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Centers for Disease Control and Prevention recommendation for treatment of uncomplicated gonorrhea (NG) were revised in December 2020 and include ceftriaxone monotherapy when chlamydial infection was excluded. We evaluated the impact of these revised treatment recommendations using data from a network of sexually transmitted disease (STD) clinics before the change in guidelines. We performed a cross-sectional analysis from 8 STD clinics participating in the STD Surveillance Network from January 2015 to June 2018 assessing NG/chlamydia (CT) testing episodes, nucleic acid amplification test results, CT only and NG/CT treatment records, and timing of treatment. We describe the frequency of NG and CT treatment practices and what proportion of patients treated would not have had to receive an antichlamydial agent. Of 190,589 episodes that occurred during the study period, 67,895 (35.6%) episodes were associated with a treatment record consistent with NG or chlamydia (CT only [n = 37,530] or NG/CT [n = 30,365]), most (~86%) were prescribed on the same-day as initial testing. Of the 67,895 episodes with corresponding treatment record(s), 42.1% were positive for either NG or CT compared with 3.7% were positive for NG or CT for those not associated with treatment records (n = 122,694 episodes). Among 30,365 episodes associated with NG/CT treatment records, monotherapy would only have been indicated for 10.1% (3081/30,365) of the episodes as they were treated on follow-up and were NG positive and CT negative. Treatment was prescribed in one-third of NG/CT testing episodes, with the majority provided same day. Despite changes in NG treatment guidelines to ceftriaxone monotherapy, majority of patients would continue to receive an antichlamydia agent when treated for NG in these settings.

The reported number of nationally notifiable sexually transmitted diseases decreased in March to April 2020 during the US COVID-19 pandemic; however, resurgence of some reported sexually transmitted disease cases occurred later in 2020. Supplemental digital content is available in the text., Background To describe changes in reported sexually transmitted diseases (STDs) during the US coronavirus disease 2019 pandemic, we compared the weekly number of reported nationally notifiable STDs in 2020 to 2019. Methods We reviewed cases of chlamydia, gonorrhea, and primary and secondary (P&S) syphilis reported to the US National Notifiable Disease Surveillance System in 2020. For each STD, we compare the number of 2020 cases reported for a given Morbidity and Mortality Weekly Report (MMWR) week to the number of 2019 cases reported in the same week, expressing 2020 cases as a percentage of 2019 cases. We also calculated the percent difference between 2020 and 2019 cumulative case totals as of MMWR week 50 (week of December 9). Results During MMWR weeks 1 to 11 (week of December 29, 2019–March 11, 2020), the weekly number of cases of STDs reported in 2020 as a percentage of the cases in the same week in 2019 was similar. However, 2020 numbers were much lower than 2019 numbers in week 15 (week of April 8; chlamydia, 49.8%; gonorrhea, 71.2%; and P&S syphilis, 63.7%). As of week 50, the 2020 cumulative totals compared with 2019 were 14.0% lower for chlamydia, 7.1% higher for gonorrhea, and 0.9% lower for P&S syphilis. Conclusions During March–April 2020, national case reporting for STDs dramatically decreased compared with 2019. However, resurgence in reported gonorrhea and syphilis cases later in the year suggests STD reporting may have increased in 2020, underscoring the importance of continued STD prevention and care activities.

The COVID-19 pandemic impacted sexually transmitted disease (STD) services. Of 59 US-funded STD programs, 91% reported a great deal to moderate impact from staff reassignment in April 2020, with 28% of respondents reporting permanent reassignment of disease intervention specialist staff. Telemedicine was implemented in 47%. Decreases in STD case reports were reported by most jurisdictions.

Background We estimated the lifetime medical costs attributable to sexually transmitted infections (STIs) acquired in 2018, including sexually acquired human immunodeficiency virus (HIV). Methods We estimated the lifetime medical costs of infections acquired in 2018 in the United States for 8 STIs: chlamydia, gonorrhea, trichomoniasis, syphilis, genital herpes, human papillomavirus (HPV), hepatitis B, and HIV. We limited our analysis to lifetime medical costs incurred for treatment of STIs and for treatment of related sequelae; we did not include other costs, such as STI prevention. For each STI, except HPV, we calculated the lifetime medical cost by multiplying the estimated number of incident infections in 2018 by the estimated lifetime cost per infection. For HPV, we calculated the lifetime cost based on the projected lifetime incidence of health outcomes attributed to HPV infections acquired in 2018. Future costs were discounted at 3% annually. Results Incident STIs in 2018 imposed an estimated $15.9 billion (25th-75th percentile: $14.9-16.9 billion) in discounted, lifetime direct medical costs (2019 US dollars). Most of this cost was due to sexually acquired HIV ($13.7 billion) and HPV ($0.8 billion). STIs in women accounted for about one fourth of the cost of incident STIs when including HIV, but about three fourths when excluding HIV. STIs among 15- to 24-year-olds accounted for $4.2 billion (26%) of the cost of incident STIs. Conclusions Incident STIs continue to impose a considerable lifetime medical cost burden in the United States. These results can inform health economic analyses to promote the use of cost-effective STI prevention interventions to reduce this burden.

BACKGROUND The most recent estimates of the number of prevalent and incident sexually transmitted infections (STIs) in the United States were for 2008. We provide updated estimates for 2018 using new methods. METHODS We estimated the total number of prevalent and incident infections in the United States for 8 STIs: chlamydia, gonorrhea, trichomoniasis, syphilis, genital herpes, human papillomavirus, sexually transmitted hepatitis B, and sexually transmitted HIV. Updated per-capita prevalence and incidence estimates for each STI were multiplied by the 2018 full resident population estimates to calculate the number of prevalent and incident infections. STI-specific estimates were combined to generate estimates of the total number of prevalent and incident STIs overall, and by sex and age group. Primary estimates are represented by medians, and uncertainty intervals are represented by the 25th (Q1) and 75th (Q3) percentiles of the empirical frequency distributions of prevalence and incidence for each STI. RESULTS In 2018, there were an estimated 67.6 (Q1, 66.6; Q3, 68.7) million prevalent and 26.2 (Q1, 24.0; Q3, 28.7) million incident STIs in the United States. Chlamydia, trichomoniasis, genital herpes, and human papillomavirus comprised 97.6% of all prevalent and 93.1% of all incident STIs. Persons aged 15 to 24 years comprised 18.6% (12.6 million) of all prevalent infections; however, they comprised 45.5% (11.9 million) of all incident infections. CONCLUSIONS The burden of STIs in the United States is high. Almost half of incident STIs occurred in persons aged 15 to 24 years in 2018. Focusing on this population should be considered essential for national STI prevention efforts.

Background Trichomonas vaginalis (TV) is a sexually transmitted parasite associated with multiple adverse outcomes in women. Estimating TV incidence is challenging because of its largely asymptomatic presentation. Methods Per-capita prevalence was estimated using the National Health and Nutrition Examination Survey, 2013 to 2018. Incidence was estimated using ordinary differential equations assuming static incidence at steady state and fit using Bayesian techniques. Model inputs included estimates of proportion of asymptomatic cases, natural clearance, and time to symptomatic treatment seeking. Posterior distributions were drawn, and uncertainty was reported, from 25th (Q1) to 75th (Q3) percentiles. Aggregated measures were estimated by combining component distributions. Results Among 15- to 59-year-olds in 2018, the number of prevalent TV infections was 2.6 (Q1, 2.4; Q3, 2.7) million overall, 470,000 (Q1, 414,000; Q3, 530,000) among men, and 2.1 (Q1, 2.0; Q3, 2.2) million among women; the numbers of incident infections were 6.9 (Q1, 6.2; Q3, 7.6) million, 3.3 (Q1, 2.8; Q3, 3.8) million, and 3.5 (Q1, 3.1; Q3, 4.0) million among all persons, men, and women, respectively. Persons aged 15 to 24 years comprised 15.6% and 16.3% of all prevalent and incident infections, respectively; prevalence and incidence in both sexes increased with age. Incidences in both sexes were highly dependent on estimates of natural clearance, which were based on few data. Conclusions Prevalence and incidence of TV are substantial in the United States, particularly among those 25 years or older. Although estimated prevalence is higher in women, estimated incidence is similar in men and women. Data on key parameters of TV infection are limited; future research should focus on clarifying the natural history of TV.

BACKGROUND The purpose of this study was to provide updated estimates of the average lifetime medical cost per infection for chlamydia, gonorrhea, and trichomoniasis. METHODS We adapted a published decision tree model that allowed for 7 possible outcomes of infection: (1) symptomatic infection, treated, no sequelae; (2) symptomatic infection, not treated, sequelae; (3) symptomatic infection, not treated, no sequelae; (4) asymptomatic infection, treated, sequelae; (5) asymptomatic infection, treated, no sequelae; (6) asymptomatic infection, not treated, sequelae; and (7) asymptomatic infection, not treated, no sequelae. The base case values and ranges we applied for the model inputs (i.e., the probability and cost assumptions) were based on published studies. RESULTS The estimated lifetime medical costs per infection for men and women, respectively, were $46 (95% credibility interval, $32-$62) and $262 ($127-$483) for chlamydia, $78 ($36-$145) and $254 ($96-$518) for gonorrhea, and $5 ($1-$14) and $36 ($17-$58) for trichomoniasis. Cost estimates for men were most sensitive to assumptions regarding the probability that the infection is symptomatic, the probability of treatment if asymptomatic, and the cost of treatment of infection. Cost estimates for chlamydia and gonorrhea in women were most sensitive to assumptions regarding the probability and cost of subsequent pelvic inflammatory disease. CONCLUSIONS These estimates of the lifetime medical cost per infection can inform updated estimates of the total annual cost of sexually transmitted infections in the United States, as well as analyses of the value and cost-effectiveness of sexually transmitted infection prevention interventions.

BACKGROUND In 2010 to 2017, rates of reported chlamydia decreased among young Black women but increased for White women and all men. Because chlamydia case rates can be influenced by changes in prevalence, screening, and other factors, we compared chlamydia prevalence trends in a sentinel population with national case rate trends to understand potential drivers of case rate trends. METHODS Chlamydia prevalence was calculated annually among 16- to 24-year-old entrants to the National Job Training Program (NJTP) in 2010 to 2017. An expectation-maximization-based maximum likelihood approach was used to adjust for misclassification due to imperfect test sensitivity and specificity. Models were stratified by sex, age, and race/ethnicity. A statistically significant trend in prevalence was defined as nonoverlapping 95% confidence intervals comparing 2010 and 2017. Trends in chlamydia prevalence were compared with trends in case rates using percentage change over time; relative changes ≥10% were considered meaningful. RESULTS Among NJTP entrants in 2010 to 2017, chlamydia prevalence was stable for all Black women, whereas case rates decreased for adolescents (-12%) and were stable for 20- to 24-year-olds (-4%). Among adolescent White women, prevalence was stable, whereas case rates increased (+30%). For White women aged 20 to 24 years, prevalence increased +62% and case rates increased +43%. Trends in prevalence differed from trends in case rates for all subgroups of men. CONCLUSIONS Prevalence trends in this sentinel population differed from national case rate trends for Black women, White women, and men, suggesting potential decreased screening among Black women aged 16 to 19 years, increased prevalence among White women aged 20 to 24 years, and increased screening among men.

Background Pelvic inflammatory disease (PID) is an infection of the upper genital tract that has important reproductive consequences to women. We describe the burden of and trends in PID among reproductive-aged women in the United States during 2006–2016. Methods We used data from 2 nationally representative probability surveys collecting self-reported PID history (National Health and Nutrition Examination Survey, National Survey of Family Growth); 5 datasets containing International Classification of Diseases, Ninth/Tenth Revision codes indicating diagnosed PID (Healthcare Utilization Project; National Hospital Ambulatory Medical Care Survey, emergency department component; National Ambulatory Medical Care Survey; National Disease Therapeutic Index; MarketScan); and data from a network of sexually transmitted infection (STI) clinics (Sexually Transmitted Disease Surveillance Network). Trends during 2006–2016 were estimated overall, by age group and, if available, race/ethnicity, region, and prior STIs. Results An estimated 2 million reproductive-aged women self-reported a history of PID. Three of 4 nationally representative data sources showed overall declines in a self-reported PID history, and PID emergency department and physician office visits, with small increases observed in nearly all data sources starting around 2015. Conclusions The burden of PID in the United States is high. Despite declines in burden over time, there is evidence of an increase in recent years.

Successful baking requires careful measurement, the precise mixing of ingredients and an attentive eye while the mixture is in the oven. However, the environment may have an impact on the final product. Humidity, quality of ingredients, type of oven used and altitude can all mean the difference between a perfect cake and a goopy mess. Although chlamydia control may seem quite different from baking, there are some important parallels, notably the context in which control programmes are developed, implemented and evaluated. The same inputs and approaches applied in different contexts may produce drastically different results. van Bergen et al 1 describe the methods of and conclusions from addressing the question ‘Where to go to in Chlamydia control?’ for the Netherlands in this issue of Sexually Transmitted Infections . The author and colleagues1 convened a panel that met in November 2019 and discussed expert perspectives on chlamydia control. This panel considered the interpretation of available evidence on the impact and/or effectiveness of a variety of testing scenarios: asymptomatic screening including opportunistic testing of asymptomatic patients in routine healthcare settings, syndromic testing, and at-home specimen collection and/or testing. Their paper reports on a problem analysis and the consensus viewpoint that evolved from this expert meeting, which suggested that future strategies should reduce rather than expand the role of widespread testing for asymptomatic chlamydial infections, and therefore the authors conclude that they ‘do not recommend age-based screening and widespread testing for chlamydia in asymptomatic persons in the Netherlands’.1 In this thought-provoking paper, van Bergen et al 1 focus on the assessment of three points: evidence for prevalence reductions, the rate of severe long-term complications caused by chlamydia and the potential harms of overdiagnoses and overtreatment. They find that all three points argue for the need to reassess and question current practices. …

Background Syphilis is a genital ulcerative disease caused by the bacterium Treponema pallidum that is associated with significant complications if left untreated and can facilitate the transmission and acquisition of HIV infection. The last prevalence and incidence estimates of the burden of syphilis in the United States were for 2008. Methods We generate syphilis prevalence and incidence estimates for 2018 among adults aged 14 to 49 years. We fit a simple mathematical model to 2018 case report data to generate 10,000 sets of estimates for age and sex subpopulations and summarize our estimates by their median (50th percentile); uncertainty intervals are characterized by their 25th (Q1) and 75th (Q3) percentiles. We also used our methodology to reestimate 2008 prevalence and incidence estimates. Results In 2018, there were an estimated 156,000 (Q1, 132,000; Q3, 184,000) prevalent and 146,000 (Q1, 126,000; Q3, 170,000) incident syphilitic infections in people aged 14 to 49 years. Men accounted for roughly 70% of prevalent infections and more than 80% of incident infections. In both sexes, there were more prevalent and incident infections in 25- to 49-year-olds than 14- to 24-year-olds. Using these methods to reanalyze 2008 data, syphilis prevalence and incidence estimates have increased 164% and 175%, respectively, between 2008 and 2018. Discussion Although not as common as other sexually transmitted infections, syphilis should be monitored because of its devastating sequelae. As it continues to increase in frequency, it will be important for future work to continue to track its trajectory and burden.

Background The most recent prevalence and incidence estimates for chlamydia and gonorrhea, the 2 most reported sexually transmitted infections in the United States, were for 2008. We present updated estimates of the number of prevalent and incident chlamydial and gonococcal infections for 2018. Methods We estimated chlamydial prevalence directly from the 2015 to 2018 cycles of the National Health and Nutrition Examination Survey and chlamydial incidence using a mathematical model primarily informed by National Health and Nutrition Examination Survey and case report data. Total and antimicrobial-resistant gonococcal prevalence and incidence were estimated using mathematical models primarily informed by case report and Gonococcal Isolate Surveillance Program data. Estimates were calculated for the total population, all women, and all men aged 15 to 39 years, stratified by age group. Primary estimates represent medians and uncertainty intervals represent the 25th (Q1) and 75th (Q3) percentiles of the empirical frequency distributions of prevalence and incidence for each infection. Results Among persons aged 15 to 39 years in the United States in 2018, we estimate 2.35 (Q1, 2.20; Q3, 2.51) million prevalent and 3.98 (Q1, 3.77; Q3, 4.22) million incident chlamydial infections, and an estimated 209,000 (Q1, 183,000; Q3, 241,000) prevalent and 1.57 (Q1, 1.44; Q3, 1.72) million incident gonococcal infections. Of all gonococcal infections, there were 107,000 (Q1, 94,000; Q3, 124,000) prevalent and 804,000 (Q1, 738,000; Q3, 883,000) incident infections demonstrating antimicrobial resistance or elevated minimum inhibitory concentrations to selected antibiotics. Conclusions Chlamydia and gonorrhea were very common in the United States in 2018. Estimates show that more than 800,000 newly acquired gonococcal infections in 2018 demonstrated resistance or elevated minimum inhibitory concentrations to currently or previously recommended antibiotics.

Sexually transmitted diseases, including chlamydia and gonorrhea, cause of pelvic inflammatory disease (PID) and infertility. We estimated the prevalence of infertility and infertility health care seeking.We analyzed self-reported lifetime infertility and infertility health care-seeking in women aged 18 to 49 years in the 2013 and 2015 National Health and Nutrition Examination Surveys. Weighted prevalence of infertility and infertility health care seeking, prevalence ratios (PRs), and 95% confidence intervals (CIs) were calculated.Among 2626 eligible women, 13.8% had self-reported infertility (95% CI, 12.3-15.3) with higher prevalence by age: 960, 18 to 29 years (PR, 6.4%; 95% CI, 4.8-8.0); 799, 30 to 39 years (PR, 14.8%; 95% CI, 12.2-17.3); and 867, 40 to 49 years (PR, 20.8%; 95% CI, 17.2-24.4). Non-Hispanic white women (PR, 15.4%; 95% CI, 13.0-17.8; n = 904) and non-Hispanic black women (PR, 12.9%; 95% CI, 10.3-15.5; n = 575) had the highest infertility prevalences. Women reporting PID treatment (n = 122) had higher infertility prevalence (PR, 24.2%; 95% CI, 16.2-32.2) than women without PID treatment (PR, 13.3%; 95% CI, 11.6-15.0; n = 2,485), especially among 18- to 29-year-old women (PR, 3.8; 95% CI, 1.8-8.0). Of 327 women with infertility, 60.9% (95% CI, 56.1-65.8) sought health care. Women without health care insurance sought care less frequently than women with insurance.In a nationally representative sample, 13.8% of reproductive-age women reported a history of infertility, of whom 40% did not access health care. Self-reported PID was associated with infertility, especially in young women. Annual chlamydia and gonorrhea screening to avert PID may reduce the burden of infertility in the United States.

We examined Medicaid claims data during 2004 to 2013. The proportion of sexually active females aged 15 to 25 years who had Papanicolaou testing or were pregnant significantly decreased during 2004 to 2013 (67.0% to 43.9%, P < 0.05), resulting in a slowed increasing trend in overall chlamydia screening rates. Structural-level interventions for improving chlamydia screening are urgently needed.

USA300 methicillin-resistant Staphylococcus aureus (MRSA) is increasing as a cause of severe community-associated bacteremic infections. We assessed severe sepsis in response to infection in patients with USA300 MRSA compared to non-USA300 MRSA bacteremia. A cohort study was conducted from 1997 to 2008 comparing sepsis in response to infection in 271 patients with MRSA bacteremia from 4 VA hospitals. Sixty-seven (25%) patients with MRSA bacteremia were USA300 MRSA; 204 (75%) were non-USA300 MRSA. The proportion of MRSA bacteremia caused by USA300 MRSA increased over time (χ² P < 0.0001). Adjusting for age and nosocomial infection, patients with USA300 MRSA bacteremia were more likely to have severe sepsis or septic shock in response to infection than patients with non-USA300 MRSA bacteremia (adjusted relative risk = 1.82; 95% confidence interval, 1.16-2.87; P = 0.01). This suggests that patients with USA300 MRSA are more likely to develop severe sepsis in response to their infection, which could be due to host or bacterial differences.

To assess the association of illicit drug use and USA300 methicillin-resistant Staphylococcus aureus (MRSA) bacteremia, a multicenter study was conducted at 4 Veterans Affairs medical centers during 2004–2008. The study showed that users of illicit drugs were more likely to have USA300 MRSA bacteremia (in contrast to bacteremia caused by other S. aureus strains) than were patients who did not use illicit drugs (adjusted relative risk 3.0; 95% confidence interval 1.9–4.4). The association of illicit drug use with USA300 MRSA bacteremia decreased over time (p = 0.23 for trend). Notably, the proportion of patients with USA300 MRSA bacteremia who did not use illicit drugs increased over time. This finding suggests that this strain has spread from users of illicit drugs to other populations.

Perinatal transmission of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) can result in conjunctivitis in infants. We examined national rates of reported CT/GC conjunctivitis among infants. Surveillance of these infections is heavily affected by the completeness of reported data on specimen source and age. Alternative data sources should be evaluated.

Background Sensitive/less-sensitive (S/LS) serologic assays that differentiate recent from established HIV infection may not be suitable for use in resource-limited and financially challenged countries. A more simple and affordable method is needed to address these limitations. Methods: The Serodia HIV-1/HIV-2 particle agglutination assay (PA) was modified to act as a S/LS assay. Antigen-coated gelatin particles were diluted 1:68, and sera were diluted at intervals from 1:10 to 1:80,000; HIV antibody status was confirmed at the 1:10 dilution. 37 clade B seroconversion panels from Trinidad and BBI (n = 309) were tested at each sample dilution to calibrate the PA assay; the last positive reaction (>1+) was considered the endpoint dilution (ED). The greatest sensitivity for correctly classifying recent and established infection samples was determined by ROC analyses. A subset of these panels (n = 181) was also tested by the Vironostika S/LS (DV) as a reference for comparison.

Recurrence is a common complication of Staphylococcus aureus infections. A shorter duration of antibiotic treatment for a S. aureus infection has been previously suggested as a possible risk factor for recurrence. We conducted a retrospective cohort study of patients with S. aureus infection complicated by bacteremia who survived their initial treatment (N = 397) at the VA Maryland Health Care System from 1995 to 2004 to determine if 2 weeks or less of antibiotic therapy is significantly associated with a higher rate of recurrence. Recurrence was defined as recurrence of infection because of S. aureus with the same susceptibility to methicillin within 1 year of treatment of the initial bacteremia. Seventeen percent of patients who survived their initial infection had a recurrence of infection. Mean duration of antibiotic therapy in those who recurred was longer than in those who did not recur (21 versus 18 days, P = .18). No evidence was found to support an association between a duration of therapy of 14 days or less and an increased risk for recurrence (RR, 0.68; 95% CI, 0.44–1.04). However, being HIV infected (OR, 4.59; 95% CI, 1.61–13.10), having diabetes (OR, 2.02; 95% CI, 1.13–3.61) and having an infection due to a methicillin-resistant S. aureus (MRSA) (OR, 2.11; 95% CI, 1.17–3.80) were independent risk factors for recurrence. In conclusion, 2 weeks or less of antibiotic therapy was not associated with an increased risk for recurrence. However, patients with diabetes or HIV infection and patients with MRSA infections are at an increased risk for recurrence and should be followed more closely.

Current serologic techniques for the classification of recent HIV-1 infection produce some misclassifications, and, together with the loss to follow-up of individuals, results in decreased enrollment of HIV-infected persons into appropriate intervention programs. We report on the development of a sensitive/less sensitive (S/LS) test strategy that includes a rapid assay to quickly identify persons most likely to have recent infection, followed by an enzyme immunoassay (EIA) with exquisite specificity. The Uni-Gold Recombigen HIV rapid assay (UG; Trinity Biotech, Dublin, Ireland) was procedurally-modified and calibrated as an LS test to differentiate recent (

An increase in SSTIs suggests that USA300 is becoming more virulent with a greater propensity to cause SSTIs., Until recently, methicillin-resistant Staphylococcus aureus (MRSA) has caused predominantly healthcare-associated infections. We studied MRSA infections and overall skin and soft tissue infections (SSTIs) in outpatients receiving care at the Baltimore Veterans Affairs Medical Center Emergency Care Service during 2001–2005. We found an increase in MRSA infections, from 0.2 to 5.9 per 1,000 visits (p80% of MRSA infections were caused by USA300. In addition, SSTI visits increased from 20 to 61 per 1,000 visits (p

Summary Objectives We sought to modify the Serodia HIV-1/HIV-2 particle agglutination assay (PA), a simple and cost-effective HIV assay that is used globally for the detection of HIV antibodies, as a sensitive/less sensitive test (S/LS) to identify recently infected individuals and to estimate HIV incidence. Methods The Serodia PA test was modified as an S/LS test (PA-LS) by using HIV antigen-coated gelatin particles at a dilution of 1:68 and a specific diluent, and calibrated using 37 HIV clade B seroconversion panels (309 samples) from Trinidad and from a commercial source that were tested at dilution intervals from 1:10 to 1:80000. The greatest sensitivity for correctly classifying samples from recent and established infections was determined by receiver operator curve (ROC) analysis. Results At a 1:40000 sample dilution and a days post-seroconversion cutoff of 190 days, the PA-LS test yielded a 97% sensitivity for classifying recent and established infection samples. Furthermore, at a 1:20000 dilution, the positive predictive value for correctly identifying recently infected individuals was 99%. The PA-LS test offers a 30–44-fold cost saving over currently available S/LS tests. Conclusion A modified, low cost and simple-to-perform PA test is appropriate for use in resource-limited countries, and has exhibited excellence in distinguishing recent from established HIV infection.