Frequency of missed cases of probable acute West Nile virus (WNV) infection when testing for WNV RNA alone or WNV immunoglobulin M alone

Immunoglobulin M for Acute Infection: True or False?

Immunoglobulin M (IgM) tests have clear clinical utility but also suffer disproportionately from false-positive results, which in turn can lead to misdiagnoses, inappropriate therapy, and premature closure of a diagnostic workup. Despite numerous reports in the literature, many clinicians and laboratorians remain unaware of this issue. In this brief review, a series of virology case examples is presented. However, a false-positive IgM can occur with any pathogen. Thus, when an accurate diagnosis is essential for therapy, prognosis, infection control, or public health, when the patient is sick enough to be hospitalized, or when the clinical or epidemiologic findings do not fit, IgM detection should not be accepted as a stand-alone test. Rather, whenever possible, the diagnosis should be confirmed by other means, including testing of serial samples and the application of additional test methods.

Combining reverse-transcription multiplex PCR and microfluidic electrophoresis to simultaneously detect seven mosquito-transmitted zoonotic encephalomyelitis viruses

Several mosquito-transmitted viruses are causative agents for zoonotic encephalomyelitis. Rapid identification of these viruses in mosquito populations is an effective method for surveying these diseases. To detect multiple mosquito-transmitted viral agents, including West Nile virus, Saint Louis encephalitis virus, Venezuelan equine encephalomyelitis virus, Western equine encephalomyelitis virus, Eastern equine encephalomyelitis virus, Highlands J virus and Japanese encephalitis virus, an assay using multiplex reverse-transcription PCR combined with microfluidic electrophoresis was developed and evaluated. Tailed nested primers were used in the assay to amplify specific viral genomic segments, and products with specific length were further analyzed by using a microfluidic electrophoresis chip. The assay exhibited good specificity and analytical sensitivity (10(2) copies/µL). This technology can be helpful in the quarantine and surveillance of exotic encephalomyelitis viruses which are transmitted by mosquitoes.

Antibody and Viral Nucleic Acid Testing of Serum and Cerebrospinal Fluid for Diagnosis of Eastern Equine Encephalitis

Eastern equine encephalitis diagnostic serum antibody can appear 6 days after the onset of symptoms, and its numbers can increase 4-fold in 4 days, arguing for early and frequent serum testing. In populations where cerebrospinal fluid viral nucleic acid testing sensitivity and specificity remain undetermined, cerebrospinal antibody testing should also be performed.

Latest developments and challenges in the diagnosis of human West Nile virus infection

West Nile virus (WNV) is a mosquito-borne flavivirus responsible for an increasing number of human outbreaks of neuroinvasive disease in Europe and in North America. Notwithstanding the improvements in the knowledge of virus epidemiology and clinical course of infection and the development of new laboratory tests, the diagnosis of WNV infection remains challenging and many cases still remain unrecognized. WNV genome diversity, transient viremia with low viral load and cross-reactivity with other flaviviruses of the antibodies induced by WNV infection are important hurdles that require the diagnosis to be performed by experienced laboratories. Herein, we present and discuss the novel findings on the molecular epidemiology and clinical features of WNV infection in humans with special focus on Europe, the performance of diagnostic tests and the novel methods that have been developed for the diagnosis of WNV infection. A view on how the field might evolve in the future is also presented.

Laboratory diagnosis of viral infection

Since the last Handbook of Clinical Neurology volume on this topic, viral diagnosis has made tremendous strides, moving from the margin to the mainstream of clinical care. For many years, conventional virus isolation was the mainstay of viral diagnosis since it was sensitive and “open-minded.” However, growth in conventional cell culture entails an inherent delay that limits its clinical impact. Although rapid culture and viral antigen methods detect fewer pathogens and are less sensitive than conventional culture, both require less expertise and have greatly reduced time to result. Polymerase chain reaction has ushered in a new era in virology, especially in the diagnosis of neurologic diseases. Molecular amplification methods are rapid, highly sensitive, can be automated, quantitative, and detect viruses not amenable to routine culture. User-friendly, walk-away tests with results in an hour, as well as multiplex tests that can detect 20 viruses in a single reaction, are now a reality. As the variety of test methods and commercial products proliferate, the challenges for clinicians and laboratories are selecting which tests to utilize in which clinical scenarios, and understanding how to interpret the results. The advantages and limitations of each method are discussed in this chapter, with special attention to neurologic disease.

Diagnosis of west nile virus human infections: overview and proposal of diagnostic protocols considering the results of external quality assessment studies

West Nile virus, genus Flavivirus, is transmitted between birds and occasionally other animals by ornithophilic mosquitoes. This virus also infects humans causing asymptomatic infections in about 85% of cases and <1% of clinical cases progress to severe neuroinvasive disease. The virus also presents a threat since most infections remain unapparent. However, the virus contained in blood and organs from asymptomatically infected donors can be transmitted to recipients of these infectious tissues. This paper reviews the presently available methods to achieve the laboratory diagnosis of West Nile virus infections in humans, discussing the most prominent advantages and disadvantages of each in light of the results obtained during four different External Quality Assessment studies carried out by the European Network for ‘Imported’ Viral Diseases (ENIVD).