West Nile virus encephalitis: A report of two cases and review of neuroradiological features

A Scoping Review of Arthropod-Borne Flavivirus Infections in Solid Organ Transplant Recipients

Arthropod-borne flaviviruses (ABFs), transmitted by mosquitoes or ticks, are increasing due to climate change and globalization. This scoping review examines the epidemiology, clinical characteristics, diagnostics, treatment, and outcomes of ABF infection in solid organ transplant recipients (SOTRs). A database search up to January 25, 2024, focused on ABFs such as West Nile virus (WNV), dengue virus (DENV), Japanese encephalitis virus (JEV), Powassan virus (POWV), yellow fever virus (YFV), and Zika virus (ZIKV), limited to SOTRs. We identified 173 WNV cases from 84 studies, with 28 donor-derived infections (DDIs). Common clinical features included fever (78.5%), altered mental status (65.1%), and weakness or paralysis (45.6%). Treatment involved reducing immunosuppression (IS) in 93 cases, with intravenous immunoglobulin (IVIG), interferon alfa-2b, and ribavirin used in 75 cases. Seven cases involved graft loss or rejection post-infection. WNV infection had a 23.7% mortality rate, with severe neurological complications in 43.9% For DENV infection, 386 cases from 47 studies were identified, including 14 DDI cases. Symptoms included fever (85%), myalgias (56.4%), and headache or retro-orbital pain (34.6%). Severe dengue occurred in 50 cases (13.0%). IVIG was administered in six cases. Reduction in IS was reported in 116 patients. DENV mortality rate was 4.9%. Additionally, 26 cases of less common ABFs such as JEV, POWV, YFV, and ZIKV were described. In summary, ABF infections among SOTRs are associated with higher morbidity and mortality compared to the general population, emphasizing the need for improved preventive strategies, timely diagnosis, and optimized management protocols.

Neuroinvasive West Nile Virus Infection in Immunosuppressed and Immunocompetent Adults

Importance

West Nile virus (WNV) is the leading cause of human arboviral disease in the US, peaking during summer. The incidence of WNV, including its neuroinvasive form (NWNV), is increasing, largely due to the expanding distribution of its vector, the Culex mosquito, and climatic changes causing heavy monsoon rains. However, the distinct characteristics and outcomes of NWNV in individuals who are immunosuppressed (IS) and individuals who are not IS remain underexplored.

Objective

To describe and compare clinical and radiographic features, treatment responses, and outcomes of NWNV infection in individuals who are IS and those who are not IS.

Design, Setting, and Participants

This retrospective cohort study used data from the Mayo Clinic Hospital system collected from July 2006 to December 2021. Participants were adult patients (age ≥18 years) with established diagnosis of NWNV infection. Data were analyzed from May 12, 2020, to July 20, 2023.

Exposure

Immunosuppresion.

Main Outcomes and Measures

Outcomes of interest were clinical and radiographic features and 90-day mortality among patients with and without IS.

Results

Of 115 participants with NWNV infection (mean [SD] age, 64 [16] years; 75 [66%] male) enrolled, 72 (63%) were not IS and 43 (37%) were IS. Neurologic manifestations were meningoencephalitis (98 patients [85%]), encephalitis (10 patients [9%]), and myeloradiculitis (7 patients [6%]). Patients without IS, compared with those with IS, more frequently reported headache (45 patients [63%] vs 18 patients [42%]) and myalgias (32 patients [44%] vs 9 patients [21%]). In contrast, patients with IS, compared with those without, had higher rates of altered mental status (33 patients [77%] vs 41 patients [57%]) and myoclonus (8 patients [19%] vs 8 patients [4%]). Magnetic resonance imaging revealed more frequent thalamic T2 fluid-attenuated inversion recovery hyperintensities in individuals with IS than those without (4 patients [11%] vs 0 patients). Individuals with IS had more severe disease requiring higher rates of intensive care unit admission (26 patients [61%] vs 24 patients [33%]) and mechanical ventilation (24 patients [56%] vs 22 patients [31%]). The 90-day all-cause mortality rate was higher in the patients with IS compared with patients without IS (12 patients [28%] vs 5 patients [7%]), and this difference in mortality persisted after adjusting for Glasgow Coma Scale score (adjusted hazard ratio, 2.22; 95% CI, 1.07-4.27; P = .03). Individuals with IS were more likely to receive intravenous immunoglobulin than individuals without IS (12 individuals [17%] vs 24 individuals [56%]), but its use was not associated with survival (hazard ratio, 1.24; 95% CI, 0.50-3.09; P = .64).

Conclusions and Relevance

In this cohort study of individuals with NWNV infection, individuals with IS had a higher risk of disease complications and poor outcomes than individuals without IS, highlighting the need for innovative and effective therapies to improve outcomes in this high-risk population.

Neuroinvasive disease due to West Nile virus: Clinical and imaging findings associated with a re-emerging pathogen

The West Nile virus (WNV) is an arbovirus than can infect human beings and cause severe neuroinvasive disease. Taking the outbreak that occurred in Spain in 2020 as a reference, this article reviews the clinical and imaging findings for neuroinvasive disease due to WNV. We collected demographic, clinical, laboratory, and imaging (CT and MRI) variables for 30 patients with WNV infection diagnosed at our center. The main clinical findings were fever, headache, and altered levels of consciousness. Neuroimaging studies, especially MRI, are very useful in the diagnosis and follow-up of these patients. The most common imaging findings were foci of increased signal intensity in the thalamus and brainstem in T2-weighted sequences; we illustrate these findings in cases from our hospital.

Severe West Nile Virus Neuroinvasive Disease: Clinical Characteristics, Short- and Long-Term Outcomes

West Nile Virus Neuroinvasive Disease (WNV NID) requires prolonged intensive care treatment, resulting in high mortality and early disability. Long-term results are lacking. We have conducted an observational retrospective study with a prospective follow-up of WNV NID patients treated at the Intensive Care Unit (ICU), University Hospital for Infectious Diseases, Zagreb, Croatia, 2013–2018. Short-term outcomes were vital status, length of stay (LOS), modified Rankin Scale (mRS), and disposition at discharge. Long-term outcomes were vital status and mRS at follow-up. Twenty-three patients were identified, 78.3% males, median age 72 (range 33–84) years. Two patients (8.7%) died in the ICU, with no lethal outcomes after ICU discharge. The median ICU LOS was 19 days (range 5–73), and the median hospital LOS was 34 days (range 7–97). At discharge, 15 (65.2%) patients had moderate to severe/mRS 3–5, 6 (26.0%) had slight disability/mRS 2–1, no patients were symptom-free/mRS 0. Ten (47.6%) survivors were discharged to rehabilitation facilities. The median time to follow-up was nine months (range 6–69). At follow-up, seven patients died (30.5%), five (21.7%) had moderate to severe/mRS 3–5, one (4.3%) had slight disability/mRS 2–1, six (26.1%) had no symptoms/mRS 0, and four (17.4%) were lost to follow-up. Briefly, ten (43.5%) survivors improved their functional status, one (4.3%) was unaltered, and one (4.3%) aggravated. In patients with severe WNV NID, intensive treatment in the acute phase followed by inpatient rehabilitation resulted in significant recovery of functional status after several months.

Three case reports of West Nile virus neuroinvasive disease: lessons from real-life clinical practice

Background

Despite being an uncommon cause of meningoencephalitis, West Nile virus (WNV) recently provoked significant outbreaks throughout Europe. West Nile neuroinvasive disease (WNND) is associated with significant morbidity and mortality in older and compromised individuals, while its diagnosis may be demanding for the clinician. Here discussed are three cases of WNND with a focus on the diagnostic challenges they presented due to atypical clinical presentation and laboratory findings.

Case presentation

Between July and September 2020 three patients presented to our attention with signs and symptoms compatible with meningoencephalitis. Among routine procedures, they underwent lumbar puncture and imaging. In the absence of microbiological isolates, biological samples were sent for serology and NAATs for WNV. Following diagnosis, the patients gradually recovered and were discharged either home or to rehabilitation facilities.

Conclusions

The laboratory findings here discussed, in particular CSF parameters, are only partially consistent with those described in the literature, which highlights the need for further research. While serology and NAATs on blood and urine appear the most reliable techniques in the diagnostic work-up of WNND, utility of NAATs on CSF specimens is limited by the kinetics of WNV viremia in biological fluids. This report underlines that WNND should always be included in the differential diagnosis of meningoencephalitis during WNV transmission period.

Neuroinvasive disease due to West Nile virus: clinical and imaging findings associated with a re-emerging pathogen

The West Nile virus (WNV) is an arbovirus than can infect human beings and cause severe neuroinvasive disease. Taking the outbreak that occurred in Spain in 2020 as a reference, this article reviews the clinical and imaging findings for neuroinvasive disease due to WNV. We collected demographic, clinical, laboratory, and imaging (CT and MRI) variables for 30 patients with WNV infection diagnosed at our center. The main clinical findings were fever, headache, and altered levels of consciousness. Neuroimaging studies, especially MRI, are very useful in the diagnosis and follow-up of these patients. The most common imaging findings were foci of increased signal intensity in the thalamus and brainstem in T2-weighted sequences; we illustrate these findings in cases from our hospital.