Use of Testing for West Nile Virus and Other Arboviruses

Recent insights on pattern recognition receptors and the interplay of innate immune responses against West Nile Virus infection

The recent outbreaks of neurotropic West Nile Virus (WNV) in humans are of grave public health concern, requiring a thorough understanding of the host immune response to develop effective therapeutic interventions. Innate immunity contributes to the primary immune response against WNV infection aimed at controlling and eliminating the virus from the body. As soon as WNV infects the body, pattern recognition receptors (PRRs) recognize viral pathogen-associated molecular patterns, particularly viral RNA, and initiate innate immune responses. This review explores the diverse PRRs in sensing WNV infection and orchestrating immune defenses. Specifically, this paper reviews the role of PRRs in WNV infection, encompassing both findings from mouse models and current clinical studies. Activation of PRRs triggers signaling pathways that induce the expression of antiviral proteins to inhibit viral replication. Understanding the intricacies of the immune response is crucial for developing effective vaccines and therapeutic interventions against WNV infection.

Seroprevalence of West Nile Virus in Tampa Bay Florida Patients Admitted to Hospital during 2020-2021 for Respiratory Symptoms

West Nile virus (WNV) is an arbovirus spread primarily by Culex mosquitoes, with humans being a dead-end host. WNV was introduced to Florida in 2001, with 467 confirmed cases since. It is estimated that 80 percent of cases are asymptomatic, with mild cases presenting as a non-specific flu-like illness. Currently, detection of WNV in humans occurs primarily in healthcare settings via RT-PCR or CSF IgM when patients present with severe manifestations of disease including fever, meningitis, encephalitis, or acute flaccid paralysis. Given the short window of detectable viremia and requirement for CSF sampling, most WNV infections never receive an official diagnosis. This study utilized enzyme-linked immunosorbent assay (ELISA) to detect WNV IgG antibodies in 250 patient serum and plasma samples collected at Tampa General Hospital during 2020 and 2021. Plaque reduction neutralization tests were used to confirm ELISA results. Out of the 250 patients included in this study, 18.8% of them were IgG positive, consistent with previous WNV exposure. There was no relationship between WNV exposure and age or sex.

The clinical epidemiology, management, and outcomes of patients diagnosed with encephalitis in North Carolina, 2015-2020

IMPORTANCE

Despite the relatively high mortality and the difficulty in diagnosis, nearly one-third of patients hospitalized with a documented diagnosis of encephalitis did not undergo a lumbar puncture (LP). When an LP was performed, pathogen-specific testing was greatly underutilized. Infectious etiologies were most common, but over 40% of cases were idiopathic at discharge. These findings suggest that there is a substantial opportunity to improve the quality of care through more accurate and timely diagnosis.

The utility of a Bayesian predictive model to forecast neuroinvasive West Nile virus disease in the United States of America, 2022

Arboviruses (arthropod-borne-viruses) are an emerging global health threat that are rapidly spreading as climate change, international business transport, and landscape fragmentation impact local ecologies. Since its initial detection in 1999, West Nile virus has shifted from being a novel to an established arbovirus in the United States of America. Subsequently, more than 25,000 cases of West Nile neuro-invasive disease have been diagnosed, cementing West Nile virus as an arbovirus of public health importance. Given its novelty in the United States of America, high-risk ecologies are largely underdefined making targeted population-level public health interventions challenging. Using the Centers for Disease Control and Prevention ArboNET neuroinvasive West Nile virus data from 2000-2021, this study aimed to predict neuroinvasive West Nile virus human cases at the county level for the contiguous USA using a spatio-temporal Bayesian negative binomial regression model. The model includes environmental, climatic, and demographic factors, as well as the distribution of host species. An integrated nested Laplace approximation approach was used to fit our model. To assess model prediction accuracy, annual counts were withheld, forecasted, and compared to observed values. The validated models were then fit to the entire dataset for 2022 predictions. This proof-of-concept mathematical, geospatial modelling approach has proven utility for national health agencies seeking to allocate funding and other resources for local vector control agencies tackling West Nile virus and other notifiable arboviral agents.

Viral meningitis and encephalitis: an update

PURPOSE OF REVIEW

The most common infectious etiologies of meningitis and encephalitis are viruses. In this review, we will discuss current epidemiology, prevention, diagnosis, and treatment of the most common causes of viral meningitis and encephalitis worldwide.

RECENT FINDINGS

Viral meningitis and encephalitis are increasingly diagnosed as molecular diagnostic techniques and serologies have become more readily available worldwide but recent progress in novel antiviral therapies remains limited. Emerging and re-emerging viruses that have caused endemic or worldwide outbreaks or epidemics are arboviruses (e.g., West Nile virus, Japanese encephalitis, Tick borne encephalitis, Dengue, Zika, Toscana), enteroviruses (e.g., Enterovirus 71, Enterovirus D68), Parechoviruses, respiratory viruses [e.g., severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza, metapneumoviruses, measles, mumps], and herpes viruses [e.g., herpes simplex virus (HSV) type 1 (HSV-1), HSV-2, human herpes (HV) 6, varicella zoster virus (VZV)]. Future efforts should concentrate in increasing availability for those viruses with effective vaccination [e.g., Japanese encephalitis, Tick borne encephalitis, varicella zoster viruses, SARS-CoV-2, influenza], prompt initiation of those with encephalitis with treatable viruses (e.g., HSV-1, VZV), increasing the diagnostic yield by using novel techniques such as metagenomic sequencing and avoiding unnecessary antibiotics in those with viral meningitis or encephalitis.

SUMMARY

We review the current epidemiology, clinical presentation, diagnosis, and treatment of the common causative agents of viral meningitis and encephalitis worldwide.

Novel tools to study West Nile virus NS3 protease activity

West Nile Virus (WNV) belongs to a group of pathogenic viruses called flaviviruses. West Nile virus infection can be mild, causing so-called West Nile Fever (WNF) or severe neuroinvasive form of the disease (WNND), and ultimately even death. There are currently no known medications to prevent West Nile virus infection. Only symptomatic treatment is used. To date, there are no unequivocal tests enabling a quick and unambiguous assessment of WN virus infection. The aim of the research was to obtain specific and selective tools for determining the activity of the West Nile virus serine proteinase. Using the methods of combinatorial chemistry with iterative deconvolution, the substrate specificity of the enzyme in non-primed and primed positions was determined. The FRET ABZ-Ala-Lys-Gln-Arg-Gly-Gly-Thr-Tyr(3-NO₂)-NH₂ substrate was obtained, characterized by kinetic parameters (KM = 4.20 ± 0.32 × 10^-5 M) as for the majority of proteolytic enzymes. The obtained sequence was used to develop and synthesize highly sensitive functionalized quantum dot-based protease probes (QD). A QD WNV NS3 protease probe was obtained to detect an increase in fluorescence of 0.05 nmol enzyme in the assay system. This value was at least 20 times lower than that observed with the optimized substrate. The obtained result may be the basis for further research on the potential use of the WNV NS3 protease in the diagnosis of West Nile virus infection.

A Potential Role for Substance P in West Nile Virus Neuropathogenesis

Of individuals who develop West Nile neuroinvasive disease (WNND), ~10% will die and >40% will develop long-term complications. Current treatment recommendations solely focus on supportive care; therefore, we urgently need to identify novel and effective therapeutic options. We observed a correlation between substance P (SP), a key player in neuroinflammation, and its receptor Neurokinin-1 (NK1R). Our study in a wild-type BL6 mouse model found that SP is upregulated in the brain during infection, which correlated with neuroinvasion and damage to the blood−brain barrier. Blocking the SP/NK1R interaction beginning at disease onset modestly improved survival and prolonged time to death in a small pilot study. Although SP is significantly increased in the brain of untreated WNND mice when compared to mock-infected animals, levels of WNV are unchanged, indicating that SP likely does not play a role in viral replication but may mediate the immune response to infection. Additional studies are necessary to define if SP plays a mechanistic role or if it represents other mechanistic pathways.

Diagnostic approach and update on encephalitis

PURPOSE OF REVIEW

The present article gives an update and outlines the fundamental principles of clinical reasoning and a diagnostic approach to a patient suspected to have acute encephalitis.

RECENT FINDINGS

Encephalitis remains to be associated with significant mortality and neurological morbidity. Unfortunately, the etiologic diagnosis remains elusive for the majority of the patients with encephalitis preventing targeted therapies. Clinicians could utilize clues such as duration of symptoms, exposure history, cerebrospinal fluid profile, neuroimaging findings and locations, and entertain certain opportunistic infections in immunosuppressed individuals. A comprehensive diagnostic for the most common viral and autoimmune etiologies should be systematically done and prompt empiric antiviral therapy should be started. Evaluation and therapy for autoimmune etiologies should be done for patients with a negative viral work up. Brain biopsy and metagenomic sequencing should be considered for patients with unknown etiologies that are clinically worsening.

SUMMARY

Encephalitis remains with unacceptable mortality and morbidity with the most common etiologies being idiopathic. A comprehensive diagnostic work up and prompt antiviral and autoimmune therapies are of paramount importance to improve the outcomes of this devastating disease.

Neurology of Acute Viral Infections

As specialists in acute neurology, neurohospitalists are often called upon to diagnose and manage acute viral infections affecting the nervous system. In this broad review covering the neurology of several acute viral infections, our aim is to provide key diagnostic and therapeutic pearls of practical use to the busy neurohospitalist. We will review acute presentations, diagnosis, and treatment of human herpesviruses, arboviruses, enteroviruses, and some vaccine-preventable viruses. The neurological effects of coronaviruses, including COVID-19, are not covered in this review.

Comorbid conditions as risk factors for West Nile neuroinvasive disease in Ontario, Canada: a population-based cohort study

West Nile neuroinvasive disease (WNND) is a severe neurological illness that can result from West Nile virus (WNV) infection, with long-term disability and death being common outcomes. Although WNV arrived in North America over two decades ago, risk factors for WNND are still being explored. The objective of this study was to identify WNND comorbid risk factors in the Ontario population using a retrospective, population-based cohort design. Incident WNV infections from laboratory records between 1 January 2002 – 31 December 2012 were individually-linked to health administrative databases to ascertain WNND outcomes and comorbid risk factors. WNND incidence was compared among individuals with and without comorbidities using risk ratios (RR) calculated with log binomial regression.

Three hundred and forty-five individuals developed WNND (18.3%) out of 1884 WNV infections. West Nile encephalitis was driving most associations with comorbidities. Immunocompromised (aRR 2.61 [95% CI 1.23–4.53]) and male sex (aRR 1.32 [95% CI 1.00–1.76]) were risk factors for encephalitis, in addition to age, for which each 1-year increase was associated with a 2% (aRR 1.02 [95% CI 1.02–1.03]) relative increase in risk. Our results suggest that individuals living with comorbidities are at higher risk for WNND, in particular encephalitis, following WNV infection.

Zoonotic Disease Testing Practices in Pediatric Patients with Meningitis and Encephalitis in a Subtropical Region

Emerging vector-borne and zoonotic pathogens can cause neuroinvasive disease in children; utilization of appropriate diagnostic testing can be low, hindering diagnosis and clinical management of these cases. We must understand factors that influence healthcare providers’ decisions to order diagnostic testing. We reviewed medical charts for pediatric meningitis and encephalitis patients (90 days–18 years) between 2010 and 2017 and analyzed variables associated with testing for known neuroinvasive zoonotic pathogens in the southern United States: West Nile virus (WNV), Bartonella spp., and Rickettsia spp. Among 620 cases of meningitis and encephalitis, ~1/3 (n = 209, 34%) were tested for WNV. Fewer cases were tested for Bartonella (n = 77, 12%) and Rickettsia (n = 47, 8%). Among those tested, 14 (7%) WNV, 7 (9%) Bartonella, and 6 (13%) Rickettsia cases were identified. Factors predicting testing were similar between all agents: clinical presentation of encephalitis, focal neurologic symptoms, new onset seizure, and decreased Glasgow Coma Scale on admission. Cases with a history of arthropod contact were more likely to be tested; however, we did not see an increase in testing during the summer season, when vector exposure typically increases. While our test utilization was higher than that reported in other studies, improvement is needed to identify zoonotic causes of neuroinvasive diseases.

Distinguishing cytomegalovirus meningoencephalitis from other viral central nervous system infections

BACKGROUND

Hallmarks of cytomegalovirus (CMV) meningoencephalitis include fever, altered mental status, or meningismus with pleocytosis, elevated protein and hypoglycorrhachia on cerebrospinal fluid (CSF) analysis. Magnetic resonance imaging may show ventriculitis, ependymitis or periventricular enhancement. Studies are limited comparing clinical and laboratory characteristics to other viral etiologies.

OBJECTIVES

This multi-center, retrospective cohort analysis reviewed patients with CMV meningitis or encephalitis and compared clinical features, laboratory findings and outcomes to the most common viral causes of meningoencephalitis.

STUDY DESIGN

Patients with encephalitis or aseptic meningitis and detectable genetic material by polymerase chain reaction were identified. Clinical characteristics, laboratory findings and neuroimaging were collected from the electronic medical record. Data analysis was performed comparing CMV to other viral etiologies.

RESULTS

485 patients were evaluated and included cases of CMV (n = 36) which were compared with herpes simplex virus (n = 114), enterovirus (n = 207), varicella zoster virus (n = 41) and West Nile virus (n = 81). Human immunodeficiency virus (HIV) infection was seen more frequently in CMV infection compared with all other viral etiologies. Clinical presentations and CSF findings of other viral etiologies differ compared with CMV. Hypoglycorrhacia occurred more often with CMV compared with other viral pathogens. Outcomes were significantly worse compared with enterovirus, herpes simplex virus and varicella zoster virus but not West Nile virus.

CONCLUSIONS

CMV meningoencephalitis occurs most often in patients with HIV and encephalitis occurs more frequently than meningitis. Clinical and laboratory findings differ compared with other viral etiologies and can support consideration of CMV in the differential diagnosis of patients with meningoencephalitis.

A 20-year historical review of West Nile virus since its initial emergence in North America: Has West Nile virus become a neglected tropical disease?

After the unexpected arrival of West Nile virus (WNV) in the United States in 1999, the mosquito-borne virus quickly spread throughout North America. Over the past 20 years, WNV has become endemic, with sporadic epizootics. Concerns about the economic impact of infection in horses lead to the licensure of an equine vaccine as early as 2005, but few advances regarding human vaccines or treatments have since been made. There is a high level of virus transmission in hot/humid, subtropical climates, and high morbidity that may disproportionately affect vulnerable populations including the homeless, elderly, and those with underlying health conditions. Although WNV continues to cause significant morbidity and mortality at great cost, funding and research have declined in recent years. These factors, combined with neglect by policy makers and amenability of control measures, indicate that WNV has become a neglected tropical disease.

Virus infection of the CNS disrupts the immune-neural-synaptic axis via induction of pleiotropic gene regulation of host responses

Treatment for many viral infections of the central nervous system (CNS) remains only supportive. Here we address a remaining gap in our knowledge regarding how the CNS and immune systems interact during viral infection. By examining the regulation of the immune and nervous system processes in a nonhuman primate model of West Nile virus neurological disease, we show that virus infection disrupts the homeostasis of the immune-neural-synaptic axis via induction of pleiotropic genes with distinct functions in each component of the axis. This pleiotropic gene regulation suggests an unintended off-target negative impact of virus-induced host immune responses on the neurotransmission, which may be a common feature of various viral infections of the CNS.

Unique Cytokine Response in West Nile Virus Patients Who Developed Chronic Kidney Disease: A Prospective Cohort Study

West Nile virus (WNV) is a widespread and devastating disease, especially in those who develop neuroinvasive disease. A growing body of evidence describes sequelae years after infection, including neurological complications and chronic kidney disease (CKD). Eighty-nine out of 373 WNV-positive cases were followed for approximately two years and compared to 127 WNV-negative controls with and without CKD. Adjusted risk ratios (aRRs) were calculated via a log binomial regression to determine the impact of WNV exposure and other possible confounders on the likelihood of developing CKD. Cytokine profiles of WNV patients and controls were evaluated to characterize differences and describe potential underlying pathophysiological mechanisms. The associated risk for developing CKD was significantly associated with history of WNV infection (aRR = 1.91, 95% CI 1.13–3.25). Additionally, five distinct cytokines were found to be significantly associated with WNV infection (eotaxin, IL-8, IL-12p70, IP-10, and TNFα) after the p-value was adjusted to <0.0019 due to the Bonferroni correction. These data support that WNV infection is an independent risk factor for CKD, even after accounting for confounding comorbidities. WNV participants who developed CKD had high activity of proinflammatory markers, indicating underlying inflammatory disease. This study provides new insights into CKD resultant of WNV infection.

Infectious and Autoimmune Causes of Encephalitis in Children

BACKGROUND AND OBJECTIVES

Encephalitis can result in neurologic morbidity and mortality in children. Newly recognized infectious and noninfectious causes of encephalitis have become increasingly important over the past decade.

METHODS

We retrospectively reviewed medical records from pediatric patients in Houston diagnosed with encephalitis in both an urban and rural catchment area between 2010 and 2017. We conducted an investigation to understand the etiology, clinical characteristics, and diagnostic testing practices in this population.

RESULTS

We evaluated 231 patients who met the case definition of encephalitis, among which 42% had no recognized etiology. Among those with an identified etiology, the most common were infectious (73; 31%), including viral (n = 51; 22%), with the most frequent being West Nile virus (WNV; n = 12), and bacterial (n = 19; 8%), with the most frequent being Bartonella henselae (n = 7). Among cases of autoimmune encephalitis (n = 60; 26%), the most frequent cause was anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis (n = 31). Autoimmune causes were seen more commonly in female (P < .01) patients. Testing for herpes simplex virus and enterovirus was nearly universal; testing for anti-NMDAR encephalitis, WNV, and Bartonella was less common.

CONCLUSIONS

WNV was the most common infectious cause of encephalitis in our pediatric population despite lower testing frequency for WNV than herpes simplex virus or enterovirus. Increasing testing for anti-NMDAR encephalitis resulted in frequent identification of cases. Increased awareness and testing for WNV and Bartonella would likely result in more identified causes of pediatric encephalitis. Earlier etiologic diagnosis of encephalitides may lead to improve clinical outcomes.

Compliance with international guidelines in adults with encephalitis

Background

Encephalitis is associated with significant neurological disability and mortality. Many guidelines are published for encephalitis management but compliance with them is unknown.

Objectives

To evaluate the appropriate management and compliance to the current guidelines in adults with encephalitis.

Study design

A retrospective multicenter study at 17 hospitals in the Greater Houston area from August 1, 2008 through September 30, 2017. All cases met the definition for possible or probable encephalitis as per the international encephalitis consortium guidelines.

Results

A total of 241 adults (age >17 years) with encephalitis were enrolled. The most common etiologies were unknown (41.9 %), viral (27.8 %) and autoimmune (21.2 %). An adverse clinical outcome was seen in 49 % with 12.4 % in hospital mortality. A high compliance with guidelines (>90 %) was only seen in obtaining a brain computerized tomography (CT) scan, blood cultures and cerebrospinal fluid (CSF) gram stain and culture. A CSF herpes virus simplex (HSV) polymerase chain reaction (PCR) was done in 84 % and only repeated in 14.2 % of patients with an initial negative result. Furthermore, only two-thirds of patients were started empirically on intravenous acyclovir and antibiotics. Evaluation for other etiologies were not uniformly performed: arboviral serologies (57.3 %), CSF anti-N-Methyl-d-Aspartate Receptor (NMDA) receptor antibody (35.7 %), and CSF varicella zoster virus (VZV) PCR (32 %). The highest yield for the tests were arboviral serologies (42 %), anti-NMDA antibodies (41.2 %) and VZV PCR (16.4 %).

Conclusion

The management of encephalitis as per current guidelines is suboptimal leading to underutilization of currently available diagnostic tests and empirical therapy.

Cumulative Incidence of West Nile Virus Infection, Continental United States, 1999-2016

Using reported case data from ArboNET and previous seroprevalence data stratified by age and sex, we conservatively estimate that ≈7 million persons in the United States have been infected with West Nile virus since its introduction in 1999. Our data support the need for public health interventions and improved surveillance.

Epidemiology of Meningitis and Encephalitis in Infants and Children in the United States, 2011-2014

BACKGROUND

Large epidemiologic studies evaluating the etiologies, management decisions and outcomes of infants and children with meningitis and encephalitis in the United States are lacking.

METHODS

Children 0-17 years of age with meningitis or encephalitis as assessed by International Classification of Diseases, Ninth Revision, codes available in the Premier Healthcare Database during 2011-2014 were analyzed.

RESULTS

Six thousand six hundred sixty-five patients with meningitis or encephalitis were identified; 3030 (45.5%) were younger than 1 year of age, 295 (4.4%) were 1-2 years of age, 1460 (21.9%) were 3-9 years of age, and 1880 (28.2%) were 10-17 years of age. Etiologies included enterovirus (58.4%), unknown (23.7%), bacterial (13.0%), noninfectious (3.1%), herpes simplex virus (1.5%), other viruses (0.7%), arboviruses (0.5%) and fungal (0.04%). The majority of patients were male [3847 (57.7%)] and healthy [6094 (91.4%)] with no reported underlying conditions. Most underwent a lumbar puncture in the emergency department [5363 (80%)] and were admitted to the hospital [5363 (83.1%)]. Antibiotic therapy was frequent (92.2%) with children younger than 1 year of age with the highest rates (97.7%). Antiviral therapy was less common (31.1%). Only 539 (8.1%) of 6665 of patients received steroids. Early administration of adjunctive steroids was not associated with a reduction in mortality (P = 0.266). The overall median length of stay was 2 days. Overall mortality rate (0.5%) and readmission rates (<1%) was low for both groups.

CONCLUSION

Meningitis and encephalitis in infants and children in the United States are more commonly caused by viruses and are treated empirically with antibiotic therapy and antiviral therapy in a significant proportion of cases. Adjunctive steroids are used infrequently and are not associated with a benefit in mortality.

A Taxonomic Checklist and Relative Abundance of the Mosquitoes of New York City

This is the 1st time that a comprehensive checklist of the mosquitoes of New York City has been compiled. This list is based on an arrayed collection of 2.3 million mosquitoes trapped and identified from 1,369 locations in the city between 2000 and 2017. Forty-seven species and 6 subspecies were identified belonging to 9 mosquito genera. Culex pipiens was the most prevalent species, most frequently encountered throughout the city. Over time, species diversity in the genus Aedes has increased from 10 species in the 1930s to 23 species in the recent surveys (2000-17). Invasive species Aedes albopictus and Ae. japonicus japonicus, which were rare in 2000, are now well established in all 5 boroughs of the city.

West Nile Virus Outbreak in Houston and Harris County, Texas, USA, 2014

Since 2002, West Nile virus (WNV) has been detected every year in Houston and the surrounding Harris County, Texas. In 2014, the largest WNV outbreak to date occurred, comprising 139 cases and causing 2 deaths. Additionally, 1,286 WNV-positive mosquito pools were confirmed, the most reported in a single mosquito season.

Acute versus subacute community-acquired meningitis: Analysis of 611 patients

Community-acquired meningitis can be classified into acute and subacute presentations by the duration of illness of ≤ or >5 days, respectively. There are currently no studies comparing the clinical features, management decisions, etiologies, and outcomes between acute and subacute presentations.It is a retrospective study of adults with community-acquired meningitis hospitalized in Houston, TX between January 2005 and January 2010. An adverse clinical outcome was defined as a Glasgow Outcome Scale score of ≤4.A total of 611 patients were identified, of which 458 (75%) were acute and 153 subacute (25%). The most common etiologies were unknown in 418 (68.4%), viral in 94 (15.4%), bacterial in 47 (7.7%), fungal in 42 patients (6.9%), and other noninfectious etiologies in 6 (1%). Patients with subacute meningitis were more likely to be immunosuppressed or have comorbidities, had fungal etiologies, and had higher rates of hypoglycorrachia and abnormal neurological findings (P <.05). Patients with an acute presentation were more likely to be treated empirically with intravenous antibiotics and had higher cerebrospinal fluid pleocytosis and serum white blood cell counts (P <.05). On logistic regression, age >65 years and abnormal neurological findings were predictive of an adverse clinical outcome in both acute and subacute meningitis, whereas fever was also a significant prognostic factor in acute meningitis. (P <.05).Acute and subacute meningitis differ in regards to clinical presentations, etiologies, laboratory findings, and management decisions, but did not differ in rates of adverse clinical outcomes. Future studies including thoroughly investigated patients with new diagnostic molecular methods may show different results and outcomes.

Aseptic meningitis in adults and children: Diagnostic and management challenges

BACKGROUND

Aseptic meningitis represents a common diagnostic and management dilemma to clinicians.

OBJECTIVES

To compare the clinical epidemiology, diagnostic evaluations, management, and outcomes between adults and children with aseptic meningitis.

STUDY DESIGN

We conducted a retrospective study from January 2005 through September 2010 at 9 Memorial Hermann Hospitals in Houston, TX. Patients age≥2months who presented with community-acquired aseptic meningitis with a CSF white blood cell count >5cells/mm³ and a negative Gram stain and cultures were enrolled. Patients with a positive cryptococcal antigen, positive blood cultures, intracranial masses, brain abscesses, or encephalitis were excluded.

RESULTS

A total of 509 patients were included; 404 were adults and 105 were children. Adults were most likely to be female, Caucasian, immunosuppressed, have meningeal symptoms (headache, nausea, stiff neck, photophobia) and have a higher CSF protein (P <0.05). In contrast, children were more likely to have respiratory symptoms, fever, and leukocytosis (P <0.05). In 410 (81%) patients, the etiologies remained unknown. Adults were more likely to be tested for and to have Herpes simplex virus and West Nile virus while children were more likely to be tested for and to have Enterovirus (P <0.001). The majority of patients were admitted (96.5%) with children receiving antibiotic therapy more frequently (P <0.001) and adults receiving more antiviral therapy (P=0.001). A total of 384 patients (75%) underwent head CT scans and 125 (25%) MRI scans; all were normal except for meningeal enhancement. All patients had a good clinical outcome at discharge.

DISCUSSION

Aseptic meningitis in adults and children represent a management challenge as etiologies remained unknown for the majority of patients due to underutilization of currently available diagnostic techniques.