for syphilis.

Conclusion

Universal screening for AHI using molecular methods yielded a low performance in our study, suggesting low effectiveness for use in clinical settings. The factors associated with the serological diagnosis of HIV infection (MSM, first visit to the service, >two partners per year, recent STI, and reagent rapid test for syphilis) may help elaborate a prioritization score to be developed and validated in our region.

Author Contribution: Conception and design: EMM, LFMB, DML, and JKBC; acquisition, analysis, or interpretation of data: LPB, NGG, LPA, ASMM, and RKAC; contributed reagents/materials/analysis tools: RKAC and LMBC; drafting/revising the work: LPB, EMM, LFMB, DML, and JKBC.

Author Disclosure Statement: No competing financial interest exist.

Funding Statement: The authors received no financial support for the research, authorship, and/or publication of this article.