The Lake Victoria Island Intervention Study on Worms and Allergy-related diseases (LaVIISWA): study protocol for a randomised controlled trial

Genome-wide analysis of Schistosoma mansoni reveals limited population structure and possible praziquantel drug selection pressure within Ugandan hot-spot communities

Populations within schistosomiasis control areas, especially those in Africa, are recommended to receive regular mass drug administration (MDA) with praziquantel (PZQ) as the main strategy for controlling the disease. The impact of PZQ treatment on schistosome genetics remains poorly understood, and is limited by a lack of high-resolution genetic data on the population structure of parasites within these control areas. We generated whole-genome sequence data from 174 individual miracidia collected from both children and adults from fishing communities on islands in Lake Victoria in Uganda that had received either annual or quarterly MDA with PZQ over four years, including samples collected immediately before and four weeks after treatment. Genome variation within and between samples was characterised and we investigated genomic signatures of natural selection acting on these populations that could be due to PZQ treatment. The parasite population on these islands was more diverse than found in nearby villages on the lake shore. We saw little or no genetic differentiation between villages, or between the groups of villages with different treatment intensity, but slightly higher genetic diversity within the pre-treatment compared to post-treatment parasite populations. We identified classes of genes significantly enriched within regions of the genome with evidence of recent positive selection among post-treatment and intensively treated parasite populations. The differential selection observed in post-treatment and pre-treatment parasite populations could be linked to any reduced susceptibility of parasites to praziquantel treatment.

Profiles of inflammatory markers and their association with cardiometabolic parameters in rural and urban Uganda

Background: Inflammation may be one of the pathways explaining differences in cardiometabolic risk between urban and rural residents. We investigated associations of inflammatory markers with rural versus urban residence, and with selected cardiometabolic parameters previously observed to differ between rural and urban residents: homeostatic model assessment of insulin resistance (HOMA-IR), fasting blood glucose (FBG), blood pressure (BP) and body mass index (BMI). Methods: From two community surveys conducted in Uganda, 313 healthy individuals aged ≥ 10 years were selected by age- and sex-stratified random sampling (rural Lake Victoria island communities, 212; urban Entebbe municipality, 101). Fluorescence intensities of plasma cytokines and chemokines were measured using a bead-based multiplex immunoassay. We used linear regression to examine associations between the analytes and rural-urban residence and principal component analysis (PCA) to further investigate patterns in the relationships. Correlations between analytes and metabolic parameters were assessed using Pearson’s correlation coefficient. Results: The urban setting had higher mean levels of IL-5 (3.27 vs 3.14, adjusted mean difference [95% confidence interval] 0.12[0.01,0.23] p=0.04), IFN-⍺ (26.80 vs 20.52, 6.30[2.18,10.41] p=0.003), EGF (5.67 vs 5.07, 0.60[0.32,0.98] p<0.00001), VEGF (3.68 vs 3.28, 0.40[0.25,0.56] p<0.00001), CD40 Ligand (4.82 vs 4.51, 0.31[0.12, 0.50] p=0.001) and Serpin-E1 (9.57 vs 9.46, 0.11[0.05,0.17] p<0.00001), but lower levels of GMCSF (2.94 vs 3.05, -0.10[-0.19,-0.02] p=0.02), CCL2 (2.82 vs 3.10, -0.45[-0.70,-0.21] p<0.00001) and CXCL10 (5.48 vs 5.96, -0.49[-0.71,-0.27] p<0.00001), compared to the rural setting. In PCA, the urban setting had lower representation of some classical inflammatory mediators but higher representation of various chemoattractants and vasoactive peptides. HOMA-IR, FBG, BP and BMI were positively correlated with several principal components characterised by pro-inflammatory analytes. Conclusions: In developing countries, immunological profiles differ between rural and urban environments. Differential expression of certain pro-inflammatory mediators may have important health consequences including contributing to increased cardiometabolic risk observed in the urban environment.

Selection of sites for field trials of genetically engineered mosquitoes with gene drive

Novel malaria control strategies using genetically engineered mosquitoes (GEMs) are on the horizon. Population modification is one approach wherein mosquitoes are engineered with genes rendering them refractory to the malaria parasite, Plasmodium falciparum, coupled with a low-threshold, Cas9-based gene drive. When released into a wild vector population, GEMs preferentially transmit these parasite-blocking genes to their offspring, ultimately modifying a vector population into a nonvector one. Deploying this technology awaits ecologically contained field trial evaluations. Here, we consider a process for site selection, the first critical step in designing a trial. Our goal is to identify a site that maximizes prospects for success, minimizes risk, and serves as a fair, valid, and convincing test of efficacy and impacts of a GEM product intended for large-scale deployment in Africa. We base site selection on geographic, geological, and biological, rather than social or legal, criteria. We recognize the latter as critically important but not as a first step in selecting a site. We propose physical islands as being the best candidates for a GEM field trial and present an evaluation of 22 African islands. We consider geographic and genetic isolation, biological complexity, island size, and topography and identify two island groups that satisfy key criteria for ideal GEM field trial sites.

Phylogenetic Networks and Parameters Inferred from HIV Nucleotide Sequences of High-Risk and General Population Groups in Uganda: Implications for Epidemic Control

Phylogenetic inference is useful in characterising HIV transmission networks and assessing where prevention is likely to have the greatest impact. However, estimating parameters that influence the network structure is still scarce, but important in evaluating determinants of HIV spread. We analyzed 2017 HIV pol sequences (728 Lake Victoria fisherfolk communities (FFCs), 592 female sex workers (FSWs) and 697 general population (GP)) to identify transmission networks on Maximum Likelihood (ML) phylogenetic trees and refined them using time-resolved phylogenies. Network generative models were fitted to the observed degree distributions and network parameters, and corrected Akaike Information Criteria and Bayesian Information Criteria values were estimated. 347 (17.2%) HIV sequences were linked on ML trees (maximum genetic distance ≤4.5%, ≥95% bootstrap support) and, of these, 303 (86.7%) that consisted of pure A1 (n = 168) and D (n = 135) subtypes were analyzed in BEAST v1.8.4. The majority of networks (at least 40%) were found at a time depth of ≤5 years. The waring and yule models fitted best networks of FFCs and FSWs respectively while the negative binomial model fitted best networks in the GP. The network structure in the HIV-hyperendemic FFCs is likely to be scale-free and shaped by preferential attachment, in contrast to the GP. The findings support the targeting of interventions for FFCs in a timely manner for effective epidemic control. Interventions ought to be tailored according to the dynamics of the HIV epidemic in the target population and understanding the network structure is critical in ensuring the success of HIV prevention programs.

Allergen skin test reactivity and asthma are inversely associated with ratios of IgG4/IgE and total IgE/allergen-specific IgE in Ugandan communities

Background

Serum inhibition of allergen‐specific IgE has been associated with competing IgG4 and non‐specific polyclonal IgE. In allergen immunotherapy, beneficial responses have been associated with high IgG4/IgE ratios. Helminths potentiate antibody class switching to IgG4 and stimulate polyclonal IgE synthesis; therefore, we hypothesized a role for helminth‐associated IgG4 and total IgE in protection against atopic sensitization and clinical allergy (asthma) in tropical low‐income countries.

Methods

Among community residents of Ugandan rural Schistosoma mansoni (Sm)–endemic islands and a mainland urban setting with lower helminth exposure, and among urban asthmatic schoolchildren and non‐asthmatic controls, we measured total, Schistosoma adult worm antigen (SWA)–specific, Schistosoma egg antigen (SEA)–specific and allergen (house dust mite [HDM] and German cockroach)–specific IgE and IgG4 by ImmunoCAP^® and/or ELISA. We assessed associations between these antibody profiles and current Sm infection, the rural‐urban environment, HDM and cockroach skin prick test (SPT) reactivity, and asthma.

Results

Total IgE, total IgG4 and SWA‐, SEA‐ and allergen‐specific IgE and IgG4 levels were significantly higher in the rural, compared to the urban setting. In both community settings, both Sm infection and SPT reactivity were positively associated with allergen‐specific and total IgE responses. SPT reactivity was inversely associated with Schistosoma‐specific IgG4, allergen‐specific IgG4/IgE ratios and total IgE/allergen‐specific IgE ratios. Asthmatic schoolchildren, compared with non‐asthmatic controls, had significantly higher levels of total and allergen‐specific IgE, but lower ratios of allergen‐specific IgG4/IgE and total IgE/allergen‐specific IgE.

Conclusions and clinical relevance

Our immuno‐epidemiological data support the hypothesis that the IgG4–IgE balance and the total IgE–allergen‐specific IgE balance are more important than absolute total, helminth‐ or allergen‐specific antibody levels in inhibition of allergies in the tropics.

'We shall drink until Lake Victoria dries up': Drivers of heavy drinking and illicit drug use among young Ugandans in fishing communities

We investigated patterns and drivers of alcohol misuse and illicit drug use among young fisherfolk. We undertook this study in fishing communities on Koome Island, Lake Victoria, Uganda, from December 2017-July 2018. We conducted six group discussions with men (3) and women (3) and 33 in-depth interviews with: young people [users (n = 10); non-users (n = 2)], local leaders (n = 3), health workers (n = 2), parents (n = 5), alcohol/illicit drugs sellers/distributors (n = 5), law enforcement officers (n = 5). We sampled participants using purposive and snowball strategies. Interview themes included: knowledge, experiences and perceptions of alcohol use/illicit drug use, HIV risk behaviour and harm reduction. We mapped alcohol/illicit drug use outlets using a Geographic Information System to capture density, distribution and proximity to young people's homes. We coded and analysed qualitative data using thematic content analysis. Motivations for heavy drinking and illicit drug use were multifaceted and largely beyond individual control. Key contextual determinants included social norms around consumption (acceptability), price (affordability), and ease of purchase (availability). Prevention and harm reduction interventions to tackle alcohol misuse and illicit drug use should be aimed at the structural rather than individual level and must be conducted in tandem with strategies to control poverty and HIV.

Cross-reactive carbohydrate determinant-specific IgE obscures true atopy and exhibits ⍺-1,3-fucose epitope-specific inverse associations with asthma

Background

In high-income, temperate countries, IgE to allergen extracts is a risk factor for, and mediator of, allergy-related diseases (ARDs). In the tropics, positive IgE tests are also prevalent, but rarely associated with ARD. Instead, IgE responses to ubiquitous cross-reactive carbohydrate determinants (CCDs) on plant, insect and parasite glycoproteins, rather than to established major allergens, are dominant. Because anti-CCD IgE has limited clinical relevance, it may impact ARD phenotyping and assessment of contribution of atopy to ARD.

Methods

Using an allergen extract-based test, a glycan and an allergen (glyco)protein microarray, we mapped IgE fine specificity among Ugandan rural Schistosoma mansoni (Sm)-endemic communities, proximate urban communities, and importantly in asthmatic and nonasthmatic schoolchildren.

Results

Overall, IgE sensitization to extracts was highly prevalent (43%-73%) but allergen arrays indicated that this was not attributable to established major allergenic components of the extracts (0%-36%); instead, over 40% of all participants recognized CCD-bearing components. Using glycan arrays, we dissected IgE responses to specific glycan moieties and found that reactivity to classical CCD epitopes (core β-1,2-xylose, α-1,3-fucose) was positively associated with sensitization to extracts, rural environment and Sm infection, but not with skin reactivity to extracts or sensitization to their major allergenic components. Interestingly, we discovered that reactivity to only a subset of core α-1,3-fucose-carrying N-glycans was inversely associated with asthma.

Conclusions

CCD reactivity is not just an epiphenomenon of parasite exposure hampering specificity of allergy diagnostics; mechanistic studies should investigate whether specific CCD moieties identified here are implicated in the protective effect of certain environmental exposures against asthma.

Effect of intensive versus standard anthelminthic treatment on growth and cognition among children living in a high Schistosoma mansoni transmission setting: a study nested within a cluster-randomised trial

Background: Schistosomiasis and other worm infections have been associated with growth and cognitive impairments; however, whether treatment reverses these effects is uncertain. Moreover, mechanisms linking these infections to cognition are not clear. We aimed to compare growth and cognitive benefits of intensive versus standard anthelminthic treatment in school-aged-children and explore processes that might be involved. We hypothesised that intensive treatment would have greater benefits than standard treatment. Methods: The study was nested within a cluster-randomised trial of either quarterly single-dose praziquantel of 40mg/kg to treat Schistosoma mansoni plus triple dose albendazole of 400mg (intensive treatment) to treat soil-transmitted worms including Ascaris lumbricoides, hookworm and Trichuris trichiura, or annual single-dose praziquantel 40mg/kg plus six-monthly single-dose albendazole 400mg (standard treatment) conducted in the Koome islands in Lake Victoria, Uganda (ISRCTN47196031). Children aged 5-9 years (N=384) were assessed on primary outcomes (height, weight and eight measures of cognitive ability), worm infection, and proposed mediators of worm effects (cytokines, iron status, physical activity) at one year (intensive n=85; standard n=64) and at two years (intensive n=158; standard n=128) of the intervention. Linear regression was used to examine intervention effects on height, weight and cognitive performance. Linear mixed effects models were used to study changes in growth and cognitive performance between the two arms across the two time-points. Results: Intensive treatment resulted in lower Schistosoma mansoni prevalence than standard treatment (at one year, 41% versus 70%; adjusted odds ratio (aOR)=0.24, 95% CI: 0.12, 0.49; at two years, 39% versus 69%; aOR=0.27; 95% CI: 0.16, 0.43) but there were no significant differences in growth and cognitive outcomes at either time-point. Worms and treatment showed no consistent association with the proposed mediators of worm effects. Conclusion: Reduction in worm burden may not improve growth and cognitive outcomes in high S. mansoni transmission settings. Possible implications are discussed.

Anthelminthic treatment receipt and its predictors in Lake Victoria fishing communities, Uganda: Intervention coverage results from the LaVIISWA cluster randomised trial

BACKGROUND

Mass drug administration (MDA) is a cornerstone of control of parasitic helminths. In schistosomiasis-endemic areas with >50% of school-aged children infected, community-wide MDA with praziquantel is recommended by the World Health Organisation (WHO), with target coverage of >75%. Using data from a cluster-randomised trial of MDA treatment strategies, we aimed to describe the proportion of eligible residents who received MDA and predictors of treatment receipt, and to assess associations with helminth prevalence.

METHODS

In the Koome islands of Lake Victoria, Uganda, where baseline schistosomiasis prevalence (by single stool sample, Kato Katz) was 52% overall (all ages) and 67% among school-aged children, we conducted a cluster-randomised trial of community-wide, intensive MDA (quarterly single-dose praziquantel 40mg/kg; triple-dose albendazole 400mg) versus standard, Uganda government intervention (annual single-dose praziquantel 40mg/kg; 6-monthly single-dose albendazole). Twenty-six fishing villages were randomised, 13 per trial arm, for four years. At each treatment round, praziquantel treatment and the first dose of albendazole treatment were directly observed by the study team, registers of village residents were updated and the proportion receiving treatment among those eligible recorded.

RESULTS

During the four-year MDA, at each treatment round an average of 13,382 people were registered in the 26 villages (7,153 and 6,229 in standard and intensive intervention villages, respectively). Overall, the proportion of those eligible receiving praziquantel was lower than for albendazole (60% versus 65%), particularly in the standard arm (61% versus 71%) compared to the intensive arm (60% versus 62%). Albendazole receipt was lower when given concurrently with praziquantel. Absence was the commonest reason for non-receipt of treatment (81% albendazole, 77% praziquantel), followed by refusal (14% albendazole, 18% praziquantel). Proportions receiving treatment were lowest among school-aged children, but did not differ by sex. Longitudinal analysis of a subgroup of residents who did not move during the study period found that persistent non-receipt of treatment in this subgroup was rare. Refusal to receive treatment was highest among adults and more common among females.

CONCLUSION

In schistosomiasis high-risk communities, a combination of approaches to increasing treatment coverage, such as extended periods of treatment delivery, and the provision of incentives, may be required to achieve WHO targets.

Contrasting impact of rural, versus urban, living on glucose metabolism and blood pressure in Uganda

Background: The burden of cardiometabolic diseases, including cardiovascular diseases and diabetes, is increasing in sub-Saharan Africa and this has been linked to urbanisation. Helminths, through their immunomodulatory properties, may protect against these disorders. We hypothesised that the rural environment protects against cardiometabolic diseases and that helminths may influence rural-urban disparity of cardiometabolic disease risk. Methods: We compared metabolic parameters of individuals aged ≥10 years living in rural, high-helminth-transmission and urban, lower-helminth-transmission settings in Uganda. Cross-sectional surveys were conducted in rural Lake Victoria island fishing communities and in urban sub-wards in Entebbe municipality. Helminth infection and outcomes, including insulin resistance (computed using the homeostatic model assessment of insulin resistance [HOMA-IR]), fasting blood glucose, fasting blood lipids, blood pressure, body mass index (BMI), waist and hip circumference, were assessed. Results: We analysed 1,898 rural and 930 urban participants. Adjusting for BMI, exercise, smoking, alcohol intake, age and sex, urban residents had lower mean fasting glucose (adjusted mean difference [95%CI] 0.18 [-0.32, -0.05] p=0.01) and HOMA-IR (-0.26 [-0.40, -0.11] p=0.001) but higher blood pressure (systolic, 5.45 [3.75, 7.15] p<0.001; diastolic, 1.93 [0.57, 3.29] p=0.006). Current helminth infection did not explain the observed differences. Conclusions: In the Ugandan context, living in rural fishing communities may protect against hypertension but worsen glucose metabolism.

Variation in KSHV prevalence between geographically proximate locations in Uganda

Kaposi's sarcoma-associated herpesvirus (KSHV) transmission within endemic areas may vary. KSHV seroprevalence has been studied by different groups of researchers using different methods, making it difficult to make direct comparisons. Here we show results on KSHV seroprevalence using the same laboratory method from four different but geographically proximate populations in Uganda. Blood samples from the urban Entebbe Mother and Baby Study (EMaBS), the rural General Population Cohort (GPC), the fishing community Lake Victoria Island Intervention Study on Worms and Allergy related Diseases (LaVIISWA) and the high-risk sexual behaviour Good Health for Women Project (GHWP), were tested for IgG antibody levels to K8.1 and ORF73 recombinant proteins using ELISA. All adult participants of the EMaBS study and the GHWP were women, while the GPC (54% female) and LaVIISWA (52% female) studies had both males and females. EMaBS children were all 5 years of age while their mothers were 14 to 47 years of age. GHWP women were 15 to 45 years old, LaVIISWA participants were 1 to 72 years old while GPC participants were 1 to 103 years old. KSHV seropositivity varied in the different populations. In children aged 5 years, EMaBS had the lowest prevalence of 15% followed by GPC at 35% and LaVIISWA at 54%. In adult women, seropositivity varied from 69% (EMaBS) to 80% (LaVIISWA) to 87% (GPC) to 90% (GHWP). The reasons for the variation in prevalence are unclear but may reflect differences in the prevalence of cofactors between these four geographically proximate populations.

The Effect of Helminth Infections and Their Treatment on Metabolic Outcomes: Results of a Cluster-Randomized Trial

BACKGROUND

Helminths may protect against cardiometabolic risk through effects on inflammation and metabolism; their treatment may be detrimental to metabolic outcomes.

METHODS

In a cluster-randomized trial in 26 Ugandan fishing communities we investigated effects of community-wide intensive (quarterly single-dose praziquantel, triple-dose albendazole) vs standard (annual single-dose praziquantel, biannual single-dose albendazole) anthelminthic treatment on metabolic outcomes, and observational associations between helminths and metabolic outcomes. The primary outcome, homeostatic model assessment of insulin resistance (HOMA-IR), and secondary outcomes (including blood pressure, fasting blood glucose, lipids) were assessed after 4 years' intervention among individuals aged ≥10 years.

RESULTS

We analyzed 1898 participants. Intensive treatment had no effect on HOMA-IR (adjusted geometric mean ratio, 0.96 [95% confidence interval {CI}, .86-1.07]; P = .42) but resulted in higher mean low-density lipoprotein cholesterol (LDL-c) (2.86 vs 2.60 mmol/L; adjusted mean difference, 0.26 [95% CI, -.03 to .56]; P = .08). Lower LDL-c levels were associated with Schistosoma mansoni (2.37 vs 2.80 mmol/L; -0.25 [95% CI, -.49 to -.02]; P = .04) or Strongyloides (2.34 vs 2.69 mmol/L; -0.32 [95% CI, -.53 to -.12]; P = .003) infection. Schistosoma mansoni was associated with lower total cholesterol (4.24 vs 4.64 mmol/L; -0.25 [95% CI, -.44 to -.07]; P = .01) and moderate to heavy S. mansoni infection with lower triglycerides, LDL-c, and diastolic blood pressure.

CONCLUSIONS

Helminth infections improve lipid profiles and may lower blood pressure. Studies to confirm causality and investigate mechanisms may contribute to understanding the epidemiological transition and suggest new approaches to prevent cardiometabolic disease.

CLINICAL TRIALS REGISTRATION

ISRCTN47196031.

Urban-rural differences in immune responses to mycobacterial and tetanus vaccine antigens in a tropical setting: A role for helminths?

Several vaccines elicit lower efficacy or impaired immune responses in rural compared to urban settings, and in tropical low-income countries compared to high-income countries. An unresolved hypothesis is that immunomodulation by parasitic infections such as helminths (prevalent in rural tropical settings) contributes to suppression of vaccine responses. Among 1–17-year-old Ugandan residents of rural Schistosoma mansoni (Sm)-endemic islands and proximate urban communities with lower helminth exposure, we assessed plasma antibody and whole blood assay cytokine responses to tetanus toxoid (TT) and purified protein derivative of Mycobacterium tuberculosis (PPD). These were taken to represent recall responses to tetanus and BCG vaccination in infancy. PPD-specific responses are additionally induced by tuberculous and non-tuberculous mycobacterial exposure. Urban-rural comparisons showed that PPD-specific IFN-γ and IL-13 and TT-specific IL-13 and IgG concentrations were lower in the rural setting, but that PPD-specific IgE concentrations were higher. Among rural participants, Sm infection was inversely associated with PPD-specific IFN-γ, while nematode infection was positively associated with PPD-specific IgG. Among urban participants, Sm infection was positively associated with PPD-specific responses but inversely associated with TT-specific responses, while nematode infection was inversely associated with TT-specific IgG and IgG4, but no associations were observed with PPD-specific responses. Despite these associations, for the urban-rural comparisons there were no notable changes in test statistics after adjusting for current helminth infections, suggesting that helminths were not the sole explanation for the urban-rural differences observed. Helminths likely work in concert with other environmental exposures and operational factors to influence vaccine response.

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Vaccine (BCG, tetanus)-specific immune responses differ by urban/rural setting.

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Associations between helminths and vaccine-specific response also differ by setting.

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Urban-rural differences are not fully explained by helminth infection prevalence.

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Helminths likely work in concert with other factors to influence vaccine response.

Does Intensive Treatment Select for Praziquantel Resistance in High-Transmission Settings? Parasitological Trends and Treatment Efficacy Within a Cluster-Randomized Trial

Background

Praziquantel mass drug administration (MDA) is recommended in schistosomiasis-endemic areas. Animal models demonstrate Schistosoma parasite resistance to praziquantel after repeated exposure.

Methods

We conducted a parasitological survey in 26 fishing communities in Uganda after 4 years of quarterly (13 communities) or annual (13 communities) praziquantel MDA, with Schistosoma infection detected by single-stool-sample Kato-Katz. A test of cure was done in participants who were positive on both urine circulating cathodic antigen test and 3-sample Kato-Katz. We calculated cure rates (CRs) and egg reduction rates (ERRs) based on 3-sample Kato-Katz and infection intensity using worm-specific circulating anodic antigen (CAA) in blood, comparing these between quarterly and annually treated participants.

Results

Single-sample Kato-Katz Schistosoma mansoni prevalence was 22% in 1,056 quarterly treated participants and 34% in 1,030 annually treated participants (risk ratio, 0.62; 95% confidence interval [CI], 0.40 to 0.94). Among 110 test-of-cure participants, CRs were 65% and 51% in annually and quarterly treated villages, respectively (odds ratio, 0.65; 95% CI, 0.27 to 1.58); ERRs were 94% and 81% (difference, –13%; 95% CI, –48% to 2%). There was no impact of quarterly vs annual praziquantel on S. mansoni by CAA.

Conclusions

In this schistosomiasis hot spot, there was little evidence of decreased praziquantel efficacy. However, in the absence of alternative therapies, there remains a need for continued vigilance of praziquantel efficacy in the MDA era.

Phylogenetic and Demographic Characterization of Directed HIV-1 Transmission Using Deep Sequences from High-Risk and General Population Cohorts/Groups in Uganda

Across sub-Saharan Africa, key populations with elevated HIV-1 incidence and/or prevalence have been identified, but their contribution to disease spread remains unclear. We performed viral deep-sequence phylogenetic analyses to quantify transmission dynamics between the general population (GP), fisherfolk communities (FF), and women at high risk of infection and their clients (WHR) in central and southwestern Uganda. Between August 2014 and August 2017, 6185 HIV-1 positive individuals were enrolled in 3 GP and 10 FF communities, 3 WHR enrollment sites. A total of 2531 antiretroviral therapy (ART) naïve participants with plasma viral load >1000 copies/mL were deep-sequenced. One hundred and twenty-three transmission networks were reconstructed, including 105 phylogenetically highly supported source–recipient pairs. Only one pair involved a WHR and male participant, suggesting that improved population sampling is needed to assess empirically the role of WHR to the transmission dynamics. More transmissions were observed from the GP communities to FF communities than vice versa, with an estimated flow ratio of 1.56 (95% CrI 0.68–3.72), indicating that fishing communities on Lake Victoria are not a net source of transmission flow to neighboring communities further inland. Men contributed disproportionally to HIV-1 transmission flow regardless of age, suggesting that prevention efforts need to better aid men to engage with and stay in care.

Contrasting impact of rural, versus urban, living on glucose metabolism and blood pressure in Uganda

Background: The burden of cardiometabolic diseases, including cardiovascular diseases and diabetes, is increasing in sub-Saharan Africa and this has been linked to urbanisation. Helminths, through their immunomodulatory properties, may protect against these disorders. We hypothesised that the rural environment protects against cardiometabolic diseases and that helminths may influence rural-urban disparity of cardiometabolic disease risk. Methods: We compared metabolic parameters of individuals aged ≥10 years living in rural, high-helminth-transmission and urban, lower-helminth-transmission settings in Uganda. Cross-sectional surveys were conducted in rural Lake Victoria island communities and in urban sub-wards in Entebbe municipality. Helminth infection and outcomes, including insulin resistance (computed using the homeostatic model assessment of insulin resistance [HOMA-IR]), fasting blood glucose, fasting blood lipids, blood pressure, body mass index (BMI), waist and hip circumference, were assessed. Results: We analysed 1,898 rural and 930 urban participants. Adjusting for BMI, exercise, smoking, alcohol intake, age and sex, urban residents had lower mean fasting glucose (adjusted mean difference [95%CI] -0.13 [-0.24, -0.01] p=0.04) and HOMA-IR (-0.13 [-0.25, -0.01] p=0.04) but higher blood pressure (systolic, 4.64 [3.23, 6.06] p<0.001; diastolic, 1.89 [0.81, 2.97] p=0.001). Current helminth infection did not explain the observed differences. Conclusions: In low-income countries, rural living may protect against hypertension but impair glucose metabolism.

Comparing Alcohol Use Disorders Identification Test (AUDIT) with Timeline Follow Back (TLFB), DSM-5 and Phosphatidylethanol (PEth) for the assessment of alcohol misuse among young people in Ugandan fishing communities

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Validated tools are needed to evaluate alcohol-reduction interventions in low income countries.

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Among young Ugandans ACASI-administered 30-day and 12-month-AUDIT have good diagnostic properties.

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Self-reported AUDIT provides an efficient means of assessing alcohol misuse.

Background

Validated tools for assessing alcohol use among young people in low-income countries are needed to estimate prevalence and evaluate alcohol-reduction interventions. We validated Alcohol Use Disorders Identification Test (AUDIT) against Timeline Follow Back (TLFB), Diagnostic and Statistical Manual of Mental Disorders (DSM-5) and phosphatidylethanol (PEth); and the 30-day-AUDIT against the 12-months-AUDIT among young Ugandans.

Methods

In 2018, we collected retrospective data on 30-day and 12-month AUDIT, TLFB and DSM-5 in a cross-sectional study of 15–24 year old residents of Ugandan fishing communities. AUDIT was administered by Audio Computer Assisted Self-Interviewing (ACASI) and DSM-5 and TLFB by psychiatric nurses. We determined PEth16:0/18:1 levels from dried blood spots using liquid chromatography tandem-mass spectrometry (heavy usage, ≥210 ng/mL) and calculated sensitivity and specificity of AUDIT against the other measures.

Results

Among 1281 participants (52.7% male, mean age 20 years), half (n = 659; 51.4%) reported ever drinking alcohol, 19.4% had 12-month-AUDIT ≥ 8 (21.5% men; 17.0% women), and 24.2% had 30-day-AUDIT ≥ 8 (29.0% men; 18.9% women). Twenty percent of participants had detectable PEth with 55 (4.3%) classified as heavy drinkers; 50.7% reported ≥ 2 symptoms on DSM-5 and 6.3% reported binge drinking in the previous month based on TLFB (8.9% men, 3.5% women). The 30-day-AUDIT ≥ 8 had sensitivity 86.7%, 95%CI: 81.8%–90.7% and specificity 90.9%, 95%CI:89.0%–92.6% versus 12-month-AUDIT ≥ 8. Both 30-day and 12-month-AUDIT ≥ 8 were sensitive and specific markers of heavy drinking by PEth (12-month-AUDIT sensitivity = 80.0%; 95%CI:67.0%–89.6%; specificity = 83.3%; 95%CI:81.1%–85.3%). The 30-day-AUDIT was a sensitive and specific marker of binge drinking based on TLFB (sensitivity = 82.7%; 95%CI:72.7%–90.2%, specificity = 79.8%; 95%CI:77.4%–82.1%); 12-month-AUDIT had lower sensitivity. Both 30-day and 12-month AUDIT ≥ 8 were highly specific but insensitive markers of having DSM-5 ≥ 2 symptoms.

Conclusion

Among young people in Uganda, ACASI-administered 30-day and 12-month-AUDIT have good diagnostic properties compared to PEth, DSM-5 and TLFB. Self-reported AUDIT provides a quick and valid means of assessing alcohol misuse in these communities.

Kaposi's sarcoma-associated herpesvirus seropositivity is associated with parasite infections in Ugandan fishing communities on Lake Victoria islands

We investigated the impact of helminths and malaria infection on Kaposi's sarcoma associated herpesvirus (KSHV) seropositivity, using samples and data collected from a cluster-randomised trial of intensive versus standard anthelminthic treatment. The trial was carried out in 2012 to 2016 among fishing communities on Lake Victoria islands in Uganda. Plasma samples from 2881 participants from two household surveys, the baseline (1310 participants) and the final (1571 participants) surveys were tested for KSHV IgG antibody responses to K8.1 and ORF73 recombinant proteins using ELISA. The baseline survey was carried out before the trial intervention while the final survey was carried out after three years of the trial intervention. Additionally, a subset sample of 372 participants from the final survey was tested for IgE, IgG and IgG4 antibody concentrations to S. mansoni adults worm antigen (SWA) and S. mansoni egg antigen (SEA) using ELISA. Infection by helminths (S. mansoni, N. americanus, T. trichiura and S. stercoralis) was diagnosed using real-time PCR, urine circulating cathodic antigen (CCA) and stool microscopy (Kato-Katz method) while malaria infection was diagnosed using microscopy. We analysed the relationship between helminth and malaria infections and KSHV seropositivity using regression modelling, allowing for survey design. At baseline, 56% of the participants were male while 48% of the participants were male in the final survey. The most prevalent helminth infection was S. mansoni (at baseline 52% and 34% in the final survey by microscopy, 86% by CCA and 50% by PCR in the final survey). KSHV seropositivity was 66% (baseline) and 56% (final survey) among those 1-12 years and >80% in those 13+ years in both surveys; malaria parasitaemia prevalence was 7% (baseline) and 4% (final survey). At baseline, individuals infected with S. mansoni (detected by microscopy) were more likely to be KSHV seropositive (aOR = 1.86 (1.16, 2.99) p = 0.012) and had higher anti-K8.1 antibody levels (acoefficient = 0.03 (0.01, 0.06) p = 0.02). In the final survey, S. mansoni (by microscopy, adjusted Odds Ratio (aOR = 1.43 (1.04-1.95), p = 0.028) and malaria parasitaemia (aOR = 3.49 (1.08-11.28), p = 0.038) were positively associated with KSHV seropositivity. Additionally, KSHV seropositive participants had higher S. mansoni-specific IgE and IgG antibody concentrations in plasma. Furthermore, HIV infected individuals on cART were less likely to be KSHV seropositive compared to HIV negative individuals (aOR = 0.46 (0.30, 0.71) p = 0.002). Schistosoma species skew the immune response towards Th2 and regulatory responses, which could impact on KSHV reactivation if co-infected with both organisms.

The Impact of Intensive Versus Standard Anthelminthic Treatment on Allergy-related Outcomes, Helminth Infection Intensity, and Helminth-related Morbidity in Lake Victoria Fishing Communities, Uganda: Results From the LaVIISWA Cluster-randomized Trial

BACKGROUND

The prevalence of allergy-related diseases is increasing in low-income countries. Parasitic helminths, common in these settings, may be protective. We hypothesized that intensive, community-wide, anthelminthic mass drug administration (MDA) would increase allergy-related diseases, while reducing helminth-related morbidity.

METHODS

In an open, cluster-randomized trial (ISRCTN47196031), we randomized 26 high-schistosomiasis-transmission fishing villages in Lake Victoria, Uganda, in a 1:1 ratio to receive community-wide intensive (quarterly single-dose praziquantel plus albendazole daily for 3 days) or standard (annual praziquantel plus 6 monthly single-dose albendazole) MDA. Primary outcomes were recent wheezing, skin prick test positivity (SPT), and allergen-specific immunoglobulin E (asIgE) after 3 years of intervention. Secondary outcomes included helminths, haemoglobin, and hepatosplenomegaly.

RESULTS

The outcome survey comprised 3350 individuals. Intensive MDA had no effect on wheezing (risk ratio [RR] 1.11, 95% confidence interval [CI] 0.64-1.93), SPT (RR 1.10, 95% CI 0.85-1.42), or asIgE (RR 0.96, 95% CI 0.82-1.12). Intensive MDA reduced Schistosoma mansoni infection intensity: the prevalence from Kato Katz examinations of single stool samples from each patient was 23% versus 39% (RR 0.70, 95% CI 0.55-0.88), but the urine circulating cathodic antigen test remained positive in 85% participants in both trial arms. Hookworm prevalence was 8% versus 11% (RR 0.55, 95% CI 0.31-1.00). There were no differences in anemia or hepatospenomegaly between trial arms.

CONCLUSIONS

Despite reductions in S. mansoni intensity and hookworm prevalence, intensive MDA had no effect on atopy, allergy-related diseases, or helminth-related pathology. This could be due to sustained low-intensity infections; thus, a causal link between helminths and allergy outcomes cannot be discounted. Intensive community-based MDA has a limited impact in high-schistosomiasis-transmission fishing communities, in the absence of other interventions.

CLINICAL TRIALS REGISTRATION

ISRCTN47196031.

Microarray assessment of N-glycan-specific IgE and IgG profiles associated with Schistosoma mansoni infection in rural and urban Uganda

Core β-1,2-xylose and α-1,3-fucose are antigenic motifs on schistosome N-glycans, as well as prominent IgE targets on some plant and insect glycoproteins. To map the association of schistosome infection with responses to these motifs, we assessed plasma IgE and IgG reactivity using microarray technology among Ugandans from rural Schistosoma mansoni (Sm)-endemic islands (n = 209), and from proximate urban communities with lower Sm exposure (n = 62). IgE and IgG responses to core β-1,2-xylose and α-1,3-fucose modified N-glycans were higher in rural versus urban participants. Among rural participants, IgE and IgG to core β-1,2-xylose were positively associated with Sm infection and concentration peaks coincided with the infection intensity peak in early adolescence. Responses to core α-1,3-fucose were elevated regardless of Sm infection status and peaked before the infection peak. Among urban participants, Sm infection intensity was predominantly light and positively associated with responses to both motifs. Principal component and hierarchical cluster analysis reduced the data to a set of variables that captured core β-1,2-xylose- and α-1,3-fucose-specific responses, and confirmed associations with Sm and the rural environment. Responses to core β-1,2-xylose and α-1,3-fucose have distinctive relationships with Sm infection and intensity that should further be explored for associations with protective immunity, and cross-reactivity with other exposures.

Do helminth infections underpin urban-rural differences in risk factors for allergy-related outcomes?

Background

It is proposed that helminth exposure protects against allergy‐related disease, by mechanisms that include disconnecting risk factors (such as atopy) from effector responses.

Objective

We aimed to assess how helminth exposure influences rural‐urban differences in risk factors for allergy‐related outcomes in tropical low‐ and middle‐income countries.

Methods

In cross‐sectional surveys in Ugandan rural Schistosoma mansoni (Sm)‐endemic islands, and in nearby mainland urban communities with lower helminth exposure, we assessed risk factors for atopy (allergen‐specific skin prick test [SPT] reactivity and IgE [asIgE] sensitization) and clinical allergy‐related outcomes (wheeze, urticaria, rhinitis and visible flexural dermatitis), and effect modification by Sm exposure.

Results

Dermatitis and SPT reactivity were more prevalent among urban participants, urticaria and asIgE sensitization among rural participants. Pairwise associations between clinical outcomes, and between atopy and clinical outcomes, were stronger in the urban survey. In the rural survey, SPT positivity was inversely associated with bathing in lakewater, Schistosoma‐specific IgG4 and Sm infection. In the urban survey, SPT positivity was positively associated with age, non‐Ugandan maternal tribe, being born in a city/town, BCG scar and light Sm infection. Setting (rural vs urban) was an effect modifier for risk factors including Sm‐ and Schistosoma‐specific IgG4. In both surveys, the dominant risk factors for asIgE sensitization were Schistosoma‐specific antibody levels and helminth infections. Handwashing and recent malaria treatment reduced odds of asIgE sensitization among rural but not urban participants. Risk factors for clinical outcomes also differed by setting. Despite suggestive trends, we did not find sufficient evidence to conclude that helminth (Sm) exposure explained rural‐urban differences in risk factors.

Conclusions and clinical relevance

Risk factors for allergy‐related outcomes differ between rural and urban communities in Uganda but helminth exposure is unlikely to be the sole mechanism of the observed effect modification between the two settings. Other environmental exposures may contribute significantly.

The First Norovirus Longitudinal Seroepidemiological Study From Sub-Saharan Africa Reveals High Seroprevalence of Diverse Genotypes Associated With Host Susceptibility Factors

Background

Human noroviruses (HuNoVs) are a prominent cause of gastroenteritis, yet fundamental questions remain regarding epidemiology, diversity, and immunity in sub-Saharan African children. We investigated HuNoV seroprevalence and genetic and sociodemographic risk factors in Ugandan children.

Methods

We randomly screened 797 participants of a longitudinal birth cohort (Entebbe, EMaBS) and 378 from a cross-sectional survey (rural Lake Victoria, LaVIISWA), for antibodies against HuNoV genotypes by ELISA. We used linear regression modeling to test for associations between HuNoV antibody levels and sociodemographic factors, and with the human susceptibility rs601338 FUT2 secretor SNP and histo-blood group antigens (A/B/O).

Results

Of EMaBS participants, 76.6% were seropositive by age 1, rising to 94.5% by age 2 years. Seroprevalence in 1 year olds of the rural LaVIISWA survey was even higher (95%). In the birth cohort, 99% of seropositive 2 year olds had responses to multiple HuNoV genotypes. We identified associations between secretor status and genogroup GII antibody levels (GII.4 P = 3.1 × 10-52), as well as ABO and GI (GI.2 P = 2.1 × 10-12).

Conclusions

HuNoVs are highly prevalent in Ugandan children, indicating a substantial burden of diarrhea-associated morbidity with recurrent infections. Public health interventions, including vaccination, and increased surveillance are urgently needed.

van Dam G, Corstjens PL, Hughes P, Ding S, Pantaleo G, Kaleebu P, Elliott AM, Kamali A. Effect of high-intensity versus low-intensity praziquantel treatment on HIV disease progression in HIV and Schistosoma mansoni co-infected patients: a randomised controlled trial

Background: It has been hypothesised that Schistosoma co-infection exacerbates HIV progression, and hence anthelminthic intervention in co-infected individuals will delay it. We evaluated effects of high-intensity versus low-intensity praziquantel treatment of schistosomiasis on HIV disease progression among co-infected patients from fishing populations around Lake Victoria, Uganda. Methods: Between August 2012 and September 2015, we conducted an open-label randomised, controlled trial. Adults, antiretroviral therapy-naïve, CD4 counts ≥350 cells/μl, HIV and S. mansoni co-infected, were randomised 1:1 to praziquantel (40mg/kg) given quarterly (starting at enrolment) or annually (starting 12 weeks after enrolment; such that low-intensity participants were still untreated when sampled at 12 weeks). A non-randomised HIV-positive S. mansoni-negative comparison group was recruited. The primary outcome was mean change in plasma viral load at 12 and 60 weeks. Results: In total 363 participants (high-intensity 113, low-intensity 113, comparison group 137) were recruited; 96 (85.0%), 97 (85.8%) and 107 (78.1%) completed 60 weeks of follow up, respectively. Adjusting for baseline age and viral load, the geometric mean ratio (aGMR [95%CI]) viral load for high-intensity vs low-intensity groups at 12 weeks was 0.90 [0.65, 1.25] p=0.55 and at 60 weeks 1.88 [0.78, 4.53] p=0.16. Results in the comparison group were similar to trial arms. High-intensity, compared to low-intensity, treatment resulted in substantially lower S. mansoni prevalence at all follow up visits (p<0.05). Conclusions: In communities with a high burden of both S. mansoni and HIV infection, high-intensity treatment of S. mansoni does not delay HIV progression despite relevant benefit for parasite clearance. Trial registration: ISRCTN15371662 (17/11/2016).

van Dam G, Corstjens PL, Hughes P, Ding S, Pantaleo G, Kaleebu P, Elliott AM, Kamali A. Effect of high-intensity versus low-intensity praziquantel treatment on HIV disease progression in HIV and Schistosoma mansoni co-infected patients: a randomised controlled trial

Background: It has been hypothesised that Schistosoma co-infection exacerbates HIV progression, and hence anthelminthic intervention in co-infected individuals will delay it. We evaluated effects of high-intensity versus low-intensity praziquantel treatment of schistosomiasis on HIV disease progression among co-infected patients from fishing populations around Lake Victoria, Uganda. Methods: Between August 2012 and September 2015, we conducted an open-label randomised, controlled trial. Adults, antiretroviral therapy-naïve, CD4 counts ≥350 cells/μl, HIV and S. mansoni co-infected, were randomised 1:1 to praziquantel (40mg/kg) given quarterly (starting at enrolment) or annually (starting 12 weeks after enrolment; such that low-intensity participants were still untreated when sampled at 12 weeks). A non-randomised HIV-positive S. mansoni-negative comparison group was recruited. The primary outcome was mean change in plasma viral load at 12 and 60 weeks. Results: In total 363 participants (high-intensity 113, low-intensity 113, comparison group 137) were recruited; 96 (85.0%), 97 (85.8%) and 107 (78.1%) completed 60 weeks of follow up, respectively. Adjusting for baseline age and viral load, the geometric mean ratio (aGMR [95%CI]) viral load for high-intensity vs low-intensity groups at 12 weeks was 0.90 [0.65, 1.25] p=0.55 and at 60 weeks 1.88 [0.78, 4.53] p=0.16. Results in the comparison group were similar to trial arms. High-intensity, compared to low-intensity, treatment resulted in substantially lower S. mansoni prevalence at all follow up visits (p<0.05). Conclusions: In communities with a high burden of both S. mansoni and HIV infection, high-intensity treatment of S. mansoni does not delay HIV progression despite relevant benefit for parasite clearance. Trial registration: ISRCTN15371662 (17/11/2016).

Schistosoma mansoni-specific immune responses and allergy in Uganda

Low allergy‐related disease (ARD) prevalence in low‐income countries may be partly attributed to helminth infections. In the Schistosoma mansoni (Sm)‐endemic Lake Victoria islands (Uganda), we recently observed positive helminth‐allergy associations, despite low ARD prevalence. To understand how Sm‐induced cytokine and antibody profiles might influence allergic response profiles in this population, we assessed Schistosoma worm (SWA)‐ and egg antigen (SEA)‐specific Th1 (IFN‐γ), Th2 (IL‐5, IL‐13) and regulatory (IL‐10) cytokine profiles (n = 407), and total (n = 471), SWA‐, SEA‐ and allergen (house dust mite [HDM] and cockroach)‐specific (as)IgE and IgG4 profiles (n = 2117) by ELISA. Wheeze was inversely associated with SWA‐specific IFN‐γ (P < .001) and IL‐10 (P = .058), and SEA‐specific IL‐5 (P = .004). Conversely, having a detectable asIgE response was positively associated with SWA‐specific IL‐5 (P = .006) and IL‐10 (P < .001). Total, SWA‐, SEA‐ and allergen‐specific IgE and IgG4 responses were higher among Sm Kato‐Katz positive (SmKK+) and skin prick test (SPT)+ individuals compared to SmKK‐ and SPT‐ individuals. However, total and asIgG4/IgE ratios were lower among SPT+ and wheezing individuals. We conclude that, in this population, helminth‐induced antibody and cytokine responses may underlie individual positive helminth‐atopy associations, while the overall IgG4‐IgE balance may contribute to the low overall prevalence of clinical allergies in such settings.

Perceptions about interventions to control schistosomiasis among the Lake Victoria island communities of Koome, Uganda

Background

Praziquantel-based mass treatment is the main approach to controlling schistosomiasis mansoni in endemic areas. Interventions such as provision and use of safe water, minimising contact with infested water, disposal of stool in latrines and snail control provide key avenues to break the transmission cycle and can sustain the benefits of mass treatment in the long term. Efforts are also being made to develop a schistosomiasis vaccine which, if effective, might reduce the incidence of re-infection after treatment. However, any interventions deployed need to be acceptable to, and sustainable by, the target communities.

Methods

In this qualitative study, we investigated the perceptions of six Lake Victoria island communities of Koome, Uganda, about interventions to control Schistosoma mansoni infection and their willingness to participate in Schistosoma vaccine trials. Thirty-two in-depth interviews, 12 key informant interviews and 10 focus group discussions were conducted. Data were analysed using a thematic content approach.

Findings

Intestinal schistosomiasis was not regarded as a serious health problem because a mass treatment programme is in place. However, the communities lack safe water sources and latrines. Mass treatment with praziquantel, safe water supplies and use of toilets were deemed the most acceptable interventions by the participants. The communities are willing to participate in Schistosoma vaccine trials.

Conclusion/Significance

Knowledge of a community’s perception about interventions to control schistosomiasis can be valuable to policy makers and programme implementers intending to set up interventions co-managed by the community members. In this study, the views of the Lake Victoria island communities of Koome are presented. This study also provides data to guide further work on alternative interventions such as Schistosoma vaccine trials in these communities.

Schistosomiasis, a neglected tropical disease caused by the blood fluke Schistosoma, is still a huge burden in sub-Saharan Africa. The modalities for its control are mass treatment of the population with praziquantel, minimising contact with infested water, provision and use of safe water, intermediate host snail control and disposal of stool in toilets/latrines. For sustainable control of the parasite, the recipient communities need to embrace the interventions. In this study, we investigated the perceptions of fishing communities on the Lake Victoria Islands about interventions to control schistosomiasis and their willingness to participate in Schistosoma vaccine trials. We assessed their knowledge of schistosomiasis, their views on the interventions and the interventions most acceptable to them. We show that the community members of this schistosomiasis-endemic area prefer mass treatment with praziquantel, safe water supplies and use of toilets to minimise contact with infested water and snail control. The communities are also willing to participate in Schistosoma vaccine trials. This information is valuable to policy makers and programme implementers intending to set up interventions co-managed by the recipient communities. In addition, the study provides support for future Schistosoma vaccine trials in these communities.

Allergy and immunology in Africa: Challenges and unmet needs

The tremendous increase in allergy in the African continent cannot simply be explained by the change in public hygiene. There are many "prehygiene" communities with sewage-contaminated water supplies, helminth infestations, bare footedness, and poor housing, and still there is a high prevalence of allergic disease. Africans can be exposed to many risk factors facilitating severe asthma and wheezing, including airborne viruses, smoke, indoor dampness, cockroaches, and poor access to health care. Although the reporting on food allergy is inadequate to perform systematic reviews or meta-analyses, the available data suggest that food allergy is underdiagnosed. The rate of new HIV infections in high-prevalence settings in Africa remains unacceptably high. Although the annual number of new HIV infections in Sub-Saharan Africa has decreased lately, new HIV infections in the Middle East and North Africa region have increased; however, the current prevalence of 0.1% is still among the lowest globally. Africa is densely populated, and consanguineous mating is high in some areas of North and Sub-Saharan Africa. This allows for emergence of many autosomal recessive primary immunodeficiency diseases. There is urgent need for the establishment of primary immunodeficiency disease registries, stem cell transplantation facilities, and neonatal screening programs. To address these expanding problems and perform local cutting-edge research, Africans need to be empowered by motivated governments, dedicated funds, and compassionate scientific partnership.

The effect of current Schistosoma mansoni infection on the immunogenicity of a candidate TB vaccine, MVA85A, in BCG-vaccinated adolescents: An open-label trial

INTRODUCTION

Helminth infection may affect vaccine immunogenicity and efficacy. Adolescents, a target population for tuberculosis booster vaccines, often have a high helminth burden. We investigated effects of Schistosoma mansoni (Sm) on the immunogenicity and safety of MVA85A, a model candidate tuberculosis vaccine, in BCG-vaccinated Ugandan adolescents.

METHODS

In this phase II open label trial we enrolled 36 healthy, previously BCG-vaccinated adolescents, 18 with no helminth infection detected, 18 with Sm only. The primary outcome was immunogenicity measured by Ag85A-specific interferon gamma ELISpot assay. Tuberculosis and schistosome-specific responses were also assessed by whole-blood stimulation and multiplex cytokine assay, and by antibody ELISAs.

RESULTS

Ag85A-specific cellular responses increased significantly following immunisation but with no differences between the two groups. Sm infection was associated with higher pre-immunisation Ag85A-specific IgG4 but with no change in antibody levels following immunisation. There were no serious adverse events. Most reactogenicity events were of mild or moderate severity and resolved quickly.

CONCLUSIONS

The significant Ag85A-specific T cell responses and lack of difference between Sm-infected and uninfected participants is encouraging for tuberculosis vaccine development. The implications of pre-existing Ag85A-specific IgG4 antibodies for protective immunity against tuberculosis among those infected with Sm are not known. MVA85A was safe in this population.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02178748.

The impact of prenatal exposure to parasitic infections and to anthelminthic treatment on antibody responses to routine immunisations given in infancy: Secondary analysis of a randomised controlled trial

Background

Chronic parasitic infections are associated with active immunomodulation which may include by-stander effects on unrelated antigens. It has been suggested that pre-natal exposure to parasitic infections in the mother impacts immunological development in the fetus and hence the offspring’s response to vaccines, and that control of parasitic infection among pregnant women will therefore be beneficial.

Methodology/Principal findings

We used new data from the Entebbe Mother and Baby Study, a trial of anthelminthic treatment during pregnancy conducted in Uganda, to further investigate this hypothesis. 2705 mothers were investigated for parasitic infections and then randomised to albendazole (400mg) versus placebo and praziquantel (40mg/kg) during pregnancy in a factorial design. All mothers received sulfadoxine/pyrimethamine for presumptive treatment of malaria. Offspring received Expanded Programme on Immunisation vaccines at birth, six, 10 and 14 weeks. New data on antibody levels to diphtheria toxin, three pertussis antigens, Haemophilus influenzae type B (HiB) and Hepatitis B, measured at one year (April 2004 –May 2007) from 1379 infants were analysed for this report. Additional observational analyses relating maternal infections to infant vaccine responses were also conducted. Helminth infections were highly prevalent amongst mothers (hookworm 43.1%, Mansonella 20.9%, Schistosoma mansoni 17.3%, Strongyloides 11.7%, Trichuris 8.1%) and 9.4% had malaria at enrolment. In the trial analysis we found no overall effect of either anthelminthic intervention on the measured infant vaccine responses. In observational analyses, no species was associated with suppressed responses. Strongyloidiasis was associated with enhanced responses to pertussis toxin, HiB and Hep B vaccine antigens.

Conclusions/Significance

Our results do not support the hypothesis that routine anthelminthic treatment during pregnancy has a benefit for the infant’s vaccine response, or that maternal helminth infection has a net suppressive effect on the offspring’s response to vaccines.

Trial Registration

ISRCTN.com ISRCTN32849447

Parasitic infections, such as worms and malaria, have potent effects on the human immune system. These effects include modification of immune responses in the fetus and infant if a mother has a parasitic infection during pregnancy. These immunological changes can influence the way a child responds to the same infection when exposed in later life. It has been suggested that the immunological changes might also influence how the child responds to the vaccines given in infancy, and that treating mothers for parasitic infections when they are pregnant might be helpful. In this study we compared responses to vaccines between infants of mothers who had, or had not, been treated for worms while they were pregnant. We found no overall differences. We also compared vaccine responses between groups of mothers with and without parasitic infections. We found no evidence that the parasitic infections were associated with reduced responses in the children. This means that, although treating worms during pregnancy may have some benefits, improvements in the children’s responses to vaccines are not likely to be among them.

Schistosome-Derived Molecules as Modulating Actors of the Immune System and Promising Candidates to Treat Autoimmune and Inflammatory Diseases

It is long known that some parasite infections are able to modulate specific pathways of host's metabolism and immune responses. This modulation is not only important in order to understand the host-pathogen interactions and to develop treatments against the parasites themselves but also important in the development of treatments against autoimmune and inflammatory diseases. Throughout the life cycle of schistosomes the mammalian hosts are exposed to several biomolecules that are excreted/secreted from the parasite infective stage, named cercariae, from their tegument, present in adult and larval stages, and finally from their eggs. These molecules can induce the activation and modulation of innate and adaptive responses as well as enabling the evasion of the parasite from host defense mechanisms. Immunomodulatory effects of helminth infections and egg molecules are clear, as well as their ability to downregulate proinflammatory cytokines, upregulate anti-inflammatory cytokines, and drive a Th2 type of immune response. We believe that schistosomes can be used as a model to understand the potential applications of helminths and helminth-derived molecules against autoimmune and inflammatory diseases.

Helminths are positively associated with atopy and wheeze in Ugandan fishing communities: results from a cross-sectional survey

Background

Parasitic helminths are potent immunomodulators and chronic infections may protect against allergy‐related disease and atopy. We conducted a cross‐sectional survey to test the hypothesis that in heavily helminth‐exposed fishing villages on Lake Victoria, Uganda, helminth infections would be inversely associated with allergy‐related conditions.

Methods

A household survey was conducted as baseline to an anthelminthic intervention trial. Outcomes were reported wheeze in last year, atopy assessed both by skin prick test (SPT) and by the measurement of allergen‐specific IgE to dust mites and cockroach in plasma. Helminth infections were ascertained by stool, urine and haemoparasitology. Associations were examined using multivariable regression.

Results

Two thousand three hundred and sixteen individuals were surveyed. Prevalence of reported wheeze was 2% in under‐fives and 5% in participants ≥5 years; 19% had a positive SPT; median Dermatophagoides‐specific IgE and cockroach‐specific IgE were 1440 and 220 ng/ml, respectively. S. mansoni, N. americanus, S. stercoralis, T. trichiura, M. perstans and A. lumbricoides prevalence was estimated as 51%, 22%, 12%, 10%, 2% and 1%, respectively. S. mansoni was positively associated with Dermatophagoides‐specific IgE [adjusted geometric mean ratio (aGMR) (95% confidence interval) 1.64 (1.23, 2.18)]; T. trichiura with SPT [adjusted odds ratio (aOR) 2.08 (1.38, 3.15)]; M. perstans with cockroach‐specific IgE [aGMR 2.37 (1.39, 4.06)], A. lumbricoides with wheeze in participants ≥5 years [aOR 6.36 (1.10, 36.63)] and with Dermatophagoides‐specific IgE [aGMR 2.34 (1.11, 4.95)]. No inverse associations were observed.

Conclusions

Contrary to our hypothesis, we found little evidence of an inverse relationship between helminths and allergy‐related outcomes, but strong evidence that individuals with certain helminths were more prone to atopy in this setting.

Schistosoma mansoni and HIV infection in a Ugandan population with high HIV and helminth prevalence

Objectives

Recent reports suggest that Schistosoma infection may increase the risk of acquiring human immunodeficiency virus (HIV). We used data from a large cross‐sectional study to investigate whether Schistosoma mansoni infection is associated with increased HIV prevalence.

Methods

We conducted a household survey of residents in island fishing communities in Mukono district, Uganda, between October 2012 and July 2013. HIV status was assessed using rapid test kits. Kato‐Katz (KK) stool tests and urine‐circulating cathodic antigen (CCA) were used to test for Schistosoma infection. Multivariable logistic regression, allowing for the survey design, was used to investigate the association between S. mansoni infection and HIV infection.

Results

Data from 1412 participants aged 13 years and older were analysed (mean age 30.3 years, 45% female). The prevalence of HIV was 17.3%. Using the stool Kato‐Katz technique on a single sample, S. mansoni infection was detected in 57.2% (719/1257) of participants; urine CCA was positive in 73.8% (478/650) of those tested. S. mansoni infection was not associated with HIV infection. [KK (aOR = 1.04; 95% CI: 0.74–1.47, P = 0.81), CCA (aOR = 1.53; 95% CI: 0.78–3.00, P = 0.19)]. The median S. mansoni egg count per gram was lower in the HIV‐positive participants (P = 0.005).

Conclusions

These results add to the evidence that S. mansoni has little effect on HIV transmission, but may influence egg excretion.