Petersen edit

West Nile Virus: Background and Ecology: 

West Nile Virus: Background and Ecology First isolated in West Nile district, Uganda, 1937 Commonly found in humans and birds and other vertebrates in Africa, Eastern Europe, West Asia, and the Middle East, but has not previously been documented in the Western Hemisphere Basic transmission cycle involves mosquitoes feeding on birds infected with the West Nile virus Infected mosquitoes then transmit West Nile virus to humans and animals when taking a blood meal West Nile Virus: Background and Ecology

The Japanese Encephalitis Serocomplexof the Family Flaviviridae: 

The Japanese Encephalitis Serocomplex of the Family Flaviviridae

West Nile Virus Outbreaks: 

West Nile Virus Outbreaks Israel – 1951-1954, 1957, 2000 France – 1962, 2000 South Africa – 1974 Romania – 1996 Italy – 1997 Russia – 1999 United States – 1999-2002

Spread of West Nile Virus in the U.S. 7/30/02: 

Humans 2001 2000 1999 2002 Spread of West Nile Virus in the U.S. 7/30/02

1999 - 2002 Verified WNV Surveillance Results Reported to ArboNet: 

1999 - 2002 Verified WNV Surveillance Results Reported to ArboNet

WNV Case-Patient Demographics & Mortality United States, 1999-2001: 

WNV Case-Patient Demographics & Mortality United States, 1999-2001 WNV Case-Patient Demographics & Mortality United States, 1999-2001

Date of Symptom Onset, West Nile VirusUnited States, 1999-2001: 

Date of Symptom Onset, West Nile Virus United States, 1999-2001

1999 and 2000 Serosurvey Results : 

1999 and 2000 Serosurvey Results

Clinical Epidemiology: 

Clinical Epidemiology Incubation period 3 - 14 days 20% develop “West Nile fever” 1 in 150 develop meningoencephalitis Advanced age primary risk factor for severe neurological disease and death

West Nile Fever: Classic Clinical Description: 

West Nile Fever: Classic Clinical Description Mild dengue-like illness of sudden onset Duration 3 - 6 days Fever, lymphadenopathy, headache, abdominal pain, vomiting, rash, conjunctivitis, eye pain, anorexia Symptoms of West Nile fever in contemporary outbreaks not fully studied West Nile Fever: Classic Clinical Description

Symptoms of Hospitalized Patients withWest Nile Virus, New York City, 1999: 

Symptoms of Hospitalized Patients with West Nile Virus, New York City, 1999 2% Lymphadenopathy 19% Rash 27% Diarrhea 46% Change in mental status 47% Headache 51% Vomiting 53% Nausea 56% Weakness 90% Fever

Neurological Presentations of West Nile Virus Infection: 

Neurological Presentations of West Nile Virus Infection New York City 1999 Encephalitis/meningoencephalitis 62% Meningitis 32% Complete flaccid paralysis 10% Confused with Guillain-Barre syndrome EMG and nerve conduction velocity studies indicating both axonal and demyelinating lesions, with axonal lesions most prominent Previous series Ataxia, extrapyramidal signs, cranial nerve abnormalities, myelitis, optic neuritis, seizures

Neurological Presentations of West Nile Virus Infection: 

Neurological Presentations of West Nile Virus Infection Preliminary data 2002 Complaints of weakness out of proportion to evidence on physical exam Myoclonus nearly a universal finding Some patients have Parkinsonian-like signs

Outcome of West Nile Virus Infection among Hospitalized Patients: 

Outcome of West Nile Virus Infection among Hospitalized Patients At discharge (NY and NJ, 2000) More than half did not return to functional level Only one-third fully ambulatory At one year (NYC 1999 patients) Fatigue 67%, memory loss 50%, difficulty walking 49%, muscle weakness 44%, depression 38%

Predictors of Death among West Nile Virus-Infected Patients: 

Predictors of Death among West Nile Virus-Infected Patients Change in level of consciousness Encephalitis with severe muscle weakness Advanced age Possibly diabetes mellitus or immunosuppression

Treatment: 

Treatment Supportive treatment About 25% require ICU care; 10% mechanical ventilation Ribavirin and interferon-a2b In-vitro activity in high doses One reported comatose patient did not improve Worse outcome with ribavirin in open-label trial in Israel – unclear patient selection

Risk of West Nile Virus Transmission Through Blood Transfusion: 

Risk of West Nile Virus Transmission Through Blood Transfusion Concern: most WNV infections have no or only mild symptoms, and transient viremia occurs after infection Transfusion-transmission of WNV or other related flaviviruses not reported, but plausible Mathematical modeling: estimated risk of transfusion-transmission was 2 in 10,000 during NYC outbreak (Transfusion, Aug 2002) WNV should be considered in persons who develop unexplained fever, meningitis, or encephalitis after transfusion

Laboratory Findings from WNV Outbreaks in New York and Israel: 

Laboratory Findings from WNV Outbreaks in New York and Israel Total leukocyte count normal or slightly elevated Hyponatremia occasionally in patients with encephalitis CSF Leukocytes 0 - 1782 cells/mm3, mostly lymphocytes Protein universally elevated 51 - 899 mg/dL Glucose normal CT brain: no evidence of acute disease MRI in one-third showed enhancement of leptomeninges, periventricular areas, or both