West Nile Virus Jo Hofmann, MD State Epidemiologist for Communicable Disease Washington State Department of Health Focus on clinical aspects of human infection

Washington State Department of Health Overview and learning objectives Review: Review:  Clinical features of human West Nile virus (WNV) infections  Routes of WNV transmission in humans Learning objectives Learning objectives  Describe symptoms of the most common illness associated with WNV infection  Identify the most common route of virus transmission  Describe two new methods of surveillance for WNV infections

Washington State Department of Health WNV infection: clinical syndromes West Nile fever West Nile fever  Mild infection West Nile neuroinvasive disease West Nile neuroinvasive disease  Meningitis  Encephalitis  Acute flaccid paralysis (AFP)  Polio-like syndrome  Movement disorders  Involuntary muscle spasms  Parkinson’s-like syndromes  Other neurological manifestations

Washington State Department of Health Human infection with WNV ~80% No symptoms ~20% West Nile fever <1% WNND Fatal WNV infection: <0.1% of all infections 10% of WNND 1/150 of all infections cause West Nile neuroinvasive disease (WNND) Very crude estimates

West Nile virus infections, by age group & clinical category -- United States, 2003 Source: Hayes, N. 5th Nat’l Conf. on West Nile Virus, 2004 Washington State Department of Health

West Nile fever Self-limited illness with sudden onset Self-limited illness with sudden onset  Fever, headache, muscle aches, fatigue  Nausea, vomiting  Rash, swollen lymph nodes  Symptoms can be debilitating, may persist for weeks Does not progress to West Nile neuroinvasive disease Does not progress to West Nile neuroinvasive disease

Washington State Department of Health The disease formerly known as West Nile meningoencephalitis The disease formerly known as West Nile meningoencephalitis Rarest WNV infection Rarest WNV infection Neurological symptoms occur 1-2 days after onset of fever Neurological symptoms occur 1-2 days after onset of fever WNND includes WNND includes  Meningitis - stiff neck, headache, abnormal cerebrospinal fluid  Encephalitis - confusion, seizures  Acute flaccid paralysis (AFP) West Nile neuroinvasive disease

Washington State Department of Health West Nile virus-associated 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.)  No sensory symptoms  Abnormal cerebrospinal fluid Affects young, healthy patients compared with other WN neuroinvasive disease Affects young, healthy patients compared with other WN neuroinvasive disease Fever, headache may be absent Fever, headache may be absent May occur with or w/o meningitis or encephalitis May occur with or w/o meningitis or encephalitis

Dude, where’s my blood meal?

Washington State Department of Health Newly described routes of WNV transmission Transfusion of blood, platelets, fresh frozen plasma Transfusion of blood, platelets, fresh frozen plasma Organ transplantation Organ transplantation Perinatal exposure (infected mother to newborn) Perinatal exposure (infected mother to newborn) Breastfeeding Breastfeeding Occupational exposure (laboratory accidents, alligator and poultry farming) Occupational exposure (laboratory accidents, alligator and poultry farming)

Washington State Department of Health WNV infections following transfusion First recognized in 2002 First recognized in 2002 >60 suspected cases investigated; 23 cases confirmed following transfusion from 16 infected donors >60 suspected cases investigated; 23 cases confirmed following transfusion from 16 infected donors Sources: red blood cells, platelets, and plasma Sources: red blood cells, platelets, and plasma Nationwide screening of blood donations began July 2003 – new method of surveillance for WNV infections Nationwide screening of blood donations began July 2003 – new method of surveillance for WNV infections

Washington State Department of Health Screening the blood supply Asking donors about symptoms Asking donors about symptoms Screening donations with nucleic acid amplification test (NAAT) – detects virus Screening donations with nucleic acid amplification test (NAAT) – detects virus Contaminated products destroyed, donors contacted Contaminated products destroyed, donors contacted Blood banks report infected blood products to state health departments Blood banks report infected blood products to state health departments 6.2 million units screened in 2003 – >1000 donors infected with WNV reported 6.2 million units screened in 2003 – >1000 donors infected with WNV reported

Washington State Department of Health Confirmed and probable transfusion-associated WNV infection, 2003 Occurred in epicenter of outbreak Occurred in epicenter of outbreak  Three in Texas  One each in Nebraska, Iowa, Kansas Onset of symptoms during peak of outbreak: August through October Onset of symptoms during peak of outbreak: August through October Average age of cases 63 years Average age of cases 63 years Five developed WNND (encephalitis) Five developed WNND (encephalitis)

Washington State Department of Health Perinatal transmission of WNV First described in U.S. in 2002 First described in U.S. in 2002 Several children born to mothers with confirmed WNV infection Several children born to mothers with confirmed WNV infection  Some with neurological defects A large series of cases from still being investigated A large series of cases from still being investigated CDC has on-line reporting site for registry of pregnancy-associated cases CDC has on-line reporting site for registry of pregnancy-associated cases

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

Washington State Department of Health Summary Most WNV infections are asymptomatic Most WNV infections are asymptomatic Most common illness is West Nile fever Most common illness is West Nile fever The most common route of transmission is through the bite of an infected mosquito The most common route of transmission is through the bite of an infected mosquito  Transfusion and pregnancy associated cases Screening of blood donors and web-based reporting of pregnancy associated cases are new surveillance methods Screening of blood donors and web-based reporting of pregnancy associated cases are new surveillance methods

Questions?

Washington State Department of Health References Interim guidelines for the evaluation of infants born to mothers infected with West Nile virus during pregnancy. MMWR 2004;53:154-7Interim guidelines for the evaluation of infants born to mothers infected with West Nile virus during pregnancy. MMWR 2004;53:154-7 Transmission of West Nile virus from an organ donor to four transplant recipients. New Engl Jour Med 2003;348: Transmission of West Nile virus from an organ donor to four transplant recipients. New Engl Jour Med 2003;348: Possible West Nile virus transmission to an infant through breast-feeding - Michigan MMWR 2002; 51:877-8.Possible West Nile virus transmission to an infant through breast-feeding - Michigan MMWR 2002; 51:877-8.

Washington State Department of Health References Petersen LR, Marfin AA. West Nile Virus: a primer for the clinician. Ann Intern Med 2002;137:173-9.Petersen LR, Marfin AA. West Nile Virus: a primer for the clinician. Ann Intern Med 2002;137: Investigations of West Nile virus infections in recipients of blood transfusions. MMWR 2002;51:973-4.Investigations of West Nile virus infections in recipients of blood transfusions. MMWR 2002;51: Neurologic manifestations and outcome of West Nile virus infection. JAMA. 2003;290:511-5.Neurologic manifestations and outcome of West Nile virus infection. JAMA. 2003;290: CDC WNV clinical guidance website:CDC WNV clinical guidance website: