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West Nile Encephalitis

Enceph West Nile Fever

West Nile encephalitis is a viral encephalopathy caused by the West Nile virus and transmitted primarily by the Culex mosquito. West Nile virus is a part of the Flaviviridae family and is endemic to parts of Africa and Asia.


Presentation

West Nile encephalitis (WNE) is one of the illnesses caused by West Nile virus (WNV) infection. Most individuals infected with WNV are asymptomatic, some develop West Nile fever, and a small percentage develop neuroinvasive disease. WNV is transmitted to humans mainly via mosquito bites. The incubation period ranges from 2 days to 2 weeks [1]. WNE can present in a number of ways, albeit similar to other types of viral encephalitis. Patients usually have a fever, headache, and altered mental status.

Initial symptoms and signs of illness may include myalgia, arthralgia, or pharyngitis and are often nonspecific. Those at the extremes of age have more pronounced symptoms. Aseptic meningitis may occur simultaneously with encephalitis, resulting in signs of meningism. The severity of illness is proportional to the extent of viral invasion. Changes in the mental status range from acute confusion to coma.

Gastrointestinal upset (nausea and vomiting) is common. Gait instability, coarse tremor, and bulbar palsy have been described [2]. Less frequently reported are seizures and cerebral edema [3]. Parkinsonism, extrapyramidal manifestations, myoclonus, and muscle weakness mimicking lower motor neuron lesions, also form part of the clinical picture [4].

WNE could present with acute flaccid paralysis, which is also directly caused by WNV infection. The presence of muscle weakness distinguishes WNE from other encephalitides. Facial nerve palsies present acutely or over the course of a few weeks [5]. Elderly individuals are at an increased risk [6].

Further presenting features of WNE are ophthalmologic manifestations, lymphadenopathy (especially of the submental nodes), and a maculopapular rash on the trunk [5].

Fever
  • CASE REPORT: We report the case of a 46-year-old woman who presented with fever, altered mental status, and maculopapular rash, who was diagnosed with locally acquired WNV encephalitis.[ncbi.nlm.nih.gov]
  • (inanition) (of unknown origin) (persistent) (with chills) (with rigor) R50.9 ICD-10-CM Diagnosis Code R50.9 Fever, unspecified 2016 2017 2018 2019 Billable/Specific Code Applicable To Fever NOS Fever of unknown origin [FUO] Fever with chills Fever with[icd10data.com]
  • Patients usually have a fever, headache, and altered mental status. Initial symptoms and signs of illness may include myalgia, arthralgia, or pharyngitis and are often nonspecific. Those at the extremes of age have more pronounced symptoms.[symptoma.com]
  • Abstract Although most human cases of West Nile (WN) fever are benign, approximately 1% produce severe neurological illness. Meningitis and/or encephalitis comprise 75% of hospitalized cases with seizures in 10-15%.[ncbi.nlm.nih.gov]
Fatigue
  • Localized Stage (early) Early symptoms of Lyme disease include fever, fatigue, and muscle and joint aches, which can also be associated with a variety of other illnesses.[navicenthealth.org]
  • The most common symptom observed in these patients was fatigue (25.93%). Other symptoms included dizziness (7.4%), decreased sense of hearing (7.4%) and decreased sense of smell (7.4%). Reduced power in limbs was found in 33.33% of the cases.[ncbi.nlm.nih.gov]
  • Re: Modafinil for treatment of fatigue in post-polio syndrome: a randomized controlled trial. Neurology. 2008 Feb 26;70(9):736-7; author reply 737-8. No abstract available.[rarediseases.org]
  • Most people with this type of West Nile virus disease recover completely, but fatigue and weakness can last for weeks or months. Serious symptoms in a few people.[cdc.gov]
Chills
  • ) (with rigor) R50.9 ICD-10-CM Diagnosis Code R50.9 Fever, unspecified 2016 2017 2018 2019 Billable/Specific Code Applicable To Fever NOS Fever of unknown origin [FUO] Fever with chills Fever with rigors Hyperpyrexia NOS Persistent fever Pyrexia NOS West[icd10data.com]
  • Early symptoms are nonspecific and include fever, chills, malaise, headache, ocular pain or photophobia, myalgia, and occasionally a maculopapular rash (more common in children) and gastrointestinal upset.[medical-dictionary.thefreedictionary.com]
  • Photo Credit Dolly Faibyshev for The New York Times Work Out and Chill? Cool temperature workouts may be the answer for those who want to exercise without becoming a hot mess.[nytimes.com]
  • A 39-year-old man known to have adult polycystic kidney disease and previous cadaveric renal transplant for which he received cyclosporin A developed fever, chills, headache, and myalgia.[jamanetwork.com]
High Fever
  • See a doctor if you develop symptoms such as high fever, confusion, muscle weakness, severe headache, or stiff neck. Spread West Nile virus is spread to people and animals through the bite of infected mosquitoes.[bchu.org]
  • This illness can cause confusion, a high fever, and a severe headache. Other symptoms include nausea, vomiting, and a stiff neck and back. West Nile virus is not spread by touching a person who has the virus.[myhealth.alberta.ca]
  • Symptoms of severe illness include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis.[cdc.gov]
Rigor
  • ) R50.9 ICD-10-CM Diagnosis Code R50.9 Fever, unspecified 2016 2017 2018 2019 Billable/Specific Code Applicable To Fever NOS Fever of unknown origin [FUO] Fever with chills Fever with rigors Hyperpyrexia NOS Persistent fever Pyrexia NOS West Nile (viral[icd10data.com]
Nausea
  • Gastrointestinal upset (nausea and vomiting) is common. Gait instability, coarse tremor, and bulbar palsy have been described. Less frequently reported are seizures and cerebral edema.[symptoma.com]
  • Signs and symptoms include the sudden onset of drowsiness, headache and nausea due to encephalitis, pain in the abdomen, a rash, and swollen glands (lymphadenopathy). These features are usually but not always mild.[medicinenet.com]
  • Other symptoms include nausea, vomiting, and a stiff neck and back. West Nile virus is not spread by touching a person who has the virus. Almost all cases are from mosquito bites. Most people with this illness get better after treatment.[myhealth.alberta.ca]
  • In adults and older children, symptoms include: fever drowsiness bad headache and stiff neck nausea muscle tremors dizziness. In young children the symptoms include: fever floppiness irritability drowsiness fits.[ww2.health.wa.gov.au]
  • It may be of sudden onset, and symptoms may include drowsiness, severe frontal headache, maculopapular rash, abdominal pain, loss of appetite, nausea, and generalized lymphadenopathy.[medical-dictionary.thefreedictionary.com]
Vomiting
  • CASE PRESENTATION: A 57-year-old Caucasian woman presented with fever, dizziness, balance difficulties, vomiting, dancing eye, altered speech, tremor, generalized myoclonus and failure to rise or stand.[ncbi.nlm.nih.gov]
  • Other symptoms include nausea, vomiting, and a stiff neck and back. West Nile virus is not spread by touching a person who has the virus. Almost all cases are from mosquito bites. Most people with this illness get better after treatment.[myhealth.alberta.ca]
  • Gastrointestinal upset (nausea and vomiting) is common. Gait instability, coarse tremor, and bulbar palsy have been described. Less frequently reported are seizures and cerebral edema.[symptoma.com]
  • Early signs of west nile include fever, weakness, nausea and vomiting. Doctors recommend getting help if symptoms last more than 3-4 days. Only about one in 150 people infected with west nile ever develop severe symptoms.[wkyt.com]
  • About 1 in 5 people who are infected develop a fever with other symptoms such as headache, body aches, joint pains, vomiting, diarrhea, or rash.[cdc.gov]
Hypertension
  • Other chronic medical problems included a history of prostate cancer in remission, dyslipidemia, and hypertension. He also had a history of “visual seizures” for which he was taking daily antiepileptic medication.[hindawi.com]
  • People with certain medical conditions, such as cancer, diabetes, hypertension, kidney disease, and people who have received organ transplants, are also at greater risk. Recovery from severe illness might take several weeks or months.[cdc.gov]
Photophobia
  • Early symptoms are nonspecific and include fever, chills, malaise, headache, ocular pain or photophobia, myalgia, and occasionally a maculopapular rash (more common in children) and gastrointestinal upset.[medical-dictionary.thefreedictionary.com]
  • There was no evidence of tongue biting, urinary incontinence, photophobia, or nuchal rigidity. Muscle strength, tone, and deep tendon reflexes were normal and symmetric. Babinski signs were absent. Sensory examination was normal.[hindawi.com]
Headache
  • A 58-yr-old Korean man was admitted with headache and cognitive dysfunction. The patient had been on a business trip in Guinea. Cerebrospinal fluid (CSF) showed pleocytosis.[ncbi.nlm.nih.gov]
  • Symptoms are flu-like and may include fever, headache, body aches, and/or a skin rash. The elderly and people with weak immune systems are more likely to have severe cases.[bchu.org]
  • Your child has a severe headache. Your child has a stiff neck. Your child is nauseated or is vomiting. Your child is confused or cannot think clearly.[myhealth.alberta.ca]
  • In adults and older children, symptoms include: fever drowsiness bad headache and stiff neck nausea muscle tremors dizziness. In young children the symptoms include: fever floppiness irritability drowsiness fits.[ww2.health.wa.gov.au]
  • Patients usually have a fever, headache, and altered mental status. Initial symptoms and signs of illness may include myalgia, arthralgia, or pharyngitis and are often nonspecific. Those at the extremes of age have more pronounced symptoms.[symptoma.com]
Confusion
  • This illness can cause confusion, a high fever, and a severe headache. Other symptoms include nausea, vomiting, and a stiff neck and back. West Nile virus is not spread by touching a person who has the virus.[myhealth.alberta.ca]
  • […] that is asymptomatic in the majority of cases but that can present in rare occasions with mild flulike symptoms such as low-grade fever, arthralgia, myalgia, and/or rash, or with neurologic manifestations including meningitis, encephalitis with mental confusion[orpha.net]
  • Changes in the mental status range from acute confusion to coma. Gastrointestinal upset (nausea and vomiting) is common. Gait instability, coarse tremor, and bulbar palsy have been described. Less frequently reported are seizures and cerebral edema.[symptoma.com]
  • More than one third of adult survivors of WNV infection continue to experience muscular weakness, cognitive impairment (for example, confusion, difficulty concentrating), or both after 12 months.[medical-dictionary.thefreedictionary.com]
  • See a doctor if you develop symptoms such as high fever, confusion, muscle weakness, severe headache, or stiff neck. Spread West Nile virus is spread to people and animals through the bite of infected mosquitoes.[bchu.org]
Tremor
  • CASE PRESENTATION: A 57-year-old Caucasian woman presented with fever, dizziness, balance difficulties, vomiting, dancing eye, altered speech, tremor, generalized myoclonus and failure to rise or stand.[ncbi.nlm.nih.gov]
  • Abstract We present a case of a 50-year-old man who presented to Winthrop-University Hospital in the midst of the 2002 West Nile encephalitis (WNE) outbreak with the cardinal clinical findings of WNE, ie, fever, encephalopathy, weakness, and muscle tremors[ncbi.nlm.nih.gov]
  • […] majority of cases but that can present in rare occasions with mild flulike symptoms such as low-grade fever, arthralgia, myalgia, and/or rash, or with neurologic manifestations including meningitis, encephalitis with mental confusion or disorientation, tremors[orpha.net]
  • Gait instability, coarse tremor, and bulbar palsy have been described. Less frequently reported are seizures and cerebral edema.[symptoma.com]
  • Over a period of several days, his mental status improved completely to baseline and his fever and tremors subsided.[hindawi.com]
Seizure
  • Occipital lobe seizures, often mimicking other primary seizure types due to extra-occipital spread, is uncommon in adults and especially so from an infectious origin.[ncbi.nlm.nih.gov]
  • The transient nature of his encephalopathy raised suspicion of a generalized seizure as the inciting event with resultant temporary postictal state.[hindawi.com]
  • Less frequently reported are seizures and cerebral edema. Parkinsonism, extrapyramidal manifestations, myoclonus, and muscle weakness mimicking lower motor neuron lesions, also form part of the clinical picture.[symptoma.com]
  • The patient remained in a coma with occasional partial seizure activity that manifested as rhythmic clonic movements. This partial seizure activity diminished and ceased after repeated intravenous injections of diazepam.[jamanetwork.com]
  • For example, call if: Your child has a seizure. Call your doctor or nurse call line now or seek immediate medical care if: Your child has a fever. Your child has a severe headache. Your child has a stiff neck. Your child is nauseated or is vomiting.[myhealth.alberta.ca]
Altered Mental Status
  • CASE REPORT: We report the case of a 46-year-old woman who presented with fever, altered mental status, and maculopapular rash, who was diagnosed with locally acquired WNV encephalitis.[ncbi.nlm.nih.gov]
  • Patients usually have a fever, headache, and altered mental status. Initial symptoms and signs of illness may include myalgia, arthralgia, or pharyngitis and are often nonspecific. Those at the extremes of age have more pronounced symptoms.[symptoma.com]
  • Because West Nile Virus (WNV) neuroinvasive disease has a high mortality rate in immunosuppressed patients, a high index of suspicion is required in patients who present with fever, altered mental status, and other neurological symptoms.[hindawi.com]
  • The patients’ symptoms included headache, altered mental status, dysphasia, fever, neck stiffness, malaise, arthralgias, and macular skin rash. All but one patient had a complete recovery.[ajnr.org]

Workup

The main diagnostic test for WNV infection is the IgM antibody-capture enzyme-linked immunosorbent assay (MAC-ELISA) [7]. IgM antibodies may be detected in serum, however, when they are present in cerebrospinal fluid (CSF) this indicates central nervous system (CNS) invasion by the virus (as IgM does not cross the blood-brain barrier). Eventually, this confirms the diagnosis of West Nile encephalitis. The majority of patients will test positive at the time of presentation [8]. Moreover, nearly all patients are MAC-ELISA positive after a week of symptomatic illness.

Immunological assays may be supplemented by the use of nucleic acid amplification test (NAAT), thus improving the detection rate to over 90%. One advantage that NAAT has over immunology is that it can detect viral infection even in immunosuppressed patients who may produce a scarce amount of antibodies.

Raised white blood cell count may be a feature of WNE, although it is not always present. Increased leukocytes, either neutrophils or lymphocytes, and elevated protein level are some of the CSF findings [9]. T2-weighted magnetic resonance imaging (MRI) may sometimes reveal brainstem and periventricular lesions [10] [11].

Hyponatremia
  • Laboratory evaluation was significant only for mild hyponatremia (132 mmol/L) and elevated creatinine kinase (236 mmol/L). Tests for liver function, complete blood count, and urinalysis were unremarkable.[hindawi.com]

Treatment

  • Her opsoclonus-myoclonus syndrome appeared associated with West Nile encephalitis and had an unfavorable evolution despite treatment.[ncbi.nlm.nih.gov]
  • Hamsters offer an inexpensive model for studying the pathogenesis and treatment of WN virus encephalitis.[ncbi.nlm.nih.gov]
  • Topical treatments may be prescribed for infections that affect the skin and nails while fluconazole pills are the treatment of choice for thrush.[navicenthealth.org]
  • After a treatment with interferon-α 3mu, follow up CSF findings recovered completely after 3 months later. The first case of West Nile encephalitis in Korea was imported from Guinea, and was cured successfully.[ncbi.nlm.nih.gov]
  • Treatment There is no specific treatment for this virus. Antibiotics are not effective. There are no vaccines approved for use against this virus.[bchu.org]

Prognosis

  • Prognosis may be related to the degree of relative lymphopenia on presentation, the degree of elevation of serum ferritin levels and advanced age.[ncbi.nlm.nih.gov]
  • West Nile meningitis, which represents 40% of West Nile neuroinvasive disease, is associated with a favorable prognosis with 20% in-hospital mortality rate as well as persistent Parkinsonian symptoms in up to 40% of survivors [5].[clinicalcorrelations.org]
  • To our knowledge, no statistics for prognosis are available in the literature.[ajnr.org]
  • Long-term prognosis for clinical West Nile virus infection. Emerg. Infect. Dis. 2004; 10 :1405–1411. doi: 10.3201/eid1008.030879. [ PMC free article ] [ PubMed ] [ CrossRef ] 72.[ncbi.nlm.nih.gov]

Etiology

  • OBJECTIVE: To detect the etiology of the acute encephalitis syndrome outbreak. STUDY DESIGN: Investigation of outbreak was undertaken by collection of brief clinical history and epidemiological details along with the specimens for viral diagnosis.[ncbi.nlm.nih.gov]
  • Histopathologic and immunopathologic examinations performed on human autopsy materials helped guide subsequent laboratory and epidemiologic investigations that led to identification of the etiologic agent.[ncbi.nlm.nih.gov]
  • There was no evidence for any other etiology responsible for her opsoclonus-myoclonus syndrome. Her opsoclonus-myoclonus syndrome appeared associated with West Nile encephalitis and had an unfavorable evolution despite treatment.[ncbi.nlm.nih.gov]
  • Although the temporal relationship of rhabdomyolysis and neurological WNV illness suggested a common etiology, these patients presented with complex clinical conditions which may have led to development of rhabdomyolysis from other causes.[ncbi.nlm.nih.gov]
  • The etiology was confirmed to be West Nile virus lineage 1. Many encephalitis patients from this outbreak exhibited neurological sequelae post recovery.[ncbi.nlm.nih.gov]

Epidemiology

  • STUDY DESIGN: Investigation of outbreak was undertaken by collection of brief clinical history and epidemiological details along with the specimens for viral diagnosis.[ncbi.nlm.nih.gov]
  • Histopathologic and immunopathologic examinations performed on human autopsy materials helped guide subsequent laboratory and epidemiologic investigations that led to identification of the etiologic agent.[ncbi.nlm.nih.gov]
  • OBJECTIVES: To raise awareness of an important epidemiologic cause of febrile illness with neurologic involvement in the United States.[ncbi.nlm.nih.gov]
  • The objective of this investigation was to describe the clinical and epidemiological features of identified cases of WNV neuroinvasive disease and rhabdomyolysis.[ncbi.nlm.nih.gov]
  • Medical College Hospital, Vandanam, Alappuzha, Kerala, India. 2 Epidemiology Group, National Institute of Virology, Pune, India.[ncbi.nlm.nih.gov]
Sex distribution
Age distribution

Pathophysiology

  • Pathophysiology, vector transmission, clinical manifestations and laboratory findings are discussed in this article.[ncbi.nlm.nih.gov]
  • Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test West Nile virus (WNV) is a mosquito-borne flavivirus (single stranded RNA virus) that primarily infects birds, but occasionally[mayomedicallaboratories.com]

Prevention

  • Prevention effort should be focused on the elderly ( 60 years old) people who have a higher risk of severe sequelae. The state health authorities should create awareness among people in order to prevent the transmission of disease. J. Med.[ncbi.nlm.nih.gov]
  • Emphasis is placed on the PNP's role of providing anticipatory guidance concerning prevention of outbreaks and physical management that focuses on the elimination of mosquito-breeding areas, reducing personal exposure, and biological control of mosquito[ncbi.nlm.nih.gov]
  • Centers for Disease Control and Prevention, Fort Collins, CO 80522 James M. Hughes, M.D. Centers for Disease Control and Prevention, Atlanta, GA 30333[nejm.org]
  • The risk of exposure to WNV can be reduced by preventing mosquito bites. Residents can prevent mosquito bites by: Using mosquito repellents. Read label directions carefully. Wearing long sleeves and pants if you are outside between dusk and dawn.[dover.nj.us]
  • Researchers at the Centers for Disease Control and Prevention (CDC) estimate that 300,000 cases of Lyme disease are diagnosed throughout the United States every year.[navicenthealth.org]

References

Article

  1. Mostashari F,Bunning ML, Kitsutani PT, et al. Epidemic West Nile encephalitis, New York, 1999: results of a household-based seroepidemiological survey. Lancet. 2001;358(9278):261–264.
  2. Bode AV, Sejvar JJ, Pape WJ, Campbell GL, Marfin AA. West Nile virus disease: a descriptive study of 228 patients hospitalized in a 4-county region of Colorado in 2003. Clin Infect Dis. 2006;42(9):1234–1240.
  3. Sayao AL, Suchowersky O, Al-Khathaami A, et al. Calgary experience with West Nile virus neurological syndrome during the late summer of 2003. Can J Neurol Sci. 2004;31(2):194–203.
  4. Pepperell C, Rau N, Krajden S, et al. West Nile virus infection in 2002. CMAJ. 2003;168(11):1399–1405.
  5. Hayes EB, Sejvar JJ, Zaki SR, Lanciotti RS, Bode AV, Campbell GL. Virology, pathology, and clinical manifestations of West Nile virus disease. Emerg Infect Dis. 2005;11(8):1174–1179.
  6. Hayes EB, Komar N, Nasci RS, Montgomery SP, O’Leary DR, Campbell GL. Epidemiology and transmission dynamics of West Nile virus disease. Emerg Infect Dis. 2005;11(8):1167–1173.
  7. Roehrig JT, Nash D, Maldin B, et al. Persistence of virus-reactive serum immunoglobulin M antibody in confirmed West Nile virus encephalitis cases. Emerg Infect Dis. 2003;9(3):376–379.
  8. Tilley PA, Fox JD, Jayaraman GC, Preiksaitis JK. Nucleic acid testing for West Nile virus RNA in plasma enhances rapid diagnosis of acute infection in symptomatic patients. J Infect Dis. 2006;193(10):1361–1364.
  9. Tyler KL, Pape J, Goody RJ, Corkill M, Kleinschmidt-DeMasters BK. CSF findings in 250 patients with serologically confirmed West Nile virus meningitis and encephalitis. Neurology. 2006;66(3):361–365.
  10. Gyure KA. West Nile virus infections. J Neuropathol Exp Neurol. 2009;68(10):1053–1060.
  11. Ali M, Safriel Y, Sohi J, et al. West Nile virus infection: MR imaging findings in the nervous system. AJNR Am J Neuroradiol. 2005;26(2):289–297.

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Last updated: 2018-06-22 00:43