West Nile VirusWest Nile Virus

Jo Hofmann, MDJo Hofmann, MDState Epidemiologist for State Epidemiologist for Communicable DiseaseCommunicable Disease

Washington State Department of Washington State Department of Health Health

Focus on clinical aspects of human infection

Washington State Department of Health

Overview and learning Overview and learning objectives objectives

• Review:Review: Clinical features of human West Nile Clinical features of human West Nile

virus (WNV) infectionsvirus (WNV) infections Routes of WNV transmission in humansRoutes of WNV transmission in humans

• Learning objectivesLearning objectives Describe symptoms of the most common Describe symptoms of the most common

illness associated with WNV infectionillness associated with WNV infection Identify the most common route of virus Identify the most common route of virus

transmissiontransmission Describe two new methods of Describe two new methods of

surveillance for WNV infectionssurveillance for WNV infections

Washington State Department of Health

WNV infection: clinical WNV infection: clinical syndromessyndromes

• West Nile feverWest Nile fever Mild infection Mild infection

• West Nile neuroinvasive disease West Nile neuroinvasive disease MeningitisMeningitis EncephalitisEncephalitis Acute flaccid paralysis (AFP)Acute flaccid paralysis (AFP)

Polio-like syndromePolio-like syndrome Movement disordersMovement disorders

Involuntary muscle spasmsInvoluntary muscle spasmsParkinson’s-like syndromesParkinson’s-like syndromes

Other neurological manifestationsOther neurological manifestations

Washington State Department of Health

Human infection with WNVHuman infection with WNV

~80%No symptoms

~20%West Nile fever

<1%WNND

Fatal WNV infection: <0.1% of all infections10% of WNND

1/150 of all infectionscause West Nileneuroinvasive

disease (WNND) Very crude estimates

0

1

2

3

4

5

Age group (yr)

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West Nile Neuroinvasive DiseaseWest Nile Fever

West Nile virus infections, by age group West Nile virus infections, by age group & clinical category -- United States, 2003& clinical category -- United States, 2003

Source: Hayes, N. 5th Nat’l Conf. on West Nile Virus, 2004 Washington State Department of Health

Washington State Department of Health

West Nile feverWest Nile fever

• Self-limited illness with sudden Self-limited illness with sudden onsetonset Fever, headache, muscle aches, Fever, headache, muscle aches,

fatigue fatigue Nausea, vomitingNausea, vomiting Rash, swollen lymph nodesRash, swollen lymph nodes Symptoms can be debilitating, may Symptoms can be debilitating, may

persist for weekspersist for weeks• Does not progress to West Nile Does not progress to West Nile

neuroinvasive disease neuroinvasive disease

Washington State Department of Health

• The disease formerly known as West The disease formerly known as West Nile meningoencephalitisNile meningoencephalitis

• Rarest WNV infectionRarest WNV infection• Neurological symptoms occur 1-2 days Neurological symptoms occur 1-2 days

after onset of fever after onset of fever • WNND includes WNND includes

Meningitis - stiff neck, headache, Meningitis - stiff neck, headache, abnormal cerebrospinal fluid abnormal cerebrospinal fluid

Encephalitis - confusion, seizuresEncephalitis - confusion, seizures Acute flaccid paralysis (AFP)Acute flaccid paralysis (AFP)

West Nile neuroinvasive West Nile neuroinvasive diseasedisease

Washington State Department of Health

West Nile virus-associated West Nile virus-associated acute flaccid paralysis (AFP)acute flaccid paralysis (AFP)

• Rare, cases seen during outbreaks Rare, cases seen during outbreaks • Symptoms look like poliomyelitis (polio)Symptoms look like poliomyelitis (polio)

Asymmetrical weakness (left > right, etc.)Asymmetrical weakness (left > right, etc.) No sensory symptoms No sensory symptoms Abnormal cerebrospinal fluidAbnormal cerebrospinal fluid

• Affects young, healthy patients Affects young, healthy patients compared with other WN neuroinvasive compared with other WN neuroinvasive diseasedisease

• Fever, headache may be absent Fever, headache may be absent • May occur with or w/o meningitis or May occur with or w/o meningitis or

encephalitisencephalitis

Dude, where’s my blood meal?

Washington State Department of Health

Newly described Newly described routes of WNV transmissionroutes of WNV transmission

• Transfusion of blood, platelets, fresh Transfusion of blood, platelets, fresh frozen plasma frozen plasma

• Organ transplantationOrgan transplantation• Perinatal exposure (infected mother Perinatal exposure (infected mother

to newborn)to newborn)• BreastfeedingBreastfeeding• Occupational exposure (laboratory Occupational exposure (laboratory

accidents, alligator and poultry accidents, alligator and poultry farming)farming)

Washington State Department of Health

WNV infections WNV infections following transfusionfollowing transfusion

• First recognized in 2002First recognized in 2002• >60 suspected cases investigated; 23 >60 suspected cases investigated; 23

cases confirmed following transfusion cases confirmed following transfusion from 16 infected donorsfrom 16 infected donors

• Sources: red blood cells, platelets, and Sources: red blood cells, platelets, and plasma plasma

• Nationwide screening of blood Nationwide screening of blood donations began July 2003 – new donations began July 2003 – new method of surveillance for WNV method of surveillance for WNV infectionsinfections

Washington State Department of Health

Screening the blood supplyScreening the blood supply

• Asking donors about symptomsAsking donors about symptoms• Screening donations with nucleic acid Screening donations with nucleic acid

amplification test (NAAT) – detects virusamplification test (NAAT) – detects virus• Contaminated products destroyed, Contaminated products destroyed,

donors contacteddonors contacted• Blood banks report infected blood Blood banks report infected blood

products to state health departments products to state health departments • 6.2 million units screened in 2003 – 6.2 million units screened in 2003 –

>1000 donors infected with WNV >1000 donors infected with WNV reported reported

Washington State Department of Health

Confirmed and probable Confirmed and probable transfusion-associated WNV transfusion-associated WNV

infection, 2003infection, 2003

• Occurred in epicenter of outbreak Occurred in epicenter of outbreak Three in TexasThree in Texas One each in Nebraska, Iowa, KansasOne each in Nebraska, Iowa, Kansas

• Onset of symptoms during peak of Onset of symptoms during peak of outbreak: August through Octoberoutbreak: August through October

• Average age of cases 63 years Average age of cases 63 years • Five developed WNND Five developed WNND

(encephalitis)(encephalitis)

Washington State Department of Health

Perinatal Perinatal transmission of WNVtransmission of WNV

• First described in U.S. in 2002First described in U.S. in 2002• Several children born to mothers Several children born to mothers

with confirmed WNV infection with confirmed WNV infection Some with neurological defectsSome with neurological defects

• A large series of cases from 2003-A large series of cases from 2003-2004 still being investigated 2004 still being investigated

• CDC has on-line reporting site for CDC has on-line reporting site for registry of pregnancy-associated registry of pregnancy-associated casescases

Contents

MMWR 2001;50:343-5

West Nile Virus Questions and Answers

West Nile Virus Home >West Nile Virus infection acquired during pregnancy

West Nile virus disease during pregnancy

In 2002, the Centers for Diseases Control and Prevention (CDC) Division of Vector-Borne Diseases (DVBID) published the first report of intrauterine WNV transmission, in which the infant had congenital abnormalities (MMWR 2001;50:343-5). This single case does not provide proof of a causal relationship between WNV infection during pregnancy and such abnormalities. The CDC is enhancing surveillance to learn more about intrauterine WNV transmission and birth outcomes. Healthcare providers and state and local health departments are encouraged to report cases of known or suspected WNV disease (WN fever or meningoencephalitis) during pregnancy.

Health Care Providers: to report a case of WNV disease during pregnancy, please call 970-266-3525 or send us your contact information in the box provided below. We will contact you promptly. Please do not submit confidential patient information. Note: Because local health professionals need to be involved in the evaluation, reports cannot be accepted directly from individual patients.

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Coming soon: web-based reporting WNV infection

during pregnancy: Healthcare providers report on-line

States/local HD informed when their providers report

Providers contacted for follow-up and specimens needed for testing

For now:Call state/local health department or CDC @ 970-221-6400

Washington State Department of Health

Summary Summary

• Most WNV infections are asymptomaticMost WNV infections are asymptomatic• Most common illness is West Nile feverMost common illness is West Nile fever• The most common route of transmission is The most common route of transmission is

through the bite of an infected mosquitothrough the bite of an infected mosquito Transfusion and pregnancy associated cases Transfusion and pregnancy associated cases

• Screening of blood donors and web-based Screening of blood donors and web-based reporting of pregnancy associated cases reporting of pregnancy associated cases are new surveillance methodsare new surveillance methods

Questions?

Washington State Department of Health

ReferencesReferences• Interim guidelines for the evaluation of infants born to Interim guidelines for the evaluation of infants born to

mothers infected with West Nile virus during pregnancy. mothers infected with West Nile virus during pregnancy. MMWR 2004;53:154-7MMWR 2004;53:154-7

• Transmission of West Nile virus from an organ donor to Transmission of West Nile virus from an organ donor to four transplant recipients. New Engl Jour Med four transplant recipients. New Engl Jour Med 2003;348:2196-2203.2003;348:2196-2203.

• Possible West Nile virus transmission to an infant Possible West Nile virus transmission to an infant through breast-feeding - Michigan 2002. through breast-feeding - Michigan 2002. MMWR 2002; 51:877-8.MMWR 2002; 51:877-8.

Washington State Department of Health

ReferencesReferences• Petersen LR, Marfin AA. West Nile Virus: a primer for Petersen LR, Marfin AA. West Nile Virus: a primer for

the clinician. Ann Intern Med 2002;137:173-9.the clinician. Ann Intern Med 2002;137:173-9.

• Investigations of West Nile virus infections in recipients Investigations of West Nile virus infections in recipients of blood transfusions. MMWR 2002;51:973-4.of blood transfusions. MMWR 2002;51:973-4.

• Neurologic manifestations and outcome of West Nile Neurologic manifestations and outcome of West Nile virus infection. JAMA. 2003;290:511-5. virus infection. JAMA. 2003;290:511-5.

• CDC WNV clinical guidance website:CDC WNV clinical guidance website:http://www.cdc.gov/ncidod/dvbid/westnile/clinical_guidance.htm