Pathogen-pathogen interaction: a syndemic model of complex biosocial processes in disease

Combined multiplex panel test results are a poor estimate of disease prevalence without adjustment for test error

Multiplex panel tests identify many individual pathogens at once, using a set of component tests. In some panels the number of components can be large. If the panel is detecting causative pathogens for a single syndrome or disease then we might estimate the burden of that disease by combining the results of the panel, for example determining the prevalence of pneumococcal pneumonia as caused by many individual pneumococcal serotypes. When we are dealing with multiplex test panels with many components, test error in the individual components of a panel, even when present at very low levels, can cause significant overall error. Uncertainty in the sensitivity and specificity of the individual tests, and statistical fluctuations in the numbers of false positives and false negatives, will cause large uncertainty in the combined estimates of disease prevalence. In many cases this can be a source of significant bias. In this paper we develop a mathematical framework to characterise this issue, we determine expressions for the sensitivity and specificity of panel tests. In this we identify a counter-intuitive relationship between panel test sensitivity and disease prevalence that means panel tests become more sensitive as prevalence increases. We present novel statistical methods that adjust for bias and quantify uncertainty in prevalence estimates from panel tests, and use simulations to test these methods. As multiplex testing becomes more commonly used for screening in routine clinical practice, accumulation of test error due to the combination of large numbers of test results needs to be identified and corrected for.

Alterations in fecal virome and bacteriome virome interplay in children with autism spectrum disorder

Emerging evidence suggests autism spectrum disorder (ASD) is associated with altered gut bacteria. However, less is known about the gut viral community and its role in shaping microbiota in neurodevelopmental disorders. Herein, we perform a metagenomic analysis of gut-DNA viruses in 60 children with ASD and 64 age- and gender-matched typically developing children to investigate the effect of the gut virome on host bacteria in children with ASD. ASD is associated with altered gut virome composition accompanied by the enrichment of Clostridium phage, Bacillus phage, and Enterobacteria phage. These ASD-enriched phages are largely associated with disrupted viral ecology in ASD. Importantly, changes in the interplay between the gut bacteriome and virome seen in ASD may influence the encoding capacity of microbial pathways for neuroactive metabolite biosynthesis. These findings suggest an impaired bacteriome-virome ecology in ASD, which sheds light on the importance of bacteriophages in pathogenesis and the development of microbial therapeutics in ASD.

Identification and Aggressiveness of Fusarium Species Associated with Onion Bulb (Allium cepa L.) during Storage

Plant pathogens present a major challenge to crop production, leading to decreased yield and quality during growth and storage. During long-term storage, healthy onions can develop diseases from latent pathogen infections. This poses a challenge for onion growers because infected bulbs without visible symptoms can lead to significant crop losses during the growing season. In this study, we aimed to isolate and identify Fusarium species from yellow onion bulbs (Allium cepa L.) that developed disease symptoms during storage. The aggressiveness of these strains against onion bulbs and seedlings was also evaluated. The isolated strains were further subjected to morphological and molecular differentiation. The results revealed that all 16 isolated strains belonged to the Fusarium complex species incarnatum-equiseti and Fusarium fujikuroi, namely, F. proliferatum (98%), F. oxysporum (1%), and Fusarium sp. (1%). Koch's postulate analysis of isolated strains revealed varying aggressiveness on onion bulbs and plants depending on fungal species. Disease symptoms developed more slowly on plants than on onion bulb plants according to Koch's postulates. Moreover, the results revealed that Fusarium strains that can infect onion plants were less pathogenic to onion bulbs and vice versa. In addition, three isolates were found to be non-pathogenic to onions. Furthermore, the in vitro control of Fusarium species through Bacillus velezensis KS04-AU and Streptomyces albidoflavus MGMM6 showed high potential for controlling the growth of these pathogenic fungi. These results may contribute to the development of environmentally friendly approaches for controlling onion spoilage caused by pathogens during storage.

Alteration of the gut microbiota profile in children with autism spectrum disorder in China

Background

Autism spectrum disorder (ASD) is associated with alterations in the gut microbiome. However, there are few studies on gut microbiota of children with ASD in China, and there is a lack of consensus on the changes of bacterial species.

Purpose

Autism spectrum disorder (ASD) is associated with alterations in the gut microbiome. However, there are few studies on gut microbiota of children with ASD in China, and there is a lack of consensus on the changes of bacterial species.

Methods

We used 16S rRNA sequencing to analyze ASD children (2 to 12 years), HC (2 to 12 years).

Results

Our findings showed that the α-diversity, composition, and relative abundance of gut microbiota in the ASD group were significantly different from those in the HC groups. Compared with the HC group, the α-diversity in the ASD group was significantly decreased. At the genus level, the relative abundance of g_Faecalibacterium, g_Blautia, g_Eubacterium_eligens_group, g_Parasutterella, g_Lachnospiraceae_NK4A136_group and g_Veillonella in ASD group was significantly increased than that in HC groups, while the relative abundance of g_Prevotella 9 and g_Agathobacter was significantly decreased than that in HC groups. In addition, KEGG pathway analysis showed that the microbial functional abnormalities in ASD patients were mainly concentrated in metabolic pathways related to fatty acid, amino acid metabolism and aromatic compound metabolism, and were partially involved in neurotransmitter metabolism.

Conclusion

This study revealed the characteristics of gut microbiota of Chinese children with ASD and provided further evidence of gut microbial dysbiosis in ASD.

Challenges and perspectives in research and teaching of host pathogen interaction topics: new post-pandemic times to Brazil and other South American countries

Here is our proposal to improve learning in biomedical sciences for graduate and undergraduate courses with a broad vision integrating disciplines such as molecular cell biology, biochemistry, and biophysics around concepts of pathogen interaction within vertebrate and invertebrate hosts. Our paradigm is based on the possibility offered by the pandemic to have remote activities that give access to students and researchers from different places in Brazil and Latin American countries to discuss science. A multidisciplinary view of host-pathogen interaction allows us to understand better the mechanisms involved in the pathology of diseases, as well as to formulate broad strategies for the diagnosis, treatment, and control of thereof. The approach to integrating heterogeneous groups in science involves the critical analysis of national scientific resource distribution, where only some have the possibilities to conduct competitive scientific research. Solid theoretical training, contact, collaboration with groups of excellence, and training within a multidisciplinary network are our proposals for a permanent platform of scientific strengthening and dissemination for Latin America. Here we will review the concept of host-pathogen interaction, the type of institutions where it is taught and researched, new trends in active teaching methodologies, and the current political context in science.

The effects of antibiotics and illness on gut microbial composition in the fawn-footed mosaic-tailed rat (Melomys cervinipes)

The gut microbiota are critical for maintaining the health and physiological function of individuals. However, illness and treatment with antibiotics can disrupt bacterial community composition, the consequences of which are largely unknown in wild animals. In this study, we described and quantified the changes in bacterial community composition in response to illness and treatment with antibiotics in a native Australian rodent, the fawn-footed mosaic-tailed rat (Melomys cervinipes). We collected faecal samples during an undiagnosed illness outbreak in a captive colony of animals, and again at least one year later, and quantified the microbiome at each time point using 16s ribosomal rRNA gene sequencing. Gut bacterial composition was quantified at different taxonomic levels, up to family. Gut bacterial composition changed between time periods, indicating that illness, treatment with antibiotics, or a combination affects bacterial communities. While some bacterial groups increased in abundance, others decreased, suggesting differential effects and possible co-adapted and synergistic interactions. Our findings provide a greater understanding of the dynamic nature of the gut microbiome of a native Australian rodent species and provides insights into the management and ethical well-being of animals kept under captive conditions.

COVID-19, Mental Health, and Chronic Illnesses: A Syndemic Perspective

BACKGROUND

The COVID-19 pandemic is an epidemiological and psychological crisis; what it does to the body is quite well known by now, and more research is underway, but the syndemic impact of COVID-19 and mental health on underlying chronic illnesses among the general population is not completely understood.

METHODS

We carried out a literature review to identify the potential impact of COVID-19 and related mental health issues on underlying comorbidities that could affect the overall health of the population.

RESULTS

Many available studies have highlighted the impact of COVID-19 on mental health only, but how complex their interaction is in patients with comorbidities and COVID-19, the absolute risks, and how they connect with the interrelated risks in the general population, remain unknown. The COVID-19 pandemic can be recognized as a syndemic due to; synergistic interactions among different diseases and other health conditions, increasing overall illness burden, emergence, spread, and interactions between infectious zoonotic diseases leading to new infectious zoonotic diseases; this is together with social and health interactions leading to increased risks in vulnerable populations and exacerbating clustering of multiple diseases.

CONCLUSION

There is a need to develop evidence to support appropriate and effective interventions for the overall improvement of health and psychosocial wellbeing of at-risk populations during this pandemic. The syndemic framework is an important framework that can be used to investigate and examine the potential benefits and impact of codesigning COVID-19/non-communicable diseases (NCDs)/mental health programming services which can tackle these epidemics concurrently.

Mental Health, Social Connectedness, and Fear During the COVID-19 Pandemic: A Qualitative Perspective from Older Women with HIV

Older women with HIV (WWH) confront significant biopsychosocial challenges that may be exacerbated by the COVID-19 pandemic. Between May 2020 and April 2021, following a resiliency intervention conducted as part of a randomized parent trial, 24 cisgender WWH (M = 58 years old) completed quantitative assessments and qualitative interviews exploring the impact of COVID-19 on mental health. Qualitative data were analyzed via rapid analysis. Most participants were Black (62.5%) and non-Hispanic or Latina (87.5%). Emergent themes included (1) increased anxiety and depression; (2) a loss of social connectedness; (3) fear of unknown interactions among COVID-19, HIV, and other comorbidities; and (4) the use of largely adaptive strategies to cope with these issues. Findings suggest that older WWH face significant COVID-19-related mental health challenges, compounding existing stressors. As the pandemic persists, it will be important to assess the impact of these stressors on wellbeing, identify effective coping strategies, and provide increased support to mitigate COVID-19-related mental health issues over time. Trial Registration: ClinicalTrials.gov identifier: NCT03071887.

Biocultural perspectives of infectious diseases and demographic evolution: Tuberculosis and its comorbidities through history

Anthropologists recognize the importance of conceptualizing health in the context of the mutually evolving nature of biology and culture through the biocultural approach, but biocultural anthropological perspectives of infectious diseases and their impacts on humans (and vice versa) through time are relatively underrepresented. Tuberculosis (TB) has been a constant companion of humans for thousands of years and has heavily influenced population health in almost every phase of cultural and demographic evolution. TB in human populations has been dramatically influenced by behavior, demographic and epidemiological shifts, and other comorbidities through history. This paper critically discusses TB and some of its major comorbidities through history within a biocultural framework to show how transitions in human demography and culture affected the disease-scape of TB. In doing so, I address the potential synthesis of biocultural and epidemiological transition theory to better comprehend the mutual evolution of infectious diseases and humans.

Type 2 diabetes and depressive symptoms in the adult population in Mexico: a syndemic approach based on National Health and Nutrition Survey

Background

The syndemic approach allows the analysis of clusters of diseases that affect a population in contexts of geographic, social and economic inequalities at the same moment and time. This study aims to analyze, from a syndemic perspective, the relationship between type 2 diabetes (T2D) and depressive symptoms in Mexican adults and its association with individual, contextual and structural factors.

Methods

Observational, cross-sectional study based on secondary data from Mexico’s National Health and Nutrition Survey 2018–19. The sample of this study consisted of 16 835 adults, which represented a total of 78 463 734 persons aged ≥ 20 years. Bivariate descriptive analyses were performed and logistic regression models were estimated to analyze the association between T2D and depressive symptoms with various co-variables. In addition, interactions between T2D and depressive symptoms with obesity, educational level, and socioeconomic status were tested.

Results

In the study population, 12.2% of adults aged 20 years and older self-reported having T2D, 14.7% had depressive symptoms and 2.8% had both diseases. There was a statistically significant relationship between T2D and depressive symptoms. The prevalence of T2D and depressive symptoms was higher compared to people who did not have these two conditions. Obesity increased the probability of having T2D, while violence was statistically associated with people having depressive symptoms. A low level of education increased the odds ratio of having T2D and depressive symptoms.

Conclusion

The availability of analytical frameworks such as the syndemic perspective could help to identify areas of opportunity for decision making and actions for population groups that–because of their individual, contextual and structural disadvantages–are at greater risk of experiencing poorer health outcomes due to the presence of T2D and depressive symptoms.

Underdevelopment of the gut microbiota and bacteria species as non-invasive markers of prediction in children with autism spectrum disorder

OBJECTIVE

The gut microbiota has been suggested to play a role in autism spectrum disorder (ASD). We postulate that children with ASD harbour an altered developmental profile of the gut microbiota distinct from that of typically developing (TD) children. Here, we aimed to characterise compositional and functional alterations in gut microbiome in association with age in children with ASD and to identify novel faecal bacterial markers for predicting ASD.

DESIGN

We performed deep metagenomic sequencing in faecal samples of 146 Chinese children (72 ASD and 74 TD children). We compared gut microbial composition and functions between children with ASD and TD children. Candidate bacteria markers were identified and validated by metagenomic analysis. Gut microbiota development in relation to chronological age was assessed using random forest model.

RESULTS

ASD and chronological age had the most significant and largest impacts on children's faecal microbiome while diet showed no correlation. Children with ASD had significant alterations in faecal microbiome composition compared with TD children characterised by increased bacterial richness (p=0.021) and altered microbiome composition (p<0.05). Five bacterial species were identified to distinguish gut microbes in ASD and TD children, with areas under the receiver operating curve (AUC) of 82.6% and 76.2% in the discovery cohort and validation cohort, respectively. Multiple neurotransmitter biosynthesis related pathways in the gut microbiome were depleted in children with ASD compared with TD children (p<0.05). Developing dynamics of growth-associated gut bacteria (age-discriminatory species) seen in TD children were lost in children with ASD across the early-life age spectrum.

CONCLUSIONS

Gut microbiome in Chinese children with ASD was altered in composition, ecological network and functionality compared with TD children. We identified novel bacterial markers for prediction of ASD and demonstrated persistent underdevelopment of the gut microbiota in children with ASD which lagged behind their respective age-matched peers.

Psychological and Emotional Impact of COVID-19 Pandemic on People Living with Chronic Disease: HIV and Cancer

People living with chronic disease (PLWCD) are the frailest category, both for the risk of severe COVID-19 illness and for the impact on the care continuum. Aim of this study was to analyze coping strategies and resilience in people living with HIV (PLWH) compared to people living with oncological diseases (PLWOD) during COVID-19 pandemic. We administrated an anonymous questionnaire, which explored the emotional experience, the demographic factors linked to a COVID-19-related stress syndrome, the patient’s perception about the adequacy of clinical undertaking from the hospital and the resilience. We analyzed 324 questionnaires. There were no significant differences in prevalence of psychological distress among the whole cohort; however, PLWOD were calmer, less troubled, and more serene than PLWH. Moreover, PLWH smoked more, ate more, and gained more weight than PLWOD. Most patients didn’t feel lonely and continued to take pleasure from their activities. No differences in resilience were found between the groups. In the whole cohort lower levels of resilience were found in patients that were unemployed, with history of psychological disorders and in those who experienced more feelings of anger, anxiety and concern. In our study, patients seemed to preserve their well-being, and to activate adaptive coping during the pandemic.

Interactions among 17 respiratory pathogens: a cross-sectional study using clinical and community surveillance data

Background

Co-circulating respiratory pathogens can interfere with or promote each other, leading to important effects on disease epidemiology. Estimating the magnitude of pathogen-pathogen interactions from clinical specimens is challenging because sampling from symptomatic individuals can create biased estimates.

Methods

We conducted an observational, cross-sectional study using samples collected by the Seattle Flu Study between 11 November 2018 and 20 August 2021. Samples that tested positive via RT-qPCR for at least one of 17 potential respiratory pathogens were included in this study. Semi-quantitative cycle threshold (Ct) values were used to measure pathogen load. Differences in pathogen load between monoinfected and coinfected samples were assessed using linear regression adjusting for age, season, and recruitment channel.

Results

21,686 samples were positive for at least one potential pathogen. Most prevalent were rhinovirus (33·5%), Streptococcus pneumoniae (SPn, 29·0%), SARS-CoV-2 (13.8%) and influenza A/H1N1 (9·6%). 140 potential pathogen pairs were included for analysis, and 56 (40%) pairs yielded significant Ct differences (p < 0.01) between monoinfected and co-infected samples. We observed no virus-virus pairs showing evidence of significant facilitating interactions, and found significant viral load decrease among 37 of 108 (34%) assessed pairs. Samples positive with SPn and a virus were consistently associated with increased SPn load.

Conclusions

Viral load data can be used to overcome sampling bias in studies of pathogen-pathogen interactions. When applied to respiratory pathogens, we found evidence of viral-SPn facilitation and several examples of viral-viral interference. Multipathogen surveillance is a cost-efficient data collection approach, with added clinical and epidemiological informational value over single-pathogen testing, but requires careful analysis to mitigate selection bias.

Spatial epidemiology: An empirical framework for syndemics research

Syndemics framework describes two or more co-occurring epidemics that synergistically interact with each other and the complex structural social forces that sustain them leading to excess disease burden. The term syndemic was first used to describe the interaction between substance abuse, violence, and AIDS by Merrill Singer. A broader range of syndemic studies has since emerged describing the framework's applicability to other public health scenarios. With syndemic theory garnering significant attention, the focus is shifting towards developing robust empirical analytical approaches. Unfortunately, the complex nature of the disease-disease interactions nested within several social contexts complicates empirical analyses. In answering the call to analyze syndemics at the population level, we propose the use of spatial epidemiology as an empirical framework for syndemics research. Spatial epidemiology, which typically relies on geographic information systems (GIS) and statistics, is a discipline that studies spatial variations to understand the geographic landscape and the risk environment within which disease epidemics occur. GIS maps provide visualization aids to investigate the spatial distribution of disease outcomes, the associated social factors, and environmental exposures. Analytical inference, such as estimation of disease risks and identification of spatial disease clusters, can provide a detailed statistical view of spatial distributions of diseases. Spatial and spatiotemporal models can help us to understand, measure, and analyze disease syndemics as well as the social, biological, and structural factors associated with them in space and time. In this paper, we present a background on syndemics and spatial epidemiological theory and practice. We then present a case study focused on the HIV and HCV syndemic in West Virginia to provide an example of the use of GIS and spatial analytical methods. The concepts described in this paper can be considered to enhance understanding and analysis of other syndemics for which space-time data are available.

The Syndemic Theory, the COVID-19 Pandemic, and The Epidemics of Non-Communicable Diseases (NCDs)

Background: The syndemic theory is based on the interaction of two or more epidemics. This phenomenon is important in the current COVID-19 pandemic. Results: This pandemic affects all aspects of human life, including the management of non-communicable diseases (NCDs) such as cancer, diabetes, hypertension, and so on. This effect may have an impact not only on the management of the underlying NCDs but also on the infection and prognosis of COVID-19. Another aspect of this syndemic is that the health policies in each country have been revolutionized as a result of this pandemic, and the association of COVID-19 with other NCDs necessitates the implementation of new policies to properly manage this syndemic. Conclusion: In this paper, we review the syndemic theory, how the COVID-19 pandemic could be classified as a syndemic with other NCDs, and how this pandemic changes circumstances for policymakers in any country, particularly the Islamic Republic of Iran.

The syndemic burden of HIV/AIDS in Africa amidst the COVID-19 pandemic

INTRODUCTION

The human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) has long affected millions of individuals across the globe. Historically, the prevalence of this disease is particularly noted within the African continent. Before the coronavirus disease 2019 (COVID-19) pandemic, many African countries struggled to effectively manage the increasing burden associated with HIV/AIDS. There is now a need to reassess this in a COVID-19 pandemic context so that the impact of COVID-19 on HIV/AIDS healthcare within Africa can be adequately evaluated.

METHODS

Data collection was performed on the PubMed, Ovid MEDLINE and Embase bibliographical databases with a predefined search strategy. Searches were performed in blind duplicate and all articles considering COVID-19 and HIV/AIDS within African healthcare were considered.

RESULTS

The COVID-19 pandemic has severely exacerbated the many issues surrounding HIV/AIDS care within many African countries. These impacts are noticeable in medical, psychological, and socio-political contexts.

CONCLUSIONS

Before efforts are made to improve the provision of HIV/AIDS and COVID-19 care within Africa, it is important that this issue is brought to the attention of the scientific and clinical community so that the continent can receive the necessary support and aid.

Sexual Exposure to HIV Infection during the COVID-19 Pandemic in Men Who Have Sex with Men (MSM): A Multicentric Study

The practice of sex with casual partners without the use of adequate prevention in the period of social distancing due to the COVID-19 pandemic among men who have sex with men (MSM) can expose them to the risk of infection by the HIV virus. To assess this, we conducted an online survey in April and May 2020 in the entire national territory of Brazil and Portugal. We used the snowball technique for sampling, associated with circulation in social networks, totaling 2934 participants. Bivariate and multivariate logistic regression was used to produce the adjusted Odds Ratio (aOR). Eight-hundred-and-forty-two (28.7%) MSM presented at-risk sexual exposure in this period. In general, the types of sexual practices that most increased the chances of sexual exposure were having multiple partners (aOR:14.045); having practiced chemsex (aOR:2.246) and group sex (aOR:2.431), as well as presenting a history of at-risk sexual exposure (aOR:5.136). When we consider each country separately, the chances are increased in Brazil since the probability of the outcome was increased in those who practiced group sex (aOR:5.928), had multiple partners (aOR:19.132), and reported a sexual history of at-risk exposure (aOR:8.861). Our findings indicate that practices that are classically associated with greater chances of engaging in risky sexual exposure to HIV infection were the factors that most increased the chances of acquiring the virus in the pandemic context.

Harnessing Eco-Evolutionary Dynamics of Xanthomonads on Tomato and Pepper to Tackle New Problems of an Old Disease

Bacterial spot is an endemic seedborne disease responsible for recurring outbreaks on tomato and pepper around the world. The disease is caused by four diverse species, Xanthomonas gardneri, Xanthomonas euvesicatoria, Xanthomonas perforans, and Xanthomonas vesicatoria. There are no commercially available disease-resistant tomato varieties, and the disease is managed by chemical/biological control options, although these have not reduced the incidence of outbreaks. The disease on peppers is managed by disease-resistant cultivars that are effective against X. euvesicatoria but not X. gardneri. A significant shift in composition and prevalence of different species and races of the pathogen has occurred over the past century. Here, I attempt to review ecological and evolutionary processes associated with the population dynamics leading to disease emergence and spread. The goal of this review is to integrate the knowledge on population genomics and molecular plant-microbe interactions for this pathosystem to tailor disease management strategies.

The Manifesto of Pharmacoenosis: Merging HIV Pharmacology into Pathocoenosis and Syndemics in Developing Countries

Pathocoenosis and syndemics theories have emerged in the last decades meeting the frequent need of better understanding interconnections and reciprocal influences that coexistent communicable and non-communicable diseases play in a specific population. Nevertheless, the attention to pharmacokinetic and pharmacodynamics interactions of co-administered drugs for co-present diseases is to date limitedly paid to alert against detrimental pharmacological combos. Low and middle-income countries are plagued by the highest burden of HIV, tuberculosis, malaria, and helminthiasis, and they are experiencing an alarming rise in non-communicable disorders. In these settings, co-infections and comorbidities are common, but no tailored prescribing nor clinical trials are used to assess and exploit existing opportunities for the simultaneous and potentially synergistic treatment of intertwined diseases. Pharmacoenosis is the set of interactions that take place within a host as well as within a population due to the compresence of two or more diseases and their respective treatments. This framework should pilot integrated health programmes and routine clinical practice to face drug–drug interaction issues, avoiding negative co-administrations but also exploiting potential favourable ones to make the best out of the worst situations; still, to date, guiding data on the latter possibility is limited. Therefore, in this narrative review, we have briefly described both detrimental and favourable physiopathological interactions between HIV and other common co-occurring pathologies (malaria, tuberculosis, helminths, and cardiovascular disorders), and we have presented examples of advantageous potential pharmacological interactions among the drugs prescribed for these diseases from a pharmacokinetics, pharmacodynamics, and pharmacogenetics standpoint.

The Relationship Between Violence Syndemics and Sexual Risk Behaviors Among African American Adolescents: Implications for Future Research

PURPOSE

We present a conceptual framework based on a review of the literature to highlight the interconnecting and reinforcing elements of a violence syndemic and how this syndemic influences sexual risk behaviors among African American heterosexual adolescents.

METHODS

We review existing peer-reviewed published research from 2000 to 2020 that links a violence syndemic (i.e., racism and race-related stress, neighborhood and police violence, peer violence, and family violence and disruptions) to adolescent sexual risk behaviors. Empirical findings and theoretical underpinnings are used to document this relationship and illuminate the factors that mediate this relationship.

RESULTS

Empirical studies support the links between specific types of violence and sexual risk behaviors among African American adolescents. Further, existing studies point to the important relationships among the specific types of violence, supporting a violence syndemic approach.

CONCLUSIONS

While more researchers are examining socio-ecological contextual factors as important predictors for sexual risk behaviors, there remains inadequate understanding about how violence types reinforce one another to heighten sexual risk behaviors among African American heterosexual adolescents. This article presents new directions for adolescent research, especially how a violence syndemic approach can be used to explain sexual risk, but also to refocus intervention design on the complex burdens experienced by this population.

Evaluation of virologic suppression rates during the COVID-19 pandemic with outpatient interdisciplinary HIV care

Introduction

The Coronavirus Disease 2019 (COVID-19) pandemic has presented social distancing challenges leading healthcare systems to adapt and utilize telemedicine platforms more than ever before. Reducing patient exposure to COVID-19 became a primary concern, especially for populations at an increased risk for severe illness, such as human immunodeficiency virus (HIV) positive patients.

Objectives

The primary objective of this study was to measure the impact of pharmacy services including telehealth through the percentage of virologically suppressed patients (HIV ribonucleic acid [RNA] < 200 copies/mL) during the pre-COVID and post-COVID time periods. Secondary objectives included the percentage of patients with undetectable viral loads (HIV RNA < 20 copies/mL), percentage of patients with cluster of differentiation 4 (CD4) cell counts greater than 200 cells/mm³, and changes in CD4 cell counts and percentages pre-COVID and post-COVID.

Methods

This was a retrospective chart review at a single center HIV primary care clinic in Brooklyn, NY evaluating electronic medical records (EMRs) of 211 HIV-positive patients. Pre-COVID was defined as 1 year prior to March 13, 2020, and post-COVID was defined as March 13 to July 20, 2020.

Results

Viral load suppression rates for pre and post-COVID were 88.6% and 85.3%, respectively (P = .28). Undetectable viral load rates for pre and post-COVID were approximately 81.5% and 74.4% (P = .096). Mean CD4 cell counts and percentages were 617 cells/mm³ and 29% for pre-COVID, and 460 cells/mm³ and 22% for post-COVID. CD4 cell counts greater than 200 cells/mm³ pre-COVID and post-COVID was 92.6% and 78.3%, respectively (P = .001).

Conclusion

Utilization of pharmacy services including telehealth, may allow clinical pharmacists to collaboratively provide remote services without jeopardizing patient outcomes. Larger studies are needed to confirm these findings, and display the long-term impact and satisfaction of these services.

Intersectionality and syndemics: A commentary

This commentary addresses the possibilities and pitfalls of putting intersectionality and syndemics into conversation with each other. We engage with two studies published in this issue: the first on the health-related vulnerabilities among LGBTQ + Latinx men in Orlando after the Pulse nightclub shooting, and the other on syndemic health issues brought about by social and structural inequities among young Black gay, bisexual, and other men who have sex with men (GBM). Both manuscripts suggest that intersectionality and sydemics can be integrated or possibly merged to build effective health equity focused interventions for marginalized populations. We, however, argue that there are several methodological, ontological, and epistemological challenges in bringing together intersectionality and syndemics. Our argument coalesces around three key points. First, we contend that while it is feasible to think of their integration as useful to the study of health disparities, syndemics offers no added benefit to health scholarship grounded in intersectional analysis. Second, we argue that assumptions of common ground between intersectionality and syndemics rest on equating theories of interaction and additivity with critiques of mutual configurations of ideology, power structures, and social categories. Finally, we maintain that if intersectionality and syndemics are to be in conversation with each other, it must be done with the recognition and examination of where each framework situates itself relative to methodology, praxis, and power. Using our own work and those of intersectional feminist scholars, we demonstrate how the stakes of intersectionality diverge radically from those of syndemics, and how syndemics has the potential to undermine the significance of intersectionality for addressing issues of health equity.

The SARS-CoV-2 pandemic: A syndemic perspective

The SARS-CoV-2 pandemic has affected communities, populations, and countries throughout the world. As the SARS-CoV-2 pandemic developed, the extent to which the disease interacted with already existing endemic, non-communicable and infectious diseases became evident, hence deeply influencing health outcomes. Additionally, a synergistic effect has been demonstrated also with socio-economic, cultural, and contextual determinants of health which seem to contribute to poorer health and accumulating social disadvantages. In this essay, using as a starting point the syndemic theory that translates the cumulative and intertwined factors between different epidemics, we argue that the SARS-CoV-2 is a one health issue of a syndemic nature and that the failure to acknowledge this contributes to weakened policy-making processes and public health responses and ineffective health policies and programs.

The COVID-19 Pandemic: an Appraisal of its Impact on Human Immunodeficiency Virus Infection and Pre-Eclampsia

PURPOSE OF REVIEW

The impact of the coronavirus disease 2019 (COVID-19) pandemic is profound, with distressing consequences on many individuals, especially those with co-morbidities. Pregnant women are one such group of individuals who are at in increased risk of contracting COVID-19, due to their immunocompromised state. In South Africa, HIV infection and pre-eclampsia are the leading causes of maternal morbidity and mortality, with South Africa being the HIV epicentre of the world. The relationship between COVID-19 superimposed on HIV infection and preeclampsia is complex and uncertain due to their different immune responses, and therefore requires further research.

RECENT FINDINGS

Notably evidence suggests that pregnant women with chronic comorbidities (HIV and pre-eclampsia) may be at a greater risk of contracting or encountering complications from COVID-19. Maternal stress, during a pandemic, as well as home delivery have become potential options for pregnant woman. Nonetheless there is currently a paucity of information on the combined effect of COVID-19 in HIV-associated preeclampsia. Understanding the pathogenesis of COVID-19 could potentially aid in developing effective treatment strategies for COVID-19 in HIV associated preeclampsia. This review article presents a comprehensive analysis of the current data in relation to COVID-19 and its effect on pregnant women, including symptoms, pathogenesis and the possible risk of vertical transmission. This paper also reviews its' interactions and effects on preeclamptic and HIV positive pregnant women with suspected or confirmed COVID-19.

The Burden of COVID-19 in People Living with HIV: A Syndemic Perspective

The emergence of the novel coronavirus disease known as COVID-19 creates another health burden for people living with HIV (PLWH) who face multiple morbidities and may be at heightened risk for severe physical health illness from COVID-19. Our abilities to address these morbidities in PLWH must be considered alongside the socially-produced burdens that both place this population at risk for COVID-19 and heighten the likelihood of adverse outcomes. These burdens can affect the physical, emotional, and social well-being of PLWH and interfere with the delivery of effective healthcare and access to HIV treatment. We posit that a syndemic framework can be used to conceptualize the potential impact of COVID-19 among PLWH to inform the development of health programming services.

Global public health efforts to address HIV and related communicable disease syndemics

PURPOSE OF REVIEW

To review recent progress in public health efforts to address HIV, and the extent to which key approaches can be applied to three key epidemics that commonly co-occur with HIV: TB, viral hepatitis, and STIs.

RECENT FINDINGS

The public health approach to tackling HIV in low-income and middle-income settings relied on standardized treatment regimens and monitoring approaches, task sharing and community involvement, and decentralized and integrated service delivery. These approaches can all be applied to three key epidemics that commonly co-occur with HIV: TB, viral hepatitis, and STIs.

SUMMARY

HIV, viral hepatitis, and STIs share common routes of infection, and HIV weakens the immune system, increasing the risk of TB. A public health approach can be applied to address these syndemics.

A randomized comparison trial of culturally adapted HIV prevention approaches for Native Americans reducing trauma symptoms versus substance misuse: The Healing Seasons protocol

Native Americans (NA) experience interrelated risks of trauma exposure, substance use, and HIV risk behaviors that put them at increased risk for HIV infection. Despite these known risk factors, there are very few published randomized trials testing interventions to reduce trauma-related symptoms and substance misuse among NA.

METHODS

The Healing Seasons study is a randomized comparsion trial of two counseling strategies, Narrative Exposure Therapy (NET) addressing PTSD or Motivational interviewing with cognitive behavioral therapy skills training (MIST) addressing substance misuse as a means to prevent HIV among NA. Using a community-based participatory research approach, we adapted both evidence-based interventions to be specific to the risk contexts and realities of NA and to include psychoeducational and skill-building components that include cultural-specific stories, virtues, and traditional treatment strategies. Participants, 16 years and older, were recruited from a Pacific Northwest tribal community, screened over the phone, enrolled in person, and randomized in equal numbers to NET or MIST. We stratified by age (16-29 years and 30 or older) and gender (male or female identified) to ensure balance between treatment arms. The primary outcomes were number of sex partners and frequency of sexual acts (with and without condoms), sex under the influence of substances, frequency of substance use, and PTSD severity.

DISCUSSION

Behavioral interventions for NA are needed to prevent HIV risk behaviors when faced with trauma symptoms and substance misuse. This study will provide evidence to determine feasibility and efficacy of addressing related risk factors as part of counseling-based HIV prevention intervention to reduce sexual risk among this population.

TRIAL REGISTRATION

ClinicalTrials.gov number, NCT03112369, registered April 12, 2017.

Whither syndemics?: Trends in syndemics research, a review 2015-2019

As originally conceived, syndemics refers to complex epidemics involving two types of adverse interaction - the clustering and interactions of two or more diseases or health conditions (the biological-biological interface) and social environmental factors (the biological-social interface). The theory has been widely applied in the fields of medicine, public health and anthropology, but how the concept is conceptualised and investigated in new syndemics literature remains unclear. This paper offers a scoping review of recent syndemics literature aiming to address the question: Where have scholars taken the syndemics concept? Five bibliographic databases were searched for titles containing 'syndemic[s]' revealing 334 records. A total of 143 journal articles, 23 book chapters, 21 commentaries, 2 books and 5 dissertations were assessed. Citations were classified into five categories: syndemics (n = 22), potential syndemics (n = 34), socially determined heightened burden of disease (n = 29), harmful disease cluster (n = 32) and additive adverse conditions (n = 71). The limited number of citations meeting the definition of a syndemic arrangement highlights the challenges related to describing and empirically supporting the biological-biological and biological-social relationships. Nevertheless, there is value in retaining the original, holistic, biosocial meaning of syndemics to identify and detail the casual pathways and mechanisms of interactions.

N-Acyl Homoserine Lactones and Lux Solos Regulate Social Behaviour and Virulence of Pseudomonas syringae pv. actinidiae

The phyllosphere is a complex environment where microbes communicate through signalling molecules in a system, generally known as quorum sensing (QS). One of the most common QS systems in Gram-negative proteobacteria is based on the production of N-acyl homoserine lactones (AHLs) by a LuxI synthase and their perception by a LuxR sensor. Pseudomonas syringae pv. actinidiae (Psa), the aetiological agent of the bacterial canker of kiwifruit, colonises plant phyllosphere before penetrating via wounds and natural openings. Since Psa genome encodes three LuxR solos without a cognate LuxI, this bacterium may perceive diffusible signals, but it cannot produce AHLs, displaying a non-canonical QS system. The elucidation of the mechanisms underlying the perception of environmental cues in the phyllosphere by this pathogen and their influence on the onset of pathogenesis are of crucial importance for a long-lasting and sustainable management of the bacterial canker of kiwifruit. Here, we report the ability of Psa to sense its own population density and the presence of surrounding bacteria. Moreover, we show that Psa can perceive AHLs, indicating that AHL-producing neighbouring bacteria may regulate Psa virulence in the host. Our results suggest that the ecological environment is important in determining Psa fitness and pathogenic potential. This opens new perspectives in the use of more advanced biochemical and microbiological tools for the control of bacterial canker of kiwifruit.

Sex work, discrimination, drug use and violence: a pattern for HIV risk among transgender sex workers compared to MSM sex workers and other MSM in Guatemala

The risk of HIV infection is higher among transgender women and cisgender men who have sex with men (MSM) compared to the general population due in part to social and contextual factors. This study aimed to determine the prevalence and association of alcohol and drug abuse, discrimination and violence among transgender sex workers compared to cisgender male sex workers and cisgender men who had not received money for sex in Guatemala City. In 2010, transgender women and cisgender men who had had sex with men or transgender women were recruited into a cross-sectional behavioural survey. Among transgender women, 86% received money for sex in the past year. Transgender sex workers were more likely to use drugs and binge drink, three times as likely to be discriminated against and eight times as likely to be forced to have sex compared to non-sex worker men. Male sex workers were twice as likely to use illicit drugs or experience physical violence and six times as likely to experience forced sex compared to non-sex worker men. Transgender and male sex workers would benefit from harm reduction for substance use, violence prevention, response and strategies to mitigate discrimination.

Estimation of temporal covariances in pathogen dynamics using Bayesian multivariate autoregressive models

It is well recognised that animal and plant pathogens form complex ecological communities of interacting organisms within their hosts, and there is growing interest in the health implications of such pathogen interactions. Although community ecology approaches have been used to identify pathogen interactions at the within-host scale, methodologies enabling robust identification of interactions from population-scale data such as that available from health authorities are lacking. To address this gap, we developed a statistical framework that jointly identifies interactions between multiple viruses from contemporaneous non-stationary infection time series. Our conceptual approach is derived from a Bayesian multivariate disease mapping framework. Importantly, our approach captures within- and between-year dependencies in infection risk while controlling for confounding factors such as seasonality, demographics and infection frequencies, allowing genuine pathogen interactions to be distinguished from simple correlations. We validated our framework using a broad range of synthetic data. We then applied it to diagnostic data available for five respiratory viruses co-circulating in a major urban population between 2005 and 2013: adenovirus, human coronavirus, human metapneumovirus, influenza B virus and respiratory syncytial virus. We found positive and negative covariances indicative of epidemiological interactions among specific virus pairs. This statistical framework enables a community ecology perspective to be applied to infectious disease epidemiology with important utility for public health planning and preparedness.

Disease-causing microorganisms, including viruses, bacteria, protozoa and fungi, form complex communities within animals and plants. These microorganisms can coexist harmoniously or even beneficially, or they may competitively interact for host resources. Well-studied examples include interactions between viruses and bacteria in the respiratory tract. Whilst ecological studies have revealed that some pathogens do interact within their hosts, identifying interactions from available population scale data from health authorities is challenging. This is exacerbated by a lack of large-scale data describing the infection patterns of multiple pathogens within single populations over long time frames. Furthermore, methods for evaluating whether infection frequencies of different pathogens fluctuate together or not over time cannot readily account for alternative explanations. For example, human pathogens may have related seasonal patterns depending on the age groups they infect and the weather conditions they survive in, and not because they are interacting. We developed a robust statistical framework to identify pathogen-pathogen interactions from population scale diagnostic data. This framework serves as a crucial step in identifying such important interactions and will guide new studies to elucidate their underpinning mechanisms. This will have important consequences for public health preparedness and the design of effective disease control interventions.

Pseudomonas aeruginosa-Derived Volatile Sulfur Compounds Promote Distal Aspergillus fumigatus Growth and a Synergistic Pathogen-Pathogen Interaction That Increases Pathogenicity in Co-infection

Pathogen-pathogen interactions in polymicrobial infections are known to directly impact, often to worsen, disease outcomes. For example, co-infection with Pseudomonas aeruginosa and Aspergillus fumigatus, respectively the most common bacterial and fungal pathogens isolated from cystic fibrosis (CF) airways, leads to a worsened prognosis. Recent studies of in vitro microbial cross-talk demonstrated that P. aeruginosa-derived volatile sulfur compounds (VSCs) can promote A. fumigatus growth in vitro. However, the mechanistic basis of such cross-talk and its physiological relevance during co-infection remains unknown. In this study we combine genetic approaches and GC-MS-mediated volatile analysis to show that A. fumigatus assimilates VSCs via cysteine (CysB)- or homocysteine (CysD)-synthase. This process is essential for utilization of VSCs as sulfur sources, since P. aeruginosa-derived VSCs trigger growth of A. fumigatus wild-type, but not of a ΔcysBΔcysD mutant, on sulfur-limiting media. P. aeruginosa produces VSCs when infecting Galleria mellonella and co-infection with A. fumigatus in this model results in a synergistic increase in mortality and of fungal and bacterial burdens. Interestingly, the increment in mortality is much greater with the A. fumigatus wild-type than with the ΔcysBΔcysD mutant. Therefore, A. fumigatus' ability to assimilate P. aeruginosa derived VSCs significantly triggers a synergistic association that increases the pathobiology of infection. Finally, we show that P. aeruginosa can promote fungal growth when growing on substrates that resemble the lung environment, which suggests that this volatile based synergism is likely to occur during co-infection of the human respiratory airways.

When deservingness policies converge: US immigration enforcement, health reform and patient dumping

As immigration and health policy continue to be contentious topics globally, anthropologists must examine how policy creates notions of health-related deservingness, which may have broad consequences. This paper explores hidden relationships between immigration enforcement laws and the most recent health reform law in the United States, the Patient Protection and Affordable Care Act (ACA), which excludes immigrants from certain types of health services. Findings in this paper show how increasingly harsh immigration enforcement efforts provide health facilities a 'license to discriminate' against undocumented immigrants, resulting in some facilities 'dumping' undocumented patients or unlawfully transferring them from one hospital to another. Due to changes made through the ACA, patient dumping disproportionately complicates public hospitals' financial viability and may have consequences on public facilities' ability to provide care for all indigent patients. By focusing on the converging consequences of immigrant policing and health reform, findings in this paper ultimately show that examining deservingness assessments and how they become codified into legislation, which I call 'deservingness projects', can reveal broader elements of state power and demonstrate how such power extends beyond targeted populations. Exercises of state power can thus have 'spillover effects' that harm numerous vulnerable populations, highlighting the importance of medical anthropology in documenting the broad, hidden consequences of governmental actions that construct populations as undeserving of social services.

Access to Health Care Services among Young People Exchanging Sex in Detroit

Within the related epidemics of sex exchange, drug use, and poverty, access to health care is shaped by intersecting identities, policy, and infrastructure. This study uses a unique survey sample of young adults in Detroit, who are exchanging sex on the street, in strip clubs, and at after-hours parties and other social clubs. Factors predicting access to free or affordable health care services, such as venue, patterns of sexual exchange influence, drug use and access to transportation, were examined using multivariable logistic regression and qualitative comparative analysis. The most significant predictors of low access to health care services were unstable housing and lack of access to reliable transportation. In addition, working on the street was associated with decreased access to services. Coordinated policy and programming changes are needed to increase health care access to this group, including improved access to transportation, housing, and employment, and integration of health care services.

Plant Microbiome and Its Link to Plant Health: Host Species, Organs and Pseudomonas syringae pv. actinidiae Infection Shaping Bacterial Phyllosphere Communities of Kiwifruit Plants

Pseudomonas syringae pv. actinidiae (Psa) is the causal agent of the bacterial canker, the most devastating disease of kiwifruit vines. Before entering the host tissues, this pathogen has an epiphytic growth phase on kiwifruit flowers and leaves, thus the ecological interactions within epiphytic bacterial community may greatly influence the onset of the infection process. The bacterial community associated to the two most important cultivated kiwifruit species, Actinidia chinensis and Actinidia deliciosa, was described both on flowers and leaves using Illumina massive parallel sequencing of the V3 and V4 variable regions of the 16S rRNA gene. In addition, the effect of plant infection by Psa on the epiphytic bacterial community structure and biodiversity was investigated. Psa infection affected the phyllosphere microbiome structures in both species, however, its impact was more pronounced on A. deliciosa leaves, where a drastic drop in microbial biodiversity was observed. Furthermore, we also showed that Psa was always present in syndemic association with Pseudomonas syringae pv. syringae and Pseudomonas viridiflava, two other kiwifruit pathogens, suggesting the establishment of a pathogenic consortium leading to a higher pathogenesis capacity. Finally, the analyses of the dynamics of bacterial populations provided useful information for the screening and selection of potential biocontrol agents against Psa.

Methanobacterium formicicum as a target rumen methanogen for the development of new methane mitigation interventions: A review

Methanobacterium formicicum (Methanobacteriaceae family) is an endosymbiotic methanogenic Archaean found in the digestive tracts of ruminants and elsewhere. It has been significantly implicated in global CH₄ emission during enteric fermentation processes. In this review, we discuss current genomic and metabolic aspects of this microorganism for the purpose of the discovery of novel veterinary therapeutics. This microorganism encompasses a typical H₂ scavenging system, which facilitates a metabolic symbiosis across the H₂ producing cellulolytic bacteria and fumarate reducing bacteria. To date, five genome-scale metabolic models (iAF692, iMG746, iMB745, iVS941 and iMM518) have been developed. These metabolic reconstructions revealed the cellular and metabolic behaviors of methanogenic archaea. The characteristics of its symbiotic behavior and metabolic crosstalk with competitive rumen anaerobes support understanding of the physiological function and metabolic fate of shared metabolites in the rumen ecosystem. Thus, systems biological characterization of this microorganism may provide a new insight to realize its metabolic significance for the development of a healthy microbiota in ruminants. An in-depth knowledge of this microorganism may allow us to ensure a long term sustainability of ruminant-based agriculture.

In situ relationships between microbiota and potential pathobiota in Arabidopsis thaliana

A current challenge in microbial pathogenesis is to identify biological control agents that may prevent and/or limit host invasion by microbial pathogens. In natura, hosts are often infected by multiple pathogens. However, most of the current studies have been performed under laboratory controlled conditions and by taking into account the interaction between a single commensal species and a single pathogenic species. The next step is therefore to explore the relationships between host-microbial communities (microbiota) and microbial members with potential pathogenic behavior (pathobiota) in a realistic ecological context. In the present study, we investigated such relationships within root-associated and leaf-associated bacterial communities of 163 ecologically contrasted Arabidopsis thaliana populations sampled across two seasons in southwest of France. In agreement with the theory of the invasion paradox, we observed a significant humped-back relationship between microbiota and pathobiota α-diversity that was robust between both seasons and plant organs. In most populations, we also observed a strong dynamics of microbiota composition between seasons. Accordingly, the potential pathobiota composition was explained by combinations of season-specific microbiota operational taxonomic units. This result suggests that the potential biomarkers controlling pathogen's invasion are highly dynamic.

Predictors of Facebook User Engagement With Health-Related Content for Gay, Bisexual, and Other Men Who Have Sex With Men: Content Analysis

Background

Social media is used by community-based organizations (CBOs) to promote the well-being of gay and bisexual men (GBM). However, few studies have quantified which factors facilitate the diffusion of health content tailored for sexual minorities.

Objective

The aim of this study was to identify post characteristics that can be leveraged to optimize the health promotion efforts of CBOs on Facebook.

Methods

The Facebook application programming interface was used to collect 5 years’ of posts shared across 10 Facebook pages administered by Vancouver-based CBOs promoting GBM health. Network analysis assessed basic indicators of network structure. Content analyses were conducted using informatics-based approaches. Hierarchical negative binomial regression of post engagement data was used to identify meaningful covariates of engagement.

Results

In total, 14,071 posts were shared and 21,537 users engaged with these posts. Most users (n=13,315) engaged only once. There was moderate correlation between the number of posts and the number of CBOs users engaged with (r=.53, P<.001). Higher user engagement was positively associated with positive sentiment, sharing multimedia, and posting about pre-exposure prophylaxis, stigma, and mental health. Engagement was negatively associated with asking questions, posting about dating, and sharing posts during or after work (versus before).

Conclusions

Results highlight the existence of a core group of Facebook users who facilitate diffusion. Factors associated with greater user engagement present CBOs with a number of strategies for improving the diffusion of health content.

Psychosocial Syndemic Correlates of Sexual Compulsivity Among Men Who Have Sex with Men: A Meta-Analysis

Efforts have been made to better understand sexual compulsivity by examining salient psychosocial syndemic correlates, though examination of such factors has yielded inconclusive results. Given that research on sexual compulsivity has predominately involved men who have sex with men (MSM), the aims of the current study were to establish the mean effect sizes of seven psychosocial syndemic indicators with sexual compulsivity, to determine if the effect varied as a function of the type of psychosocial syndemic, and investigate the potential moderating effects using MSM samples. A total of 95 studies were included for analyses among the psychosocial syndemic indicators of interest (i.e., depression, anxiety, alcohol use, drug use, intimate partner violence, childhood sexual abuse, and sexual risk behavior). Results revealed a medium mean effect size of sexual compulsivity, the strength of which was significantly moderated by type of psychosocial syndemic indicator. Significant mean effect sizes for all syndemic indicators on sexual compulsivity were found, with depression and anxiety having the strongest relationships; significant moderating effects were found and are discussed. Findings highlight clinical considerations regarding sexual compulsivity and its role within the HIV syndemic framework among MSM.

Molecular epidemiology of infectious diseases

Molecular epidemiology (ME) is a branch of epidemiology developed by merging molecular biology into epidemiological studies. In this paper, the authors try to discuss the ways that molecular epidemiology studies identify infectious diseases' causation and pathogenesis, and unravel infectious agents' sources, reservoirs, circulation pattern, transmission pattern, transmission probability, and transmission order. They bring real-world examples of research works in each area to make each study design more understandable. They also address some research areas and study design aspects that need further attention in future. They close with some thoughts about future directions in this field and emphasize on the need for training competent molecular epidemiology specialists that are capable of dealing with rapid advances in the field.

Multicausal etiology of the enteric syndrome in rabbits from Mexico

Enteropathies in rabbits are difficult to diagnose; their etiology involves pathogens that act synergistically, causing damage to the intestine. The aim of the present study was isolate enteric pathogens from rabbits in Mexico. Using parasitological, bacteriological and molecular analyses, we screened 58 samples of the intestinal content of rabbits having a clinical history of enteric disease from the southeastern part of the State of Mexico. Out of the 58 samples analyzed, a total of 86 identifications were made, Eimeria spp. were found in 77.5%, followed by Aeromonas spp. in 15.5% and Escherichia coli in 8.6%, which were identified as enteropathogenic E. coli (EPEC), and the presence of the following agents was also confirmed: Salmonella spp., Klebsiella spp., Streptococcus spp., Staphylococcus aureus, Enterococcus spp., Mannheimia spp. and Rotavirus. The concurrent presence of Eimeria spp. with Aeromonas was frequent (15.5%); there was statistical significance for the presence of an association between the clinical profiles and Eimeria spp. (p=0.000), Mannheimia spp. (p=0.001), Salmonella spp., Klebsiella spp., Streptococcus spp. and Enterococcus spp. (p=0.006).

Bias Due to Correlation Between Times-at-Risk for Infection in Epidemiologic Studies Measuring Biological Interactions Between Sexually Transmitted Infections: A Case Study Using Human Papillomavirus Type Interactions

The clustering of human papillomavirus (HPV) infections in some individuals is often interpreted as the result of common risk factors rather than biological interactions between different types of HPV. The intraindividual correlation between times-at-risk for all HPV infections is not generally considered in the analysis of epidemiologic studies. We used a deterministic transmission model to simulate cross-sectional and prospective epidemiologic studies measuring associations between 2 HPV types. When we assumed no interactions, the model predicted that studies would estimate odds ratios and incidence rate ratios greater than 1 between HPV types even after complete adjustment for sexual behavior. We demonstrated that this residual association is due to correlation between the times-at-risk for different HPV types, where individuals become concurrently at risk for all of their partners' HPV types when they enter a partnership and are not at risk when they are single. This correlation can be controlled in prospective studies by restricting analyses to susceptible individuals with an infected sexual partner. The bias in the measured associations was largest in low-sexual-activity populations, cross-sectional studies, and studies which evaluated infection with a first HPV type as the exposure. These results suggest that current epidemiologic evidence does not preclude the existence of competitive biological interactions between HPV types.

Health and epidemiological approaches of Trypanosoma evansi and equine infectious anemia virus in naturally infected horses at southern Pantanal

Equine infectious anemia virus (EIAV) and Trypanossoma evansi are endemic in Brazilian Pantanal Biome, an important area for livestock production. In this sense, we evaluated the epidemiological single and co-infection effects of T. evansi and EIAV in naturally infected horses in the southern Pantanal wetland by serological tests and hematological assays. Both higher seroprevalence and heath poor condition of the sampled animals were associated with differences in horse management between farms. We found that the negative animals for both infectious agents (NN) represented the major group in F1 (37%), and the smallest group in F2 (19%). Furthermore, we recorded higher EIAV seroprevalence (56%) in F2, compared to F1 (38%). We observed that T. evansi infection was mostly related to young horses, as seen by their higher seroprevalence, ranging from 70.7% in the beginning of the rainy season to 81% in the end of flood period, in comparison with the values of 42% and 68%, respectively, in working animals. on the other hand, working animals showed a higher seroprevalence for EIAV (48%) in both seasons than young horses. We observed that the management of working horses could be a risk factor of EIAV infection. On the other hand, as T. evansi is maintained in the study region by many species of wild mammals, the mechanical transmission through blood-sucking vectors ensures the infection to horses since early. Our results showed that single or co-infection by EIAV and T. evansi caused different degree of anemia in the infected animals. Moreover, the health of horses in Brazilian Pantanal is also influenced by differences in horse management and environmental circumstances.

Strategies and methodological basics for prevention of sexually transmitted infections in the high-risk subpopulations

A review article presents theoretical basics of the development of innovative STI prevention programs for high-risk groups Urgent need for integrated multidisciplinary preventive strategies aimed at correcting risky behaviors and adapted for the particular vulnerable populations is justified.

Within-host competitive interactions as a mechanism for the maintenance of parasite diversity

Variation among parasite strains can affect the progression of disease or the effectiveness of treatment. What maintains parasite diversity? Here I argue that competition among parasites within the host is a major cause of variation among parasites. The competitive environment within the host can vary depending on the parasite genotypes present. For example, parasite strategies that target specific competitors, such as bacteriocins, are dependent on the presence and susceptibility of those competitors for success. Accordingly, which parasite traits are favoured by within-host selection can vary from host to host. Given the fluctuating fitness landscape across hosts, genotype by genotype (G×G) interactions among parasites should be prevalent. Moreover, selection should vary in a frequency-dependent manner, as attacking genotypes select for resistance and genotypes producing public goods select for cheaters. I review competitive coexistence theory with regard to parasites and highlight a few key examples where within-host competition promotes diversity. Finally, I discuss how within-host competition affects host health and our ability to successfully treat infectious diseases.