HLA-A*23 Is Associated With Lower Odds of Acute Retroviral Syndrome in Human Immunodeficiency Virus Type 1 Infection: A Multicenter Sub-Saharan African Study

The role of human leukocyte antigen (HLA) class I and killer immunoglobulin-like receptor molecules in mediating acute retroviral syndrome (ARS) during human immunodeficiency virus type 1 (HIV-1) infection is unclear. Among 72 sub-Saharan African adults, HLA-A*23 was associated with lower odds of ARS (adjusted odds ratio, 0.10 [95% confidence interval, .01-.48]; P = .009), which warrants further studies to explore its role on HIV-1-specific immunopathogenesis.

Temporal trends and transmission dynamics of pre-treatment HIV-1 drug resistance within and between risk groups in Kenya, 1986-2020

BACKGROUND

Evidence on the distribution of pre-treatment HIV-1 drug resistance (HIVDR) among risk groups is limited in Africa. We assessed the prevalence, trends and transmission dynamics of pre-treatment HIVDR within and between MSM, people who inject drugs (PWID), female sex workers (FSWs), heterosexuals (HETs) and perinatally infected children in Kenya.

METHODS

HIV-1 partial pol sequences from antiretroviral-naive individuals collected from multiple sources between 1986 and 2020 were used. Pre-treatment reverse transcriptase inhibitor (RTI), PI and integrase inhibitor (INSTI) mutations were assessed using the Stanford HIVDR database. Phylogenetic methods were used to determine and date transmission clusters.

RESULTS

Of 3567 sequences analysed, 550 (15.4%, 95% CI: 14.2-16.6) had at least one pre-treatment HIVDR mutation, which was most prevalent amongst children (41.3%), followed by PWID (31.0%), MSM (19.9%), FSWs (15.1%) and HETs (13.9%). Overall, pre-treatment HIVDR increased consistently, from 6.9% (before 2005) to 24.2% (2016-20). Among HETs, pre-treatment HIVDR increased from 6.6% (before 2005) to 20.2% (2011-15), but dropped to 6.5% (2016-20). Additionally, 32 clusters with shared pre-treatment HIVDR mutations were identified. The majority of clusters had R0 ≥ 1.0, indicating ongoing transmissions. The largest was a K103N cluster involving 16 MSM sequences sampled between 2010 and 2017, with an estimated time to the most recent common ancestor (tMRCA) of 2005 [95% higher posterior density (HPD), 2000-08], indicating propagation over 12 years.

CONCLUSIONS

Compared to HETs, children and key populations had higher levels of pre-treatment HIVDR. Introduction of INSTIs after 2017 may have abrogated the increase in pre-treatment RTI mutations, albeit in the HET population only. Taken together, our findings underscore the need for targeted efforts towards equitable access to ART for children and key populations in Kenya.

Impact of the COVID-19 pandemic on routine HIV care and antiretroviral treatment outcomes in Kenya: A nationally representative analysis

BACKGROUND

The COVID-19 pandemic adversely disrupted global health service delivery. We aimed to assess impact of the pandemic on same-day HIV diagnosis/ART initiation, six-months non-retention and initial virologic non-suppression (VnS) among individuals starting antiretroviral therapy (ART) in Kenya.

METHODS

Individual-level longitudinal service delivery data were analysed. Random sampling of individuals aged >15 years starting ART between April 2018 -March 2021 was done. Date of ART initiation was stratified into pre-COVID-19 (April 2018 -March 2019 and April 2019 -March 2020) and COVID-19 (April 2020 -March 2021) periods. Mixed effects generalised linear, survival and logistic regression models were used to determine the effect of COVID-19 pandemic on same-day HIV diagnosis/ART initiation, six-months non-retention and VnS, respectively.

RESULTS

Of 7,046 individuals sampled, 35.5%, 36.0% and 28.4% started ART during April 2018 -March 2019, April 2019 -March 2020 and April 2020 -March 2021, respectively. Compared to the pre-COVID-19 period, the COVID-19 period had higher same-day HIV diagnosis/ART initiation (adjusted risk ratio [95% CI]: 1.09 [1.04-1.13], p<0.001) and lower six-months non-retention (adjusted hazard ratio [95% CI]: 0.66 [0.58-0.74], p<0.001). Of those sampled, 3,296 (46.8%) had a viral load test done at a median 6.2 (IQR, 5.3-7.3) months after ART initiation. Compared to the pre-COVID-19 period, there was no significant difference in VnS during the COVID-19 period (adjusted odds ratio [95% CI]: 0.79 [95%% CI: 0.52-1.20], p = 0.264).

CONCLUSIONS

In the short term, the COVID-19 pandemic did not have an adverse impact on HIV care and treatment outcomes in Kenya. Timely, strategic and sustained COVID-19 response may have played a critical role in mitigating adverse effects of the pandemic and point towards maturity, versatility and resilience of the HIV program in Kenya. Continued monitoring to assess long-term impact of the COVID-19 pandemic on HIV care and treatment program in Kenya is warranted.

Sexual risk-taking behavior amongst emerging adults in a tertiary institution of learning in Coastal Kenya: A qualitative study of stakeholders' perspectives using causal loop mapping

BACKGROUND

It is known from previous studies that university students in sub-Saharan Africa (sSA) engage in sexual risk-taking behaviour (SRTB). However, there is paucity of data on factors contributing to SRTB among university students (emerging adults) at the Kenyan Coast thus hindering intervention planning. This study seeks to provide an in-depth qualitative understanding of the factors contributing to SRTB and their interconnectedness among university students at the Kenyan Coast combining qualitative research with a systems thinking approach.

METHODS

Using the ecological model, and employing in-depth interviews, we explored the perceptions of twenty-six key informants (twenty-one emerging adults and five other stakeholders) on what constitutes and influences SRTB among emerging adults at a tertiary institution of learning in Coastal Kenya. Data were analysed using a thematic framework approach. A causal loop diagram (CLD) was developed to map the interconnectedness of the correlates of SRTB.

RESULTS

Our findings show that unprotected sex, transactional sex, cross-generational sex, multiple sex partnerships, gender-based violence, sex under influence of alcohol/drugs, early sex debut, and sharing sex toys were common SRTBs. Based on the ecological model and CLD, most of the reported risk factors were interconnected and operated at the individual level.

CONCLUSION

Our study shows that emerging adults are frequently engaging in unprotected sex. Enhancing sexuality education programs for students in Kenyan universities and strengthening support systems including counselling for those using alcohol/drugs may help reduce SRTB among emerging adults in Kenyan universities.

Leveraging electronic medical records for HIV testing, care, and treatment programming in Kenya-the national data warehouse project

BACKGROUND

Aggregate electronic data repositories and population-level cross-sectional surveys play a critical role in HIV programme monitoring and surveillance for data-driven decision-making. However, these data sources have inherent limitations including inability to respond to public health priorities in real-time and to longitudinally follow up clients for ascertainment of long-term outcomes. Electronic medical records (EMRs) have tremendous potential to bridge these gaps when harnessed into a centralised data repository. We describe the evolution of EMRs and the development of a centralised national data warehouse (NDW) repository. Further, we describe the distribution and representativeness of data from the NDW and explore its potential for population-level surveillance of HIV testing, care and treatment in Kenya.

MAIN BODY

Health information systems in Kenya have evolved from simple paper records to web-based EMRs with features that support data transmission to the NDW. The NDW design includes four layers: data warehouse application programming interface (DWAPI), central staging, integration service, and data visualization application. The number of health facilities uploading individual-level data to the NDW increased from 666 in 2016 to 1,516 in 2020, covering 41 of 47 counties in Kenya. By the end of 2020, the NDW hosted longitudinal data from 1,928,458 individuals ever started on antiretroviral therapy (ART). In 2020, there were 936,869 individuals who were active on ART in the NDW, compared to 1,219,276 individuals on ART reported in the aggregate-level Kenya Health Information System (KHIS), suggesting 77% coverage. The proportional distribution of individuals on ART by counties in the NDW was consistent with that from KHIS, suggesting representativeness and generalizability at the population level.

CONCLUSION

The NDW presents opportunities for individual-level HIV programme monitoring and surveillance because of its longitudinal design and its ability to respond to public health priorities in real-time. A comparison with estimates from KHIS demonstrates that the NDW has high coverage and that the data maybe representative and generalizable at the population-level. The NDW is therefore a unique and complementary resource for HIV programme monitoring and surveillance with potential to strengthen timely data driven decision-making towards HIV epidemic control in Kenya. DATABASE LINK: ( https://dwh.nascop.org/ ).

Phylogeographic Assessment Reveals Geographic Sources of HIV-1 Dissemination Among Men Who Have Sex With Men in Kenya

HIV-1 transmission dynamics involving men who have sex with men (MSM) in Africa are not well understood. We investigated the rates of HIV-1 transmission between MSM across three regions in Kenya: Coast, Nairobi, and Nyanza. We analyzed 372 HIV-1 partial pol sequences sampled during 2006-2019 from MSM in Coast (N = 178, 47.9%), Nairobi (N = 137, 36.8%), and Nyanza (N = 57, 15.3%) provinces in Kenya. Maximum-likelihood (ML) phylogenetics and Bayesian inference were used to determine HIV-1 clusters, evolutionary dynamics, and virus migration rates between geographic regions. HIV-1 sub-subtype A1 (72.0%) was most common followed by subtype D (11.0%), unique recombinant forms (8.9%), subtype C (5.9%), CRF 21A2D (0.8%), subtype G (0.8%), CRF 16A2D (0.3%), and subtype B (0.3%). Forty-six clusters (size range 2-20 sequences) were found-half (50.0%) of which had evidence of extensive HIV-1 mixing among different provinces. Data revealed an exponential increase in infections among MSM during the early-to-mid 2000s and stable or decreasing transmission dynamics in recent years (2017-2019). Phylogeographic inference showed significant (Bayes factor, BF > 3) HIV-1 dissemination from Coast to Nairobi and Nyanza provinces, and from Nairobi to Nyanza province. Strengthening HIV-1 prevention programs to MSM in geographic locations with higher HIV-1 prevalence among MSM (such as Coast and Nairobi) may reduce HIV-1 incidence among MSM in Kenya.

Quantifying rates of HIV-1 flow between risk groups and geographic locations in Kenya: A country-wide phylogenetic study

In Kenya, HIV-1 key populations including men having sex with men (MSM), people who inject drugs (PWID) and female sex workers (FSW) are thought to significantly contribute to HIV-1 transmission in the wider, mostly heterosexual (HET) HIV-1 transmission network. However, clear data on HIV-1 transmission dynamics within and between these groups are limited. We aimed to empirically quantify rates of HIV-1 flow between key populations and the HET population, as well as between different geographic regions to determine HIV-1 'hotspots' and their contribution to HIV-1 transmission in Kenya. We used maximum-likelihood phylogenetic and Bayesian inference to analyse 4058 HIV-1 pol sequences (representing 0.3 per cent of the epidemic in Kenya) sampled 1986-2019 from individuals of different risk groups and regions in Kenya. We found 89 per cent within-risk group transmission and 11 per cent mixing between risk groups, cyclic HIV-1 exchange between adjoining geographic provinces and strong evidence of HIV-1 dissemination from (i) West-to-East (i.e. higher-to-lower HIV-1 prevalence regions), and (ii) heterosexual-to-key populations. Low HIV-1 prevalence regions and key populations are sinks rather than major sources of HIV-1 transmission in Kenya. Targeting key populations in Kenya needs to occur concurrently with strengthening interventions in the general epidemic.

Predictors of testing history and new HIV diagnosis among adult outpatients seeking care for symptoms of acute HIV infection in coastal Kenya: a cross-sectional analysis of intervention participants in a stepped-wedge HIV testing trial

Background

HIV testing is the first step to stop transmission. We aimed to evaluate HIV testing history and new diagnoses among adult outpatients in Kenya aged 18–39 years seeking care for symptoms of acute HIV infection (AHI).

Methods

The Tambua Mapema Plus study, a stepped-wedge trial, enrolled patients presenting to care at six primary care facilities with symptoms of AHI for a targeted HIV-1 nucleic acid (NA) testing intervention compared with standard provider-initiated testing using rapid antibody tests. Intervention participants underwent a questionnaire and NA testing, followed by rapid tests if NA-positive. Multinomial logistic regression was used to analyse factors associated with never testing or testing > 1 year ago (“late retesting”) relative to testing ≤ 1 year ago (“on-time testers”). Logistic regression was used to analyse factors associated with new diagnosis. All analyses were stratified by sex.

Results

Of 1,500 intervention participants, 613 (40.9%) were men. Overall, 250 (40.8%) men vs. 364 (41.0%) women were late retesters, and 103 (16.8%) men vs. 50 (5.6%) women had never tested prior to enrolment. Younger age, single status, lower education level, no formal employment, childlessness, sexual activity in the past 6 weeks, and > 1 sexual partner were associated with testing history among both men and women. Intimate partner violence > 1 month ago, a regular sexual partner, and concurrency were associated with testing history among women only. New diagnoses were made in 37 (2.5%) participants (17 men and 20 women), of whom 8 (21.6%) had never tested and 16 (43.2%) were late retesters. Newly-diagnosed men were more likely to have symptoms for > 14 days, lower education level and no religious affiliation and less likely to be young, single, and childless than HIV-negative men; newly-diagnosed women were more likely to report fever than HIV-negative women. Among men, never testing was associated with fivefold increased odds (95% confidence interval 1.4–20.9) of new diagnosis relative to on-time testers in adjusted analyses.

Conclusion

Most new HIV diagnoses were among participants who had never tested or tested > 1 year ago. Strengthening provider-initiated testing targeting never testers and late retesters could decrease time to diagnosis among symptomatic adults in coastal Kenya.

Trial registration

ClinicalTrials.gov Identifier: NCT03508908 registered on 26/04/2018.

Alcohol and illicit drug use among young people living with HIV compared to their uninfected peers from the Kenyan coast: prevalence and risk indicators

BACKGROUND

In sub-Saharan Africa, there is paucity of research on substance use patterns among young people living with HIV (YLWH). To address the gap, we sought to: i) determine the prevalence of substance use, specifically alcohol and illicit drug use, among YLWH compared to their HIV-uninfected peers; ii) investigate the independent association between young people's HIV infection status and substance use; iii) investigate the risk indicators for substance use among these young people.

METHODS

Between November 2018 and September 2019, a cross-sectional study was conducted at the Kenyan coast recruiting 819 young people aged 18-24 years (407 HIV-positive). Alcohol and drug use disorders identification tests (AUDIT and DUDIT) were administered via audio computer-assisted self-interview alongside other measures. Logistic regression was used to determine substance use risk indicators.

RESULTS

The point prevalence of current substance use was significantly lower among YLWH than HIV-uninfected youths: current alcohol use, 13% vs. 24%, p <  0.01; current illicit drug use, 7% vs. 15%, p <  0.01; current alcohol and illicit drug use comorbidity, 4 vs. 11%, p <  0.01. Past-year prevalence estimates for hazardous substance use were generally low among young people in this setting (< 10%) with no significant group differences observed. Being HIV-positive independently predicted lower odds of current substance use, but not hazardous substance use. There was overlap of some risk indicators for current substance use between young people with and without HIV including male sex, khat use and an experience of multiple negative life events, but risk indicators unique to either group were also identified. Among YLWH, none of the HIV-related factors was significantly associated with current substance use.

CONCLUSIONS

At the Kenyan coast, substance use is a reality among young people. The frequency of use generally appears to be low among YLWH compared to the HIV-uninfected peers. Substance use prevention initiatives targeting young people, regardless of HIV infection status, are warranted in this setting to avert their potential risk for developing substance use disorders, including dependence. The multifaceted intrapersonal and interpersonal factors that place young people at risk of substance use need to be addressed as part of the substance use awareness and prevention initiatives.

A Stronger Innate Immune Response During Hyperacute Human Immunodeficiency Virus Type 1 (HIV-1) Infection Is Associated With Acute Retroviral Syndrome

BACKGROUND

Acute retroviral syndrome (ARS) is associated with human immunodeficiency virus type 1 (HIV-1) subtype and disease progression, but the underlying immunopathological pathways are poorly understood. We aimed to elucidate associations between innate immune responses during hyperacute HIV-1 infection (hAHI) and ARS.

METHODS

Plasma samples obtained from volunteers (≥18.0 years) before and during hAHI, defined as HIV-1 antibody negative and RNA or p24 antigen positive, from Kenya, Rwanda, Uganda, Zambia, and Sweden were analyzed. Forty soluble innate immune markers were measured using multiplexed assays. Immune responses were differentiated into volunteers with stronger and comparatively weaker responses using principal component analysis. Presence or absence of ARS was defined based on 11 symptoms using latent class analysis. Logistic regression was used to determine associations between immune responses and ARS.

RESULTS

Of 55 volunteers, 31 (56%) had ARS. Volunteers with stronger immune responses (n = 36 [65%]) had increased odds of ARS which was independent of HIV-1 subtype, age, and risk group (adjusted odds ratio, 7.1 [95% confidence interval {CI}: 1.7-28.8], P = .003). Interferon gamma-induced protein (IP)-10 was 14-fold higher during hAHI, elevated in 7 of the 11 symptoms and independently associated with ARS. IP-10 threshold >466.0 pg/mL differentiated stronger immune responses with a sensitivity of 84.2% (95% CI: 60.4-96.6) and specificity of 100.0% (95% CI]: 90.3-100.0).

CONCLUSIONS

A stronger innate immune response during hAHI was associated with ARS. Plasma IP-10 may be a candidate biomarker of stronger innate immunity. Our findings provide further insights on innate immune responses in regulating ARS and may inform the design of vaccine candidates harnessing innate immunity.

The Role of Phylogenetics in Discerning HIV-1 Mixing among Vulnerable Populations and Geographic Regions in Sub-Saharan Africa: A Systematic Review

To reduce global HIV-1 incidence, there is a need to understand and disentangle HIV-1 transmission dynamics and to determine the geographic areas and populations that act as hubs or drivers of HIV-1 spread. In Sub-Saharan Africa (sSA), the region with the highest HIV-1 burden, information about such transmission dynamics is sparse. Phylogenetic inference is a powerful method for the study of HIV-1 transmission networks and source attribution. In this review, we assessed available phylogenetic data on mixing between HIV-1 hotspots (geographic areas and populations with high HIV-1 incidence and prevalence) and areas or populations with lower HIV-1 burden in sSA. We searched PubMed and identified and reviewed 64 studies on HIV-1 transmission dynamics within and between risk groups and geographic locations in sSA (published 1995-2021). We describe HIV-1 transmission from both a geographic and a risk group perspective in sSA. Finally, we discuss the challenges facing phylogenetic inference in mixed epidemics in sSA and offer our perspectives and potential solutions to the identified challenges.

Benefits of enhanced infection prophylaxis at antiretroviral therapy initiation by cryptococcal antigen status

OBJECTIVES

To assess baseline prevalence of cryptococcal antigen (CrAg) positivity; and its contribution to reductions in all-cause mortality, deaths from cryptococcus and unknown causes, and new cryptococcal disease in the REALITY trial.

DESIGN

Retrospective CrAg testing of baseline and week-4 plasma samples in all 1805 African adults/children with CD4+ cell count less than 100 cells/μl starting antiretroviral therapy who were randomized to receive 12-week enhanced-prophylaxis (fluconazole 100 mg/day, azithromycin, isoniazid, cotrimoxazole) vs. standard-prophylaxis (cotrimoxazole).

METHODS

Proportional hazards models were used to estimate the relative impact of enhanced-prophylaxis vs. standard-cotrimoxazole on all, cryptococcal and unknown deaths, and new cryptococcal disease, through 24 weeks, by baseline CrAg positivity.

RESULTS

Excluding 24 (1.4%) participants with active/prior cryptococcal disease at enrolment (all treated for cryptococcal disease), 133/1781 (7.5%) participants were CrAg-positive. By 24 weeks, 105 standard-cotrimoxazole vs. 78 enhanced-prophylaxis participants died. Of nine standard-cotrimoxazole and three enhanced-prophylaxis cryptococcal deaths, seven and two, respectively, were CrAg-positive at baseline. Among deaths of unknown cause, only 1/46 standard-cotrimoxazole and 1/28 enhanced-prophylaxis were CrAg-positive at baseline. There was no evidence that relative reductions in new cryptococcal disease associated with enhanced-prophylaxis varied between baseline CrAg-positives [hazard-ratio = 0.36 (95% confidence interval 0.13-0.98), incidence 19.5 vs. 56.5/100 person-years] and CrAg-negatives [hazard-ratio = 0.33 (0.03-3.14), incidence 0.3 vs. 0.9/100 person-years; Pheterogeneity = 0.95]; nor for all deaths, cryptococcal deaths or unknown deaths (Pheterogeneity > 0.3).

CONCLUSION

Relative reductions in cryptococcal disease/death did not depend on CrAg status. Deaths of unknown cause were unlikely to be cryptococcus-related; plausibly azithromycin contributed to their reduction. Findings support including 100 mg fluconazole in an enhanced-prophylaxis package at antiretroviral therapy initiation where CrAg screening is unavailable/impractical.

Prevalence, risk and protective indicators of common mental disorders among young people living with HIV compared to their uninfected peers from the Kenyan coast: a cross-sectional study

BACKGROUND

In sub-Saharan Africa, common mental disorders (CMDs) like depression and anxiety are under-investigated amongst young people living with HIV (YLWH). To address the gap, in Kenya we: a) determined the prevalence of CMDs among YLWH compared to their uninfected peers; b) investigated HIV status as an independent predictor of CMDs in young people; c) investigated CMDs risk and protective indicators with more focus on YLWH.

METHODS

Between November 2018 and September 2019, 819 young people aged 18-24 years (407 HIV-infected) were recruited from two Counties on the Kenyan coast. Locally adapted pre-existing mental health measures, Patient Health Questionnaire (9-item) and Generalized Anxiety Disorder scale (7-item), were administered among other questionnaires via audio computer-assisted self-interview. Logistic regression was used to determine the correlates of CMDs.

RESULTS

Prevalence of CMDs was significantly elevated among YLWH compared to their uninfected peers i.e. 29% vs. 12%; p < 0.001 for depressive symptoms, 19% vs. 8%; p < 0.001 for anxiety symptoms, and 16% vs. 5%; p < 0.001 for comorbid depressive and anxiety symptoms. HIV status independently predicted depressive symptoms and its co-occurrence with anxiety symptoms. Among YLWH, negative life events, higher perceived HIV-related stigma and low adherence to antiretroviral therapy were the risk indicators for elevated CMDs. Among HIV-uninfected youths, death of both parents was a risk indicator for elevated depressive symptoms. Protective indicators against CMDs among youths with and without HIV included higher social support and health-related quality of life.

CONCLUSION

At the Kenyan coast, YLWH have significantly higher burden of CMDs compared to their uninfected peers. Being HIV-positive as a youth in this setting is predictive of more depressive symptoms and its comorbidity with anxiety symptoms. YLWH at high risk of CMDs in coastal Kenya can benefit from early detection, referral and treatment if routine screening for CMDs is integrated in their care package. The mental wellbeing of bereaving HIV-unaffected youths could be improved through continued support to help them come to terms with their loss. At the community level, programmes strengthening the social capital or improving the overall quality of life of youths with or without HIV may be beneficial to their mental health.

Beyond Their HIV Status: the Occurrence of Multiple Health Risk Behavior Among Adolescents from a Rural Setting of Sub-Saharan Africa

Background

Health risk behaviors during adolescence may cluster into patterns that might be predicted by specific factors, among which HIV may have an important role.

Method

In a cross-sectional study conducted between 2017 and 2018, clustering of HRB and its associated factors was investigated in rural Kenya among 588 adolescents (36% perinatally HIV infected; 28% perinatally HIV exposed but uninfected; and 36% HIV unexposed/uninfected). Latent class analysis of 22 behaviors followed by multinomial logistic regression were conducted. Four risk behavior classes were identified.

Results

No significant differences were found in behavioral class membership across the three HIV groups (p = 0.366). The risk of membership to the higher risk behavioral classes relative to class 1 (the substance and drug abstinent low risk takers) increased with older adolescent age (p = 0.047), increased among adolescent who experienced mental distress (p < 0.001), and those who felt unsafe in their neighborhood (p < 0.002). Better working memory (p = 0.0037) was found to be protective.

Conclusion

The results highlight a need to include screening and interventions for internalizing mental health problems and deficits in executive functioning, as well as steps to involve family members and communities to address psychosocial risk factors in adolescents in Kenya.

Determining the Origins of Human Immunodeficiency Virus Type 1 Drug-resistant Minority Variants in People Who Are Recently Infected Using Phylogenetic Reconstruction

BACKGROUND

Drug-resistant minority variants (DRMinVs) detected in patients who recently acquired human immunodeficiency virus type 1 (HIV-1) can be transmitted, generated de novo through virus replication, or technical errors. The first form is likely to persist and result in treatment failure, while the latter two could be stochastic and transient.

METHODS

Ultradeep sequencing of plasma samples from 835 individuals with recent HIV-1 infection in the United Kingdom was performed to detect DRMinVs at a mutation frequency between 2% and 20%. Sequence alignments including >110 000 HIV-1 partial pol consensus sequences from the UK HIV Drug Resistance Database (UK-HDRD), linked to epidemiological and clinical data from the HIV and AIDS Reporting System, were used for transmission cluster analysis. Transmission clusters were identified using Cluster Picker with a clade support of >90% and maximum genetic distances of 4.5% or 1.5%, the latter to limit detection to likely direct transmission events.

RESULTS

Drug-resistant majority variants (DRMajVs) were detected in 66 (7.9%) and DRMinVs in 84 (10.1%) of the recently infected individuals. High levels of clustering to sequences in UK-HDRD were observed for both DRMajV (n = 48; 72.7%) and DRMinV (n = 63; 75.0%) sequences. Of these, 43 (65.2%) with DRMajVs were in a transmission cluster with sequences that harbored the same DR mutation compared to only 3 (3.6%) sequences with DRMinVs (P < .00001, Fisher exact test). Evidence of likely direct transmission of DRMajVs was observed for 25/66 (37.9%), whereas none were observed for the DRMinVs (P < .00001).

CONCLUSIONS

Using a densely sampled HIV-infected population, we show no evidence of DRMinV transmission among recently infected individuals.

A Novel HIV-1 RNA Testing Intervention to Detect Acute and Prevalent HIV Infection in Young Adults and Reduce HIV Transmission in Kenya: Protocol for a Randomized Controlled Trial

Background

Detection and management of acute HIV infection (AHI) is a clinical and public health priority, and HIV infections diagnosed among young adults aged 18 to 39 years are usually recent. Young adults with recent HIV acquisition frequently seek care for symptoms and could potentially be diagnosed through the health care system. Early recognition of HIV infection provides considerable individual and public health benefits, including linkage to treatment as prevention, access to risk reduction counseling and treatment, and notification of partners in need of HIV testing.

Objective

The Tambua Mapema Plus study aims to (1) test 1500 young adults (aged 18-39 years) identified by an AHI screening algorithm for acute and prevalent (ie, seropositive) HIV, linking all newly diagnosed HIV-infected patients to care and offering immediate treatment; (2) offer assisted HIV partner notification services to all patients with HIV, testing partners for acute and prevalent HIV infection and identifying local sexual networks; and (3) model the potential impact of these two interventions on the Kenyan HIV epidemic, estimating incremental costs per HIV infection averted, death averted, and disability-adjusted life year averted using data on study outcomes.

Methods

A modified stepped-wedge design is evaluating the yield of this HIV testing intervention at 4 public and 2 private health facilities in coastal Kenya before and after intervention delivery. The intervention uses point-of-care HIV-1 RNA testing combined with standard rapid antibody tests to diagnose AHI and prevalent HIV among young adults presenting for care, employs HIV partner notification services to identify linked acute and prevalent infections, and follows all newly diagnosed patients and their partners for 12 months to ascertain clinical outcomes, including linkage to care, antiretroviral therapy (ART) initiation and virologic suppression in HIV-infected patients, and pre-exposure prophylaxis uptake in uninfected individuals in discordant partnerships.

Results

Enrollment started in December 2017. As of April 2020, 1374 participants have been enrolled in the observation period and 1500 participants have been enrolled in the intervention period, with 13 new diagnoses (0.95%) in the observation period and 37 new diagnoses (2.47%), including 2 AHI diagnoses, in the intervention period. Analysis is ongoing and will include adjusted comparisons of the odds of the following outcomes in the observation and intervention periods: being tested for HIV infection, newly diagnosed with prevalent or acute HIV infection, linked to care, and starting ART by week 6 following HIV diagnosis. Participants newly diagnosed with acute or prevalent HIV infection in the intervention period are being followed for outcomes, including viral suppression by month 6 and month 12 following ART initiation and partner testing outcomes.

Conclusions

The Tambua Mapema Plus study will provide foundational data on the potential of this novel combination HIV prevention intervention to reduce ongoing HIV transmission in Kenya and other high-prevalence African settings.

Trial Registration

ClinicalTrials.gov NCT03508908; https://clinicaltrials.gov/ct2/show/NCT03508908

International Registered Report Identifier (IRRID)

DERR1-10.2196/16198

HIV-1 Transmission Patterns Within and Between Risk Groups in Coastal Kenya

HIV-1 transmission patterns within and between populations at different risk of HIV-1 acquisition in Kenya are not well understood. We investigated HIV-1 transmission networks in men who have sex with men (MSM), injecting drug users (IDU), female sex workers (FSW) and heterosexuals (HET) in coastal Kenya. We used maximum-likelihood and Bayesian phylogenetics to analyse new (N = 163) and previously published (N = 495) HIV-1 polymerase sequences collected during 2005-2019. Of the 658 sequences, 131 (20%) were from MSM, 58 (9%) IDU, 109 (17%) FSW, and 360 (55%) HET. Overall, 206 (31%) sequences formed 61 clusters. Most clusters (85%) consisted of sequences from the same risk group, suggesting frequent within-group transmission. The remaining clusters were mixed between HET/MSM (7%), HET/FSW (5%), and MSM/FSW (3%) sequences. One large IDU-exclusive cluster was found, indicating an independent sub-epidemic among this group. Phylodynamic analysis of this cluster revealed a steady increase in HIV-1 infections among IDU since the estimated origin of the cluster in 1987. Our results suggest mixing between high-risk groups and heterosexual populations and could be relevant for the development of targeted HIV-1 prevention programmes in coastal Kenya.

Presence, persistence and effects of pre-treatment HIV-1 drug resistance variants detected using next generation sequencing: A Retrospective longitudinal study from rural coastal Kenya

BACKGROUND

The epidemiology of HIV-1 drug resistance (HIVDR) determined by Sanger capillary sequencing, has been widely studied. However, much less is known about HIVDR detected using next generation sequencing (NGS) methods. We aimed to determine the presence, persistence and effect of pre-treatment HIVDR variants detected using NGS in HIV-1 infected antiretroviral treatment (ART) naïve participants from rural Coastal Kenya.

METHODS

In a retrospective longitudinal study, samples from HIV-1 infected participants collected prior [n = 2 time-points] and after [n = 1 time-point] ART initiation were considered. An ultra-deep amplicon-based NGS assay, calling for nucleotide variants at >2.0% frequency of viral population, was used. Suspected virologic failure (sVF) was defined as a one-off HIV-1 viral load of >1000 copies/ml whilst on ART.

RESULTS

Of the 50 eligible participants, 12 (24.0% [95% CI: 13.1-38.2]) had at least one detectable pre-treatment HIVDR variant against Protease Inhibitors (PIs, n = 6 [12%]), Nucleoside Reverse Transcriptase Inhibitors (NRTIs, n = 4 [8.0%]) and Non-NRTIs (n = 3 [6.0%]). Overall, 15 pre-treatment resistance variants were detected (frequency, range: 2.3-92.0%). A positive correlation was observed between mutation frequency and absolute load for NRTI and/or NNRTI variants (r = 0.761 [p = 0.028]), but not for PI variants (r = -0.117 [p = 0.803]). Participants with pre-treatment NRTI and/or NNRTI resistance had increased odds of sVF (OR = 6.0; 95% CI = 1.0-36.9; p = 0.054).

CONCLUSIONS

Using NGS, pre-treatment resistance variants were common, though observed PI variants were unlikely transmitted, but rather probably generated de novo. Even when detected from a low frequency, pre-treatment NRTI and/or NNRTI resistance variants may adversely affect treatment outcomes.

HIV-1 subtype diversity, transmission networks and transmitted drug resistance amongst acute and early infected MSM populations from Coastal Kenya

Background

HIV-1 molecular epidemiology amongst men who have sex with men (MSM) in sub-Saharan Africa remains not well characterized. We aimed to determine HIV-1 subtype distribution, transmission clusters and transmitted drug resistance (TDR) in acute and early infected MSM from Coastal Kenya.

Methods

Analysis of HIV-1 partial pol sequences from MSM recruited 2005–2017 and sampled within six months of the estimated date of infection. Volunteers were classified as men who have sex with men exclusively (MSME) or with both men and women (MSMW). HIV-1 subtype and transmission clusters were determined by maximum-likelihood phylogenetics. TDR mutations were determined using the Stanford HIV drug resistance database.

Results

Of the 97 volunteers, majority (69%) were MSMW; 74%, 16%, 9% and 1% had HIV-1 subtypes A1, D, C or G, respectively. Overall, 65% formed transmission clusters, with substantial mixing between MSME and MSMW. Majority of volunteer sequences were either not linked to any reference sequence (56%) or clustered exclusively with sequences of Kenyan origin (19%). Eight (8% [95% CI: 4–16]) had at least one TDR mutation against nucleoside (n = 2 [2%]) and/or non-nucleoside (n = 7 [7%]) reverse transcriptase inhibitors. The most prevalent TDR mutation was K103N (n = 5), with sequences forming transmission clusters of two and three taxa each. There were no significant differences in HIV-1 subtype distribution and TDR between MSME and MSMW.

Conclusions

This HIV-1 MSM epidemic was predominantly sub-subtype A1, of Kenyan origin, with many transmission clusters and having intermediate level of TDR. Targeted HIV-1 prevention, early identification and care interventions are warranted to break the transmission cycle amongst MSM from Coastal Kenya.

Cumulative Psychosocial Risk is a Salient Predictor of Depressive Symptoms among Vertically HIV-Infected and HIV-Affected Adolescents at the Kenyan Coast

BACKGROUND

Little is known of mental health outcomes among vertically HIV-infected or HIV-affected adolescents in Africa.

OBJECTIVES

The current study set out to describe depressive symptoms and their correlates among vertically HIV-infected and HIV-affected adolescents at the Kenyan Coast.

METHODS

130 adolescents (vertically HIV-infected [n = 44], HIV-affected [n = 53], and unexposed [n = 33]) and their caregivers participated in this cross-sectional study. An adapted version of the Beck Depression Inventory-11 (BDI) was administered to examine depressive symptoms in both adolescents and caregivers, together with measures of sociodemographic, medical, and anthropometric characteristics.

FINDINGS

Our analysis indicated a main effect of HIV status on mean BDI scores in HIV-infected (18.4 [SD = 8.3) and HIV-affected (16.8 [SD = 7.3]) adolescents compared to the community controls (12.0 [SD = 7.9]), F (2, 127) = 6.704, P = .002, η² = .095. Post hoc analysis showed that BDI scores of HIV-infected adolescents were higher than those of community controls (P < .001). Similarly, HIV-affected adolescents had BDI scores that were higher than those of community controls (P = .007). However, there was no difference in BDI scores between HIV-infected and HIV-affected adolescents (P = .304). A path analytic model indicated that cumulative psychosocial risk (orphanhood, family poverty, and caregiver depressive symptoms) were positive predictors of BDI scores among adolescents, while nutritional status had a limited role.

CONCLUSIONS

Both HIV-infected and HIV-affected adolescents are at a high risk of experiencing depressive symptoms, largely due to the multiple psychosocial risk factors in their environment. The provision of adequate psychosocial support and counseling needs to become an integral part of the care program for adolescents from families living with HIV/AIDS at the Kenyan coast and other similar settings.

Prevalence and correlates of home delivery amongst HIV-infected women attending care at a rural public health facility in Coastal Kenya

BACKGROUND

Home delivery, referring to pregnant women giving birth in the absence of a skilled birth attendant, is a significant contributor to maternal mortality, and is encouragingly reported to be on a decline in the general population in resource limited settings. However, much less is known about home delivery amongst HIV-infected women in sub-Saharan Africa (sSA). We described the prevalence and correlates of home delivery among HIV-infected women attending care at a rural public health facility in Kilifi, Coastal Kenya.

METHODS

A cross-sectional design using mixed methods was used. Quantitative data were collected using interviewer-administered questionnaires from HIV-infected women with a recent pregnancy (within 5 years, n = 425), whilst qualitative data were collected using focused group discussions (FGD, n = 5). Data were analysed using logistic regression and a thematic framework approach respectively.

RESULTS

Overall, 108 (25.4%, [95% CI: 21.3-29.8]) participants delivered at home. Correlates of home delivery included lack of formal education (aOR 12.4 [95% CI: 3.4-46.0], p<0.001), history of a previous home delivery (2.7 [95% CI:1.2-6.0], p = 0.019) and being on highly active antiretroviral therapy (HAART, 0.4 [95% CI:0.2-0.8], p = 0.006).Despite a strong endorsement against home delivery, major thematic challenges included consumer-associated barriers, health care provider associated barriers and structural barriers.

CONCLUSION

A quarter of HIV-infected women delivered at home, which is comparable to estimates reported from the general population in this rural setting, and much lower than estimates from other sSA settings. A tailored package of care targeting women with no formal education and with a history of a previous home delivery, coupled with interventions towards scaling up HAART and improving the quality of maternal care in HIV-infected women may positively contribute to a decline in home delivery and subsequent maternal mortality in this setting.

Cytomegalovirus viraemia is associated with poor growth and T-cell activation with an increased burden in HIV-exposed uninfected infants

Objective:

Factors associated with poor health in HIV-exposed-uninfected (HEU) infants are poorly defined. We describe the prevalence and correlates of cytomegalovirus (CMV) viraemia in HEU and HIV-unexposed-uninfected (HUU) infants, and quantify associations with anthropometric, haematological, and immunological outcomes.

Design:

Cross-sectional, including HEU and HUU infants from rural coastal Kenya.

Methods:

Infants aged 2–8 months were studied. The primary outcome was CMV viraemia and viral load, determined by quantitative PCR. Correlates were tested by logistic and linear regression; coefficients were used to describe associations between CMV viraemia and clinical/immunological parameters.

Results:

In total, 42 of 65 (64.6%) infants had CMV viraemia [median viral load, 3.0 (interquartile ranges: 2.7–3.5) log₁₀ IU/ml]. Compared to community controls, HEU infants had six-fold increased odds of being viraemic (adjusted odds ratio 5.95 [95% confidence interval: 1.82–19.36], P = 0.003). Age, but not HEU/HUU status, was a strong correlate of CMV viral load (coefficient = −0.15, P = 0.009). CMV viral load associated negatively with weight-for-age (WAZ) Z-score (coefficient =  −1.06, P = 0.008) and head circumference-for-age Z-score (coefficient =  −1.47, P = 0.012) and positively with CD8⁺ T-cell coexpression of CD38/human leucocyte antigen DR (coefficient = 15.05, P = 0.003).

Conclusion:

The odds of having CMV viraemia was six-fold greater in HEU than HUU infants when adjusted for age. CMV viral load was associated with adverse growth and heightened CD8⁺ T-cell immune activation. Longitudinal assessments of the clinical effects of primary CMV infection and associated immunomodulation in early life in HEU and HUU populations are warranted.

What influences feeding decisions for HIV-exposed infants in rural Kenya?

BACKGROUND

Infant feeding in the context of human immunodeficiency virus (HIV) poses unique challenges to mothers and healthcare workers in balancing the perceived risks of HIV transmission and nutritional requirements. We aimed to describe the decision-making processes around infant feeding at a rural HIV clinic in Kenya.

METHODS

We used a qualitative study design. Between March and August 2011, we conducted in-depth interviews (n = 9) and focus group discussions (n = 10) with purposively selected hospital and community respondents at Kilifi County Hospital, Kenya. These respondents had all experienced of infant feeding in the context of HIV. These interviews were informed by prior structured observations of health care worker interactions with carers during infant feeding counselling sessions.

RESULTS

Overall, women living with HIV found it difficult to adhere to the HIV infant feeding guidance. There were three dominant factors that influenced decision making processes: 1) Exclusive breastfeeding was not the cultural norm, therefore practising it raised questions within the family and community about a mother's parenting capabilities and HIV status. 2) Women living with HIV lacked autonomy in decision-making on infant feeding due to socio-cultural factors. 3) Non-disclosure of HIV status to close members due to the stigma.

CONCLUSION

Infant feeding decision-making by women living with HIV in rural Kenya is constrained by a lack of autonomy, stigma and poverty. There is an urgent need to address these challenges through scaling up psycho-social and gender empowerment strategies for women, and introducing initiatives that promote the integration of HIV infant feeding strategies into other child health services.

Proportions of circulating follicular helper T cells are reduced and correlate with memory B cells in HIV-infected children

INTRODUCTION

HIV causes defects in memory B cells in children, but the mechanisms of those defects have not been fully elucidated. One possible mechanism is the lack of T-cell help to B cells during immune reactions. However, few studies have assessed the effect of HIV on follicular helper T cells (TFH cells) in children.

METHODS

In this study, follicular-homing CD4 T cells and memory B cells were assessed in HIV-infected children and compared with children from the community. CXCR5 and CD45RO were used as markers of follicular-homing T cells and memory T cells, respectively. Memory TFH cells were identified as CD3+CD8-CD4+CXCR5+CD45RO+PD1+. Central memory T cells were identified based on CCR7 expression. Relationship between the proportions of follicular-homing CD4 T cells and memory B cells were determined in multivariable regression models.

RESULTS

Highly viremic HIV-infected children had lower proportions of memory TFH cells when compared with community control children. In multivariable analyses, high proportions of memory TFH cells were associated with increased percentages of resting memory B cells after adjusting for other covariates.

CONCLUSION

The impact of HIV on follicular helper T cells could influence the accumulation of memory B cells in HIV-infected children.

A mixed methods approach to adapting and evaluating the functional assessment of HIV infection (FAHI), Swahili version, for use with low literacy populations

BACKGROUND

Despite bearing the largest HIV-related burden, little is known of the Health-Related Quality of Life (HRQoL) among people living with HIV in sub-Saharan Africa. One of the factors contributing to this gap in knowledge is the lack of culturally adapted and validated measures of HRQoL that are relevant for this setting.

AIMS

We set out to adapt the Functional Assessment of HIV Infection (FAHI) Questionnaire, an HIV-specific measure of HRQoL, and evaluate its internal consistency and validity.

METHODS

The three phase mixed-methods study took place in a rural setting at the Kenyan Coast. Phase one involved a scoping review to describe the evidence base of the reliability and validity of FAHI as well as the geographical contexts in which it has been administered. Phase two involved in-depth interviews (n = 38) to explore the content validity, and initial piloting for face validation of the adapted FAHI. Phase three was quantitative (n = 103) and evaluated the internal consistency, convergent and construct validities of the adapted interviewer-administered questionnaire.

RESULTS

In the first phase of the study, we identified 16 studies that have used the FAHI. Most (82%) were conducted in North America. Only seven (44%) of the reviewed studies reported on the psychometric properties of the FAHI. In the second phase, most of the participants (37 out of 38) reported satisfaction with word clarity and content coverage whereas 34 (89%) reported satisfaction with relevance of the items, confirming the face validity of the adapted questionnaire during initial piloting. Our participants indicated that HIV impacted on their physical, functional, emotional, and social wellbeing. Their responses overlapped with items in four of the five subscales of the FAHI Questionnaire establishing its content validity. In the third phase, the internal consistency of the scale was found to be satisfactory with subscale Cronbach's α ranging from 0.55 to 0.78. The construct and convergent validity of the tool were supported by acceptable factor loadings for most of the items on the respective sub-scales and confirmation of expected significant correlations of the FAHI subscale scores with scores of a measure of common mental disorders.

CONCLUSION

The adapted interviewer-administered Swahili version of FAHI questionnaire showed initial strong evidence of good psychometric properties with satisfactory internal consistency and acceptable validity (content, face, and convergent validity). It gives impetus for further validation work, especially construct validity, in similar settings before it can be used for research and clinical purposes in the entire East African region.

Dengue and Chikungunya Virus Infections among Young Febrile Adults Evaluated for Acute HIV-1 Infection in Coastal Kenya

Background

Fever is common among patients seeking care in sub-Saharan Africa (sSA), but causes other than malaria are rarely diagnosed. We assessed dengue and chikungunya virus infections among young febrile adults evaluated for acute HIV infection (AHI) and malaria in coastal Kenya.

Methods

We tested plasma samples obtained in a cross-sectional study from febrile adult patients aged 18–35 years evaluated for AHI and malaria at urgent care seeking at seven health facilities in coastal Kenya in 2014–2015. Dengue virus (DENV) and chikungunya virus (CHIKV) were amplified using quantitative real-time reverse-transcription polymerase chain reaction. We conducted logistic regression analyses to determine independent predictors of dengue virus infection.

Results

489 samples that were negative for both AHI and malaria were tested, of which 43 (8.8%, 95% confidence interval [CI]: 6.4–11.7) were positive for DENV infection. No participant was positive for CHIKV infection. DENV infections were associated with clinic visits in the rainy season (adjusted odds ratio (AOR) = 3.0, 95% CI: 1.3–6.5) and evaluation at a private health facility (AOR 5.2, 95% CI: 2.0–13.1) or research health facility (AOR = 25.6, 95% CI: 8.9–73.2) instead of a public health facility.

Conclusion

A high prevalence of DENV infections was found in febrile young adult patients evaluated for AHI. Our data suggests that DENV, along with AHI and malaria, should be considered in the differential diagnosis of the adult patient seeking care for fever in coastal Kenya.

Adaptation and Latent Structure of the Swahili Version of Beck Depression Inventory-II in a Low Literacy Population in the Context of HIV

Objective

We set out to adapt the Beck Depression Inventory (BDI)-II in Kenya and examine its factorial structure.

Methods

In the first phase we carried out in-depth interviews involving 29 adult members of the community to elicit their understanding of depression and identify aspects of the BDI-II that required adaptation. In the second phase, a modified version of BDI-II was administered to 221 adults randomly selected from the community to allow for the evaluation of its psychometric properties. In the third phase of the study we evaluated the discriminative validity of BDI-11 by comparing a randomly chosen community sample (n = 29) with caregivers of adolescents affected by HIV (n = 77).

Results

A considerable overlap between the BDI symptoms and those generated in the interviews was observed. Relevant idioms and symptoms such as ‘thinking too much’ and ‘Kuchoka moyo (having a tired heart)’ were identified. The administration of the BDI had to be modified to make it suitable for the low literacy levels of our participants. Fit indices for several models (one factorial, two-factor model and a three factor model) were all within acceptable range. Evidence indicated that while multidimensional models could be fitted, the strong correlations between the factors implied that a single factor model may be the best suited solution (alpha [0.89], and a significant correlation with locally identified items [r = 0.51]) confirmed the good psychometric properties of the adapted BDI-II. No evidence was found to support the hypothesis that somatization was more prevalent. Lastly, caregivers of HIV affected adolescents had significantly higher scores compared to adults randomly selected from the community F(1, 121) = 23.31, p < .001 indicating the discriminative validity of the adapted BDI = II.

Conclusions

With an adapted administration procedure, the BDI-II provides an adequate measure of depressive symptoms which can be used alongside other measures for proper diagnosis in a low literacy population.

'Everyone has a secret they keep close to their hearts': challenges faced by adolescents living with HIV infection at the Kenyan coast

Background

The upsurge in the uptake of antiretroviral therapy (ART) has led to a significant increase in the survival of vertically acquired HIV infected children, many of whom are currently living into adolescence and early adulthood. However little if anything is known of the lived experiences and the challenges faced by HIV positive adolescents in the African context. We set out to investigate psychosocial challenges faced by HIV infected adolescents on the Kenyan coast.

Methods

A total of 44 participants (12 HIV-infected adolescents, 7 HIV uninfected adolescents, and 25 key informants) took part in this qualitative study, using individually administered in-depth interviews. A framework approach was used to analyze the data using NVIVO software.

Results

We observed that the challenges faced by adolescents in rural Kenya could be placed into six major themes: poverty, poor mental and physical health, the lack of a school system that is responsive to their needs, challenges in how to disclose to peers and family members, high levels of stigma in its various forms, and challenges of medical adherence leading to the need for close monitoring.

Conclusion

In this African community, vertically acquired HIV-infected adolescents face a complex set of social, economic and medical challenges. Our study points to the urgent need to develop multisectorial intervention support programmes to fully address these challenges.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-016-2854-y) contains supplementary material, which is available to authorized users.

Control of Viremia Enables Acquisition of Resting Memory B Cells with Age and Normalization of Activated B Cell Phenotypes in HIV-Infected Children

HIV affects the function of all lymphocyte populations, including B cells. Phenotypic and functional defects of B cells in HIV-infected adults have been well characterized, but defects in children have not been studied to the same extent. We determined the proportion of B cell subsets and frequencies of Ag-specific memory B cells in peripheral blood from HIV-infected children and healthy controls, using flow cytometry and B cell ELISPOT, respectively. In addition, we measured the quantities and avidities of plasma Abs against various Ags by ELISA. We also determined plasma levels of BAFF and expression of BAFF receptors on B cells. Children with high HIV viremia had increased proportions of activated mature B cells, tissue-like memory B cells and plasmablasts, and low proportions of naive B cells when compared with community controls and children with low HIV viremia, similar to adults infected with HIV. HIV-infected groups had lower proportions of resting memory B cells than did community controls. Notably, high HIV viremia prevented the age-dependent accumulation of class-switched resting memory B cells. HIV-infected children, regardless of the level of viremia, showed lower quantities and avidities of IgG and lower frequencies of memory B cells against Expanded Program on Immunization vaccines. The HIV-infected children had an altered BAFF profile that could have affected their B cell compartment. Therefore, B cell defects in HIV-infected children are similar to those seen in HIV-infected adults. However, control of HIV viremia is associated with normalization of activated B cell subsets and allows age-dependent accumulation of resting memory B cells.

Incidence and predictors of attrition from antiretroviral care among adults in a rural HIV clinic in Coastal Kenya: a retrospective cohort study

Background

Scale up of antiretroviral therapy (ART) has led to substantial declines in HIV related morbidity and mortality. However, attrition from ART care remains a major public health concern and has been identified as one of the key reportable indicators in assessing the success of ART programs. This study describes the incidence and predictors of attrition among adults initiating ART in a rural HIV clinic in Coastal Kenya.

Methods

A retrospective cohort study design was used. Adults (≥15 years) initiated ART between January 2008 and December 2010 were followed up for two years. Attrition was defined as individuals who were either reported dead or lost to follow up (LFU, ≥ 180 days late since the last clinic visit). Kaplan Meier survival probabilities and Weibull baseline hazard regression analyses were used to model the incidence and predictors of time to attrition.

Results

Of the 928 eligible participants, 308 (33.2% [95% CI, 30.2 – 36.3]) underwent attrition at an incident rate of 23.1 (95% CI, 20.6 – 25.8)/100 pyo. Attrition at 6 and 12 months was 18.4% (95% CI, 16.0 – 21.1) and 23.2% (95% CI, 19.9 – 25.3) respectively. Gender (male vs. female, adjusted hazard ratio [95% CI], p-value: 1.5 [1.1 – 2.0], p = 0.014), age (15 – 24 vs. ≥ 45 years, 2.2 [1.3 – 3.7], p = 0.034) and baseline CD4 T-cell count (100 – 350 cells/uL vs. <100 cells/uL, 0.5 [0.3 – 0.7], p = 0.002) were independent predictors of time to attrition.

Conclusions

A third of individuals initiating ART were either reported dead or LFU during two years of care, with more than a half of these occurring within six months of treatment initiation. Practical and sustainable biomedical interventions and psychosocial support systems are warranted to improve ART retention in this setting.

HIV-1 virologic failure and acquired drug resistance among first-line antiretroviral experienced adults at a rural HIV clinic in coastal Kenya: a cross-sectional study

Background

An increasing number of people on antiretroviral therapy (ART) in sub-Saharan Africa has led to declines in HIV related morbidity and mortality. However, virologic failure (VF) and acquired drug resistance (ADR) may negatively affect these gains. This study describes the prevalence and correlates of HIV-1 VF and ADR among first-line ART experienced adults at a rural HIV clinic in Coastal Kenya.

Methods

HIV-infected adults on first-line ART for ≥6 months were cross-sectionally recruited between November 2008 and March 2011. The primary outcome was VF, defined as a one-off plasma viral load of ≥400 copies/ml. The secondary outcome was ADR, defined as the presence of resistance associated mutations. Logistic regression and Fishers exact test were used to describe correlates of VF and ADR respectively.

Results

Of the 232 eligible participants on ART over a median duration of 13.9 months, 57 (24.6% [95% CI: 19.2 – 30.6]) had VF. Fifty-five viraemic samples were successfully amplified and sequenced. Of these, 29 (52.7% [95% CI: 38.8 – 66.3]) had at least one ADR, with 25 samples having dual-class resistance mutations. The most prevalent ADR mutations were the M184V (n = 24), K103N/S (n = 14) and Y181C/Y/I/V (n = 8). Twenty-six of the 55 successfully amplified viraemic samples (47.3%) did not have any detectable resistance mutation. Younger age (15–34 vs. ≥35 years: adjusted odd ratios [95% CI], p-value: 0.3 [0.1–0.6], p = 0.002) and unsatisfactory adherence (<95% vs. ≥95%: 3.0 [1.5–6.5], p = 0.003) were strong correlates of VF. Younger age, unsatisfactory adherence and high viral load were also strong correlates of ADR.

Conclusions

High levels of VF and ADR were observed in younger patients and those with unsatisfactory adherence. Youth-friendly ART initiatives and strengthened adherence support should be prioritized in this Coastal Kenyan setting. To prevent unnecessary/premature switches, targeted HIV drug resistance testing for patients with confirmed VF should be considered.

Pediatric kidney transplantation in the developing world: challenges and solutions

The prevalence of pediatric RRT and transplantation are low in developing countries, 6-12 and <1 to 5 per million child population (pmcp), respectively. This is due to low GDP/capita of <$10 000, government expenditure on health of <2.6-9% of GDP and paucity of facilities. The reported incidence of pediatric CKD and ESRD is <1.0-8 and 3.4-35 pmcp, respectively. RRT and transplantation are offered mostly in private centers in cities where HD costs $20-100/session and transplants $10 000-20 000. High costs and long distance to centers results in treatment refusal in up to 35% of the cases. In this backdrop 75-85% of children with ESRD are disfranchised from RRT and transplantation. Our center initiated an integrated dialysis-transplant program funded by a community-government partnership where RRT and transplantation was provided "free of cost" with life long follow-up and medication. Access to free RRT at doorsteps and transplantation lead to societal acceptance of transplantation as the therapy of choice for ESRD. This enabled us to perform 475 pediatric transplants in 25 years with 1- and 5-year graft survival of 96% and 81%, respectively. Our model shows that pediatric transplantation is possible in developing countries when freely available and accessible to all who need it in the public sector.

Low prevalence of transmitted HIV type 1 drug resistance among antiretroviral-naive adults in a rural HIV clinic in Kenya

Low levels of HIV-1 transmitted drug resistance (TDR) have previously been reported from many parts of sub-Saharan Africa (sSA). However, recent data, mostly from urban settings, suggest an increase in the prevalence of HIV-1 TDR. Our objective was to determine the prevalence of TDR mutations among HIV-1-infected, antiretroviral (ARV)-naive adults enrolling for care in a rural HIV clinic in Kenya. Two cross-sectional studies were carried out between July 2008 and June 2010. Plasma samples from ARV-naive adults (>15 years old) at the time of registering for care after HIV diagnosis and before starting ARVs were used. A portion of the pol subgenomic region of the virus containing the protease and part of the reverse transcriptase genes was amplified and sequenced. TDR mutations were identified and interpreted using the Stanford HIV drug resistance database and the WHO list for surveillance of drug resistance strains. Overall, samples from 182 ARV-naive adults [mean age (95% CI): 34.9 (33.3-36.4) years] were successfully amplified and sequenced. Two TDR mutations to nucleoside reverse transcriptase inhibitors [n=1 (T215D)] and protease inhibitors [n=1 (M46L)] were identified, giving an overall TDR prevalence of 1.1% (95% CI: 0.1-3.9). Despite reports of an increase in the prevalence of HIV-1 TDR in some urban settings in sSA, we report a prevalence of HIV-1 TDR of less than 5% at a rural HIV clinic in coastal Kenya. Continued broader surveillance is needed to monitor the extent of TDR in sSA.

HIV type 1 in a rural coastal town in Kenya shows multiple introductions with many subtypes and much recombination

The extent of HIV-1 diversity was examined among patients attending a rural district hospital in a coastal area of Kenya. The pol gene was sequenced in samples from 153 patients. Subtypes were designated using the REGA, SCUEAL, and jpHMM programs. The most common subtype was A1, followed by C and D; A2 and G were also detected. However, a large proportion of the samples was found to be recombinants, which clustered within the pure subtype branches. Phylogeographic analysis of Kilifi sequences compared with those from other regions of Africa showed that while many sequences were closely related to sequences from Kenya, others were most closely related to known sequences from other parts of Africa, including West Africa. Overall, these data indicate that there have been multiple introductions of HIV-1 into this small rural town and surroundings with ongoing diversity being generated by recombination.

Dynamics and constraints of early infant diagnosis of HIV infection in Rural Kenya

A cohort design was used to determine uptake and drop out of 213 HIV-exposed infants eligible for Early Infant Diagnosis (EID) of HIV. To explore service providers and care givers knowledge, attitudes and perceptions of the EID process, observations and in-depth interviews were conducted. 145 (68%) infants enrolled after 2 months of age. 139 (65%) dropped out before follow up to 18 months old. 60 (43%) drop outs occurred within 2 months of enrolment. Maternal factors associated with infant drop out were maternal loss to follow up (48 [68%] vs. 8 [20%], P < 0.001) and younger maternal age (27.2 vs. 30.1 years, P = 0.033). Service providers and caregivers had inadequate training, knowledge and understanding of EID. Poverty and lack of social support were challenges in accessing EID services. EID should be more closely aligned within PMTCT services, integrated with routine mother and child health (MCH) activities and its implementation more closely monitored.

Anti-inflammatory activity of crude saponin extracts from five Nigerian medicinal plants

Crude saponin extracts of five medicinal plants used in the treatment of inflammatory diseases like rheumatoid arthritis, gout and haemorrhoids were screened for anti-inflammatory activity using carrageenan-induced rat paw oedema test. These plants were the whole plant of Schwenkia americana Linn (WSA), the rhizomes of Asparagus africanus Lam (RAA), the leaves of Dichrostachys cinerea Linn (LDC), the stem bark of Ficus iteophylla Miq (BFI) and the leaves of Indigofera pulchra Willd (LIP). A modify traditional method of crude saponins extraction was used to give the following percentage yields: WSA-2.74%, RAA-3.59%, LDC-1.62%, BFI-0.81% and LIP-1.57% respectively. Thin-layer chromatography was used to identify the type of saponins present in the extracts. The acute toxicity study of the crude saponin extracts in mice gave the following intraperitoneal LD50: WSA-471.2mg/kg, RAA- 1264.9mg/kg, LDC-1264.9 mg/kg, BFI-118.3mg/kg and LIP-1264.9 mg/kg respectively. The anti-inflammatory study of the extracts showed statistically significant (P<0.05) decreases in the rat paw-oedema as compared to the control. The percentage inhibitions of the extracts after four hours were as follow: WSA-61%, RAA-55%, LDC-72%, BFI-66% and LIP-40% respectively. These values were found to be comparable to that of ketoprofen-63%. The study showed that the anti-inflammatory properties attributable to these plants may be due to their saponins contents.

Early loss to follow-up of recently diagnosed HIV-infected adults from routine pre-ART care in a rural district hospital in Kenya: a cohort study

OBJECTIVE

To determine the rate and predictors of early loss to follow-up (LTFU) for recently diagnosed HIV-infected, antiretroviral therapy (ART)-ineligible adults in rural Kenya.

METHODS

Prospective cohort study. Clients registering for HIV care between July 2008 and August 2009 were followed up for 6 months. Baseline data were used to assess predictors of pre-ART LTFU (not returning for care within 2 months of a scheduled appointment), LTFU before the second visit and LTFU after the second visit. Logistic regression was used to determine factors associated with LTFU before the second visit, while Cox regression was used to assess predictors of time to LTFU and LTFU after the second visit.

RESULTS

Of 530 eligible clients, 178 (33.6%) were LTFU from pre-ART care (11.1/100 person-months). Of these, 96 (53.9%) were LTFU before the second visit. Distance (>5 km vs. <1 km: adjusted hazard ratio 2.6 [1.9-3.7], P < 0.01) and marital status (married vs. single: 0.5 [0.3-0.6], P < 0.01) independently predicted pre-ART LTFU. Distance and marital status were independently associated with LTFU before the second visit, while distance, education status and seasonality showed weak evidence of predicting LTFU after the second visit. HIV disease severity did not predict pre-ART LTFU.

CONCLUSIONS

A third of recently diagnosed HIV-infected, ART-ineligible clients were LTFU within 6 months of registration. Predictors of LTFU among ART-ineligible clients are different from those among clients on ART. These findings warrant consideration of an enhanced pre-ART care package aimed at improving retention and timely ART initiation.

Analgesic and anti-inflammatory activities of Asparagus africanus root extract

The methanolic extract of the roots of Asparagus africanus Lam (Liliaceae) which contains mainly saponins and carbohydrate showed significant analgesic and anti-inflammatory activities (P<0.05) in the tail-flick/hot-plate test and egg albumen-induced rat paw oedema tests that were comparable to the test drugs (morphine 20 mg/kg and indomethacin 50 mg/kg respectively). These results indicate that the extract possesses analgesic and anti-inflammatory properties.

Nitric oxide synthase inhibition in thoroughbred horses augments O2 extraction at rest and submaximal exercise, but not during short-term maximal exercise

REASON FOR PERFORMING STUDY

Work is required to establish the role of endogenous nitric oxide (NO) in metabolism of resting and exercising horses.

OBJECTIVES

To examine the effects of NO synthase inhibition on O2 extraction and anaerobic metabolism at rest, and during submaximal and maximal exertion.

METHODS

Placebo and NO synthase inhibition (with Nomega-nitro-L-arginine methyl ester [L-NAME] administered at 20 mg/kg bwt i.v.) studies were performed in random order, 7 days apart on 7 healthy, exercise-trained Thoroughbred horses at rest and during incremental exercise leading to 120 sec of maximal exertion at 14 m/sec on a 3.5% uphill grade.

RESULTS

At rest, NO synthase inhibition significantly augmented the arterial to mixed-venous blood O2 content gradient and O2 extraction as mixed-venous blood O2 tension and saturation decreased significantly. While NO synthase inhibition did not affect arterial blood-gas tensions in exercising horses, the exercise-induced increment in haemoglobin concentration and arterial O2 content was attenuated. In the L-NAME study, during submaximal exercise, mixed-venous blood O2 tension and haemoglobin-O2 saturation decreased to a greater extent causing O2 extraction to increase significantly. During maximal exertion, arterial hypoxaemia, desaturation of haemoglobin and hypercapnia of a similar magnitude developed in both treatments. Also, the changes in mixed-venous blood O2 tension and haemoglobin-O2 saturation, arterial to mixed-venous blood O2 content gradient, O2 extraction and markers of anaerobic metabolism (lactate and ammonia production, and metabolic acidosis) were not different from those in the placebo study.

CONCLUSION

Endogenous NO production augments O2 extraction at rest and during submaximal exertion, but not the during short-term maximal exercise. Also, NO synthase inhibition does not affect anaerobic metabolism at rest or during exertion.

POTENTIAL RELEVANCE

It is unlikely that endogenous NO release modifies aerobic or anaerobic metabolism in horses performing short-term maximal exertion.

Pre-exercise hypervolaemia is not detrimental to arterial oxygenation of horses performing a prolonged exercise protocol simulating the second day of a 3-day equestrian event

REASONS FOR PERFORMING STUDY

Hyperhydration, prior to prolonged moderate-intensity exercise simulating the 2nd day of a 3-day equestrian event (E3DEC), may induce arterial hypoxaemia detrimental to performance.

OBJECTIVES

Because moderate-intensity exercise does not induce arterial hypoxaemia in healthy horses, the effects of pre-exercise hypervolaemia on arterial oxygenation were examined during a prolonged exercise protocol.

METHODS

Blood-gas studies were carried out on 7 healthy, exercise-trained Thoroughbred horses in control and hyperhydration experiments. The study conformed to a randomised crossover design. The sequence of treatments was randomised for each horse and 7 days were allowed between studies. Hyperhydration was induced by administering 0.425 g/kg bwt NaCl via nasogastric tube followed by free access to water. The exercise protocol was carried out on a treadmill set at a 3% uphill grade and consisted of walking at 2 m/sec for 2 min, trotting for 10 min at 3.7 m/sec, galloping for 2 min at 14 m/sec (which elicited maximal heart rate), trotting for 20 min at 3.7 m/sec, walking for 10 min at 1.8 m/sec, cantering for 8 min at 9.2 m/sec, trotting for 1 min at 5 m/sec and walking for 5 min at 2 m/sec.

RESULTS

NaCl administration induced a significant mean +/- s.e. 15.5 +/- 1.1% increase in plasma volume as indicated by a significant reduction in plasma protein concentration. In either treatment, whereas arterial hypoxaemia was not observed during periods of submaximal exercise, short-term maximal exertion caused significant arterial hypoxaemia, desaturation of haemoglobin, hypercapnoea, and acidosis in both treatments. However, the magnitude of exercise-induced arterial hypoxaemia, desaturation of haemoglobin, hypercapnoea, and acidosis in both treatments remained similar, and statistically significant differences between treatments could not be demonstrated.

CONCLUSIONS

It was concluded that significant pre-exercise expansion of plasma volume by this method does not adversely affect the arterial oxygenation of horses performing a prolonged exercise protocol simulating the 2nd day of an E3DEC.

Hyperhydration prior to a simulated second day of the 3-day moderate intensity equestrian competition does not cause arterial hypoxemia in Thoroughbred horses

Dehydration and the associated impairment of cardiovascular and thermoregulatory function comprise major veterinary problems in horses performing prolonged exercise, particularly under hot and humid conditions. For these reasons, there is considerable interest in using pre-exercise hyperhydration to help maintain blood volume in the face of the excessive fluid loss associated with sweat production during prolonged exertion. However, recently it was reported that pre-exercise hyperhydration causes arterial hypoxemia in horses performing moderate intensity exercise simulating the second day of an equestrian 3-day event competition (E3DEC) which may adversely affect performance (Sosa Leon et al. in Equine Vet J Suppl 34:425-429, 2002). These findings are contrary to data from horses performing short-term maximal exertion, wherein hyperhydration did not affect arterial O2 tension/saturation. Thus, our objective in the present study was to examine the impact of pre-exercise hyperhydration on arterial oxygenation of Thoroughbred horses performing an exercise test simulating the second day of an E3DEC. Control and hyperhydration studies were carried out on seven healthy Thoroughbred horses in random order, 7 days apart. In the control study, horses received no medications. In the hyperhydration experiments, nasogastric administration of NaCl (0.425 g/kg) 5 h pre-exercise induced a plasma volume expansion of 10.9% at the initiation of exercise. This methodology for inducing hypervolemia was different from that of Sosa Leon et al. (2002). Blood-gas tensions/pH as well as plasma protein, hemoglobin and blood lactate concentrations were measured pre-exercise and during the exercise test. Our data revealed that pre-exercise hyperhydration neither adversely affected arterial O2 tension nor hemoglobin-O2 saturation at any time during the exercise test simulating the second day of an E3DEC. Further, it was observed that arterial blood CO2 tension, pH, and blood lactate concentrations also were not affected by pre-exercise hyperhydration. However, hemodilution in hyperhydrated horses caused an attenuation of the expansion in the arterial to mixed-venous blood O2 content gradient during phases B and D of the exercise protocol, which was likely offset by an increase in cardiac output. It is concluded that pre-exercise hyperhydration of horses induced in the manner described above is not detrimental to arterial oxygenation of horses performing an exercise test simulating the second day of an E3DEC.

The efficacy of excimer laser (308 nm) for vitiligo at different body sites

BACKGROUND

The treatment with XeCl-excimer laser generated 308-nm UVB radiation has shown promising results in patients with vitiligo.

OBJECTIVE

In this controlled, prospective trial we studied the primary efficacy (start and grade of repigmentation) and patient's satisfaction of XeCl-excimer laser for treatment of vitiligo patches at different body sites and re-evaluated the achieved repigmentation 12 months after the end of therapy.

METHODS

Twenty-five patients with generalized or localized vitiligo with a total of 85 lesions at different body sites were enrolled in this study. Vitiligo patches were treated with 308-nm XeCl-excimer laser 3 times a week for 6 to 10 weeks. The overall repigmentation grade of each treated lesion was evaluated once a week on a 5 point scale rating from 0 (no repigmentation), 1 (1-5%), 2 (6-25%), 3 (26-50%), 4 (51-75%), to 5 (76-100%).

RESULTS

Twenty-four patients completed the study. Within 6 to 10 weeks of treatment 67% of the patients (16/24) developed follicular repigmentation of at least one of their vitiligo lesions. Lesion repigmentation started after a mean of 13 treatments in lesions located on the face, trunk, arm, and/or leg (high-responder location), and after a mean of 22 treatments in lesions located on the elbow, wrist, dorsum of the hand, knee, and/or dorsum of the foot (low-responder location). Untreated control lesions and lesions located on the fingers did not achieve any repigmentation. After 10 weeks of treatment repigmentation of more than 75% was found in 25% (7/28) of lesions of the high-responder location group versus 2% (1/43) of lesions of the low-responder location group. In most cases, laser-induced repigmentation was persistent, as determined 12 months after the end of treatment.

CONCLUSIONS

308-nm excimer laser is an effective modality for the treatment of vitiligo. However, similar to other non-surgical treatment modalities, the therapeutic effect is mainly dependent on the location of vitiligo lesions.

Optimal weekly frequency of 308-nm excimer laser treatment in vitiligo patients

BACKGROUND

Recently the beneficial effect of excimer laser treatment has been reported for patients with vitiligo. The influence of treatment frequency on this effect is not clear.

OBJECTIVES

To determine the optimal frequency of 308-nm excimer laser therapy for vitiligo.

METHODS

In this prospective, university-based hospital study over 12 weeks we enrolled 14 patients. Each had at least three stable vitiligo lesions in the same body area. The three stable vitiligo lesions in each subject were randomly assigned to receive excimer laser treatment once (1 x), twice (2 x) and three times (3 x) weekly, respectively. The initial ultraviolet (UV) dose was 50 mJ cm(-2) less than the 308-nm minimal erythematous dose in vitiligo skin. The UV dose was increased at each treatment session according to the erythematous response to the previous treatment.

RESULTS

Thirteen subjects were treated for at least 6 weeks; seven were treated for all 12 weeks. At 6 weeks, the repigmentation rates for treated lesions were 8% (1/13) after 1 x weekly treatment, 23% (3/13) after 2 x weekly treatment and 62% (8/13) after 3 x weekly treatment (P = 0.0134; 3 x vs. 1 x weekly); at 12 weeks, these rates were 46% (6/13), 62% (8/13) and 69% (9/13), respectively (P = NS; 3 x vs. 1 x weekly). Repigmentation initiation correlated with treatment number, regardless of frequency (P = NS). As shown by Kaplan-Meier analysis, repigmentation occurred earliest in the most frequently treated lesions (P = 0.0336). At 12 weeks, the projected repigmentation rates for 1 x, 2 x and 3 x weekly treatment approached each other (60%, 79% and 82%, respectively); the mean repigmentation grades (on a scale of 0-5) for 1 x, 2 x and 3 x weekly treatment were 1.7, 2.4 and 3.3, respectively (P = 0.018; 3 x vs. 1 x weekly). Laser-induced repigmentation persisted in most cases over the entire follow-up of 12 months after the end of treatment.

CONCLUSIONS

308-nm excimer laser therapy is effective against vitiligo. Although repigmentation occurs fastest with 3 x weekly treatment, the ultimate repigmentation initiation seems to depend entirely on the total number of treatments, not their frequency. However, treatment periods of more than 12 weeks may be necessary to obtain a satisfactory clinical repigmentation, particularly when vitiligo lesions are treated only 1 x or 2 x compared with 3 x weekly.

[Dyschromatosis universalis hereditaria. An unusually rare clinical picture]

A 30-year old male patient presented with a rare congenital pigment disturbance, dyschromatosis universalis hereditaria. Clinically, he displayed mottled hyperpigmentation covering almost the entire skin surface with accentuation in skin folds. The lesions had been present since birth. He was the only family member showing these changes. He had no other medical problems and took no medications.

Nitric oxide synthase inhibition does not affect the exercise-induced arterial hypoxemia in Thoroughbred horses

Because sensitivity of equine pulmonary vasculature to endogenous as well as exogenous nitric oxide (NO) has been demonstrated, we examined whether endogenous NO production plays a role in exercise-induced arterial hypoxemia. We hypothesized that inhibition of NO synthase may alter the distribution of ventilation-perfusion mismatching, which may affect the exercise-induced arterial hypoxemia. Arterial blood-gas variables were examined in seven healthy, sound Thoroughbred horses at rest and during incremental exercise protocol leading to galloping at maximal heart rate without (control; placebo = saline) and with N(omega)-nitro-L-arginine methyl ester (L-NAME) administration (20 mg/kg iv). The experiments were carried out in random order, 7 days apart. At rest, L-NAME administration caused systemic hypertension, pulmonary hypertension, and bradycardia. During 120 s of galloping at maximal heart rate, significant arterial hypoxemia, desaturation of hemoglobin, hypercapnia, hyperthermia, and acidosis occurred in the control as well as in NO synthase inhibition experiments. However, statistically significant differences between the treatments were not found. In both treatments, exercise caused a significant rise in hemoglobin concentration, but the increment was significantly attenuated in the NO synthase inhibition experiments, and, therefore, arterial O(2) content (Ca(O(2))) increased to significantly lower values. These data suggest that, whereas L-NAME administration does not affect pulmonary gas exchange in exercising horses, it may affect splenic contraction, which via an attenuation of the rise in hemoglobin concentration and Ca(O(2)) may limit performance at higher workloads.

Inhibition of nitric oxide synthase with L-NAME does not increase lactate production at rest or during short-term high-intensity exercise in Thoroughbred horses

The present study was carried out to determine whether inhibition of nitric oxide (NO) synthase promotes anaerobic metabolism in exercising horses, resulting in a significantly increased blood lactate concentration. N(omega)-nitro-L-arginine methyl ester (L-NAME) is a potent inhibitor of NO synthase that has been tested in horses and other species. Two sets of experiments, namely placebo (saline control) and L-NAME (20 mg/kg, i.v.) studies, were carried out on seven healthy, sound, exercise-trained, Thoroughbred horses in random order, 6 to 7 days apart. In both experiments, an incremental exercise protocol was used and data were obtained at rest, during submaximal exercise performed at 8 m/s on a 4.5% uphill grade, and during galloping at 14 m/s on a 4.5% uphill grade--a workload that not only elicited maximal heart rate and induced exercise-induced pulmonary haemorrhage, but also could not be sustained for more than 90 s. Measurements were also made in the recovery period. Mixed-venous blood samples, obtained at matched intervals in the two sets of experiments, were analysed in triplicate for determining the lactate concentration. Following administration of L-NAME, significant bradycardia occurred at rest (27 +/- 1 vs 37 +/- 2 beats/min in the placebo trials; p<0.0001) as well as during submaximal exercise (183 +/- 4 vs 200 +/- 4 beats/min in the placebo trials; p<0.001), but the heart rate increased during galloping at 14 m/s on a 4.5% uphill grade to reach values observed in the placebo trials (215 +/- 2 beats/min) and significant differences were not found. At rest, the mixed-venous blood lactate concentration was similar in the two experiments. With exercise, the mixed-venous blood lactate concentration increased progressively as work intensity increased in both trials, but significant differences were not found between the placebo and the L-NAME experiments during submaximal exercise, near-maximal exercise or recovery. These experiments demonstrated that inhibition of NO synthase in Thoroughbred horses does not promote enhanced anaerobic metabolism at rest or during short-term incremental exercise leading to galloping at maximal heart rate.

Effect of prior high-intensity exercise on exercise-induced arterial hypoxemia in Thoroughbred horses

Strenuously exercising horses exhibit arterial hypoxemia and exercise-induced pulmonary hemorrhage (EIPH), the latter resulting from stress failure of pulmonary capillaries. The present study was carried out to examine whether the structural changes in the blood-gas barrier caused by a prior bout of high-intensity short-term exercise capable of inducing EIPH would affect the arterial hypoxemia induced during a successive bout of exercise performed at the same workload. Two sets of experiments, double- and single-exercise-bout experiments, were carried out on seven healthy, sound Thoroughbred horses. Experiments were carried out in random order, 7 days apart. In the double-exercise experiments, horses performed two successive bouts (each lasting 120 s) of galloping at 14 m/s on a 3.5% uphill grade, separated by an interval of 6 min. Exertion at this workload induced arterial hypoxemia within 30 s of the onset of galloping as well as desaturation of Hb, a progressive rise in arterial PCO2, and acidosis as exercise duration increased from 30 to 120 s. In the single-exercise-bout experiments, blood-gas/pH data resembled those from the first run of the double-exercise experiments, and all horses experienced EIPH. Thus, in the double-exercise experiments, before the horses performed the second bout of galloping at 14 m/s on a 3.5% uphill grade, stress failure of pulmonary capillaries had occurred. Although arterial hypoxemia developed during the second run, arterial PO2 values were significantly (P < 0.01) higher than in the first run. Thus prior exercise not only failed to accentuate the severity of arterial hypoxemia, it actually diminished the magnitude of exercise-induced arterial hypoxemia. The decreased severity of exercise-induced arterial hypoxemia in the second run was due to an associated increase in alveolar PO2, as arterial PCO2 was significantly lower than in the first run. Thus our data do not support a role for structural changes in the blood-gas barrier related to the stress failure of pulmonary capillaries in causing the exercise-induced arterial hypoxemia in horses.