Mouse transcriptome reveals potential signatures of protection and pathogenesis in human tuberculosis.

Although mouse infection models have been extensively used to study the host response to Mycobacterium tuberculosis, their validity in revealing determinants of human tuberculosis (TB) resistance and disease progression has been heavily debated. Here, we show that the modular transcriptional signature in the blood of susceptible mice infected with a clinical isolate of M. tuberculosis resembles that of active human TB disease, with dominance of a type I interferon response and neutrophil activation and recruitment, together with a loss in B lymphocyte, natural killer and T cell effector responses. In addition, resistant but not susceptible strains of mice show increased lung B cell, natural killer and T cell effector responses in the lung upon infection. Notably, the blood signature of active disease shared by mice and humans is also evident in latent TB progressors before diagnosis, suggesting that these responses both predict and contribute to the pathogenesis of progressive M. tuberculosis infection.

Author Correction: Progression of whole-blood transcriptional signatures from interferon-induced to neutrophil-associated patterns in severe influenza.

In the version of this article initially published, a source of funding was not included in the Acknowledgements section. That section should include the following: P.J.M.O. was supported by EU FP7 PREPARE project 602525. The error has been corrected in the HTML and PDF version of the article.

Progression of whole-blood transcriptional signatures from interferon-induced to neutrophil-associated patterns in severe influenza.

Transcriptional profiles and host-response biomarkers are used increasingly to investigate the severity, subtype and pathogenesis of disease. We now describe whole-blood mRNA signatures and concentrations of local and systemic immunological mediators in 131 adults hospitalized with influenza, from whom extensive clinical and investigational data were obtained by MOSAIC investigators. Signatures reflective of interferon-related antiviral pathways were common up to day 4 of symptoms in patients who did not require mechanical ventilator support; in those who needed mechanical ventilation, an inflammatory, activated-neutrophil and cell-stress or death ('bacterial') pattern was seen, even early in disease. Identifiable bacterial co-infection was not necessary for this 'bacterial' signature but was able to enhance its development while attenuating the early 'viral' signature. Our findings emphasize the importance of timing and severity in the interpretation of host responses to acute viral infection and identify specific patterns of immune-system activation that might enable the development of novel diagnostic and therapeutic tools for severe influenza.

Weight Gain and Metabolic Changes in Patients With First-Episode Psychosis or Early-Phase Schizophrenia Treated With Olanzapine: A Meta-Analysis.

BACKGROUND: Patients with first-episode psychosis or early-phase schizophrenia are susceptible to olanzapine-associated weight gain and cardiometabolic dysregulation. This meta-analysis characterized weight and metabolic effects observed during olanzapine treatment in randomized clinical trials in this vulnerable patient population. METHODS: PubMed, EMBASE, and Dialog were searched for randomized controlled trials (RCTs) reporting weight or cardiometabolic outcomes associated with olanzapine treatment in first-episode psychosis or early-phase schizophrenia. Random-effects meta-analysis and meta-regression were conducted using R v4.0.5. RESULTS: Of 1203 records identified, 26 RCTs informed the analyses. The meta-analytic mean (95% CI) weight gain was 7.53 (6.42-8.63) kg in studies (n = 19) that reported weight gain with olanzapine treatment. Stratified by duration, the mean (95% CI) weight gain was significantly higher in studies >13 weeks in duration than in those lasting ≤13 weeks: 11.35 (10.05-12.65) vs 5.51 (4.73-6.28) kg, respectively. Despite between-study variability, increases from baseline in most glycemic and lipid parameters were generally small in studies of both ≤13 and >13 weeks. There were no correlations, however, between weight gain and metabolic parameter changes when stratified by study duration. CONCLUSIONS: In RCTs enrolling patients with first-episode psychosis or early-phase schizophrenia, olanzapine was consistently associated with weight gain that was greater in studies lasting >13 weeks compared with those of ≤13 weeks. Metabolic changes observed across studies suggest that RCTs may underestimate metabolic sequelae vs real-world treatment observations. Patients with first-episode psychosis or early-phase schizophrenia are vulnerable to olanzapine-associated weight gain; strategies minimizing olanzapine-associated weight gain should be carefully considered.

Caretakers' stated willingness to pay for children's spectacles in cross river state, Nigeria and its implication for a cross-subsidisation scheme: a cross-sectional study.

BACKGROUND: Understanding caretakers' willingness to pay (WTP) for their children's spectacles is essential to improving the sustainability of refractive error services and spectacle provision. Therefore, we investigated the willingness of caretakers to pay for their children's spectacles in a multi-centre study to develop a spectacle cross-subsidisation scheme in the Cross River State (CRS), Nigeria. METHODS: We administered the questionnaire to all caretakers whose children were referred from school vision screenings to four eye centres for full refraction assessment and dispensing of corrective spectacles from 9 August to 31 October 2019. We collected information on socio-demography, children's refractive error types, and spectacle prescription and then asked the caretakers about their WTP for the spectacles using a structured questionnaire and bidding format (in the local currency, Naira, ₦). RESULTS: A total of 137 respondents (response rate = 100%) from four centres were interviewed: with greater proportion of women (n = 92, 67.1%), aged between 41 and 50 years (n = 59, 43.1%), government employees (n = 64, 46.7%) and had acquired college or university education (n = 77, 56.2%). Of the 137 spectacles dispensed to their children, 74 (54.0%) had myopia or myopic astigmatism (equal to or greater than 0.50D). The mean stated WTP for the sample population was ₦3,560 (US$ 8.9) (SD ± ₦1,913.4). Men (p = 0.039), those with higher education (p < 0.001), higher monthly incomes (p = 0.042), and government employees (p = 0.001) were more willing to pay ₦3,600 (US$9.0) or more. CONCLUSION: Combining our previous findings from marketing analysis, these findings provided a basis to plan for a children's spectacles cross-subsidisation scheme in CRS. Further research will be needed to determine the acceptability of the scheme and the actual WTP.

Olanzapine/samidorphan combination consistently mitigates weight gain across various subgroups of patients.

OBJECTIVE: A combination of olanzapine and the opioid receptor antagonist samidorphan (OLZ/SAM) has been approved in the United States for the treatment of adults with schizophrenia or adults with bipolar I disorder. In a phase 3 study in adults with schizophrenia (ENLIGHTEN-2), OLZ/SAM treatment was associated with significantly less weight gain compared with olanzapine. Prespecified subgroup analyses explored the consistency of the weight mitigation effect of OLZ/SAM vs olanzapine across demographic subgroups in ENLIGHTEN-2. METHODS: The multicenter, randomized, double-blind ENLIGHTEN-2 study (NCT02694328) included outpatients aged 18-55 years with a diagnosis of schizophrenia based on DSM-5 criteria, a body mass index (BMI) of 18 to 30 kg/m2, and stable body weight (self-reported change ≤5% for ≥3 months before study entry). Patients were randomized 1:1 to receive OLZ/SAM or olanzapine for 24 weeks. Co-primary endpoints (previously reported) were percent change in body weight and proportion of patients with at least 10% weight gain from baseline at week 24. Prespecified exploratory subgroup analyses by sex, age, self-reported race, and baseline BMI were conducted. RESULTS: At week 24, treatment with OLZ/SAM resulted in numerically less percent weight gain than with olanzapine across all subgroups evaluated. The proportion of patients with at least 10% weight gain was smaller in each subgroup treated with OLZ/SAM vs olanzapine. CONCLUSION: In these exploratory subgroup analyses from the ENLIGHTEN-2 study, weight-mitigating effects of OLZ/SAM vs olanzapine were observed consistently across patient subgroups and were in line with results from the overall study population.

Borrelia burgdorferi Sensu Stricto DNA in Field-Collected Haemaphysalis longicornis Ticks, Pennsylvania, United States.

We collected questing Haemaphysalis longicornis ticks from southeastern counties of Pennsylvania, USA. Of 263 ticks tested by PCR for pathogens, 1 adult female was positive for Borrelia burgdorferi sensu stricto, yielding a 0.4% infection rate. Continued monitoring of this invasive tick is essential to determine its public health role.

Long-term safety and durability of effect with a combination of olanzapine and samidorphan in patients with schizophrenia: results from a 1-year open-label extension study.

BACKGROUND: Combination olanzapine and samidorphan (OLZ/SAM), in development for schizophrenia and bipolar I disorder, is intended to provide the efficacy of olanzapine while mitigating olanzapine-associated weight gain. OLZ/SAM safety, tolerability, and efficacy from a 52-week open-label extension study in patients with schizophrenia are reported. METHODS: Patients previously completing the 4-week, double-blind ENLIGHTEN-1 study switched from OLZ/SAM, olanzapine, or placebo to OLZ/SAM. Assessments included adverse events (AEs), weight, vital signs, Positive and Negative Syndrome Scale (PANSS), and Clinical Global Impression-Severity (CGI-S) scores. Baseline was prior to first dose of OLZ/SAM in the extension study. RESULTS: In total, 281 patients enrolled, 277 received ≥1 OLZ/SAM dose, and 183 (66.1%) completed 52 weeks. Reasons for discontinuation included patient withdrawal (15.5%), loss to follow-up (6.9%), AEs (5.8%), and lack of efficacy (1.8%). AEs were reported in 136 (49.1%) patients; increased weight (13%) and somnolence (8%) were most common. Ten serious AEs were reported in eight patients (2.9%); none were considered treatment related. There were no deaths. Mean (SD) baseline weight was 79.1 (17.8) kg. Mean weight change from baseline to week 52 was 1.86 kg (2.79% increase). PANSS total and CGI-S scores continued to decline over 52 weeks (mean [95% CI] changes from baseline to week 52: -16.2 [-18.5, -14.0] and -0.9 [-1.0, -0.8], respectively). CONCLUSION: OLZ/SAM was generally well tolerated in this extension study; most patients completed the 52-week treatment period with sustained improvement in schizophrenia symptoms. Mean increases in weight stabilized by week 6 with limited subsequent change through end of treatment.

Complement pathway gene activation and rising circulating immune complexes characterize early disease in HIV-associated tuberculosis.

The transition between latent and active tuberculosis (TB) occurs before symptom onset. Better understanding of the early events in subclinical disease will facilitate the development of diagnostics and interventions that improve TB control. This is particularly relevant in the context of HIV-1 coinfection where progression of TB is more likely. In a recent study using [18F]-fluoro-2-deoxy-d-glucose positron emission/computed tomography (FDG-PET/CT) on 35 asymptomatic, HIV-1-infected adults, we identified 10 participants with radiographic evidence of subclinical disease, significantly more likely to progress than the 25 participants without. To gain insight into the biological events in early disease, we performed blood-based whole genome transcriptomic analysis on these participants and 15 active patients with TB. We found transcripts representing the classical complement pathway and Fcγ receptor 1 overabundant from subclinical stages of disease. Levels of circulating immune (antibody/antigen) complexes also increased in subclinical disease and were highly correlated with C1q transcript abundance. To validate our findings, we analyzed transcriptomic data from a publicly available dataset where samples were available in the 2 y before TB disease presentation. Transcripts representing the classical complement pathway and Fcγ receptor 1 were also differentially expressed in the 12 mo before disease presentation. Our results indicate that levels of antibody/antigen complexes increase early in disease, associated with increased gene expression of C1q and Fcγ receptors that bind them. Understanding the role this plays in disease progression may facilitate development of interventions that prevent this, leading to a more favorable outcome and may also be important to diagnostic development.

Ecology and Epidemiology of Tickborne Pathogens, Washington, USA, 2011-2016.

Tickborne diseases are rare in Washington, USA, and the ecology of these pathogens is poorly understood. We integrated surveillance data from humans and ticks to better describe their epidemiology and ecology. During 2011-2016, a total of 202 tickborne disease cases were reported in Washington residents. Of these, 68 (34%) were autochthonous, including cases of Lyme disease, Rocky Mountain spotted fever, tickborne relapsing fever, and tularemia. During May 2011-December 2016, we collected 977 host-seeking ticks, including Ixodes pacificus, I. angustus, I. spinipalpis, I. auritulus, Dermacentor andersoni, and D. variabilis ticks. The prevalence of Borrelia burgdorferi sensu stricto in I. pacificus ticks was 4.0%; of B. burgdorferi sensu lato, 3.8%; of B. miyamotoi, 4.4%; and of Anaplasma phagocytophilum, 1.9%. We did not detect Rickettsia rickettsii in either Dermacentor species. Case-patient histories and detection of pathogens in field-collected ticks indicate that several tickborne pathogens are endemic to Washington.

THE EFFECT OF ANESTHETIC TIME AND CONCENTRATION ON BLOOD GASES, ACID-BASE STATUS, AND ELECTROLYTES IN KOI (CYPRINUS CARPIO) ANESTHETIZED WITH BUFFERED TRICAINE METHANESULFONATE (MS-222).

Anesthesia is commonly employed in aquatic medicine to facilitate physical exams, diagnostics, and surgical interventions. Tricaine methanesulfonate (MS-222) is the most commonly used anesthetic for fish and is currently the only anesthetic approved by the US Food and Drug Administration Center for Veterinary Medicine for food-producing fish. Despite the frequency of anesthetic procedures in fish, anesthetic monitoring remains rudimentary in many facilities. This study evaluated the impact on blood gases, acid-base balance, and electrolytes in koi (Cyprinus carpio) anesthetized at concentrations of 100 mg/L and 150 mg/L MS-222. Blood samples from 25 fish per treatment were collected at 5 and 20 min of anesthetic immersion. Forty-nine of 50 fish recovered uneventfully from anesthesia; one fish did not recover and was euthanatized. Results showed significant increases in partial pressure of carbon dioxide (pCO2) (P = 0.006) and hyperglycemia (P = <0.0001) with increasing anesthetic concentration and time under anesthesia and a significant decrease in partial pressure of oxygen (pO2) with increased anesthetic time (P = 0.021). There were several electrolyte changes observed with both increasing anesthetic time and concentration. All electrolytes except potassium remained within published reference ranges for koi, while potassium showed a significant decrease in concentration associated with anesthetic time and concentration. The results of this study indicate that MS-222 at 100 mg/L and 150 mg/L represent safe anesthetic concentrations for koi undergoing minimally invasive diagnostics; however, koi anesthetized with MS-222 at a concentration of 150 mg/L experienced more significant changes in blood gases, acid-base balance, and electrolyte concentrations.

Differential Production of Type I IFN Determines the Reciprocal Levels of IL-10 and Proinflammatory Cytokines Produced by C57BL/6 and BALB/c Macrophages.

Pattern recognition receptors detect microbial products and induce cytokines, which shape the immunological response. IL-12, TNF-α, and IL-1ß are proinflammatory cytokines, which are essential for resistance against infection, but when produced at high levels they may contribute to immunopathology. In contrast, IL-10 is an immunosuppressive cytokine, which dampens proinflammatory responses, but it can also lead to defective pathogen clearance. The regulation of these cytokines is therefore central to the generation of an effective but balanced immune response. In this study, we show that macrophages derived from C57BL/6 mice produce low levels of IL-12, TNF-α, and IL-1ß, but high levels of IL-10, in response to TLR4 and TLR2 ligands LPS and Pam3CSK4, as well as Burkholderia pseudomallei, a Gram-negative bacterium that activates TLR2/4. In contrast, macrophages derived from BALB/c mice show a reciprocal pattern of cytokine production. Differential production of IL-10 in B. pseudomallei and LPS-stimulated C57BL/6 and BALB/c macrophages was due to a type I IFN and ERK1/2-dependent, but IL-27-independent, mechanism. Enhanced type I IFN expression in LPS-stimulated C57BL/6 macrophages was accompanied by increased STAT1 and IFN regulatory factor 3 activation. Furthermore, type I IFN contributed to differential IL-1ß and IL-12 production in B. pseudomallei and LPS-stimulated C57BL/6 and BALB/c macrophages via both IL-10-dependent and -independent mechanisms. These findings highlight key pathways responsible for the regulation of pro- and anti-inflammatory cytokines in macrophages and reveal how they may differ according to the genetic background of the host.

The Blood Transcriptome of Experimental Melioidosis Reflects Disease Severity and Shows Considerable Similarity with the Human Disease.

Melioidosis, a severe human disease caused by the bacterium Burkholderia pseudomallei, has a wide spectrum of clinical manifestations ranging from acute septicemia to chronic localized illness or latent infection. Murine models have been widely used to study the pathogenesis of infection and to evaluate novel therapies or vaccines, but how faithfully they recapitulate the biology of human melioidosis at a molecular level is not known. In this study, mice were intranasally infected with either high or low doses of B. pseudomallei to generate either acute, chronic, or latent infection and host blood and tissue transcriptional profiles were generated. Acute infection was accompanied by a homogeneous signature associated with induction of multiple innate immune response pathways, such as IL-10, TREM1, and IFN signaling, largely found in both blood and tissue. The transcriptional profile in blood reflected the heterogeneity of chronic infection and quantitatively reflected the severity of disease. Genes associated with fibrosis and tissue remodeling, including matrix metalloproteases and collagen, were upregulated in chronically infected mice with severe disease. Transcriptional signatures of both acute and chronic melioidosis revealed upregulation of iNOS in tissue, consistent with the expression of IFN-γ, but also Arginase-1, a functional antagonist of the iNOS pathway, and was confirmed by immunohistochemistry. Comparison of these mouse blood datasets by pathway and modular analysis with the blood transcriptional signature of patients with melioidosis showed that many genes were similarly perturbed, including Arginase-1, IL-10, TREM1, and IFN signaling, revealing the common immune response occurring in both mice and humans.

Detecting Burrowing Owl Bloodmeals in Pulex irritans (Siphonaptera: Pulicidae).

Pulex irritans L. is a cosmopolitan flea species that infests a wide variety of hosts. In North America it generally parasitizes large wild mammals, but in the Pacific Northwest an association has emerged between P. irritans and the western burrowing owl (Athene cunicularia hypugaea). While investigators have recognized this association for decades, it has not been clear if P. irritans feeds on burrowing owls, or if the owls serve exclusively as phoretic hosts. Here we describe using a real-time assay that was originally developed to identify bloodmeals in Ugandan cat fleas (Ctenocephalides felis Bouché) to detect burrowing owl DNA in P. irritans collected from burrowing owls in southern Idaho. Of 50 fleas tested, 12 had no detectable vertebrate bloodmeal. The remaining 38 (76%) contained burrowing owl DNA. The assay did not detect vertebrate DNA in unfed fleas exposed to owl or mouse pelts and is therefore unlikely to detect DNA in fleas from vertebrates that have served exclusively as phoretic hosts. We conclude that P. irritans feeds on burrowing owls. We discuss the potential implications of this finding for burrowing owl conservation and enzootic plague dynamics.

Molecular Survey of Bartonella Species and Yersinia pestis in Rodent Fleas (Siphonaptera) From Chihuahua, Mexico.

Rodent fleas from northwestern Chihuahua, Mexico, were analyzed for the presence of Bartonella and Yersinia pestis. In total, 760 fleas belonging to 10 species were tested with multiplex polymerase chain reaction analysis targeting the gltA (338-bp) and pla genes (478-bp) of Bartonella and Y. pestis, respectively. Although none was positive for Y. pestis, 307 fleas were infected with Bartonella spp., resulting in an overall prevalence of 40.4%. A logistic regression analysis indicated that the presence of Bartonella is more likely to occur in some flea species. From a subset of Bartonella-positive fleas, phylogenetic analyses of gltA gene sequences revealed 13 genetic variants clustering in five phylogroups (I­V), two of which were matched with known pathogenic Bartonella species (Bartonella vinsonii subsp. arupensis and Bartonella washoensis) and two that were not related with any previously described species or subspecies of Bartonella. Variants in phylogroup V, which were mainly obtained from Meringis spp. fleas, were identical to those reported recently in their specific rodent hosts (Dipodomys spp.) in the same region, suggesting that kangaroo rats and their fleas harbor other Bartonella species not reported previously. Considering the Bartonella prevalence and the flea genotypes associated with known pathogenic Bartonella species, we suggest that analysis of rodent and flea communities in the region should continue for their potential implications for human health. Given that nearby locations in the United States have reported Y. pestis in wild animals and their fleas, we suggest conducting larger-scale studies to increase our knowledge of this bacterium.

An interferon-inducible neutrophil-driven blood transcriptional signature in human tuberculosis.

Tuberculosis (TB), caused by infection with Mycobacterium tuberculosis, is a major cause of morbidity and mortality worldwide. Efforts to control it are hampered by difficulties with diagnosis, prevention and treatment. Most people infected with M. tuberculosis remain asymptomatic, termed latent TB, with a 10% lifetime risk of developing active TB disease. Current tests, however, cannot identify which individuals will develop disease. The immune response to M. tuberculosis is complex and incompletely characterized, hindering development of new diagnostics, therapies and vaccines. Here we identify a whole-blood 393 transcript signature for active TB in intermediate and high-burden settings, correlating with radiological extent of disease and reverting to that of healthy controls after treatment. A subset of patients with latent TB had signatures similar to those in patients with active TB. We also identify a specific 86-transcript signature that discriminates active TB from other inflammatory and infectious diseases. Modular and pathway analysis revealed that the TB signature was dominated by a neutrophil-driven interferon (IFN)-inducible gene profile, consisting of both IFN-gamma and type I IFN-alphabeta signalling. Comparison with transcriptional signatures in purified cells and flow cytometric analysis suggest that this TB signature reflects changes in cellular composition and altered gene expression. Although an IFN-inducible signature was also observed in whole blood of patients with systemic lupus erythematosus (SLE), their complete modular signature differed from TB, with increased abundance of plasma cell transcripts. Our studies demonstrate a hitherto underappreciated role of type I IFN-alphabeta signalling in the pathogenesis of TB, which has implications for vaccine and therapeutic development. Our study also provides a broad range of transcriptional biomarkers with potential as diagnostic and prognostic tools to combat the TB epidemic.

TPL-2-ERK1/2 signaling promotes host resistance against intracellular bacterial infection by negative regulation of type I IFN production.

Tuberculosis, caused by Mycobacterium tuberculosis, remains a leading cause of mortality and morbidity worldwide, causing ≈ 1.4 million deaths per year. Key immune components for host protection during tuberculosis include the cytokines IL-12, IL-1, and TNF-α, as well as IFN-γ and CD4(+) Th1 cells. However, immune factors determining whether individuals control infection or progress to active tuberculosis are incompletely understood. Excess amounts of type I IFN have been linked to exacerbated disease during tuberculosis in mouse models and to active disease in patients, suggesting tight regulation of this family of cytokines is critical to host resistance. In addition, the immunosuppressive cytokine IL-10 is known to inhibit the immune response to M. tuberculosis in murine models through the negative regulation of key proinflammatory cytokines and the subsequent Th1 response. We show in this study, using a combination of transcriptomic analysis, genetics, and pharmacological inhibitors, that the TPL-2-ERK1/2 signaling pathway is important in mediating host resistance to tuberculosis through negative regulation of type I IFN production. The TPL-2-ERK1/2 signaling pathway regulated production by macrophages of several cytokines important in the immune response to M. tuberculosis as well as regulating induction of a large number of additional genes, many in a type I IFN-dependent manner. In the absence of TPL-2 in vivo, excess type I IFN promoted IL-10 production and exacerbated disease. These findings describe an important regulatory mechanism for controlling tuberculosis and reveal mechanisms by which type I IFN may promote susceptibility to this important disease.

Yersinia murine toxin is not required for early-phase transmission of Yersinia pestis by Oropsylla montana (Siphonaptera: Ceratophyllidae) or Xenopsylla cheopis (Siphonaptera: Pulicidae).

Plague, caused by Yersinia pestis, is characterized by quiescent periods punctuated by rapidly spreading epizootics. The classical 'blocked flea' paradigm, by which a blockage forms in the flea's proventriculus on average 1-2 weeks post-infection (p.i.), forces starving fleas to take multiple blood meals, thus increasing opportunities for transmission. Recently, the importance of early-phase transmission (EPT), which occurs prior to blockage formation, has been emphasized during epizootics. Whilst the physiological and molecular mechanisms of blocked flea transmission are well characterized, the pathogen-vector interactions have not been elucidated for EPT. Within the blocked flea model, Yersinia murine toxin (Ymt) has been shown to be important for facilitating colonization of the midgut within the flea. One proposed mechanism of EPT is the regurgitation of infectious material from the flea midgut during feeding. Such a mechanism would require bacteria to colonize and survive for at least brief periods in the midgut, a process that is mediated by Ymt. Two key bridging vectors of Y. pestis to humans, Oropsylla montana (Siphonaptera: Ceratophyllidae) or Xenopsylla cheopis (Siphonaptera: Pulicidae), were used in our study to test this hypothesis. Fleas were infected with a mutant strain of Y. pestis containing a non-functional ymt that was shown previously to be incapable of colonizing the midgut and were then allowed to feed on SKH-1 mice 3 days p.i. Our results show that Ymt was not required for EPT by either flea species.

Evaluation of the effect of host immune status on short-term Yersinia pestis infection in fleas with implications for the enzootic host model for maintenance of Y. pestis during interepizootic periods.

Plague, a primarily flea-borne disease caused by Yersinia pestis, is characterized by rapidly spreading epizootics separated by periods of quiescence. Little is known about how and where Y. pestis persists between epizootics. It is commonly proposed, however, that Y pestis is maintained during interepizootic periods in enzootic cycles involving flea vectors and relatively resistant host populations. According to this model, while susceptible individuals serve as infectious sources for feeding fleas and subsequently die of infection, resistant hosts survive infection, develop antibodies to the plague bacterium, and continue to provide bloodmeals to infected fleas. For Y. pestis to persist under this scenario, fleas must remain infected after feeding on hosts carrying antibodies to Y. pestis. Studies of other vector-borne pathogens suggest that host immunity may negatively impact pathogen survival in the vector. Here, we report infection rates and bacterial loads for fleas (both Xenopsylla cheopis (Rothschild) and Oropsylla montana (Baker)) that consumed an infectious bloodmeal and subsequently fed on an immunized or age-matched naive mouse. We demonstrate that neither the proportion of infected fleas nor the bacterial loads in infected fleas were significantly lower within 3 d of feeding on immunized versus naive mice. Our findings thus provide support for one assumption underlying the enzootic host model of interepizootic maintenance of Y. pestis.

Needs and views on eye health and women's empowerment and theory of change map: implication on the development of a women-targeted eyecare programme for older Zanzibari craftswomen.

OBJECTIVES: To assess needs and views regarding eye health and empowerment from craftswomen's perspectives to develop a theory of change (ToC) for a women-targeted eyecare programme. MATERIAL AND METHODS: Eighteen stakeholders participated in a 2-day consultation workshop in Zanzibar. The composition was (1) 15 women and 3 men; (2) Unguja (n=8), Pemba (n=6) and Tanzania mainland (n=4) and (3) craftswomen (n=14) and governmental stakeholders (n=4). Thematic analysis determined the craftswomen's needs and views regarding eye health and empowerment and subsequently inputs, activities, outputs, outcomes and impact to develop the programme's initial ToC. In refining the initial ToC, we used insights from a qualitative study suggesting that improved near vision is perceived by craftswomen as a potential source of empowerment across economic, psychological, social, political and educational dimensions. RESULTS: The eye conditions experienced by the craftswomen were eye irritation caused by foreign bodies, the need for near spectacles and other eye morbidities. They were advised by the cooperatives to visit eye health centres for treatment. The main barriers to accessing services were inaccessibility and unaffordability of eye services and a lack of eye health knowledge and practices. Nineteen subthemes on women empowerment (economic n=4, social n=4, psychological n=6, education n=2 and political n=3) were obtained. We created a ToC on how investing in improving craftswomen near vision could achieve empowerment. CONCLUSION: The participants provided insights into their needs and how they would like the eyecare programme to be implemented and how they see they could be empowered in the process.