Infection Research Articles

Recombinant Ixodes scapularis Calreticulin Binds Complement Proteins but Does Not Protect Borrelia burgdorferi from Complement Killing.

Ixodes scapularis is a blood-feeding obligate ectoparasite responsible for transmitting the Lyme disease (LD) agent, Borrelia burgdorferi. During the feeding process, I. scapularis injects B. burgdorferi into the host along with its saliva, facilitating the transmission and colonization of the LD agent. Tick calreticulin (CRT) is one of the earliest tick saliva proteins identified and is currently utilized as a biomarker for tick bites. Our recent findings revealed elevated levels of CRT in the saliva proteome of B. burgdorferi-infected I. scapularis nymphs compared to uninfected ticks. Differential precipitation of proteins (DiffPOP) and LC-MS/MS analyses were used to identify the interactions between Ixs (I. scapularis) CRT and human plasma proteins and further explore its potential role in shielding B. burgdorferi from complement killing. We observed that although yeast-expressed recombinant (r) IxsCRT binds to the C1 complex (C1q, C1r, and C1s), the activator of complement via the classical cascade, it did not inhibit the deposition of the membrane attack complex (MAC) via the classical pathway. Intriguingly, rIxsCRT binds intermediate complement proteins (C3, C5, and C9) and reduces MAC deposition through the lectin pathway. Despite the inhibition of MAC deposition in the lectin pathway, rIxsCRT did not protect a serum-sensitive B. burgdorferi strain (B314/pBBE22Luc) from complement-induced killing. As B. burgdorferi establishes a local dermal infection before disseminating to secondary organs, it is noteworthy that rIxsCRT promotes the replication of B. burgdorferi in culture. We hypothesize that rIxsCRT may contribute to the transmission and/or host colonization of B. burgdorferi by acting as a decoy activator of complement and by fostering B. burgdorferi replication at the transmission site.

Laser Hemorrhoidoplasty vs Conventional Milligan-Morgan Hemorrhoidectomy for Treatment of Third and Fourth Degree Hemorrhoids: A Prospective Comparative Study

Abstract Background Hemorrhoids are the most common disease of anal canal affecting a large number of people at least once during their lifetime and can interfere with their daily functioning. Surgical treatment is the best available option for symptomatic hemorrhoid cases, which are refractory to medical treatment. In spite of many modifications made to the hemorrhoid surgical techniques, postoperative pain and discomfort remain the major concern for patients, which is why they often refuse to undergo surgical treatment. Laser ablation has opened new possibilities for the minimally invasive treatment of hemorrhoids. Objective To compare the outcomes between laser hemorrhoidoplasty and the conventional Milligan-Morgan hemorrhoidectomy for treatment of third and fourth degree haemorrhoids especially postoperative pain, bleeding, and recurrence. Patients and Methods Recent studies have proven that laser ablation was much better regarding postoperative pain and hemorrhage in the various degrees of hemorrhoids. Our study also confirmed that laser ablation technique has shorter operative time, less severe postoperative pain, bleeding and comparable regression of hemorrhoid columns. Studies with longer follow-up period (around 2 years) have also reported effectiveness of laser for the treatment of hemorrhoids which was confirmed in our study over 6 months. Results Although some studies showed that wound inflammation or hemorrhoid thrombosis could be a problem however our study showed no postoperative local infection in the group treated with laser ablation and only two patients were presented with thrombosis of external hemorrhoid 7–10 days after the surgery, which was resolved with medical treatment. Conclusion Laser hemorroidoplasty has better outcomes than the traditional surgical resection of hemorrhoid disease for the control of grade III and IV symptomatic refractory hemorrhoids specially regarding post-operative pain and bleeding which are the main concerns for most patients.

Seasonal Dynamics of Symptomatic and Asymptomatic Plasmodium falciparum and Plasmodium vivax Infections in Coendemic Low-Transmission Settings, South Ethiopia.

Ethiopia has a plan to eliminate malaria in selected low-transmission districts by 2025. However, complex factors such as seasonality, focal heterogeneity, and coendemicity of Plasmodium vivax and Plasmodium falciparum, and asymptomatic cases, along with other factors, pose challenges. This longitudinal study assessed these dynamics and associated factors in three elimination-targeted settings in southern Ethiopia. The study included rural districts (Wonago and Yirgacheffe) and an urban setting (Dilla town) with 504 participants from 168 households per season. The study covered the peak and minor malaria transmission seasons and the dry season. Finger-prick blood was collected for microscopy, rapid diagnostic tests, and 18S-rRNA-based quantitative polymerase chain reaction (qPCR). During the dry season, P. vivax accounted for most infections (64.5%, 71/110) and symptomatic malaria (50.9%, 29/57), whereas P. falciparum dominated during the peak transmission season (45.7%, 42/92 infections and 58.1%, 25/43 of symptomatic cases). Treatment-seeking behavior was low, with 65.3% (143/219) of symptomatic individuals not seeking treatment. Dilla town had significantly higher infection prevalence (29.6%, 149/504, P <0.001) in all seasons compared with the rural sites. The incidence rate was 12/1,000 person-seasons by qPCR and 5/1,000 person-seasons by microscopy. Urban residents, those with low hemoglobin levels, nonuse of mosquito nets, and proximity to stagnant water had a significantly higher risk of infection (P <0.001). Tailored approaches are needed in elimination-targeted areas, focusing on urban settings, Plasmodium species, and strengthening community-level interventions for behavioral change and active case detection.

Reduced risk for Omicron SARS-CoV-2 infection observed in older adults with hybrid immunity.

Hybrid SARS-CoV-2 immunity may provide longer duration protection against severe SARS-CoV-2 infection and hospitalisation than purely vaccine-derived immunity. Older adults represent a high-risk group for severe disease, yet available data is skewed towards younger adults. A prospective longitudinal study at a large London long-term care facility (LTCF) was conducted from March 2020 to April 2022 to assess the effect of hybrid versus vaccine-only immunity on SARS-CoV-2 infection in older adults during Omicron variant dominance. Hybrid immunity was assessed by a combination of SARS-CoV-2 polymerase chain reaction testing weekly (asymptomatic screening) and as required (symptomatic testing), as well as serial SARS-CoV-2 serology. 280 participants (median age 82yrs, IQR 76-88yrs; 95.4% male) were followed up. 168/280 (60%) had evidence of hybrid immunity prior to the Omicron variant wave. Participants with hybrid immunity had substantially lower odds of acquiring COVID-19 infection during the Omicron wave compared to those with vaccine-only immunity (unadjusted odds ratio 0.26, 95% CI 0.14-0.47, chi-squared P < .0001). Participants with hybrid immunity had an odds ratio of 0.40 (0.19-0.79) for asymptomatic infection and 0.15 (0.06-0.34) for symptomatic infection (Likelihood ratio test, P < .0001). Our data highlight potential opportunities to target ongoing booster vaccination campaigns for those most at risk of severe infection. Reporting of data in older adults will be of particular value to examine the effect of hybrid immunity as new variants continue to emerge and vaccination strategies evolve.

Treating Infected Non-Healing Venous Leg Ulcers with Medical-Grade Honey: A Prospective Case Series.

Venous leg ulcers (VLUs) are hard-to-heal wounds and are prone to microbial colonization. Innovative and improved therapies are thus required to resolve local infection and enhance the wound healing process. The objective of this study was to evaluate the effectiveness of medical-grade honey (MGH) for the treatment of clinically infected and non-healing VLUs. This prospective case series included nine patients with an average age of 83.4 years (range: 75-91 years) with a total of eleven VLUs, previously ineffectively treated with various products. Major risk factors for the appearance of VLUs were chronic venous insufficiency, advanced age, multiple comorbidities (particularly cardiovascular diseases), and impaired mobility. All wounds presented with local signs of infection. Upon presentation, treatment was commenced with a range of MGH-based products (L-Mesitran®). Clinical signs of infection were eliminated by MGH after 2.2 weeks on average (range: 1-4 weeks), and wounds were completely healed after 7 weeks on average (range: 3-18 weeks). No further complications or recurrences were observed. MGH has a broad-spectrum antimicrobial activity and promotes rapid healing, thus improving patients' quality of life. Moreover, MGH-based products are safe, easy to use, cost-effective, and can effectively treat VLUs alone or in combination with standard-of-care therapies.

Serum levels of IL-6 and IL-10 on admission correlate with complications in elderly patients with hip fracture

ObjectivesAgeing may cause a progressive pro-inflammatory environment and alter functionality of different immune-cell populations. The aim of the present study is to examine the influence of certain serum immunological parameters on hospitalization stay and complications in patients who have suffered a hip fracture. Patients and methodsA prospective study was carried out with 87 patients (63 women) presenting with either trochanteric femoral fracture or Garden IV displaced subcapital fracture. The average age was 84.43 ± 9, ranging from 65 to 104 years old. Data regarding different comorbidities were recorded at the time of arrival. The morning after patient's admission peripheral blood samples were obtained and a series of immunological parameters were determined: leukocyte formula, platelets count, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), IL-6 and IL-10 levels, T-lymphocytes count, number of cells/mm3 and percentages of CD3, CD4, CD8, CD3-/CD16/56+ (NK cells), and CD3-/CD19+ (B cells). ResultsIL-6 serum levels presented a positive and significant correlation with higher levels of CRP (p < 0.001), IL-10 (p = 0.002), and higher percentages of NK CD56+ cells (p = 0.046). IL-6 serum levels at hospitalization presented a positive and significant correlation with a longer hospitalization stay (p = 0.037). Hospitalization increased by 0.231 days for every 1 pg/mL above the IL-6 mean value (40.43 pg/mL). Lower serum IL-10 levels on admission were associated with the appearance of symptomatic urinary tract infection during hospitalization (p = 0.032). Higher number of CD19+ cells/mm3 presented a significant relationship with pneumonia (p = 0.018) and symptomatic urinary tract infection (p = 0.0019). ConclusionsIL-6 serum levels on admission showed a positive and significant correlation with a longer hospitalization stay in elderly patients presenting with hip fracture. Lower levels of IL-10 in peripheral blood on admission were associated with symptomatic urinary tract infections. A higher number of CD19+ cells/mm³ was significantly associated with pneumonia and symptomatic urinary tract infection. These immunological variables on admission may serve as risk indicators of complications during hospitalization.

Long- and short-term outcomes after transvenous lead extraction in a large single-centre patient cohort using the clinical frailty scale as a risk assessment tool

Background and aimsThe rate of cardiac implantable electronic device (CIED) implantations and the need for transvenous lead extraction (TLE) are growing worldwide. This study examined a large Swedish cohort with the aim of identifying possible predictors of post-TLE mortality with special focus on systemic infection patients and frailty. MethodsThis was a single centre study. Records of patients undergoing TLE between 2010 and 2018 were analysed. Statistical analyses were conducted to compare baseline characteristics of patients with different indications and identify risk factors of 30-day and 1-year mortality. ResultsA total of 893 patients were identified. Local infection was the dominant indication and pacemaker was the most common CIED. The mean age was 65 ± 16 years, 73 % were male and median follow-up was 3.9 years. Heart failure was the most common comorbidity. Patients with systemic infection were significantly older, frailer and had significantly higher levels of comorbidities. 30-day mortality and 1-year mortality rates were 2.5 % and 9.9 %, respectively. Systemic infection and chronic kidney disease (CKD) were independently associated with 30-day and 1-year mortality. Clinical frailty scale (CFS) 5–7 correlated independently with 1-year mortality in the entire cohort and specifically in systemic infection patients. CKD, cardiac resynchronization therapy and CFS 5–7 were significant risk factors for long-term mortality (death >1 year after TLE) in multivariable analysis. ConclusionsSystemic infection, kidney failure in addition to the novel parameter of frailty were associated with post-TLE all-cause mortality. These risk factors should be considered during pre-procedure risk stratification to improve post-TLE outcomes.

Establishment of a multisite umbrella cohort study protocol to describe the epidemiology and aetiologies of acute undifferentiated febrile illness in Latin America

IntroductionAcute undifferentiated febrile illnesses (AUFIs) impose a large burden in the tropics. Understanding of AUFI’s epidemiology is limited. Insufficient diagnostic capacity hinders the detection of outbreaks. The lack of interconnection...

Development and validation of a machine learning-based interpretable model for predicting sepsis by complete blood cell parameters

BackgroundSepsis, a severe infectious disease, carries a high mortality rate. Early detection and prompt treatment are crucial for reducing mortality and improving prognosis. The aim of this research is to develop a clinical prediction model using machine learning algorithms, leveraging complete blood cell (CBC) parameters, to detect sepsis at an early stage. MethodsThe study involved 572 patients admitted to West China Hospital of Sichuan University between July 2020 and September 2021. Among them, 215 were diagnosed with sepsis, while 357 had local infections. Demographic information was collected, and 57 CBC parameters were analyzed to identify potential predictors using techniques such as the Least Absolute Shrinkage and Selection Operator (LASSO), Random Forest (RF), Support Vector Machine (SVM), and eXtreme Gradient Boosting (XGBoost). The prediction model was built using Logistic Regression and evaluated for diagnostic specificity, discrimination, and clinical applicability including metrics such as the area under the curve (AUC), calibration curve, clinical impact curve, and clinical decision curve. Additionally, the model's diagnostic performance was assessed on a separate validation cohort. Shapley's additive explanations (SHAP), and breakdown (BD) profiles were used to explain the contribution of each variable in predicting the outcome. ResultsAmong all the machine learning methods' prediction models, the LASSO-based model (λ = min) demonstrated the highest diagnostic performance in both the discovery cohort (AUC = 0.9446, P < 0.001) and the validation cohort (AUC = 0.9001, P < 0.001). Furthermore, upon local analysis and interpretation of the model, we demonstrated that LY-Z, MO-Z, and PLT-I had the most significant impact on the outcome. ConclusionsThe predictive model based on CBC parameters can be utilized as an effective approach for the early detection of sepsis.

Hypophosphataemia and late-onset sepsis in extremely preterm neonates: A case-control study.

Late-onset sepsis (LOS) is common in extreme prematurity. These infants are at risk of refeeding syndrome-associated hypophosphataemia. Our objective was to investigate whether hypophosphataemia predisposes to LOS in extremely premature neonates. A retrospective case-control study of neonates born before 29 weeks' gestation in an Australian NICU from 2016 to 2020. Cases developed LOS or localised infection. Two controls, matched within 2 gestational weeks and 90 calendar days, were selected per case. Amongst 48 cases and 93 controls, cases were smaller at birth (767 g vs. 901 g, P = 0.01), but were otherwise comparable. Hypophosphataemia was more common in cases (26% vs. 15%, P = 0.18). Increased intravenous protein intake in the first week was protective against LOS (OR = 0.9, 95% CI 0.76-1.00, P = 0.04); median 2.1 g/kg/day in cases, 2.3 g/kg/day in controls. Hypophosphataemia as part of refeeding syndrome is prevalent and under-recognised in extremely premature neonates. We did not find an association between hypophosphataemia and LOS. Low intravenous protein may be an independent risk factor for infection.

The significance of stone culture in the incidence of sepsis. Results from a prospective, multicenter study on Infections post Flexible UreteroreNescopy (I-FUN) and laser lithotripsy for renal stones.

Objective Sepsis is the most serious complication of flexible ureteroscopy (F-URS) and laser lithotripsy. We assessed the influence of positive stone culture (SC) on major infectious complications (sepsis, septic shock). Methods This prospective study enrolled adult patients deemed suitable for F-URS and laser lithotripsy from 9 centers (January 2022-August 2023). Inclusion criteria: kidney stone(s); preoperative mid-stream urine culture (MSU); stone(s) assessed at CT scan; SC. Exclusion criteria: bilateral procedures; ureteral stones; children. Group 1: patients with sterile SC. Group 2: patients with positive SC. Data are presented as median (interquartile range). A multivariable logistic regression analysis was performed to evaluate factors associated with having a positive SC. Results 293 were included. Median age was 51.0 (24) years. There were 167 (57.0%) males. Group 2 included 32 (2.5%) patients. Group 2 patients were significantly older [75.0 (14) vs 51.0 (23) years, p=0.02]. Stone features were similar. Major infectious complications were higher in Group 2 (15.6% vs 0.4%). One patient died due to sepsis in Group 2. 2/6 (33.3%) of patients with major infectious complications had the same pathogen in MSUC and SC. At multivariable regression analysis, diabetes (OR 3.23), symptomatic urinary infections within 3 months before surgery (OR 4.82), and preoperative stent/nephrostomy (OR 2.92) were factors significantly associated with higher odds of positive SC. Conclusions Patients with positive SC have a higher incidence of major infectious complications following F-URS lithotripsy. SC should be performed whenever feasible being a poor pathogen correlation between MSUC and SC.

Protect peripheral intravenous catheters: a study protocol for a randomised controlled trial of a novel antimicrobial dressing for peripheral intravenous catheters (ProP trial)

IntroductionPeripheral intravenous catheters (PIVCs) are the most commonly used vascular access device in hospitalised patients. Yet PIVCs may be complicated by local or systemic infections leading to increased healthcare costs....

Tracheostomy Complications Over 5 Years: Decannulation Analysis.

Tracheostomy is a life-saving surgical intervention commonly performed in patients requiring prolonged mechanical ventilation. However, the decannulation process is associated with various complications that can affect patient outcomes. This study aimed to assess complications and their management during decannulation in a cohort of tracheostomy patients at a tertiary care hospital, considering the complexities introduced by prior intubation. A retrospective cohort study was conducted involving 450 patients who underwent tracheostomy during a stipulated timeframe. Data regarding demographic characteristics, complications, and management strategies during decannulation were analysed. Special attention was given to distinguishing between complications directly related to the tracheostomy procedure and those potentially influenced by previous intubation. Out of the 450 patients, 250 experienced minor complications such as localized bleeding, oxygen desaturation, and minor infections. Another 40 faced major complications including severe haemorrhage, tracheal damage, and stenosis. Increasing age and tracheostomy duration were identified as significant predictors of complications. Pharmacological treatments, surgical interventions, and respiratory therapy were among the management strategies employed. The differentiation between complications arising from tracheostomy and prior intubation highlighted the need for comprehensive patient evaluation. Complications associated with decannulation occur frequently with varying severity. Efficient recognition and management of these complications are vital for improving patient outcomes. The study provides important insights into the challenges experienced during the decannulation process and highlights the necessity of considering prior intubation history in the management of tracheostomy decannulation to refine patient care protocols.

Specific anti-SVCV antibodies in hybrids of common carp (Cyprinus carpio) and gibel carp (Carassius gibelio) reflect heterosis advantage and genetic breakdown

Spring viraemia of carp virus (SVCV) is a disease with a serious economic impact on the farming of cyprinid fish. High susceptibility to SVCV has been documented mostly in common carp (Cyprinus carpio), whilst gibel carp (Carassius gibelio) is a weakly susceptible species. Specific anti-SVCV antibodies were analyzed in pure lines of common carp and gibel carp, and various generations of F1 and post-F1 hybrids. Specifically, we focused on anti-SVCV antibodies in weakly susceptible F1 hybrids and highly infected backcross and F2 hybrids, hypothesizing that the level of anti-SVCV antibodies will reflect heterosis advantage in F1 generations and hybrid breakdown in post-F1 generations.Backcross generations with common carp exhibited the most frequently symptomatic infections, followed by pure common carp. The high capacity of susceptible common carp to produce anti-SVCV antibodies was reported, whilst gibel carp expressed almost undetectable levels of anti-SVCV antibodies. We found the very good capacity of F1 hybrids to produce anti-SVCV antibodies, suggesting heterosis advantage. In contrast, we revealed different patterns of anti-SVCV antibodies production between maternal backcrosses (having parents with the same mtDNA – here, gibel carp) and paternal backcrosses (having parents with different mtDNA, i.e., resulting from reciprocal crosses of F1 hybrids with gibel carp mtDNA and pure common carp). Whilst both maternal backcross generations and the F2 generation of hybrids tended to produce low anti-SVCV antibodies, both paternal backcross generations expressed levels of anti SVCV-antibodies similar to those of highly susceptible common carp. The low capacity to produce anti-SVCV antibodies in F2 hybrids may be interpreted as a potential consequence of genetic disruption. However, the different capacity to induce an adaptive response in paternal hybrids and maternal hybrids (with mtDNA C. gibelio) may be interpreted as potential compensation for the cyto-nuclear breakdown hypothesized for paternal hybrids when coping with viral infection. Alternatively, the genetic background of hybrid fish, i.e. a combination of the genes of highly susceptible common carp and of less susceptible gibel carp in the hybrid genome may be responsible for this pattern.

Antibody Response to Symptomatic Infection With SARS-CoV-2 Omicron Variant Viruses, December 2021-June 2022.

We describe humoral immune responses in 105 ambulatory patients with laboratory-confirmed SARS-CoV-2 Omicron variant infection. In dried blood spot (DBS) collected within 5 days of illness onset and during convalescence, we measured binding antibody (bAb) against ancestral spike protein receptor binding domain (RBD) and nucleocapsid (N) protein using a commercial multiplex bead assay. Geometric mean bAb concentrations against RBD increased by a factor of 2.5 from 1258 to 3189 units/mL and by a factor of 47 against N protein from 5.5 to 259 units/mL between acute illness and convalescence; lower concentrations were associated with greater geometric mean ratios. Paired DBS specimens may be used to evaluate humoral response to SARS-CoV-2 infection.

Selective enzymatic debridement and modified Meek technique in the treatment of extensive burns: Preliminary observations.

Selective bromelain-based enzymatic debridement (BED) has emerged as a valid alternative for the treatment of extensive burns, with Total Body Surface Area (TBSA) > 20%. Autologous skin grafting represents the procedure of choice but the scarcity of donor sites remains the main reconstructive challenge. The modified Meek micro-grafting technique may represent a valid strategy to optimize the final outcome. A single-cohort retrospective analysis was performed, involving nine burn patients (TBSA > 20%) who underwent both BED and subsequently modified Meek technique. Demographic and clinical data (mechanism of injury, surgical treatment, complications, necessity of re-grafting, further surgery and esthetic outcome) were collected. All patients had large burns of mixed and deep dermal thickness (first, second, and third degree). All burns were enzymatically debrided postadmission and covered by the modified Meek technique. Local infection due to poor general conditions was the main complication for all patients. All but two patients survived. The selectiveness of the enzymatic debridement and dermal preservation seemed to improve the quality of scars resulting from micro-grafting. Evaluations performed at 12 ± 2 months postburn showed superior scar quality compared to areas treated with traditional (sheet/mesh) grafts. Combined BED and Meek techniques may provide an effective synergic combination for the treatment of extensive burns.

Comparison of Severity in Diabetic Ulcer Patients with and Without Sepsis

Diabetes mellitus patients in Central Java grow yearly. According to data provided by the Central Java Health Department in 2019, Diabetes mellitus ranks second as the largest non-communicable disease (NCD), covering 13,4% of the total NCD patients. The prevalence of diabetic ulcers is 15-25% of all diabetes mellitus patients in Indonesia, which concerns the author regarding the possible increase of the diabetic ulcer population in Central Java. The severity of diabetic ulcers depends on various factors, including infection and complications. The most common complication is sepsis, a systemic infection often arising from local infections that are not appropriately treated, causing progressive damage and increasing mortality rates. This study aims to examine the comparison of ulcer severity in diabetic ulcer patients with sepsis and non-sepsis complications using Meggitt Wagner's criteria. This study utilizes an analytic observational study using a cross-sectional approach. The author sampled 126 patients diagnosed with Diabetic Ulcers in 2022 at Dr. Moewardi General Hospital for this study, using a purposive sampling method. The research was conducted by looking at the patient's medical record data, and data analysis using SPSS software. The test used in this research includes a Parametric T-independent test and a Pearson bivariate relationship test. This study shows that the comparison of ulcer severity in diabetic ulcer patients with sepsis and without sepsis was statistically significant (p-value = 0.000002). The mean of the group with sepsis (3.4127) was greater than the group without sepsis (2.5238). In conclusion, the comparison of ulcer severity in diabetic ulcer patients with sepsis and without sepsis is significant. We recommend future researchers include patients’ comorbidities, total hospitalization time, and detailed information on drug use and patient adherence to treatment in their research for more nuanced findings.

Serotype-Specific Epidemiological Patterns of Inapparent versus Symptomatic Primary Dengue Virus Infections: A 17-year cohort study in Nicaragua.

Dengue is the most prevalent mosquito-borne viral disease and a major public health problem worldwide. Most primary infections with the four dengue virus serotypes (DENV1-4) are inapparent; nonetheless, whether the distribution of symptomatic versus inapparent infections by serotype varies remains unknown. Here, we present (1) the evaluation of a multiplex DENV1-4 envelope domain III multiplex microsphere-based assay (EDIII-MMBA) to serotype inapparent primary infections and (2) its application leveraging 17 years of prospective sample collection from the Nicaraguan Pediatric Dengue Cohort Study (PDCS). First, we evaluated the performance of the EDIII-MMBA with samples characterized by RT-PCR or focus reduction neutralization test. Next, we analyzed 46% (N=574) of total inapparent primary DENV infections in the PDCS with the EDIII-MMBA to evaluate the epidemiology of inapparent infections. Remaining infections were inferred using stochastic imputation, taking year and neighborhood into account. Infection incidence and percentage of inapparent, symptomatic, and severe infections were analyzed by serotype. The EDIII-MMBA demonstrated excellent overall accuracy (100%, 95.8-100%) for serotyping symptomatic and inapparent primary DENV infections when evaluated against gold-standard serotyping methods. We found that a significant majority of primary infections were inapparent, with DENV3 exhibiting the highest likelihood of symptomatic and severe primary infections (Pooled OR compared to DENV1 = 2.13, 95% CI 1.28-3.56, and 6.75, 2.01-22.62, respectively), whereas DENV2 was similar to DENV1 in both analyses. Significant within- and between-year variation in serotype distribution between symptomatic and inapparent infections and circulation of serotypes undetected in symptomatic cases were observed in multiple years. Our study indicates that case surveillance skews the perceived epidemiological footprint of DENV. We reveal a more complex and intricate pattern of serotype distribution in inapparent infections. The significant differences in infection outcomes by serotype emphasizes the need for vaccines with balanced immunogenicity and efficacy across serotypes.

Morphological, Biological, and Molecular Characterization of Type I Granuloviruses of Spodoptera frugiperda.

Granuloviruses (GVs) Betabaculovirus associated with the fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), especially those of the type I, have scarcely been studied. These GVs might be an effective alternative for the biocontrol of this insect. In this study, the native GVs SfGV-CH13 and SfGV-CH28 were isolated from FAW larvae and characterized for morphology, molecular traits, and insecticidal activity. The elapsed time between symptomatic infection of larvae and stop feeding as well as the weight of larvae before death or prior to pupation were also evaluated. Both GVs had ovoid shape and a length of 0.4 µm. They had the same DNA restriction profiles and their genome sizes were about 126 kb. The symptomatic infection with the tested GVs mainly caused flaccidity of larva body and discoloration of integument. The integument lysis was only observed in 8% of infected larvae. Infected larvae gradually stopped feeding. Overall, these symptoms are characteristic of infections caused by type I GVs, which are known as monoorganotropic or slow-killing GVs. The median lethal dose (LD50) values for SfGV-CH13 and SfGV-CH28 isolates were 5.4 × 102 and 1.1 × 103 OBs/larva, respectively. The median lethal time (LT50) ranged from 17 to 24 days. LT50 values decreased as the viral dose was increased. The elapsed time from symptomatic infection until pupation and body weight of larvae (third instar) were higher with SfGV-CH28 than SfGV-CH13. Both granulovirus isolates were able to kill the FAW larvae from the 12th day.

Strong isolation by distance and evidence of population microstructure reflect ongoing Plasmodium falciparum transmission in Zanzibar.

The Zanzibar archipelago of Tanzania has become a low-transmission area for Plasmodium falciparum. Despite being considered an area of pre-elimination for years, achieving elimination has been difficult, likely due to a combination of imported infections from mainland Tanzania and continued local transmission. To shed light on these sources of transmission, we applied highly multiplexed genotyping utilizing molecular inversion probes to characterize the genetic relatedness of 282 P. falciparum isolates collected across Zanzibar and in Bagamoyo district on the coastal mainland from 2016 to 2018. Overall, parasite populations on the coastal mainland and Zanzibar archipelago remain highly related. However, parasite isolates from Zanzibar exhibit population microstructure due to the rapid decay of parasite relatedness over very short distances. This, along with highly related pairs within shehias, suggests ongoing low-level local transmission. We also identified highly related parasites across shehias that reflect human mobility on the main island of Unguja and identified a cluster of highly related parasites, suggestive of an outbreak, in the Micheweni district on Pemba island. Parasites in asymptomatic infections demonstrated higher complexity of infection than those in symptomatic infections, but have similar core genomes. Our data support importation as a main source of genetic diversity and contribution to the parasite population in Zanzibar, but they also show local outbreak clusters where targeted interventions are essential to block local transmission. These results highlight the need for preventive measures against imported malaria and enhanced control measures in areas that remain receptive to malaria reemergence due to susceptible hosts and competent vectors. This research was funded by the National Institutes of Health, grants R01AI121558, R01AI137395, R01AI155730, F30AI143172, and K24AI134990. Funding was also contributed from the Swedish Research Council, Erling-Persson Family Foundation, and the Yang Fund. RV acknowledges funding from the MRC Centre for Global Infectious Disease Analysis (reference MR/R015600/1), jointly funded by the UK Medical Research Council (MRC) and the UK Foreign, Commonwealth & Development Office (FCDO), under the MRC/FCDO Concordat agreement and is also part of the EDCTP2 program supported by the European Union. RV also acknowledges funding by Community Jameel.