Surveillance of Flea-Borne Typhus in California, 2011-2019

Flea-borne typhus (FBT), also referred to as murine typhus, is an acute febrile disease in humans caused by the bacteria Rickettsia typhi. Currently, cases of FBT are reported for public health surveillance purposes (i.e., to detect incidence and outbreaks) in a few U.S. states. In California, healthcare providers and testing laboratories are mandated to report to their respective local public health jurisdictions whenever R. typhi or antibodies reactive to R. typhi are detected in a patient, who then report cases to state health department. In this study, we characterize the epidemiology of flea-borne typhus cases in California from 2011 to 2019. A total of 881 cases were reported during this period, with most cases reported among residents of Los Angeles and Orange Counties (97%). Demographics, animal exposures, and clinical courses for case patients were summarized. Additionally, spatiotemporal cluster analyses pointed to five areas in southern California with persistent FBT transmission.

Long-term outcomes of CPAP-treated sleep apnea patients: Impact of blood-pressure responses after CPAP initiation and of treatment adherence

BACKGROUND AND OBJECTIVE

In randomized controlled trials, continuous positive airway pressure (CPAP) is reported as lowering blood pressure (BP) with a mean systolic blood pressure effect size of 2.5 mmHg. These trials have a median follow-up of less than 6 months. Whether this initial BP response during the first months of CPAP treatment translates into a reduction in long-term cardiovascular events and mortality is unknown.

METHODS

This observational study addressed long-term hard cardiovascular outcomes and all-cause mortality in a well-defined population of 241 patients previously included in the AgirSASadom parallel randomized controlled trial (assessing whether fixed-pressure CPAP was superior to auto-adjusted CPAP in reducing BP (baseline evaluations 2010-2012)). Long-term outcomes were analyzed using a Cox survival model, and a logistic regression analysis was performed for long-term CPAP adherence.

RESULTS

Sixty-nine cardiovascular events occurred in 61 patients during a median follow-up of 113 months (interquartile range [102 ; 124]) giving an incidence of 26 for 1000 person-years. Twenty-one (8.7%) patients died. BP values at baseline (i.e., office and 24-h BP) was a strong predictor of incident cardiometabolic events and mortality (p < 0.01) whereas initial BP response after the first four months of CPAP was not related to outcomes. Long-term CPAP adherence above 4 h/night was associated with a reduction in all-cause mortality (Log-rank P = 0.02) but not in the occurrence of long-term cardiovascular events.

CONCLUSION

Independently of initial blood pressure response, long-term CPAP adherence is one of the prerequisites for reducing mortality.

Clinical Characteristics and Outcomes of SARS-CoV-2 Positive Neonates Born to Persons With SARS-CoV-2 Infection in Pregnancy in Los Angeles County, California, May 22, 2020-February 22, 2021

BACKGROUND

It is well established that pregnant persons with SARS-CoV-2 are at an increased risk for preterm birth, however, less is known about perinatal outcomes for neonates with intrauterine exposure to SARS-CoV-2.

METHODS

Characteristics of 50 SARS-CoV-2 positive neonates born to SARS-CoV-2 pregnant persons positive between May 22, 2020, and February 22, 2021, in Los Angeles County, CA, were assessed. Pattern of neonate SARS-CoV-2 test results and time to positive test was analyzed. Objective clinical severity criteria were applied to assess neonatal disease severity.

RESULTS

Median gestational age was 39 weeks with 8 (16%) neonates born preterm. Most (74%) were asymptomatic, while 13 (26%) were symptomatic from any cause. Four (8%) symptomatic neonates met criteria for severe disease, of which 2 (4%) were likely secondary to COVID-19. The other 2 with severe disease had more likely alternate diagnoses, and 1 of these neonates subsequently died at 7 months of life. Among 12 (24%) that were positive within 24 hours after birth, one was persistently positive and represented likely intrauterine transmission. Sixteen (32%) were admitted to the neonatal intensive care unit.

CONCLUSION

In this case series of 50 SARS-CoV-2 positive mother-neonate pairs, we found that most neonates were asymptomatic regardless of when they tested positive during the 14 days after birth, that there was relatively low risk of COVID-19 associated severe disease, and that intrauterine transmission can occur in rare cases. Although short-term outcomes are mostly promising, more research is needed to study long-term consequences of SARS-CoV-2 infection in neonates born to positive pregnant persons.

Current state of pediatric neuro-oncology imaging, challenges and future directions

Imaging plays a central role in neuro-oncology including primary diagnosis, treatment planning, and surveillance of tumors. The emergence of quantitative imaging and radiomics provided an uprecedented opportunity to compile mineable databases that can be utilized in a variety of applications. In this review, we aim to summarize the current state of conventional and advanced imaging techniques, standardization efforts, fast protocols, contrast and sedation in pediatric neuro-oncologic imaging, radiomics-radiogenomics, multi-omics and molecular imaging approaches. We will also address the existing challenges and discuss future directions.

Mpox Cases Among Cisgender Women and Pregnant Persons - United States, May 11-November 7, 2022

Monkeypox (mpox) cases in the 2022 outbreak have primarily occurred among adult gay, bisexual, and other men who have sex with men (MSM); however, other populations have also been affected (1). To date, data on mpox in cisgender women and pregnant persons have been limited. Understanding transmission in these populations is critical for mpox prevention. In addition, among pregnant persons, Monkeypox virus can be transmitted to the fetus during pregnancy or to the neonate through close contact during or after birth (2-5). Adverse pregnancy outcomes, including spontaneous abortion and stillbirth, have been reported in previous mpox outbreaks (3). During May 11-November 7, 2022, CDC and U.S. jurisdictional health departments identified mpox in 769 cisgender women aged ≥15 years, representing 2.7% of all reported mpox cases.^† Among cases with available data, 44% occurred in cisgender women who were non-Hispanic Black or African American (Black), 25% who were non-Hispanic White (White), and 23% who were Hispanic or Latino (Hispanic). Among cisgender women with available data, 73% reported sexual activity or close intimate contact as the likely route of exposure, with mpox lesions most frequently reported on the legs, arms, and genitals. Twenty-three mpox cases were reported in persons who were pregnant or recently pregnant^§; all identified as cisgender women based on the mpox case report form.^¶ Four pregnant persons required hospitalization for mpox. Eleven pregnant persons received tecovirimat, and no adverse reactions were reported. Continued studies on mpox transmission risks in populations less commonly affected during the outbreak, including cisgender women and pregnant persons, are important to assess and understand the impact of mpox on sexual, reproductive, and overall health.

WHITE MATTER CHANGE NEAR CEREBRAL MICROBLEEDS AFTER MTBI INVOLVES AGE AND SEX DEPENDENT COGNITIVE DECLINE

We tested the null hypothesis that, after mild traumatic brain injury (mTBI), white matter changes near cerebral microbleeds (CMBs) are associated with cognitive decline. Magnetic resonance images were acquired from 62 adults with mTBI and from 203 matched healthy controls. A week post-injury, mTBI participants had 2.7±2.6 traumatic CMBs in WM, located 6.1±4.4 mm from the cortical mantle. About 6 months later, 97% of CMBs were associated with significant reductions (34%±11%, q &lt; 0.05) in the fractional anisotropy (FA) of WM streamlines within ~1 cm of CMBs. Male sex and older age were significant risk factors for larger reductions (q &lt; 0.05). CMBs in the corpus callosum, cingulum bundle, inferior and middle longitudinal fasciculi were associated with FA changes that were significantly and positively associated with changes in cognitive functions mediated by these structures (q &lt; 0.05). These findings distinguish non-traumatic from traumatic CMBs according to CMB-related changes in surrounding WM. Our findings also challenge the assumption that traumatic CMBs are cognitively silent and identify older age and male sex as risk factors for mTBI-related cognitive decline in the presence of CMBs. In conclusion, mTBI with CMB findings on MRI can be described as a clinical endophenotype that warrants longitudinal mapping and quantification of cognitive function.

1457. Epidemiology of Human Herpesvirus-6 Meningoencephalitis in Los Angeles County, 2016-2020

Background

Human herpesvirus 6 (HHV-6) is ubiquitous and a known central nervous system (CNS) pathogen. However, HHV-6 in cerebrospinal fluid (CSF) without clinical findings of meningoencephalitis (ME) may not represent true infection, but rather, asymptomatic viral reactivation, chromosomal integration, or latent activation. With the introduction in 2015 of a rapid polymerase chain reaction (PCR) multiplex panel that simultaneously tests for 14 CNS pathogens, reports of HHV-6 PCR positive ME have increased. We sought to understand the epidemiology of HHV-6 ME by evaluating reported cases in Los Angeles County (LAC) between 2016-2020.

Methods

ME is a reportable condition in LAC. We reviewed clinical, laboratory, and radiologic data for all HHV-6 PCR positive cases reported in LAC between 2016-2020. We developed case classification categories, “unlikely,” “possible,” and “likely”, based on symptoms, CSF profile, and alternative diagnoses (see Table 1).

Results

A total of 67 HHV-6 ME cases were reported (see Table 2). Reports increased over time, with one in 2016, 12 in 2017, 17 in 2018, 20 in 2019, and 17 in 2020. Median age was 9 months (range 0d-78y), and 47 (70%) were &lt; three years old. Forty-four (66%) were male. Six (9%) were immunocompromised, including one hematopoietic stem cell transplant recipient. Nineteen (28%) had abnormal CSF, and eight (12%) received therapy for HHV-6.

Five cases (7%) were classified as “likely” HHV-6 ME, 12 (18%) “possible,” and 50 (75%) “unlikely”. The “likely” cases ranged in age from 7 months to 12 years old, and none were immunocompromised. One received antiviral therapy and was discharged to a rehabilitation facility, the other four were discharged home with full recovery.

Conclusion

The significance of HHV-6 in CSF remains challenging to determine both clinically and epidemiologically. In the setting of increased testing, increasing detection of HHV-6 in CSF may not reflect increasing rates of HHV-6 ME. The majority of reported HHV-6 ME cases were “unlikely” based on our classification. Classifying cases with alternative diagnoses as ‘unlikely” may miss cases with multiple true infections, particularly in the immunocompromised. It is important to consider clinical presentation, CSF profile and other diagnoses to understand the true burden of HHV-6 ME.

Disclosures

All Authors: No reported disclosures.

Mild Traumatic Brain Injury Results in Significant and Lasting Cortical Demyelination

Despite contributing to neurocognitive deficits, intracortical demyelination after traumatic brain injury (TBI) is understudied. This study uses magnetic resonance imaging (MRI) to map intracortical myelin and its change in healthy controls and after mild TBI (mTBI). Acute mTBI involves reductions in relative myelin content primarily in lateral occipital regions. Demyelination mapped ~6 months post-injury is significantly more severe than that observed in typical aging (p < 0.05), with temporal, cingulate, and insular regions losing more myelin (30%, 20%, and 16%, respectively) than most other areas, although occipital regions experience 22% less demyelination. Thus, occipital regions may be more susceptible to primary injury, whereas temporal, cingulate and insular regions may be more susceptible to later manifestations of injury sequelae. The spatial profiles of aging- and mTBI-related chronic demyelination overlap substantially; exceptions include primary motor and somatosensory cortices, where myelin is relatively spared post-mTBI. These features resemble those of white matter demyelination and cortical thinning during Alzheimer's disease, whose risk increases after mTBI.

Recurrent SARS-CoV-2 RNA Detection after COVID-19 Illness Onset during Pregnancy

The Surveillance for Emerging Threats to Mothers and Babies Network conducts longitudinal surveillance of pregnant persons in the United States with laboratory-confirmed severe acute respiratory syndrome coronavirus 2 infection during pregnancy. Of 6,551 infected pregnant persons in this analysis, 142 (2.2%) had positive RNA tests >90 days and up to 416 days after infection.

Age, Sex, and Cerebral Microbleeds Affect White Matter Integrity Across Adulthood After Mild Traumatic Brain Injury

The contributions of age, sex, and cerebral microbleeds (CMBs) to WM changes after mild traumatic brain injury (mTBI) have not been studied. We used diffusion tensor imaging (DTI) to map WM fractional anisotropy (FA) changes across the first ~6 months post-mTBI in 109 subjects aged 18-77 (46 females; age µ: 40 y, σ: 17 y) imaged within ~1 week post-injury and ~6 months later. After partialing out age, sex, and CMB counts, significant mean FA decreases were found in the anterior body, posterior body, and splenium of the corpus callosum (CC; p = 0.003, 0.009 and 0.015, respectively), left superficial frontal fasciculus (p = 0.008), and left branch of the corticospinal tract (CST; p = 0.007). Age contributed to mean FAs measured acutely in the CC body (p = 0.04), and chronically in the CC genu (p < 0.001), CC body (p = 0.01), and middle longitudinal fasciculi (p = 0.04), older adults exhibiting larger decreases. CMB counts were positively associated with mean FA decreases in the CC body (p = 0.04) and middle longitudinal fasciculi (p = 0.04). Significant age-by-sex and CMB count-by-age interactions mediated FA decreases in the CC genu (p = 0.02 and p = 0.03, respectively), older males exhibiting larger decreases. Thus, the CC, longitudinal fasciculi, superficial frontal WM and CST are particularly vulnerable to post-traumatic neurodegeneration moderated by age, sex and CMB count, men and older adults being at highest risk for adverse effects. Future research should investigate our findings relative to cognitive function.

470 Financial and Efficacy Analysis of a Centralised Neck of Femur Fracture Service

Aim

Osteoporotic fractures are rising in incidence, costing the National Health Service up to £1.1 billion for hospital care. The implementation of the Best Practice Tariff (BPT) of fragility fractures in 2010 created a financial incentive to achieve standards of best practice. In June 2015, a dedicated hip fracture unit (HFU) was set up at Princess Royal Hospital (PRH). The aim of this study is (A) to assess changes in performance to the BPT after the introduction of a dedicated HFU, and (B) whether the performance of a HFU is affected by direct/indirect presentation to the HFU.

Method

The performance of Brighton and Sussex University Hospitals (BSUH) to BPT pre and post HFU was assessed by a retrospective review of BPT performance data between 2015 and 2016. 870 patients who were treated for NOFF at BSUH were reviewed to assess whether the performance of the HFU was impacted by patients presenting either directly (PRH) to the HFU or indirectly (presentation to Royal Sussex County Hospital). Appropriate statistical tests were used to analyse the significant differences between these outcome measures.

Results

The comparison between pre and post HFU showed there was a significant increase in the time between A&E admission to ward, theatre or orthogeriatric (OG) assessment (P &lt; 0.001) in patients presenting indirectly to HFU compared to direct presentations.

Conclusions

Having a HFU is cost neutral, and advantages of HFU include focusing NOFF care which improves in patient care. BPT achievements could be improved by increasing the direct admission of NOFF to the HFU.

The Indigenous South American Tsimane Exhibit Relatively Modest Decrease in Brain Volume With Age Despite High Systemic Inflammation

Brain atrophy is correlated with risk of cognitive impairment, functional decline, and dementia. Despite a high infectious disease burden, Tsimane forager-horticulturists of Bolivia have the lowest prevalence of coronary atherosclerosis of any studied population and present few cardiovascular disease (CVD) risk factors despite a high burden of infections and therefore inflammation. This study (a) examines the statistical association between brain volume (BV) and age for Tsimane and (b) compares this association to that of 3 industrialized populations in the United States and Europe. This cohort-based panel study enrolled 746 participants aged 40-94 (396 males), from whom computed tomography (CT) head scans were acquired. BV and intracranial volume (ICV) were calculated from automatic head CT segmentations. The linear regression coefficient estimate β^T of the Tsimane (T), describing the relationship between age (predictor) and BV (response, as a percentage of ICV), was calculated for the pooled sample (including both sexes) and for each sex. β^T was compared to the corresponding regression coefficient estimate β^R of samples from the industrialized reference (R) countries. For all comparisons, the null hypothesis β T = β R was rejected both for the combined samples of males and females, as well as separately for each sex. Our results indicate that the Tsimane exhibit a significantly slower decrease in BV with age than populations in the United States and Europe. Such reduced rates of BV decrease, together with a subsistence lifestyle and low CVD risk, may protect brain health despite considerable chronic inflammation related to infectious burden.

Industry Sectors Highly Affected by Worksite Outbreaks of Coronavirus Disease, Los Angeles County, California, USA, March 19-September 30, 2020

Worksites with on-site operations have experienced coronavirus disease (COVID-19) outbreaks. We analyzed data for 698 nonresidential, nonhealthcare worksite COVID-19 outbreaks investigated in Los Angeles County, California, USA, during March 19, 2020‒September 30, 2020, by using North American Industry Classification System sectors and subsectors. Nearly 60% of these outbreaks occurred in 3 sectors: manufacturing (n = 184, 26.4%), retail trade (n = 137, 19.6%), and transportation and warehousing (n = 73, 10.5%). The largest number of outbreaks and largest number and highest incidence rate of outbreak-associated cases occurred in manufacturing. Furthermore, 7 of the 10 industry subsectors with the highest incidence rates were within manufacturing. Approximately 70% of outbreak-associated case-patients reported Hispanic ethnicity. Facilities employing more on-site staff had larger and longer outbreaks. Identification of highly affected industry sectors and subsectors is necessary for targeted public health planning, outreach, and response, including ensuring vaccine access, to reduce burden of COVID-19 in vulnerable workers.

Polarization Effects in Water-Mediated Selective Cation Transport across a Narrow Transmembrane Channel

Despite the progress in modeling complex molecular systems of ever-increasing complexity, a quantitatively accurate computational treatment of ion permeation through narrow membrane channels remains challenging. An important factor to reach this goal is induced electronic polarization, which is likely to impact the permeation rate of small ions through narrow molecular pores. In this work, we extended the recently developed polarizable force field based on the classical Drude oscillators to assess the role of induced polarization effects on the energetics of sodium and potassium ion transport across the gramicidin A (gA) ion channel. The inclusion of induced polarization lowers barriers present in 1D potential of mean force (PMF) for cation permeation by ∼50% compared to those obtained with the additive force field. Conductance properties calculated with 1D PMFs from Drude simulations are in better agreement with experimental results. Polarization of single-file water molecules and protein atoms forming the narrow pore has a direct impact on the free-energy barriers and cation-specific solid-state NMR chemical shifts. Sensitivity analysis indicates that small changes to water-channel interactions can alter the free energy barrier for ion permeation. These results, illustrating polarization effects present in the complex electrostatic environment of the gA channel, have broad implications for revising proposed mechanisms of ion permeation and selectivity in a variety of ion channels.

Statistical Estimation of Accelerated Biological Brain Aging After Mild Traumatic Brain Injury in Older Adults

Estimating biological brain age (BA) has the potential of identifying individuals at relatively high risk for accelerated neurodegeneration. This study compares the brain’s chronological age (CA) to its BA and reveals the BA rate of change after mild traumatic brain injury (mTBI) in an aging cohort. Using T1-weighted magnetic resonance imaging (MRI) volumes and cortical thickness, volume, surface area, and Gaussian curvature obtained using FreeSurfer software; we formulated a multivariate linear regression to determine the rate of BA increase associated with mTBI. 95 TBI patients (age in years (y): μ = 41 y, σ = 17 y; range = 18 to 83) were compared to 462 healthy controls (HCs) (age: μ = 69 y, σ = 18 y; range = 25 to 95) over a 6-month time period following mTBI. Across the initial ~6 months following injury, patients’ BAs increased by ~3.0 ± 1.2 years due to their mTBIs alone, i.e., above and beyond typical brain aging. The superior temporal and parahippocampal gyri, two structures involved in memory formation and retrieval, exhibited the fastest rates of TBI-related BA. In both hemispheres, the volume of the hippocampus decreased (left: μ=0.28%, σ=4.40%; right: μ=0.12%, σ=4.84%). These findings illustrate BA estimation techniques’ potential to identify TBI patients with accelerated neurodegeneration, whose rate is strongly associated with the risk for dementia and other aging-related neurological conditions.

Age, Sex and Cerebral Microbleed Effects On White Matter Degradation After Traumatic Brain Injury

Mild traumatic brain injury (mTBI) affects white matter (WM) integrity and accelerates neurodegeneration. This study assesses the effects of age, sex, and cerebral microbleed (CMB) load as predictors of WM integrity in 70 subjects aged 18-77 imaged acutely and ~6 months after mTBI using diffusion tensor imaging (DTI). Two-tensor unscented Kalman tractography was used to segment and cluster 73 WM structures and to map changes in their mean fractional anisotropy (FA), a surrogate measure of WM integrity. Dimensionality reduction of mean FA feature vectors was implemented using principal component (PC) analysis, and two prominent PCs were used as responses in a multivariate analysis of covariance. Acutely and chronically, older age was significantly associated with lower FA (F2,65 = 8.7, p &lt; .001, η2 = 0.2; F2,65 = 12.3, p &lt; .001, η2 = 0.3, respectively), notably in the corpus callosum and in dorsolateral temporal structures, confirming older adults’ WM vulnerability to mTBI. Chronically, sex was associated with mean FA (F2,65 = 5.0, p = 0.01, η2 = 0.1), indicating males’ greater susceptibility to WM degradation. Acutely, a significant association was observed between CMB load and mean FA (F2,65 = 5.1, p = 0.009, η2 = 0.1), suggesting that CMBs reflect the acute severity of diffuse axonal injury. Together, these findings indicate that older age, male sex, and CMB load are risk factors for WM degeneration. Future research should examine how sex- and age-mediated WM degradation lead to cognitive decline and connectome degeneration after mTBI.

Molecular epidemiology of Clostridioides difficile in domestic dogs and zoo animals

Animals such as domestic dogs and zoo animals reside in close proximity to humans and could contribute to the dissemination of Clostridioides difficile spores which are common in the community environment. The purpose of this study was to assess C. difficile colonization in domestic dogs attending a day boarding facility and zoo animals receiving systemic antibiotics. Stool samples and paw swabs were collected from dogs who attended a day boarding facility. Stool samples were also collected from zoo animals starting systemic antibiotics. Finally, environmental samples were collected from nearby public parks. Stool samples and swabs were incubated anaerobically in enrichment broth for C. difficile growth, PCR was done to confirm presence of toxin genes, and PCR ribotyping was performed for strain characterization. During the study period, 136 dog stool samples were obtained, the paws of 16 dogs were swabbed, and 250 environmental swabs from surrounding public parks were obtained. Twenty-three of 136 dog stool samples (17%) and 9 of 16 dog paws sampled (56%) grew toxigenic C. difficile. One hundred and four stool samples from 49 zoo animals were collected of which 19 (18%) grew toxigenic C. difficile. Rates of toxigenic C. difficile colonization increased significantly during antibiotic therapy (33%) and then returned to baseline during the follow-up (11%) period (p = 0.019). Fifty-five of 250 environmental swabs from public parks (22%) grew toxigenic C. difficile. Ribotypes associated with human disease including 106 and 014-020 were isolated from all sources. This study demonstrated a high rate of toxigenic C. difficile colonization in domestic dogs and zoo animals with ribotypes similar to those causing human disease. These results demonstrate the relationship between humans, animals, and the environment in the dissemination of spores.

Increased Risk for Meningococcal Disease Among Men Who Have Sex With Men in the United States, 2012-2015

Background

Several clusters of serogroup C meningococcal disease among men who have sex with men (MSM) have been reported in the United States in recent years. The epidemiology and risk of meningococcal disease among MSM is not well described.

Methods

All meningococcal disease cases among men aged 18-64 years reported to the National Notifiable Disease Surveillance System between January 2012 and June 2015 were reviewed. Characteristics of meningococcal disease cases among MSM and men not known to be MSM (non-MSM) were described. Annualized incidence rates among MSM and non-MSM were compared through calculation of the relative risk and 95% confidence intervals. Isolates from meningococcal disease cases among MSM were characterized using standard microbiological methods and whole-genome sequencing.

Results

Seventy-four cases of meningococcal disease were reported among MSM and 453 among non-MSM. Annualized incidence of meningococcal disease among MSM was 0.56 cases per 100000 population, compared to 0.14 among non-MSM, for a relative risk of 4.0 (95% confidence interval [CI], 3.1-5.1). Among the 64 MSM with known status, 38 (59%) were infected with human immunodeficiency virus (HIV). HIV-infected MSM had 10.1 times (95% CI, 6.1-16.6) the risk of HIV-uninfected MSM. All isolates from cluster-associated cases were serogroup C sequence type 11.

Conclusions

MSM are at increased risk for meningococcal disease, although the incidence of disease remains low. HIV infection may be an important factor for this increased risk. Routine vaccination of HIV-infected persons with a quadrivalent meningococcal conjugate vaccine in accordance with Advisory Committee on Immunization Practices recommendations should be encouraged.

A 2015 outbreak of flea-borne rickettsiosis in San Gabriel Valley, Los Angeles County, California

Although flea-borne rickettsiosis is endemic in Los Angeles County, outbreaks are rare. In the spring of 2015 three human cases of flea-borne rickettsiosis among residents of a mobile home community (MHC) prompted an investigation. Fleas were ubiquitous in common areas due to presence of flea-infested opossums and overabundant outdoor cats and dogs. The MHC was summarily abated in June 2015, and within five months, flea control and removal of animals significantly reduced the flea population. Two additional epidemiologically-linked human cases of flea-borne rickettsiosis detected at the MHC were suspected to have occurred before control efforts began. Molecular testing of 106 individual and 85 pooled cat fleas, blood and ear tissue samples from three opossums and thirteen feral cats using PCR amplification and DNA sequencing detected rickettsial DNA in 18.8% of the fleas. Seventeen percent of these cat fleas tested positive for R. felis-specific DNA compared to under two (<2) percent for Candidatus R. senegalensis-specific DNA. In addition, serological testing of 13 cats using a group-specific IgG-ELISA detected antibodies against typhus group rickettsiae and spotted fever group rickettsiae in six (46.2%) and one (7.7%) cat, respectively. These results indicate that cats and their fleas may have played an active role in the epidemiology of the typhus group and/or spotted fever group rickettsial disease(s) in this outbreak.

Outbreaks of flea-borne rickettsiosis are rare despite the endemic status in Los Angeles County. In the spring of 2015 three human cases of flea-borne rickettsiosis among residents of a mobile home community (MHC) prompted an investigation. Fleas were found in all common areas at the MHC due to presence of flea-infested opossums and overabundant outdoor cats and dogs. The MHC was summarily abated in June 2015, and within five months, flea control and removal of animals significantly reduced the flea population. Two additional epidemiologically-linked human cases detected at the MHC were considered to have occurred before control efforts began. Molecular testing of cat fleas, immunological testing of opossums and feral cats collected at the site indicated active transmission of flea-borne rickettsiosis. This study represents the first flea-borne rickettsial outbreak that summary abatement approach was used to reduce its intensity.

Atypical Presentation of Escherichia coli Monomicrobial Necrotizing Fasciitis in a Renal Transplant Patient: A Case Report

Skin and soft tissue infections (SSTIs) are one of most frequent infectious causes for referral to the emergency department and one of the most frequent infectious causes of hospital admissions. Escherichia coli, the most commonly occurring gram-negative pathogen involved in these infections, contributes to about 7% of all SSTIs cases where gram-positive organisms reign dominant. Patients are more susceptible to these gram-negative SSTIs if they are neutropenic, have hematologic malignancies, have undergone solid organ or hematopoietic transplantation, or have cirrhotic liver disease. Due to their immunocompromised state, the prognosis is very poor and not well understood. We report a case of an atypical presentation of an E coli monomicrobial necrotizing fasciitis in a renal transplant patient. Our findings support improved mortality with rapid aggressive interventions, such as amputation, in immunocompromised patients.

Outbreak of Serogroup C Meningococcal Disease Primarily Affecting Men Who Have Sex with Men - Southern California, 2016

During March 4-August 11, 2016, 25 outbreak-associated cases of meningococcal disease, including two deaths (8% case-fatality ratio), were reported in Southern California. Twenty-four of the cases were caused by serogroup C Neisseria meningitidis (NmC) and one by N. meningitidis with an undetermined serogroup (Figure). On June 24, 2016, in response to this increase in NmC cases, primarily among men who have sex with men (MSM) in Los Angeles County, the city of Long Beach, and Orange County, the California Department of Public Health (CDPH) issued a press release and health advisory, declaring an outbreak of NmC in Southern California (1).

K+ Block Is the Mechanism of Functional Asymmetry in Bacterial Na(v) Channels

Crystal structures of several bacterial Na_v channels have been recently published and molecular dynamics simulations of ion permeation through these channels are consistent with many electrophysiological properties of eukaryotic channels. Bacterial Na_v channels have been characterized as functionally asymmetric, and the mechanism of this asymmetry has not been clearly understood. To address this question, we combined non-equilibrium simulation data with two-dimensional equilibrium unperturbed landscapes generated by umbrella sampling and Weighted Histogram Analysis Methods for multiple ions traversing the selectivity filter of bacterial Na_vAb channel. This approach provided new insight into the mechanism of selective ion permeation in bacterial Na_v channels. The non-equilibrium simulations indicate that two or three extracellular K⁺ ions can block the entrance to the selectivity filter of Na_vAb in the presence of applied forces in the inward direction, but not in the outward direction. The block state occurs in an unstable local minimum of the equilibrium unperturbed free-energy landscape of two K⁺ ions that can be ‘locked’ in place by modest applied forces. In contrast to K⁺, three Na⁺ ions move favorably through the selectivity filter together as a unit in a loose “knock-on” mechanism of permeation in both inward and outward directions, and there is no similar local minimum in the two-dimensional free-energy landscape of two Na⁺ ions for a block state. The useful work predicted by the non-equilibrium simulations that is required to break the K⁺ block is equivalent to large applied potentials experimentally measured for two bacterial Na_v channels to induce inward currents of K⁺ ions. These results illustrate how inclusion of non-equilibrium factors in the simulations can provide detailed information about mechanisms of ion selectivity that is missing from mechanisms derived from either crystal structures or equilibrium unperturbed free-energy landscapes.

In this paper we show that bacterial voltage-gated sodium channels (Na_v) conduct ions differently in the inward direction and in the outward direction because extracellular K⁺ blocks these channels. The mechanism of block by K⁺ is revealed in the simulations only when effects of applied forces in the inward direction are considered appropriately. The block of bacterial Na_v channels by K⁺ explains the experimental findings that inward K⁺ current in bacterial Na_v channels is very small under conditions where most mammalian Na_v channels conduct significant K⁺ current. The block by K⁺ ions can occur in the bacterial Na_v channels but is very unlikely to occur in mammalian channels due to differences in the amino acid sequences of the selectivity filters of the different channels.

Meningococcal disease among men who have sex with men - United States, January 2012-June 2015

Since 2012, three clusters of serogroup C meningococcal disease among men who have sex with men (MSM) have been reported in the United States. During 2012, 13 cases of meningococcal disease among MSM were reported by the New York City Department of Health and Mental Hygiene (1); over a 5-month period during 2012–2013, the Los Angeles County Department of Public Health reported four cases among MSM; and during May–June 2015, the Chicago Department of Public Health reported seven cases of meningococcal disease among MSM in the greater Chicago area. MSM have not previously been considered at increased risk for meningococcal disease. Determining outbreak thresholds* for special populations of unknown size (such as MSM) can be difficult. The New York City health department declared an outbreak based on an estimated increased risk for meningococcal infection in 2012 among MSM and human immunodeficiency virus (HIV)–infected MSM compared with city residents who were not MSM or for whom MSM status was unknown (1). The Chicago Department of Public Health also declared an outbreak based on an increase in case counts and thresholds calculated using population estimates of MSM and HIV-infected MSM. Local public health response included increasing awareness among MSM, conducting contact tracing and providing chemoprophylaxis to close contacts, and offering vaccination to the population at risk (1–3). To better understand the epidemiology and burden of meningococcal disease in MSM populations in the United States and to inform recommendations, CDC analyzed data from a retrospective review of reported cases from January 2012 through June 2015.

Quantum effects in cation interactions with first and second coordination shell ligands in metalloproteins

Despite decades of investigations, the principal mechanisms responsible for the high affinity and specificity of proteins for key physiological cations K⁺, Na⁺, and Ca²⁺ remain a hotly debated topic. At the core of the debate is an apparent need (or lack thereof) for an accurate description of the electrostatic response of the charge distribution in a protein to the binding of an ion. These effects range from partial electronic polarization of the directly ligating atoms to long-range effects related to partial charge transfer and electronic delocalization effects. While accurate modeling of cation recognition by metalloproteins warrants the use of quantum-mechanics (QM) calculations, the most popular approximations used in major biomolecular simulation packages rely on the implicit modeling of electronic polarization effects. That is, high-level QM computations for ion binding to proteins are desirable, but they are often unfeasible, because of the large size of the reactive-site models and the need to sample conformational space exhaustively at finite temperature. Several solutions to this challenge have been proposed in the field, ranging from the recently developed Drude polarizable force-field for simulations of metalloproteins to approximate tight-binding density functional theory (DFTB). To delineate the usefulness of different approximations, we examined the accuracy of three recent and commonly used theoretical models and numerical algorithms, namely, CHARMM C36, the latest developed Drude polarizable force fields, and DFTB3 with the latest 3OB parameters. We performed MD simulations for 30 cation-selective proteins with high-resolution X-ray structures to create ensembles of structures for analysis with different levels of theory, e.g., additive and polarizable force fields, DFTB3, and DFT. The results from DFT computations were used to benchmark CHARMM C36, Drude, and DFTB3 performance. The explicit modeling of quantum effects unveils the key electrostatic properties of the protein sites and the importance of specific ion-protein interactions. One of the most interesting findings is that secondary coordination shells of proteins are noticeably perturbed in a cation-dependent manner, showing significant delocalization and long-range effects of charge transfer and polarization upon binding Ca²⁺.

Representation of Ion-Protein Interactions Using the Drude Polarizable Force-Field

Small metal ions play critical roles in numerous biological processes. Of particular interest is how metalloenzymes are allosterically regulated by the binding of specific ions. Understanding how ion binding affects these biological processes requires atomic models that accurately treat the microscopic interactions with the protein ligands. Theoretical approaches at different levels of sophistication can contribute to a deeper understanding of these systems, although computational models must strike a balance between accuracy and efficiency in order to enable long molecular dynamics simulations. In this study, we present a systematic effort to optimize the parameters of a polarizable force field based on classical Drude oscillators to accurately represent the interactions between ions (K⁺, Na⁺, Ca²⁺, and Cl^–) and coordinating amino-acid residues for a set of 30 biologically important proteins. By combining ab initio calculations and experimental thermodynamic data, we derive a polarizable force field that is consistent with a wide range of properties, including the geometries and interaction energies of gas-phase ion/protein-like model compound clusters, and the experimental solvation free-energies of the cations in liquids. The resulting models display significant improvements relative to the fixed-atomic-charge additive CHARMM C36 force field, particularly in their ability to reproduce the many-body electrostatic nonadditivity effects estimated from ab initio calculations. The analysis clarifies the fundamental limitations of the pairwise additivity assumption inherent in classical fixed-charge force fields, and shows its dramatic failures in the case of Ca²⁺ binding sites. These optimized polarizable models, amenable to computationally efficient large-scale MD simulations, set a firm foundation and offer a powerful avenue to study the roles of the ions in soluble and membrane transport proteins.

Aseptic meningitis outbreak associated with echovirus 30 among high school football players--Los Angeles County, California, 2014

On August 4, 2014, the Acute Communicable Disease Control Program of the Los Angeles County Department of Public Health received a report of three aseptic meningitis cases among football players at a county high school. An investigation was conducted to determine the extent of the outbreak, identify potential exposures, and recommend control measures. An outbreak-associated aseptic meningitis case was defined as an illness of any team or family member with onset during July 28-August 11 with 1) cerebrospinal fluid pleocytosis and negative bacterial culture or 2) an emergency department visit with headache, fever, and stiff neck. Ten cases were identified; nine in males, and one in a female; patient ages ranged from 13 to 17 years. All the patients sought care at an emergency department, and five were hospitalized, resulting in 12 total hospital days. All 10 patients have recovered. Eight patients were football players, and two were siblings of football players. The most affected subgroup was the junior varsity football team, with seven cases out of 57 players (attack rate = 12.3%); the relative risk for aseptic meningitis was higher among players who were linemen than among those who were not linemen (relative risk = 5.4 [p = 0.03]). Of the 10 patients, eight tested positive by polymerase chain reaction for enterovirus, and two were not tested. Echovirus testing was performed at the California Viral and Rickettsial Disease Laboratory. Of the eight specimens testing positive for enterovirus, seven tested positive for echovirus 30, and one specimen could not be typed because of insufficient quantity.

Non-equilibrium dynamics contribute to ion selectivity in the KcsA channel

The ability of biological ion channels to conduct selected ions across cell membranes is critical for the survival of both animal and bacterial cells. Numerous investigations of ion selectivity have been conducted over more than 50 years, yet the mechanisms whereby the channels select certain ions and reject others are not well understood. Here we report a new application of Jarzynski’s Equality to investigate the mechanism of ion selectivity using non-equilibrium molecular dynamics simulations of Na⁺ and K⁺ ions moving through the KcsA channel. The simulations show that the selectivity filter of KcsA adapts and responds to the presence of the ions with structural rearrangements that are different for Na⁺ and K⁺. These structural rearrangements facilitate entry of K⁺ ions into the selectivity filter and permeation through the channel, and rejection of Na⁺ ions. A mechanistic model of ion selectivity by this channel based on the results of the simulations relates the structural rearrangement of the selectivity filter to the differential dehydration of ions and multiple-ion occupancy and describes a mechanism to efficiently select and conduct K⁺. Estimates of the K⁺/Na⁺ selectivity ratio and steady state ion conductance for KcsA from the simulations are in good quantitative agreement with experimental measurements. This model also accurately describes experimental observations of channel block by cytoplasmic Na⁺ ions, the “punch through” relief of channel block by cytoplasmic positive voltages, and is consistent with the knock-on mechanism of ion permeation.

Comparison of enzootic risk measures for predicting West Nile disease, Los Angeles, California, USA, 2004-2010

The best model comprised enzootic surveillance data from avian, mosquito, and climate sources.

In Los Angeles, California, USA, 2 epidemics of West Nile virus (WNV) disease have occurred since WNV was recognized in 2003. To assess which measure of risk was most predictive of human cases, we compared 3 measures: the California Mosquito-Borne Virus Surveillance and Response Plan Assessment, the vector index, and the Dynamic Continuous-Area Space-Time system. A case–crossover study was performed by using symptom onset dates from 384 persons with WNV infection to determine their relative environmental exposure to high-risk conditions as measured by each method. Receiver-operating characteristic plots determined thresholds for each model, and the area under the curve was used to compare methods. We found that the best risk assessment model for human WNV cases included surveillance data from avian, mosquito, and climate sources.

Babesiosis acquired through blood transfusion, California, USA

Babesiosis was reported in a California resident who received a transfusion of blood products collected in the disease-endemic northeastern region of the United States. Babesiosis should be considered year-round in the diagnosis of febrile and afebrile patients with abnormal blood cell counts who have received blood products from disease-endemic areas.

Testing the long term stability of vancomycin ophthalmic solution

Some patients with a keratoprosthesis (artificial cornea) are required to use prophylactic vancomycin ophthalmic solution daily for life to prevent infection, a regimen which has proven to be highly successful. The objective of this study was to determine whether such vancomycin solutions would remain stable at room temperature for an extended period of time, beyond that suggested by available published stability data and used in current practice. By relaxing the storage requirement and extending the expiration date of this solution, it was hoped that patient adherence and satisfaction would increase. The studied vancomycin ophthalmic solutions were compounded at the Massachusetts Eye and Ear Infirmary, Department of Pharmacy Services, Boston, Massachusetts, and were sent to an outside laboratory for high-performance liquid chromatography potency testing at predefined time points. Vancomycin 14-mg/mL ophthalmic solution compounded with 0.005% benzalkonium retains potency for at least 60 days at room temperature and 6 months frozen. Extending the beyond-use dating of vancomycin may lead to improved patient adherence by lowering costs and increasing convenience of storage and shipment of the medication.

Murine typhus: an unrecognized suburban vectorborne disease

Murine typhus, an acute febrile illness caused by Rickettsia typhi, is distributed worldwide. Mainly transmitted by the fleas of rodents, it is associated with cities and ports where urban rats (Rattus rattus and Rattus norvegicus) are abundant. In the United States, cases are concentrated in suburban areas of Texas and California. Contrary to the classic rat-flea-rat cycle, the most important reservoirs of infection in these areas are opossums and cats. The cat flea, Ctenocephalides felis, has been identified as the principal vector. In Texas, murine typhus cases occur in spring and summer, whereas, in California, cases have been documented in summer and fall. Most patients present with fever, and many have rash and headache. Serologic testing with the indirect immunofluorescence assay is the preferred diagnostic method. Doxycycline is the antibiotic of choice and has been shown to shorten the course of illness.

Elemental and configural learning and the perception of odorant mixtures by the spiny lobster Panulirus argus

The present study used a conditioning assay to investigate if the type of learning task that spiny lobsters (Panulirus argus) were required to perform influenced the way that they perceived odorant mixtures. Mixtures were composed of 2 food-related compounds (adenosine-5'-monophosphate, betaine, or L-glutamate) at concentrations that produced the same duration of searching behavior in unconditioned animals. Aversive conditioning of search behavior coupled with generalization testing was used to evaluate perceptual similarity between related mixtures. When animals were conditioned to stop searching to a binary mixture AX, they did not generalize significantly from this mixture to either of its components (A or X), or to a binary mixture containing one novel component (AY). However, when lobsters were conditioned to avoid AX but to continue responding to AY, they generalized between AX and X and between AY and Y. The results support the hypothesis that altering the salience of a mixture's components by giving them different reinforcement contingencies changed the way that the mixtures were perceived. As a result of such conditioning, animals perceived the mixture's components as separate elements, rather than as a configuration, and, as a consequence, animals generalized between binary mixtures and their most salient or predictive components.

Requirement for the orphan steroid receptor Nur77 in apoptosis of T-cell hybridomas

Apoptosis is a phenomenon observed during development of many cell types in many organisms. It is an internal, programmed cell death characterized by DNA fragmentation into nucleosome-size pieces. Anti-CD3-induced apoptosis in T-cell hybridomas and immature thymocytes requires new gene transcription and may be related to negative selection during T-cell development. Using subtractive hybridization, we isolated a complementary DNA clone encoding the orphan steroid receptor Nur77 (refs 7-9). It shows different patterns of messenger RNA induction between apoptotic and stimulated T cells. We report here the use of gel shift analysis to demonstrate that the Nur77 protein is present at high levels in apoptotic T-cell hybridomas and apoptotic thymocytes, but not in growing T cells or stimulated splenocytes. A Nur77 dominant negative protected T-cell hybridomas from activation-induced apoptosis. Hence Nur77 is necessary for induced apoptosis in T-cell hybridomas.