Strengthening primary health care in low- and middle-income countries: furthering structural changes in the post-pandemic era.

Strengthening primary health care (PHC) is the most cost-effective approach in low- and middle-income countries (LMICs) to achieve sustainable universal health coverage (UHC), protect against health shocks, and promote health and wellbeing for all people. It has been 45 years since PHC was put on the global agenda followed by multiple efforts to advocate for more funding and improved performance of PHC. Yet, investment in PHC is still insufficient and overall performance of PHC systems is weak in LMICs, resulting in increased vulnerability and poor health outcomes especially among marginalized populations. As countries recover from the COVID-19 pandemic, which exposed the fragility of PHC platforms, it is imperative to go beyond advocacy for PHC investments and make systemic changes to strengthen PHC as the foundation of resilient and equitable health systems. We propose five gamechangers to facilitate structural changes for strengthening PHC through a focused health systems approach: (i) integration of client-centered health services at PHC level; (ii) digitization of PHC services; (iii) efficiency gains invested in essential health services; (iv) strengthening management practices for PHC at district and facility levels; and (v) advancing community engagement for PHC. To be successful, the implementation of the gamechangers must be contextualized and focus on achieving sustainable health outcomes, and therefore use implementation approaches that link essential health services to health outcomes. Through this way countries will maximize the possibility of achieving UHC and attaining the ambitious health targets of the Sustainable Development Goals (SDGs) by 2030.

Improving management of tuberculosis in people living with HIV in South Africa through integration of HIV and tuberculosis services: a proof of concept study.

BACKGROUND: South Africa's tuberculosis burden is the third highest globally and is closely associated with the country's devastating HIV epidemic. The separation of HIV and TB services in primary healthcare services in South Africa hampers TB case finding in patients who are co-infected with HIV and TB. This operational proof of concept study assessed an approach to improving tuberculosis detection and treatment by integrating tuberculosis management into HIV care. METHODS: The intervention involved workforce re-engineering accompanied by changes to the physical environment in three primary healthcare facilities in Gert Sibande district, Mpumalanga Province, that allowed HIV providers to test their HIV patients for TB and initiate and monitor TB treatment when indicated. To assess the proof of concept we compared the management of TB patients by HIV and TB providers, by reviewing the records of all facility patients who tested positive for tuberculosis between July 2015 and February 2016. We also considered the perceptions of healthcare providers and facility managers about the intervention through structured interviews. RESULTS: Approximately 30% of the 1855 patients with presumed TB in the three clinics had been identified by HIV providers. The percentage of patients consecutively tested for TB was 81.0% and 85.0% (p = 0.0551) for HIV and TB providers, respectively. Of the patients identified with TB by HIV and TB providers, 75.4% and 79.2% (p = 0.2876), respectively, were initiated on treatment. The defaulter rate was higher among HIV, compared to TB, providers (12.8% versus 4.2%). Overall, healthcare providers and facility managers had positive views of the intervention but raised concerns regarding potential increase in workload and administrative issues, as well as infection control. CONCLUSIONS: The results of this proof-of-concept study indicate that the full spectrum of TB services can be easily and effectively integrated into existing HIV care programs. However, a possible shift in the service providers' workload, including administrative tasks, must be tackled and effective infection control must be ensured. Further research is needed to assess the impact of TB service integration into the scope of HIV care (or other chronic care programs) on patient outcomes, including analysis of routine data.

Key harm reduction interventions and their impact on the reduction of risky behavior and HIV incidence among people who inject drugs in low-income and middle-income countries.

PURPOSE OF REVIEW: HIV infection rates continue to rise among people who inject drugs (PWID) in many lower- and middle-income countries (LMICs). Although progress is being made in prevention and care for PWID in some settings, coverage of essential services remains low. This article reviews the evidence for the benefits of scaling up key interventions as a combination prevention and treatment package for PWID. RECENT FINDINGS: WHO defined a comprehensive package of nine interventions for PWID, of which the following four have evidence for effectiveness in reducing HIV incidence: needle and syringe programs (NSP), medication-assisted therapy (MAT), antiretroviral therapy (ART), and HIV counseling and testing (HCT). Coverage of these interventions among PWID in LMICs varies from low (≤20%) to medium (>20-60%). At least a 60% coverage is likely to be required to reduce HIV incidence. Evidence from LMIC contexts suggests that NSP and MAT can reduce high-risk injecting behavior, HCT can reduce risky sexual behavior and ART can plausibly have preventive benefit among PWID for onward parenteral transmission with clearer evidence that antiretroviral therapy (ARV) can prevent onward sexual transmission. Modeling analysis suggests that compared with current low coverage, a scale-up of these four interventions in combination would be a beneficial and cost-effective approach. SUMMARY: The continuation of significant HIV incidence among PWID in LMIC settings is avoidable with the implementation of immediate scale-up of key harm reduction and ARV treatment interventions. Policymakers should address the structural and resource allocation barriers to allow this scale-up to occur.

HIV-1 epidemic in the Caribbean is dominated by subtype B.

BACKGROUND: The molecular epidemiology of HIV-1 in the Caribbean has been described using partial genome sequencing; subtype B is the most common subtype in multiple countries. To expand our knowledge of this, nearly full genome amplification, sequencing and analysis was conducted. METHODOLOGY/PRINCIPAL FINDINGS: Virion RNA from sera collected in Haiti, Dominican Republic, Jamaica and Trinidad and Tobago were reverse transcribed, PCR amplified, sequenced and phylogenetically analyzed. Nearly full genomes were completed for 15 strains; partial pol was done for 67 strains. All but one of the 67 strains analyzed in pol were subtype B; the exception was a unique recombinant of subtypes B and C collected in the Dominican Republic. Of the nearly full genomes of 14 strains that were subtype B in pol, all were subtype B from one end of the genome to the other and not inter-subtype recombinants. Surprisingly, the Caribbean subtype B strains clustered significantly with each other and separate from subtype B from other parts of the pandemic. CONCLUSIONS: The more complete analysis of HIV-1 from 4 Caribbean countries confirms previous research using partial genome analysis that the predominant subtype in circulation was subtype B. The Caribbean strains are phylogenetically distinct from other subtype B strains although the biological meaning of this finding is unclear.

HIV-1 epidemic in the Caribbean is dominated by subtype B.

BACKGROUND: The molecular epidemiology of HIV-1 in the Caribbean has been described using partial genome sequencing; subtype B is the most common subtype in multiple countries. To expand our knowledge of this, nearly full genome amplification, sequencing and analysis was conducted. METHODOLOGY/PRINCIPAL FINDINGS: Virion RNA from sera collected in Haiti, Dominican Republic, Jamaica and Trinidad and Tobago were reverse transcribed, PCR amplified, sequenced and phylogenetically analyzed. Nearly full genomes were completed for 15 strains; partial pol was done for 67 strains. All but one of the 67 strains analyzed in pol were subtype B; the exception was a unique recombinant of subtypes B and C collected in the Dominican Republic. Of the nearly full genomes of 14 strains that were subtype B in pol, all were subtype B from one end of the genome to the other and not inter-subtype recombinants. Surprisingly, the Caribbean subtype B strains clustered significantly with each other and separate from subtype B from other parts of the pandemic. CONCLUSIONS: The more complete analysis of HIV-1 from 4 Caribbean countries confirms previous research using partial genome analysis that the predominant subtype in circulation was subtype B. The Caribbean strains are phylogenetically distinct from other subtype B strains although the biological meaning of this finding is unclear.

Protocol for nearly full-length sequencing of HIV-1 RNA from plasma.

Nearly full-length genome sequencing of HIV-1 using peripheral blood mononuclear cells (PBMC) DNA as a template for PCR is now a relatively routine laboratory procedure. However, this has not been the case when using virion RNA as the template and this has made full genome analysis of circulating viruses difficult. Therefore, a well-developed procedure for sequencing of full-length HIV-1 RNA directly from plasma was needed. Plasma from U.S. donors representing a range of viral loads (VL) was used to develop the assay. RNA was extracted from plasma and reverse-transcribed. Two or three overlapping regions were PCR amplified to cover the entire viral genome and sequenced for verification. The success of the procedure was sensitive to VL but was routinely successful for VL greater than 10(5) and the rate declined in proportion to the VL. While the two-amplicon strategy had an advantage of increasing the possibility of amplifying a single species of HIV-1, the three-amplicon strategy was more successful in amplifying samples with low viral loads. This protocol provides a useful tool for molecular analysis to understand the HIV epidemic and pathogenesis, as well as diagnosis, therapy and future vaccine strategies.

Elevated risk for HIV infection among men who have sex with men in low- and middle-income countries 2000-2006: a systematic review.

BACKGROUND: Recent reports of high HIV infection rates among men who have sex with men (MSM) from Asia, Africa, Latin America, and the former Soviet Union (FSU) suggest high levels of HIV transmission among MSM in low- and middle-income countries. To investigate the global epidemic of HIV among MSM and the relationship of MSM outbreaks to general populations, we conducted a comprehensive review of HIV studies among MSM in low- and middle-income countries and performed a meta-analysis of reported MSM and reproductive-age adult HIV prevalence data. METHODS AND FINDINGS: A comprehensive review of the literature was conducted using systematic methodology. Data regarding HIV prevalence and total sample size was sequestered from each of the studies that met inclusion criteria and aggregate values for each country were calculated. Pooled odds ratio (OR) estimates were stratified by factors including HIV prevalence of the country, Joint United Nations Programme on HIV/AIDS (UNAIDS)-classified level of HIV epidemic, geographic region, and whether or not injection drug users (IDUs) played a significant role in given epidemic. Pooled ORs were stratified by prevalence level; very low-prevalence countries had an overall MSM OR of 58.4 (95% CI 56.3-60.6); low-prevalence countries, 14.4 (95% CI 13.8-14.9); and medium- to high-prevalence countries, 9.6 (95% CI 9.0-10.2). Significant differences in ORs for HIV infection among MSM in were seen when comparing low- and middle-income countries; low-income countries had an OR of 7.8 (95% CI 7.2-8.4), whereas middle-income countries had an OR of 23.4 (95% CI 22.8-24.0). Stratifying the pooled ORs by whether the country had a substantial component of IDU spread resulted in an OR of 12.8 (95% CI 12.3-13.4) in countries where IDU transmission was prevalent, and 24.4 (95% CI 23.7-25.2) where it was not. By region, the OR for MSM in the Americas was 33.3 (95% CI 32.3-34.2); 18.7 (95% CI 17.7-19.7) for Asia; 3.8 (95% CI 3.3-4.3) for Africa; and 1.3 (95% CI 1.1-1.6) for the low- and middle-income countries of Europe. CONCLUSIONS: MSM have a markedly greater risk of being infected with HIV compared with general population samples from low- and middle-income countries in the Americas, Asia, and Africa. ORs for HIV infection in MSM are elevated across prevalence levels by country and decrease as general population prevalence increases, but remain 9-fold higher in medium-high prevalence settings. MSM from low- and middle-income countries are in urgent need of prevention and care, and appear to be both understudied and underserved.

Lessons from a multisite international trial in the Caribbean and South America of an HIV-1 Canarypox vaccine (ALVAC-HIV vCP1452) with or without boosting with MN rgp120.

BACKGROUND: The first multicenter, international National Institutes of Allergy and Infectious Diseases (NIAID)-sponsored HIV vaccine trial took place in Brazil, Haiti, Peru and Trinidad. This randomized, double-blind, placebo-controlled, phase 2 trial evaluated the safety and immunogenicity of a clade B-derived, live canarypox HIV vaccine, vCP1452. vCP1452 was administered alone or with a heterologous boost of MN rgp120 glycoprotein. The trial was pivotal in deciding whether these vaccines advanced to phase 3 efficacy trials. METHODS: Forty seronegative volunteers per site were randomized to ALVAC alone, ALVAC plus MN rgp120, or placebo in a 0, 1, 3, and 6 month schedule. Immunogenicity was assayed by chromium-release cytotoxic T lymphocyte (CTL) responses; interferon-gamma (IFN-gamma) enzyme-linked immunosorbent spot assays (ELISpot); lymphocyte proliferation assays (LPA); neutralization; and enzyme-linked immunosorbent assays (ELISA). RESULTS: Enrollment and follow-up were excellent. Both vaccines were well tolerated. Neutralizing antibody to the laboratory-adapted MN strain was detected. Cellular immune responses, as measured by CTL, ELISpot, and LPA, did not differ between vaccines and placebos. CONCLUSIONS: The observation of disappointing immunogenicity in this and a parallel domestic study has informed future vaccine development. Equally important, challenges to doing an integrated trial across countries, cultures, languages, and differing at-risk populations were overcome. The identification of specific safety, ethical, logistic, and immunological issues in this trial established the foundation for current larger international studies.

Tenofovir and abacavir combination therapy: lessons learned from an urban clinic population.

Regimens containing abacavir (ABC), tenofovir (TDF), and lamivudine (3TC) have recently been demonstrated to have high failure rates. This poses a clinical dilemma of how to manage patients currently being treated with other regimens containing tenofovir/abacavir. We evaluated the outcomes of tenofovir/abacavir regimens in our clinical practice through a retrospective review of 2655 charts. Two hundred patients (7%) were on a tenofovir/abacavir-containing regimen. Fifty-nine patients met the criteria for analysis and were grouped into three groups: (1) antiretroviral naïve, (2) virally suppressed patients switched to TDF/ABC, and (3) patients with failure of their first antiretroviral regimen. Rates of viral suppression in the naïve, switch, and first-failure groups were 95%, 86%, and 46%, respectively. In the first-failure group, viral suppression was 66% without and 18% with a preexisting M184V. A composite analysis of the groups revealed a success rate of 86% when the regimen contained zidovudine (ZDV) and 62% when it did not. No K65R mutations were noted. These findings support continued caution in the use of TDF/ABC in combination. However, these data suggest that this combination may be successfully used in selected situations such as in combination with ZDV. In patients already virally suppressed on a TDF/ABC-containing regimen, considerations include continuing the regimen or adding zidovudine, in the attempt to protect against the development of a K65R mutation and/or virologic failure, versus changing a stable regimen.

A simple and inexpensive particle agglutination test to distinguish recent from established HIV-1 infection.

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 1:80,000. The greatest sensitivity for correctly classifying samples from recent and established infections was determined by receiver operator curve (ROC) analysis. RESULTS: At a 1:40,000 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 1:20,000 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.

Rapid clearance of virus after acute HIV-1 infection: correlates of risk of AIDS.

OBJECTIVE: Our objective was to define early virologic and immunologic determinants of human immunodeficiency virus (HIV) type 1 disease progression among 22 case subjects with acute infection from the Trinidad Seroconvertor Cohort. METHODS: A linear segmented regression model was fitted to sequential quantitative virus load measurements. Parameters of virus kinetics during different phases of primary infection were correlated with clinical and immunologic end points, by use of Kaplan-Meier estimates and Cox regression. RESULTS: Ten individuals developed acquired immunodeficiency syndrome (AIDS)-defining events. In univariate analysis, progression to AIDS was associated with rate of initial HIV clearance (P=.002), virus load during set point (P=.008), and CD4(+) cell count during steady state (P=.04). In the multivariate analysis, a rapid rate of initial clearance was the sole independent predictor of subsequent progression to AIDS and was associated with a 92% reduction in the risk of AIDS. The rate of initial clearance is inversely correlated with the number of early symptoms (r=-0.66; P=.0008). However, symptoms did not predict subsequent risk of AIDS. CONCLUSION: Among a subset of patients, rapid clearance of plasma HIV-1 after peak viremia is associated with lower viral set point, prolonged virus suppression before loss of virologic control, and decreased risk of AIDS. These findings are consistent with the hypothesis that effective immune responses during the earliest phase of infection are important determinants of the subsequent natural history.

Improved classification of recent HIV-1 infection by employing a two-stage sensitive/less-sensitive test strategy.

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 (<133 days) from established HIV infections using 178 samples from persons with known dates of infection. This method correctly classified 83.0% of recent infections, but with a high misclassification rate of persons with established infection. By performing the rapid test followed by a modified S/LS EIA, the positive predictive value of the combined results for recent infections was increased to 100%. This two-stage testing algorithm can result in an increased efficiency for the enrollment of recent infection cases over a standard EIA S/LS method alone due to provisional enrollment during an initial testing visit, and because of an increased accuracy for identifying truly recent infections. We conclude that the rapid S/LS assay provides a tool for capturing recent infection cases quickly and is particularly valuable in resource-limited settings, and that the two-stage strategy provides a more accurate identification of persons with recent HIV infection.

Fourth-generation enzyme-linked immunosorbent assay for the simultaneous detection of human immunodeficiency virus antigen and antibody

The VIDAS HIV DUO Ultra, a fourth-generation immunoassay under development for the simultaneous detection of human immunodeficiency virus type 1 (HIV-1) p24 antigen and antibodies to HIV-1 and HIV-2, was evaluated. The enzyme-linked fluorescence immunoassay, performed on the automated VIDAS instrument, is claimed to detect early and established HIV infection. The assay was challenged with a total of 2,847 samples that included 74 members of 10 seroconversion panels, 9 p24 antigen-only-reactive members of a panel of group M clades, 503 consecutively collected samples from individuals seeking care in the University of Maryland Medical System, 1,010 samples from U.S. blood donors, 1,141 samples from patients in a high-incidence population in Trinidad, 83 samples from a clinic for sexually transmitted diseases in the Bahamas, 10 confirmed HIV-1 group O samples, and 16 confirmed HIV-2 samples from the Cote d'Ivoire. Reference tests were U.S. Food and Drug Administration-licensed HIV antibody screening, p24 antigen tests, HIV confirmatory assays, and the Roche Diagnostics Amplicor HIV-1 Monitor. The VIDAS HIV DUO Ultra demonstrated 100% sensitivity and 99.5% specificity overall, with a 99.7% specificity in low-risk individuals. The analytical sensitivity, as assessed by seroconversion panels and p24 antigen in samples, was equivalent to the sensitivity of the reference assays used to characterize these panels. The VIDAS HIV DUO Ultra is accurate, offers potential advantages over conventional HIV testing for time and cost savings, has walk-away capability, and correctly identifies both early and established HIV infections.

Antenatal screening for HIV in North Trinidad. Demographic characteristics of patients, acceptability of testing and the rising prevalence of infection - Poster abstract

OBJECTIVE: To ascertain the acceptability of HIV screening in pregnancy and the prevalence of HIV in pregnant women in north Trinidad. DESIGN AND METHOD: All women attending an antenatal clinic at the Port of Spain General Hospital were offered HIV testing at booking. Written consent was obtained after testing counselling and blood samples were tested using an ELISA assay with positive results confirmed by western blot. Demographic data were also collected. HIV positive women/infant pairs were tested using a modified CDC - Thailand regime. RESULTS: A total of 338 new patients were seen between March and November 1999 of whom only 8 refused testing. Ten patients tested positive giving a prevalence of 3 percent. All of the HIV positive patients were of African or mixed race descent which reflected the population attending this clinic. CONCLUSION: Our data indicated a slowly rising prevalence of HIV in pregnant women in north Trinidad. The majority of patients (98 percent) easily accept screening.(AU)

Seroprevalence of human herpesvirus-8 (HHV-8) in countries of Southeast Asia compared to the USA, the Caribbean and Africa

Seroprevalence of HHV-8 has been studied in Malaysia, India, Sri Lanka, Thailand, Trinidad, Jamaica and the USA, in both healthy individuals and those infected with HIV. Seroprevalence was found to be low in these countries. In contrast, the African countries of Ghana, Uganda and Zambia showed high seroprevalences in both healthy and HIV-infected populations. This suggests that human herpes virus-8 (HHV-8) may be either a recently introduced virus or one that has extremely low infectivity. Nasopharyngeal and oral carcinoma patients from Malaysia, Hong Kong and Sri Lanka who have very high EBV titres to show that only 3/82 (3.7 percent) have antibody to HHV-8, demonstrating that there is little, if any, cross-relativity between antibodies to these two gamma viruses. (AU)

A study of adult T-cell leukemia/lymphoma incidence in central Brooklyn

Adult T-cell leukemia/lymphoma (ATL), a rare outcome of infection with human T-lymphotropic virus (HTLV-I), is endemic in central Brooklyn, which has a large Caribbean migrant population. Previous studies have suggested that HTLV-I prevalence in central Brooklyn may be similar to that recorded in the Caribbean islands. We established a pilot 1-year surveillance program to identify cases of ATL in 7 of 10 hospitals serving the residents of 18 zip codes of central Brooklyn with a combined population of 1,184,670. Of the 6,198 in-patient beds in the catchment area, approximately 83 percent were covered. Twelve incident cases of ATL were ascertained, all among persons of Afro-Caribbean descent, indicating an annual incidence in African-Americans in this community of approximately 3.2/100,000 person-years. Unexplained hypercalcemia was the most useful screening method, identifying 3 of 5 patients not referred for possible ATL by a local hematologist. The female:male ratio was 3:1. The age pattern was different from that reported in the Caribbean Basin and closer to the pattern seen in Japan. Our study supports evidence that HTLV-I infection and ATL are endemic in central Brooklyn and suggests that a more intensive surveillance program for this disease coupled with intervention efforts to reduce HTLV-I transmission are warranted.(Au)

The challenge of HIV/AIDS in the Caribbean at the dawn of a new millenium

The Caribbean region continues to experience an expanding HIV/AIDS epidemic. Population HIV-1 prevalence in this region is second only to that in sub-Saharan Africa, reaching 5-6 percent in Haiti and up to 3 percent in Guyana and the Bahamas. While AIDS deaths are declining in developed countries, death rates from AIDS have continued to rise in the Caribbean because of the general unavailability of newer combination therapies. Over the past decade we have witnessed the rapid transition from HIV-1/AIDS in so called risk groups such as gay men and intravenous drug users to spread within the general heterosexual community. This transition has been fuelled by the concurrence of factors which enhance HIV risk such as high rates of partner exchange and poorly or untreated concomitant sexually transmitted diseases, particularly ulcerative diseases. In countries such as Trinidad and the Bahamas an epidemic of crack cocaine use in the eighties provided a fertile milieu for rapid HIV transmission through sexual activity. Each Caribbean territory has its own version of the epidemic, but the commonalities are striking. At the dawn of a new millenium the region continues the struggle against HIV/AIDS in the face of the many problems of crumbling infrastructures a generation after independence, marginal economies, inadequate public engagement in the face of competing priorities, lack of treatment and inadequate research. Recent advances in HIV-I vaccine development may hold some promise for checking the major public health crisis facing the Caribbean at this time.(AU)

Direct and indirect estimates of HIV-1 incidence in a high prevalence population

While the worldwide AIDS epidemic continues to expand, directly measured incidence data are difficult to obtain. Methods to reliably estimate human immunodeficiency virus type 1 (HIV-1) incidence from more easily available data are particularly relevant in those parts of the world where prevalence is rising in heterosexually exposed populations. The authors set out to estimate HIV-1 incidence in a population of heterosexual sexually transmitted disease clinic attended in Trinidad who had a known high prevalence of HIV-1 subtype B. Over the period 1987-1995, HIV-1 incidence estimates from serial cross-sectional studies of HIV-1 prevalence, passive follow-up of clinic recidivists, modeling of early markers of HIV-1 infection (p24 antigen screening), and a cohort study of seronegative genital ulcer disease cases were compared. Measuring incidence density in the genital ulcer disease cases directly gave the highest estimate, 6.9 percent per annum. Screening for the detection of early HIV-1 markers yielded an incidence of 5.0 percent per annum, while estimating incidence from serial cross-sectional prevalence data and clinic recidivists gave estimates of 3.5 percent and 4.5 percent per annum, respectively. These results were found to be internally consistent. Indirect estimates of incidence based on prevalence data can give accurate surrogates of true incidence. Within limitations, even crude measures of incidence are robust enough for health planning and evaluation purposes. For planning vaccine efficacy trails, consistent conservative estimates may be used to evaluate population before targeting them to cohort studies(AU)

Incidence of HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in Jamaica and Trinidad

HTLV-I is sexually transmitted more efficiently from men to women than vice versa, and the majority of HTLV-I endemic areas report a female preponderance of HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) cases. The objective of this study was to estimate the gender and age specific incidence rates of HAM/TSP in the general population as well as in the HTLV-I-infected population in Jamaica and Trinidad and Tobago. Incidence rates for HAM/TSP were computed based on all reported incident cases in both countries between 1990 and 1994. Population cenus reports for 1990 were used to calculate the population at risk. The age-standardized HAM/TSP incidence rate (mean +/- standard error of the mean) in Jamaica was 1.8 +/- 0.2/100,000 person years (PY). Among individuals of African descent in Trinidad and Tobago, the rate was 1.7 +/- 0.4/100,000 PY. As in HTLV-I seroprevalence, the incidence rate of HAM/TSP increased with age through the fifth decade of life and was three time as high in women than in men. The HAM/TSP incidence rate, calculated as a function of the number of HTLV-I infection persons in each age stratum, is higher in women (24.7/100,000 PY) than in men 17.3/100,000 PY). With HTLV-I infection, the lifetime risk of developing HAM/TSP was estimated to be 1.9 percent overall and is slightly higher in women (1.8 percent) than in men (1.3 percent). Thus, the higher prevalence of HTLV-I in women in endemic areas does not fully explain the preponderance of female HAM/TSP, suggesting that other cofactors must be present. The higher incidence rate in women between the ages of 40 and 59 years, as well as the increase in HAM/TSP incidence rates with age, are indicative of the importance of adult-acquired HTLV-I infection, presumably through sexual transmission(AU)

Comparison of HHV-6 antibody titers in West Africa and the Caribbean

Human herpesvirus-6 (HHV-6) infections seems to be ubiquitous early in life, but antibody responses vary by geographic area. We compared HHV-6 antibody titer in 123 West African and 122 Caribbean serum samples. A quantitative immunofluorescence assay (IFA) using antigens derived from an HSB-2 cell line was used to test for IgG HHV-6 (GS strain) antibodies. The prevalence of HHV-6 antibodies was high (98 percent) in both sites. African samples had a significantly higher geometric mean titer (GMT: 697) than did Caribbean samples (GMT: 99). There was no difference between males (GMT: 260) and females (GMT: 270) overall. Children up to and including 9 years old had significantly higher titers (GMT: 483) than did all others (GMT: 237), and female children tended to have higher titers than did male children. In both areas there was a trend towards highest titer at younger age, followed by a decrease in titer in the oldest age group. Environmental and host factors may explain these geographic differences in antibody responses between two groups of African origin. (AU)