A cluster study of predictors of severe West Nile virus infection

Ocular manifestations of West Nile virus

PURPOSE OF REVIEW

Over the past two decades, the ophthalmic manifestations of West Nile virus have been more clearly established in the literature. This review aims to summarize its diagnosis and pathogenesis, with a focus on its clinical appearance, characteristic imaging features, and management.

RECENT FINDINGS

Ocular manifestations of West Nile virus present early in the disease course and are more common in cases with severe neurological involvement. The use of optical coherence tomography (OCT), optical coherence tomography angiography (OCT-A), fundus autofluorescence (FAF), fluorescein angiogram (FA), and indocyanine green angiography (ICGA) can aid in its diagnosis and management.

SUMMARY

West Nile virus infection may present with ocular findings that include anterior uveitis, vitritis, retinitis, chorioretinitis, and optic neuropathy; visual prognosis can range from excellent to poor depending on severity of involvement and the presence of secondary complications, such as occlusive vasculitis and macular ischemia. Diagnosis may be aided by multimodal imaging assessment. The ophthalmologist should have a high clinical suspicion for ocular involvement in cases of severe systemic disease.

Ocular Manifestations of Flavivirus Infections

Flaviviruses are a group of positive-sense, single-stranded RNA viruses predominantly transmitted by arthropods (mainly mosquitoes) that cause severe endemic infections and epidemics on a global scale. They represent a major cause of systemic morbidity and death and are expanding worldwide. Among this group, dengue fever, the West Nile virus, yellow fever, Japanese Encephalitis, and, recently, the Zika virus have been linked to a spectrum of ocular manifestations. These manifestations encompass subconjunctival hemorrhages and conjunctivitis, anterior and posterior uveitis (inclusive of vitritis, chorioretinitis, and retinal vasculitis), maculopathy, retinal hemorrhages, and optic neuritis. Clinical diagnosis of these infectious diseases is primarily based on epidemiological data, history, systemic symptoms and signs, and the pattern of ocular involvement. Diagnosis confirmation relies on laboratory testing, including RT-PCR and serological testing. Ocular involvement typically follows a self-limited course but can result in irreversible visual impairment. Effective treatments of flavivirus infections are currently unavailable. Prevention remains the mainstay for arthropod vector and zoonotic disease control. Effective vaccines are available only for the yellow fever virus, dengue virus, and Japanese Encephalitis virus. This review comprehensively summarizes the current knowledge regarding the ophthalmic manifestations of the foremost flavivirus-associated human diseases.

Re-Introduction of West Nile Virus Lineage 1 in Senegal from Europe and Subsequent Circulation in Human and Mosquito Populations between 2012 and 2021

West Nile virus (WNV) is a virus of the Japanese encephalitis antigenic complex and belongs to the family Flaviviridae of the genus flavivirus. The virus can cause infection in humans which in most cases is asymptomatic, however symptomatic cases exist and the disease can be severe causing encephalitis and meningoencephalitis. The virus is maintained in an enzootic cycle involving mosquitoes and birds, humans and other mammals such as horses can be accidental hosts. A mosquito-based arbovirus surveillance system and the sentinel syndromic surveillance network (4S) have been in place since 1988 and 2015 respectively, to better understand the transmission dynamics of arboviruses including WNV in Senegal. Arthropod and human samples have been collected from the field and analysed at Institut Pasteur de Dakar using different methods including RT-PCR, ELISA, plaque reduction neutralization test and viral isolation. RT-PCR positive samples have been analysed by Next Generation Sequencing. From 2012 to 2021, 7912 samples have been analysed and WNV positive cases have been detected, 20 human cases (19 IgM and 1 RT-PCR positive cases) and 41 mosquito pools. Phylogenetic analyzes of the sequences of complete genomes obtained showed the circulation of lineage 1a, with all these recent strains from Senegal identical to each other and very close to strains isolated from horse in France in 2015, Italy and Spain. Our data showed lineage 1a endemicity in Senegal as previously described, with circulation of WNV in humans and mosquitoes. Phylogenetic analyzes carried out with the genome sequences obtained also revealed exchanges of WNV strains between Europe and Senegal which could be possible via migratory birds. The surveillance systems that have enabled the detection of WNV in humans and arthropods should be extended to animals in a one-health approach to better prepare for global health threats.

Study on acupuncture in the treatment of painful diabetic peripheral neuropathy based on rs-fMRI: a protocol for systematic review and meta-analysis

INTRODUCTION

Studies have shown that acupuncture has significant therapeutic effects on painful diabetic peripheral neuropathy (PDPN) yet the precise mechanism of action underpinning these effects remains controversial. Resting-state functional MRI (rs-fMRI) is an advanced imaging technique that can be used to monitor changes in the activity of the brain, particularly in PDPN. However, the data from several studies remain inconclusive and there is currently no systematic review and meta-analysis for the use of rs-fMRI in PDPN.

METHODS AND ANALYSIS

In this study, we will select all eligible studies published on or before 30 June 2021. Four English and four Chinese databases will be searched, specifically, PubMed, Embase, Web of Science, Cochrane Library, China National Knowledge Infrastructure, WanFang database, China Science Technology Journal Database (VIP) and China Doctor/Master Dissertations Full-text Database. Only clinical trials and the first cycle of a cross-over trial linked to acupuncture for PDPN will be included in the analysis. The main outcomes include the amplitude of low-frequency fluctuation, regional homogeneity, functional connectivity of the brain, bilateral superficial peroneal nerve sensory nerve conduction velocity, bilateral dorsal current perception threshold values and the degree of subjective pain. The secondary outcomes include biochemical indicators, the degree of depression and anxiety and changes in efficiency. The study selection, data extraction and risk of bias assessment will be performed by two investigators. For statistical analyses, Review Manager V.5.4 software will be used. If necessary, heterogeneity testing, data synthesis, and subgroup analysis will be performed.

ETHICS AND DISSEMINATION

Our systematic review and meta-analysis will be based on published literature for data extraction and will not include the use of individual patient data and so no ethical approval required.

PROSPERO REGISTRATION NUMBER

CRD42021211644.

West Nile Virus: An Update on Pathobiology, Epidemiology, Diagnostics, Control and "One Health" Implications

West Nile virus (WNV) is an important zoonotic flavivirus responsible for mild fever to severe, lethal neuroinvasive disease in humans, horses, birds, and other wildlife species. Since its discovery, WNV has caused multiple human and animal disease outbreaks in all continents, except Antarctica. Infections are associated with economic losses, mainly due to the cost of treatment of infected patients, control programmes, and loss of animals and animal products. The pathogenesis of WNV has been extensively investigated in natural hosts as well as in several animal models, including rodents, lagomorphs, birds, and reptiles. However, most of the proposed pathogenesis hypotheses remain contentious, and much remains to be elucidated. At the same time, the unavailability of specific antiviral treatment or effective and safe vaccines contribute to the perpetuation of the disease and regular occurrence of outbreaks in both endemic and non-endemic areas. Moreover, globalisation and climate change are also important drivers of the emergence and re-emergence of the virus and disease. Here, we give an update of the pathobiology, epidemiology, diagnostics, control, and “One Health” implications of WNV infection and disease.

Ocular Manifestations of Emerging Flaviviruses and the Blood-Retinal Barrier

Despite flaviviruses remaining the leading cause of systemic human infections worldwide, ocular manifestations of these mosquito-transmitted viruses are considered relatively uncommon in part due to under-reporting. However, recent outbreaks of Zika virus (ZIKV) implicated in causing multiple ocular abnormalities, such as conjunctivitis, retinal hemorrhages, chorioretinal atrophy, posterior uveitis, optic neuritis, and maculopathies, has rejuvenated a significant interest in understanding the pathogenesis of flaviviruses, including ZIKV, in the eye. In this review, first, we summarize the current knowledge of the major flaviviruses (Dengue, West Nile, Yellow Fever, and Japanese Encephalitis) reported to cause ocular manifestations in humans with emphasis on recent ZIKV outbreaks. Second, being an immune privilege organ, the eye is protected from systemic infections by the presence of blood-retinal barriers (BRB). Hence, we discuss how flaviviruses modulate retinal innate response and breach the protective BRB to cause ocular or retinal pathology. Finally, we describe recently identified infection signatures of ZIKV and discuss whether these system biology-predicted genes or signaling pathways (e.g., cellular metabolism) could contribute to the pathogenesis of ocular manifestations and assist in the development of ocular antiviral therapies against ZIKV and other flaviviruses.

Prevalence of chronic comorbidities in dengue fever and West Nile virus: A systematic review and meta-analysis

Background

Flavivirus diseases such as dengue fever (DENV), West Nile virus (WNV), Zika and yellow fever represent a substantial global public health concern. Preexisting chronic conditions such as cardiovascular diseases, diabetes, obesity, and asthma were thought to predict risk of progression to severe infections.

Objective

We aimed to quantify the frequency of chronic comorbidities in flavivirus diseases to provide an estimate for their prevalence in severe and non-severe infections and examine whether chronic diseases contribute to the increased risk of severe viral expression.

Methods

We conducted a comprehensive search in PubMed, Ovid MEDLINE(R), Embase and Embase Classic and grey literature databases to identify studies reporting prevalence estimates of comorbidities in flavivirus diseases. Study quality was assessed with the risk of bias tool. Age-adjusted odds ratios (ORs) were estimated for severe infection in the presence of chronic comorbidities.

Results

We identified 65 studies as eligible for inclusion for DENV (47 studies) and WNV (18 studies). Obesity and overweight (i.e., BMI> 25 kg/m², prevalence: 24.5%, 95% CI: 18.6–31.6%), hypertension (17.1%, 13.3–21.8%) and diabetes (13.3%, 9.3–18.8%) were the most prevalent comorbidities in DENV. However, hypertension (45.0%, 39.1–51.0%), diabetes (24.7%, 20.2–29.8%) and heart diseases (25.6%, 19.5–32.7%) were the most prevalent in WNV. ORs of severe flavivirus diseases were about 2 to 4 in infected patients with comorbidities such as diabetes, hypertension and heart diseases. The small number of studies in JEV, YFV and Zika did not permit estimating the prevalence of comorbidities in these infections.

Conclusion

Higher prevalence of chronic comorbidities was found in severe cases of flavivirus diseases compared to non-severe cases. Findings of the present study may guide public health practitioners and clinicians to evaluate infection severity based on the presence of comorbidity, a critical public health measure that may avert severe disease outcome given the current dearth of clear prevention practices for some flavivirus diseases.

West Nile Virus Retinopathy and Associations with Long Term Neurological and Neurocognitive Sequelae

West Nile virus (WNV) has emerged as an important vector-borne pathogen in North America, with more than 3 million estimated to have been infected. Retinopathy from WNV infection has been previously reported in acute cases, though those prior reports did not evaluate the risk of retinopathy based on clinical severity of neurologic disease. The purpose of this cross-sectional study was to perform comprehensive ophthalmological and neurological examinations on 111 patients with a history of West Nile virus infection and describe the ocular manifestations. Out of 111 patients, 27 (24%) had evidence for West Nile virus associated retinopathy (WNVR); this observation was higher (49%) in those patients who initially presented with encephalitis. Individuals with WNVR had more frequent involvement of the macula and peripheral involvement compared to those patients without WNVR (p<0.05). WNVR was also associated with a greater likelihood of abnormal reflexes on neurological exam, poorer learning, greater dependence in activities of daily living, and lower quality of life (p<0.05). WNVR was seen more frequently in elderly patients (age > 60 years), and was associated with higher rates of diabetes mellitus and a history of encephalitis (p<0.05). A multivariable logistic regression revealed that only a history of encephalitis was independently associated with WNVR [Adjusted Odds Ratio = 4.9 (1.8–13.2); p = 0.001]. Our study found that WNVR occurs in one fourth of patients with a history of WNV infection and is more frequently observed in those with apparent severe neurological sequelae (e.g., encephalitis). The clinical relevance of WNVR was supported by its associations with dependence in activities of daily living and lower quality of life. This unique evaluation of WNV patients included fundoscopic examinations and their associations with neurologic impairment. Our findings can be used during ophthalmological consultation for the evaluation, treatment and rehabilitation phases of care for WNV patients.

Anterior ischemic optic neuropathy following dengue fever

Dengue fever is caused by a flavivirus. This infection is endemic in the tropics and warm temperate regions of the world. Ocular manifestations of dengue fever include subconjunctival, vitreous, and retinal haemorrhages; posterior uveitis; optic neuritis; and maculopathies, haemorrhage, and oedema. However anterior ischemic optic neuropathy is a rare presentation. Optic nerve ischemia most frequently occurs at the optic nerve head, where structural crowding of nerve fibers and reduction of the vascular supply may combine to impair perfusion to a critical degree and produce optic disc oedema. Here we present a case of anterior ischemic optic neurapathy associated with dengue fever.

The human hookworm vaccine: recent updates and prospects for success

Approximately 440 million people globally are afflicted by hookworm disease, one of the 17 WHO-recognized neglected tropical diseases (NTDs). The iron-deficiency anaemia attributed to this disease contributes to at least 3.2 million disability-adjusted life years (DALYs) according to the Global Burden of Disease Study 2010. The current WHO-recommended control strategies rely primarily on mass drug administration or preventive chemotherapy. However, evidence is starting to accumulate confirming that preventive chemotherapy alone will not be sufficient to reduce the reinfection rates of hookworm, especially in areas of heavy transmission. The global health and research community is currently building a consensus stressing the need for the advancement of research and innovation to bridge the gaps and identify new public health interventions for diseases such as hookworm and other NTDs. This paper presents the strategies used by the Sabin Vaccine Institute Product Development Partnership (Sabin PDP) in their ongoing endeavour for the development of a human hookworm vaccine. Recent updates and the current prospects for success of an effective human hookworm vaccine, as a new technology to be linked to or combined with drug interventions, are presented.

MR-guided focused ultrasound: a new generation treatment of Parkinson's disease, essential tremor and neuropathic pain

The application of high intense focused ultrasound (HIFU) is currently the subject of many experimental and clinical trials. The combination of HIFU with MRI guidance known as MR-guided focused ultrasound (MRgFUS) appears to be particularly promising to ablate tissues located deep in the brain. The method can be the beginning of interventional neurology and an important alternative to neurosurgery. Studies conducted to date show the effectiveness of the method both in chronic diseases and in emergency cases. The safety and effectiveness of this method have been observed in parkinsonian and essential tremor as well as in neuropathic pain. The procedure does not require anaesthesia. Ionizing radiation is not used and there is no risk of cumulative dose. Such advantages may result in low complication rates and medical justification for further development of MRgFUS.

Reduced immune cell infiltration and increased pro-inflammatory mediators in the brain of Type 2 diabetic mouse model infected with West Nile virus

Background

Diabetes is a significant risk factor for developing West Nile virus (WNV)-associated encephalitis (WNVE) in humans, the leading cause of arboviral encephalitis in the United States. Using a diabetic mouse model (db/db), we recently demonstrated that diabetes enhanced WNV replication and the susceptibility of mice to WNVE. Herein, we have examined immunological events in the brain of wild type (WT) and db/db mice after WNV infection. We hypothesized that WNV-induced migration of protective leukocytes into the brain is attenuated in the presence of diabetes, leading to a high viral load in the brain and severe disease in diabetic mice.

Methods

Nine-week old C57BL/6 WT and db/db mice were infected with WNV. Leukocyte infiltration, expression of cell adhesion molecules (CAM), neuroinflammatory responses, activation of astrocytes, and neuronal death were analyzed using immunohistochemistry, qRT-PCR, flow cytometry, and western blot.

Results

We demonstrate that infiltration of CD45⁺ leukocytes and CD8⁺T cells was significantly reduced in the brains of db/db mice, which was correlated with attenuated expression of CAM such as E-selectin and ICAM-1. WNV infection in db/db mice was associated with an enhanced inflammatory response in the brain. mRNA and protein levels of key chemokines such as CXCL10, CXCL1, CCL2, CCL5, CCL3, and G-CSF, and cytokines such as IL-1β, TNF, IL-6, IFNγ, and IL-1α were significantly elevated in the brains of db/db mice compared to WT mice. Elevated levels of cytokines also correlated with increased astrocytes activation and neuronal damage in the brains of db/db mice.

Conclusion

These data suggest that reduced leukocytes recruitment, in part, due to lower levels of CAM results in failure to clear WNV infection from the brain leading to increased production of inflammatory molecules, which mediates increased neuronal death and mortality in db/db mice. This is the first study to elucidate the expression of CAM and their correlation with the migration of leukocytes, specifically cytotoxic CD8⁺ T cells, in increasing disease severity in the diabetic mouse model.

Neurologic infections in diabetes mellitus

Even at a time when HIV/AIDS and immunosuppressive therapy have increased the number of individuals living with significant immunocompromise, diabetes mellitus (DM) remains a major comorbid disorder for several rare but potentially lethal infections, including rhino-orbital-cerebral mucormycosis and malignant external otitis. DM is also a commonly associated condition in patients with nontropical pyomyositis, pyogenic spinal infections, Listeria meningitis, and blastomycosis. As West Nile virus spread to and across North America over a decade ago, DM appeared in many series as a risk factor for death or neuroinvasive disease. More recently, in several large international population-based studies, DM was identified as a risk factor for herpes zoster. The relationships among infection, DM, and the nervous system are multidirectional. Viral infections have been implicated in the pathogenesis of type 1 and type 2 DM, while parasitic infections have been hypothesized to protect against autoimmune disorders, including type 1 DM. DM-related neurologic disease can predispose to systemic infection - polyneuropathy is the predominant risk factor for diabetic foot infection. Because prognosis for many neurologic infections depends on timely institution of antimicrobial and sometimes surgical therapy, neurologists caring for diabetic patients should be familiar with the clinical features of the neuroinfectious syndromes associated with DM.

Impaired virus clearance, compromised immune response and increased mortality in type 2 diabetic mice infected with West Nile virus

Clinicoepidemiological data suggest that type 2 diabetes is associated with increased risk of West Nile virus encephalitis (WNVE). However, no experimental studies have elucidated the role of diabetes in WNV neuropathogenesis. Herein, we employed the db/db mouse model to understand WNV immunopathogenesis in diabetics. Nine-week old C57BL/6 WT and db/db mice were inoculated with WNV and mortality, virus burden in the periphery and brain, and antiviral defense responses were analyzed. db/db mice were highly susceptible to WNV disease, exhibited increased tissue tropism and mortality than the wild-type mice, and were unable to clear the infection. Increased and sustained WNV replication was observed in the serum, peripheral tissues and brain of db/db mice, and heightened virus replication in the periphery was correlated with enhanced neuroinvasion and replication of WNV in the brain. WNV infection in db/db mice was associated with enhanced inflammatory response and compromised antiviral immune response characterized by delayed induction of IFN-α, and significantly reduced concentrations of WNV-specific IgM and IgG antibodies. The compromised immune response in db/db mice correlated with increased viremia. These data suggest that delayed immune response coupled with failure to clear the virus leads to increased mortality in db/db mice. In conclusion, this study provides unique mechanistic insight into the immunopathogenesis of WNVE observed in diabetics and can be used to develop therapeutics for the management of WNVE among diabetic patients.

The natural history of West Nile virus infection presenting with West Nile virus meningoencephalitis in a man with a prolonged illness: a case report

Introduction

Estimates indicate that West Nile virus infects approximately one and a half million people in the United States of America. Up to 1% may develop West Nile virus neuroinvasive disease, in which infected patients develop any combination of meningitis, encephalitis, or acute paralysis.

Case presentation

A 56-year-old African-American man presented to our hospital with headache, restlessness, fever, myalgias, decreased appetite, and progressive confusion. A cerebrospinal fluid examination showed mild leukocytosis and an elevated protein level. Testing for routine infections was negative. Brain T2-weighted magnetic resonance imaging scans showed marked enlargement of caudate nuclei and increased intensity within the basal ganglia and thalami. A West Nile virus titer was positive, and serial brain magnetic resonance imaging scans showed resolving abnormalities that paralleled his neurological examination.

Conclusion

This report is unusual as it portrays the natural history and long-term consequences of West Nile virus meningoencephalitis diagnosed on the basis of serial brain images.

[Role of Toscana virus in meningo-encephalitis in Tunisia]

OBJECTIVES

To detect the presence of Toscana virus (TOSV) circulation in Tunisia and to study its role in viral meningo-encephalitis.

PATIENTS AND METHODS

A total of 315 (167 sera and 178 cerobrospinal fluid [CSF]) samples was investigated. These samples are colleted from Tunisian patients with neurological diseases during the period between January 2003 and December 2009. All samples were tested negative for enterovirus, Herpes Simplex virus and West Nile virus. Detection for IgM and IgG specific to TOSV was done by ELISA tests.

RESULTS

Specific IgM for TOSV were detected in 10 % of patients with neurological diseases (31 cases). These recent infections were distributed throughout the study period and predominated during summer and automn. Patients were originated, in the majority from the coastal region. IgG were isolated in 22 cases (7 %) corresponding to previous infection.

CONCLUSION

This is the first report of TOSV circulating in Tunisia and its frequent implication in neurological diseases. These results incited to include TOSV as one of the viral etiologies to target in the diagnosis of viral meningitis and encephalitis in the country.

Prevalence of IgG antibodies against West Nile virus in blood donors during the 2003 outbreak in Tunisia

This study aimed to evaluate the prevalence of anti-West Nile virus (WNV) IgG among two populations of Tunisian blood donors living in areas where human outbreaks of WNV have occurred. Cohorts A (Monastir) and B (Mahdia) included 742 and 102 blood donors respectively. Sera were tested by IgG ELISA test and results were confirmed by PRNT test. WNV neutralizing antibodies were detected in 32 (4.3%) and in 14 (13.7%) sera in cohorts A and B respectively. The prevalence of anti-WNV IgG was significantly higher in cohort B than in cohort A (P<0.001) and was significantly lower in females than in males (P<0.001).

Emergent infectious uveitis

Infectious causes should always be considered in all patients with uveitis and it should be ruled out first. The differential diagnosis includes multiple well-known diseases including herpes, syphilis, toxoplasmosis, tuberculosis, bartonellosis, Lyme disease, and others. However, clinicians should be aware of emerging infectious agents as potential causes of systemic illness and also intraocular inflammation. Air travel, immigration, and globalization of business have overturned traditional pattern of geographic distribution of infectious diseases, and therefore one should work locally but think globally, though it is not possible always. This review recapitulates the systemic and ocular mainfestations of several emergent infectious diseases relevant to the ophthalmologist including Rickettsioses, West Nile virus infection, Rift valley fever, dengue fever, and chikungunya. Retinitis, chorioretinitis, retinal vasculitis, and optic nerve involvement have been associated with these emergent infectious diseases. The diagnosis of any of these infections is usually based on pattern of uveitis, systemic symptoms and signs, and specific epidemiological data and confirmed by detection of specific antibody in serum. A systematic ocular examination, showing fairly typical fundus findings, may help in establishing an early clinical diagnosis, which allows prompt, appropriate management.

Novel infectious agents causing uveitis

In any patient with uveitis, an infectious cause should be ruled out first. The differential diagnosis includes multiple well-known diseases including herpes, syphilis, toxoplasmosis, tuberculosis, bartonellosis, Lyme disease, and others. However, clinician should be aware of emerging infectious agents as potential causes of systemic illness and also intraocular inflammation. Air travel, immigration, and globalization of business have overturned traditional pattern of geographic distribution of infectious diseases, and therefore one should work locally but think globally. This review recapitulates the systemic and ocular manifestations of several emergent infectious diseases relevant to the ophthalmologist including Rickettsioses, West Nile virus infection, Rift valley fever, Dengue fever, and Chikungunya. Retinitis, chorioretinitis, retinal vasculitis, and optic nerve involvement have been associated with these emergent infectious diseases. The diagnosis of any of these infections is usually based on pattern of uveitis, systemic symptoms and signs, and specific epidemiological data and confirmed by detection of specific antibody in serum. A systematic ocular examination, showing fairly typical fundus findings, may help establish an early clinical diagnosis, which allows prompt, appropriate management.

Painful diabetic neuropathy: epidemiology, natural history, early diagnosis, and treatment options

OBJECTIVE

To facilitate the clinician's understanding of the basis and treatment of painful diabetic neuropathy (PDN).

BACKGROUND

PDN is one of several clinical syndromes in patients with diabetic peripheral neuropathy (DPN) and presents a major challenge for optimal management.

METHODS

A systematic review of the literature was undertaken for articles specific to PDN, using Medline databases between 1966 and 2007.

RESULTS

The epidemiology of PDN has not been well established and on the basis of available data the prevalence of pain is 10% to 20% in patients with diabetes and from 40% to 50% in those with diabetic neuropathy. It has a significant impact on the quality of life and health care costs. Pathophysiologic mechanisms underlying PDN are similar to other neuropathic pain disorders and are broadly characterized as peripheral and central sensitization. The natural course of PDN is variable, with many patients experiencing spontaneous improvement and resolution of pain. Hyperglycemia-induced pathways result in nerve dysfunction and damage, which lead to hyperexcitable peripheral and central pathways of pain. Glycemic control may prevent or partially reverse DPN and modulate PDN. Quantifying neuropathic pain is difficult, especially for clinical trials, although this has improved recently with the development of neuropathic pain-specific tools, such as the Neuropathic Pain Questionnaire and the Neuropathic Pain Symptom Inventory. Current therapeutic options are limited to symptomatic treatment and are similar to other types of neuropathic pain.

CONCLUSIONS

A better understanding of the peripheral and central mechanisms resulting in PDN is likely to promote the development of more targeted and effective treatment.

West Nile virus in the Americas

Since the first detection of West Nile virus in the Western Hemisphere in 1999, the virus has spread rapidly across the North American continent and as far south as Argentina. An unprecedented pattern of large annual epidemics of human neuroinvasive disease continues in North America, resulting in considerable public health impact. The high infection incidence in humans has resulted in non-mosquito transmission modes, such as through transfused blood and transplanted organs. West Nile virus incursion into Latin America and the Caribbean Islands has resulted in surprisingly low human, avian, and equine morbidity and mortality despite evidence that West Nile virus strains circulating in those regions are similar to those in North America.

A prospective evaluation of factors associated with chorioretinitis in patients with West Nile virus infection

PURPOSE

To identify factors associated with the development and severity of chorioretinitis (CR) in patients with West Nile virus (WNV) infection.

METHODS

Prospective study of 38 patients with WNV infection.

RESULTS

Simple analysis showed that diabetes (p = 0.027) and age older than 45 years (p = 0.03) were significantly associated with CR. When controlling for age, only association between diabetes and CR remains statistically significant. Diabetic patients' eyes were more likely to have macular involvement (p < 0.0001), 20 or more chorioretinal lesions (p < 0.001), and lesion size 500 microm or more (p < 0.01).

CONCLUSIONS

Diabetes was a risk factor for the development and severity of WNV-associated CR.

A global perspective on the epidemiology of West Nile virus

West Nile virus (WNV) (Flavivirus: Flaviviridae) is the most widespread arbovirus in the world. A significant range expansion occurred beginning in 1999 when the virus was introduced into New York City. This review highlights recent research into WNV epizootiology and epidemiology, including recent advances in understanding of the host-virus interaction at the molecular, organismal, and ecological levels. Vector control strategies, vaccines, and antivirals, which now must be considered on a global scale, are also discussed.

Choroidal neovascularization associated with West Nile virus chorioretinitis

A case of late-onset choroidal neovascularization in a patient with a history of West Nile virus chorioretinitis is described. An 86-year-old man with a history of diabetes mellitus developed bilateral West Nile virus chorioretinitis in 2001, after which his vision improved to baseline. Approximately 5 years later, the patient was found to have choroidal neovascularization in his left eye, for which he received an intravitreal injection of bevacizumab. After one injection, there was good anatomical response. Choroidal neovascularization may be a late-onset complication of West Nile virus chorioretinitis, and bevacizumab may be a good therapeutic option.

Diabetic neuropathy: classification, measurement and treatment

PURPOSE OF REVIEW

Diabetic neuropathies comprise a number of conditions affecting somatic or autonomic nerves and are the most common of the long-term diabetic complications. This review considers recent developments in the classification and noninvasive assessment of somatic neuropathy, and describes new approaches to the management of painful neuropathic symptoms.

RECENT FINDINGS

Classification of the diabetic neuropathies needs modifying to include the recently described 'prediabetic neuropathy' or 'neuropathy of impaired glucose tolerance'. There is increasing evidence to support the use of minimally invasive skin biopsies for evaluating small fibre neuropathies, and more recently, the noninvasive corneal confocal microscopy, which enables direct visualization of peripheral nerve in vivo. For those with painful neuropathic symptoms, a number of evidence-based therapies are now available.

SUMMARY

Patients with 'idiopathic neuropathy' should be screened for evidence of impaired glucose tolerance and considered for lifestyle management. Future trials of potential therapies will benefit from more relevant surrogate endpoints. Those with painful neuropathy should only be prescribed therapies whose efficacy has been confirmed by independent randomized controlled trials.

Linear pattern of West Nile virus-associated chorioretinitis is related to retinal nerve fibres organization

PURPOSE

To clarify the reason for the linear pattern of West Nile virus (WNV)-associated chorioretinitis.

METHODS

The study included 12 patients (24 eyes) with WNV-associated chorioretinitis. All the patients underwent a complete ophthalmic evaluation, including dilated fundus examination, fundus photography, fluorescein angiography, and indocyanine green angiography. Characteristics of linear streaks, particularly their relationship to the course of retinal and choroidal vessels, and pattern of retinal nerve fibres, were analysed.

RESULTS

All patients had bilateral multifocal chorioretinitis with linear clustering of chorioretinal lesions associated with a variable number of scattered lesions. Linear streaks, variable in number and length, originated from the optic disc or its vicinity in most cases. Their course in all cases appeared to closely follow the course of retinal nerve fibres, rather than that of retinal or choroidal vessels.

CONCLUSIONS

Results of our study show that the linear pattern of WNV-associated chorioretinitis is related to retinal nerve fibres organization, suggesting a contiguous spread of WNV virus from central nerve system via the optic nerve fibres to the outer retina, retinal pigment epithelium, and choroid.