Optic neuritis complicating west nile virus meningitis in a young adult

Infectious optic neuropathies: a clinical update

Different forms of optic neuropathy causing visual impairment of varying severity have been reported in association with a wide variety of infectious agents. Proper clinical diagnosis of any of these infectious conditions is based on epidemiological data, history, systemic symptoms and signs, and the pattern of ocular findings. Diagnosis is confirmed by serologic testing and polymerase chain reaction in selected cases. Treatment of infectious optic neuropathies involves the use of specific anti-infectious drugs and corticosteroids to suppress the associated inflammatory reaction. The visual prognosis is generally good, but persistent severe vision loss with optic atrophy can occur. This review presents optic neuropathies caused by specific viral, bacterial, parasitic, and fungal diseases.

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.

The evolving epidemiology of viral encephalitis

PURPOSE OF REVIEW

The introduction of West Nile virus to North America illustrates the potential emergence of novel encephalitic agents in unexpected settings. There has been continued recognition of emerging neurotropic viruses in both the developed and developing world and novel modes of transmission of these agents. This review describes recent developments in the epidemiology of West Nile virus and several other emerging viral encephalitides in the developed and developing world and the emergence of novel mechanisms of transmitting viral encephalitis.

RECENT FINDINGS

West Nile virus has continued to have a large public health impact in North America. Improvements in blood donor screening have decreased transfusion-associated transmission of the virus. Monkeypox, with associated encephalitis, occurred in the US. Chandipura virus, an infrequently recognized rhabdovirus, was attributed to large outbreaks of viral encephalitis; however, compelling evidence suggests that the relationship of illness and the virus are questionable. Recent cases of transfusion-associated and transplant-associated viral encephalitis, including West Nile virus, rabies virus, and lymphocytic choriomeningitis virus, were described.

SUMMARY

Continued West Nile virus activity in North America reinforces the fact that viruses can emerge and thrive in new environments and unexpected settings and suggests the need for continued surveillance. Transfusion-associated and transplant-associated viral encephalitis may be an underrecognized risk of these procedures.

A cluster study of predictors of severe West Nile virus infection

OBJECTIVE

To assess the value of multifocal chorioretinitis and of clinical manifestations and biologic parameters in the diagnosis of West Nile virus (WNV) infection.

PATIENTS AND METHODS

We conducted a prospective, controlled case series study during an outbreak of WNV infection between August 15 and October 24, 2003, of 64 consecutive patients who presented with clinical manifestations consistent with WNV disease. In each patient, standardized clinical and biologic data were collected. An ophthalmologic examination searching particularly for multifocal chorioretinitis was performed.

RESULTS

Of 64 patients who presented primarily with meningitis and/or encephalitis, 36 had IgM antibodies against WNV. The WNV-infected patients tended to be older (median age of 54 years vs 46 years in WNV infection and control groups, respectively) and more frequently had diabetes (30% vs 7% in WNV infection and control groups, respectively; P = .03). Multifocal chorioretinitis was found in 75% of WNV-infected patients but in no patient in the control group (P = .001). Blood glucose and amylase levels were higher in WNV-infected patients, whereas serum sodium levels were lower. The cerebrospinal fluid leukocyte count and protein levels were significantly higher in WNV meningitis or encephalitis. Overall, multifocal chorioretinitis had 100% specificity and 73% sensitivity (88% when only patients with meningitis or encephalitis were analyzed) for the diagnosis of WNV. Multivariate analysis disclosed multifocal chorioretinitis as the only predictor of WNV infection (odds ratio, 62; 95% confidence interval, 6-700; P = .001).

CONCLUSION

Multifocal chorioretinitis appears to be a specific marker of WNV infection, particularly in patients who present with meningoencephalitis. An ophthalmologic examination should be part of the routine evaluation of such patients.

Nouveaux concepts étiologiques dans l’uvéite

Uveitis remains an important cause of visual impairment, particularly in young patients. Idiopathic forms of intraocular inflammation should no longer be regarded as a presumed clinical entity, and the ophthalmologist must reconsider the specific etiology of primary uveitis when the clinical examination does not yield a definitive diagnosis or when the course of the disease on corticosteroids remains atypical. Laboratory tests based on serum analysis have limited value and should not be considered as diagnostic proof in different clinical presentations. The diagnostic management of infectious uveitis has been greatly improved by the use of molecular techniques applied to ocular fluids and tissues. Polymerase chain reaction (PCR) technology is a powerful tool that should be proposed in atypical cases of uveitis or retinitis of unclear but potentially infectious origin. This strategy is a major step before using unconventional and new immunomodulatory agents such as anti-TNF-alpha molecules. Under strict experimental conditions including adequate testing to rule out a possible contamination, PCR and its variants have changed our practical approach to intraocular inflammatory disorders and have provided new details for the understanding of infectious uveitis. The concept of pathogen-induced intraocular inflammation can be revisited in the light of molecular data obtained after anterior chamber paracentesis or diagnostic vitrectomy.

Systemic and intraocular manifestations of West Nile virus infection

Since the introduction of West Nile virus in the Western Hemisphere in 1999, the incidence of human infection has increased dramatically. As this virus spreads westward across the United States, ophthalmologists should be aware of this presently uncommon but important condition. Systemic features of West Nile virus infection are well characterized; however, the ophthalmic presentations are not widely known. Intraocular involvement with West Nile virus infection was first described in February 2003, and a variety of ophthalmic manifestations have since been recognized. A complete survey of the systemic and intraocular manifestations of West Nile virus infection relevant to the ophthalmologist is presented.

Differential diagnosis of West Nile encephalitis

PURPOSE OF REVIEW

This article reviews recent developments in West Nile encephalitis. Because of the large number of individuals infected in the United States, an expanded spectrum of the disease has been recognized. Flaccid paralysis presenting as poliomyelitis-like syndrome is being increasingly recognized.

RECENT FINDINGS

Since 1999, West Nile encephalitis in the United States has involved thousands of patients providing an opportunity to observe the protean manifestations of the virus. Recently, ophthalmological manifestations have been described that appear to be common and specific for the virus. Clinicians in endemic areas should be careful to distinguish between West Nile encephalitis and its mimics. The virus may occur in patients with underlying disorders that have encephalopathy as a clinical feature, and clinicians should test for the virus during the mosquito season, even in patients that appear to have an explanation for their encephalopathy. West Nile encephalitis may present as viral aseptic meningitis, meningoencephalitis, or encephalitis. Muscle weakness may or may not accompany any of these clinical variants. This virus may be transmitted via blood transfusion.

SUMMARY

Clinical manifestations of West Nile encephalitis continue to expand following each year's outbreaks. New neurologic and ophthalmologic manifestations continue to be described. Because of the protean manifestations, testing should be carried out during mosquito season, even in patients that have another explanation for their encephalopathy. There is no effective therapy. Flaccid paralysis may be prolonged/permanent. Prognosis may be related to the degree of relative lymphopenia on presentation, the degree of elevation of serum ferritin levels and advanced age. The course of West Nile encephalitis and its clinical manifestations are the same in normal and compromised hosts.

Les uvéites virales

Viral eye diseases are common and associated with different well-known forms of uveitis. However, experimental models and clinical observations have led to an infectious, in particular a viral etiology in different autoimmune conditions. The use of molecular techniques is particularly informative, not only to characterize the previously well-known subgroup of presumed viral uveitis, but also to define the role of these agents or emerging viruses in atypical forms of autoimmune uveitis resistant to conventional therapy. PCR detection of viral DNA in patients with uveitis is a rapid, sensitive and accurate procedure. Therefore, aqueous humor could be analyzed when uveitis is unresponsive to anti-inflammatory molecules, in order to exclude a viral condition and dramatically modify the therapeutic management. Several new viral entities have recently been identified such as cytomegalovirus-associated chronic anterior uveitis and non-necrotizing herpetic retinopathies in immunocompetent hosts. Systemic antiviral drugs should be proposed rapidly in order to control viral replication before the use of corticosteroids. Maintenance therapy based on low-dose antivirals can reduce the rate of recurrence and should be considered.

Visual Loss with West Nile Virus Infection: A Wider Spectrum of a “New” Disease

We describe a case of severe visual loss as a result of West Nile virus (WNV) infection. Associated headache and fever led to the proper diagnosis and management, but the findings of optic neuritis, retinitis, and uveitis were a surprising and prominent component of the patient's meningitis syndrome. Physicians diagnosing and treating patients with WNV infection should be alerted to the possibility of ocular and optic nerve involvement, which may leave permanent neuropathic residua.

Severe West Nile virus disease in healthy adults

The inpatient records of 44 case patients with West Nile virus infection hospitalized in 2002 were reviewed. Sixty-five percent of the case patients had encephalitis, and 35% had aseptic meningitis. There was no significant difference in the distribution of aseptic meningitis versus encephalitis among adults aged < or =50 years compared with adults aged > or =65 years. Focal weakness, likely due to anterior horn cell involvement, was present in 10 case patients (overall rate, 23%; rate among patients with encephalitis, 34%). Case patients with focal weakness who were aged < or =50 years had monoparesis, whereas those aged > or =65 years had paraparesis or quadriparesis. The overall mortality rate was 14%, and the mortality rate in patients aged > or =65 years was 35%. Increased age was associated with an increased mortality rate. The presence of paraparesis or quadriparesis was not independently predictive of mortality.