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2/26/03 SAS West Nile Virus Information for the Health Care Professional Mississippi State Department of Health 2/24/2003.

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Presentation on theme: "2/26/03 SAS West Nile Virus Information for the Health Care Professional Mississippi State Department of Health 2/24/2003."— Presentation transcript:

1 2/26/03 SAS West Nile Virus Information for the Health Care Professional Mississippi State Department of Health 2/24/2003

2 2/26/03 SAS What Is West Nile Virus? Arbovirus (arthropod-borne virus) that can cause infection/inflammation of spinal cord and or brain Illness can occur in –Birds –Humans –Horses Transmitted by mosquitoes, and rarely by blood transfusion, organ transplant, transplacental, or breast milk It has not been shown to be transmitted through contact with an infected bird, human, or horse but is theoretically possible

3 2/26/03 SAS History of West Nile Virus: Origin The first case of West Nile virus was from a woman in the West Nile Region of Uganda, Africa in 1937

4 2/26/03 SAS Watch it Spread… to 2002

5 2/26/03 SAS

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9 It’s even crossed over into Canada and Mexico…

10 Quebec Ontario Manit. Saskat. Ontario NovaScotia

11 2/26/03 SAS Human WNME (1 case), 2001 Equine WNME (<5 cases), 2002

12 2/26/03 SAS West Nile Virus: Approximate Worldwide Geographic Range

13 2/26/03 SAS Transmission How is it Spread? Primarily maintained in a bird- mosquito cycle…. …but can spill over to other animals including humans and horses

14 2/26/03 SAS Arbovirus Surveillance Mississippi Activities To identify WNV activity, the MSDH routinely performs the following activities: Dead Bird Report SurveillanceDead Bird Report Surveillance Dead Bird TestingDead Bird Testing Horse TestingHorse Testing Mosquito Collection and TestingMosquito Collection and Testing Human TestingHuman Testing

15 2/26/03 SAS “There’s a dead bird in my yard!!” The Public is encouraged to report all dead birds to their local health department or the WNV hot line: WST-NILE

16 2/26/03 SAS Signs & Symptoms: Incubation Period Signs and Symptoms MAY develop 3-15 days after being bitten by an infected mosquito

17 2/26/03 SAS Signs & Symptoms: Presentations Most are asymptomatic (80%)Most are asymptomatic (80%) Ill patients may present with a spectrum of mild (20%) to severe (<1%) illnessIll patients may present with a spectrum of mild (20%) to severe (<1%) illness Neurologic illness is often present with severe cases, or may present as it’s own entityNeurologic illness is often present with severe cases, or may present as it’s own entity

18 2/26/03 SAS Signs & Symptoms: Presentations Mild Illness (WN Fever)Mild Illness (WN Fever) –usually does not progress to severe illness Severe Illness (meningoencephalitis)Severe Illness (meningoencephalitis) –May present with neurologic component Muscle Weakness or ParalysisMuscle Weakness or Paralysis –May present only with muscle weakness or paralysis or stroke-like symptoms

19 2/26/03 SAS Signs & Symptoms: Mild Illness Self-limitingSelf-limiting Mild cases may include:Mild cases may include: –Fever –Headache –Body aches –Rash –Swollen lymph nodes –Gastrointestinal (nausea, vomiting)

20 2/26/03 SAS Signs & Symptoms: Severe Illness Encephalitis – Inflammation of the brainEncephalitis – Inflammation of the brain Meningitis - Inflammation of the lining of the brain or spinal cordMeningitis - Inflammation of the lining of the brain or spinal cord Muscle Weakness / Paralysis or other neurologic problem - Acute flaccid paralysis, tremors, myoclonusMuscle Weakness / Paralysis or other neurologic problem - Acute flaccid paralysis, tremors, myoclonus

21 2/26/03 SAS Signs & Symptoms: Severe Illness Sudden onset of: High feverHigh fever HeadacheHeadache ConfusionConfusion DisorientationDisorientation TremorsTremors Occasional seizuresOccasional seizures

22 2/26/03 SAS Signs & Symptoms: Severe Illness Other symptoms Muscle weaknessMuscle weakness ParalysisParalysis Altered reflexesAltered reflexes StuporStupor TremorsTremors May result in ComaComa DeathDeath The Elderly are at greater risk for more severe illness

23 2/26/03 SAS Laboratory Findings CBCCBC –WBC normal or elevated –Lymphocytopenia may occur –Anemia may occur ChemistryChemistry –Hyponatremia sometimes present, particularly among patients with encephalitis CSFCSF –Pleocytosis –Protein elevated –Glucose normal

24 2/26/03 SAS Diagnostic Findings CT’sCT’s –No evidence of acute disease MRI’sMRI’s –Enhancement of leptomeninges and or periventricular areas seen in 1/3 of patients

25 2/26/03 SAS Laboratory Testing IgM MAC-ELISA (antibody capture enzyme-linked immunosorbent assay)IgM MAC-ELISA (antibody capture enzyme-linked immunosorbent assay) –Most efficient diagnostic method –Serum or CSF –IgM antibody does not cross blood-brain barrier thus IgM in CSF suggests CNS infection PRNT (plaque reduction neutralization)PRNT (plaque reduction neutralization) –Confirmation test for positive serum PCR (polymerase chain reaction)PCR (polymerase chain reaction) –Inefficient due to short duration of viremia –Can help diagnose in immunocompromised CSF or tissue onlyCSF or tissue only

26 2/26/03 SAS Laboratory Testing May be difficult to interpretMay be difficult to interpret –IgM levels may persist for more than one year New infection vs old infection?New infection vs old infection? Need clinical informationNeed clinical information May need convalescent sample or IgA titer for serum samplesMay need convalescent sample or IgA titer for serum samples –Tests of a single acute-phase (serum or CSF) specimen may be diagnostically inconclusive –Cross reactivity between flaviviruses With WNV + test, may see SLE + and vice versaWith WNV + test, may see SLE + and vice versa Samples collected too acute (< 7 days) in the course of illness may yield false negative resultsSamples collected too acute (< 7 days) in the course of illness may yield false negative results

27 2/26/03 SAS Laboratory Testing Collection Include MSDH submission formInclude MSDH submission form Serum specimen of choice because fewer antibodies in CSFSerum specimen of choice because fewer antibodies in CSF Ship all samples with cold packsShip all samples with cold packs Do NOT use polystyrene tubesDo NOT use polystyrene tubes Do NOT freeze specimensDo NOT freeze specimens

28 2/26/03 SAS Laboratory Testing Collection SeraSera –Collect in tube with gel separator –Spin sample for shipping as free hemoglobin may result in false positive results –Once separated, serum can be held at 2 – 8 C CSFCSF –Can be held at 2 – 8 C

29 2/26/03 SAS Laboratory Testing IgM ELISA for WNV Results from the MSDH-PHL for acute WNV infections are interpreted as follows: Serum Reactive CASE-PROBABLEReactive CASE-PROBABLE –If also positive by PRNT CASE-CONFIRMED Gray Zone SUSPECTGray Zone SUSPECT –Not a Case –Requires convalescent sample and or PRNT Non-Reactive NEGATIVENon-Reactive NEGATIVE –May consider retesting depending on collection date

30 2/26/03 SAS Laboratory Testing IgM ELISA for WNV CSF Reactive CASE-CONFIRMEDReactive CASE-CONFIRMED –Does not require PRNT Gray Zone SUSPECTGray Zone SUSPECT –Requires convalescent sample or PRNT –Or consider paired sera Non-Reactive NEGATIVENon-Reactive NEGATIVE –Consider re-testing depending on collection date –Or consider paired sera *For immune-compromised consider PCR testing of CSF

31 2/26/03 SAS Laboratory Testing IgM ELISA for WNV CSF or Serum InconclusiveINCONCLUSIVEInconclusiveINCONCLUSIVE –Most inconclusive results are due to non-specific binding of patient serum or CSF to test components

32 2/26/03 SAS Laboratory Testing Testing free of charge by the MSDH- Public Health LabTesting free of charge by the MSDH- Public Health Lab –(601) or –1-877-WST-NILE ( ) Vaccination or infection with related flaviviruses (e.g., yellow fever, Japanese encephalitis, dengue) may result in positive testVaccination or infection with related flaviviruses (e.g., yellow fever, Japanese encephalitis, dengue) may result in positive test

33 2/26/03 SAS No specific therapy Only supportive care for severe infections HospitalizationHospitalization IV fluids,nutritionIV fluids,nutrition Ventilator supportVentilator support Prevention of secondary infectionsPrevention of secondary infections Good nursing careGood nursing care Ribavirin in high doses and interferon alpha-2b show activity in vitroRibavirin in high doses and interferon alpha-2b show activity in vitro No clinical data yet - nor for other meds, including steroids, antiseizure drugs, or osmotic agentsNo clinical data yet - nor for other meds, including steroids, antiseizure drugs, or osmotic agents

34 2/26/03 SAS Outcome of WNV Patients Mississippi 2002 Discharged to: Percent Died 6.2% Home 59.6% Nursing home 3.4% Never28.1% hospitalized hospitalized Rehab 1.7% Unknown 6.4%

35 2/26/03 SAS WNV Patients Mississippi 2002 Most patients presented with meningoencephalitis (ME)Most patients presented with meningoencephalitis (ME) Asymptomatic persons and most patients with mild illness do not seek medical careAsymptomatic persons and most patients with mild illness do not seek medical care PresentationPercent WN Fever 16% ME 84%

36 2/26/03 SAS WNV Patients Mississippi 2002 Percent Percent Fever 91.5% Headache 72.3% Muscle Weakness 56.9% Nausea50.8% Vomiting 35.8% Muscle pain34.6% Altered mental 34.6% status Percent Percent Stiff neck 29.8% Rash 25.0% Joint pain 24.5% Lethargy 24.6% Lymphadenopathy 3.7% Seizures 2.1% Signs and symptoms among MS patients:

37 2/26/03 SAS WNV Patients Physical and Cognitive Impairments Frequency of physical and cognitive complaints before and after WNV illness Frequency of physical and cognitive complaints before and after WNV illness (n=84) (n=84) COMPLAINT PRE POST Muscle Weakness4.2% 56% Difficulty walking14.4%50.6% Fatigue28% 65.5% General malaise21.5%48.8% Confusion9.6% 27.4%

38 2/26/03 SAS West Nile Virus Prevention

39 2/26/03 SAS Prevention Mosquitoes can develop in any standing water that lasts more than 4 days

40 2/26/03 SAS Prevention Properly dispose of water- Properly dispose of water- holding containers holding containers Drill holes in bottom of recycling Drill holes in bottom of recycling containers kept outdoors containers kept outdoors Cover rain water collection Cover rain water collection containers with window containers with window screening to prevent female screening to prevent female mosquitoes from laying eggs in mosquitoes from laying eggs in the water the water

41 2/26/03 SAS Prevention Make sure roof gutters Make sure roof gutters drain properly, and clean drain properly, and clean clogged gutters in the clogged gutters in the spring and fall spring and fall Change water in bird baths Change water in bird baths twice weekly twice weekly Turn over plastic wading Turn over plastic wading pools and wheelbarrows when not in use pools and wheelbarrows when not in use

42 2/26/03 SAS Prevention Clean and chlorinate swimming pools, outdoor saunas, hot tubsClean and chlorinate swimming pools, outdoor saunas, hot tubs Drain water from pool coversDrain water from pool covers Clean vegetation and debris from the edge of ornamental pondsClean vegetation and debris from the edge of ornamental ponds Use landscaping to eliminate water from your propertyUse landscaping to eliminate water from your property Fill in potholes in drivewaysFill in potholes in driveways

43 2/26/03 SAS Prevention Make sure all windows and doors have screensMake sure all windows and doors have screens Keep all screens repaired (fix holes and rips)Keep all screens repaired (fix holes and rips) Repair glass in broken windowsRepair glass in broken windows Keep doors closedKeep doors closed

44 2/26/03 SAS Prevention: Personal protection Minimize outdoor activities between dusk and dawn, many mosquitoes are active at these timesMinimize outdoor activities between dusk and dawn, many mosquitoes are active at these times However, other mosquito species can be active during the late afternoonHowever, other mosquito species can be active during the late afternoon

45 2/26/03 SAS Prevention: Personal protection Wear shoes and socks, long pants and a long-sleeved shirt when outdoors for a long period of time, or when mosquitoes are more active

46 2/26/03 SAS Prevention: Personal protection Consider use of mosquito repellents. Carefully read and follow all label instructionsConsider use of mosquito repellents. Carefully read and follow all label instructions Repellents containing 10 to 35% DEET for adultsRepellents containing 10 to 35% DEET for adults

47 2/26/03 SAS Children and Insect Repellents Keep repellents out of reach of childrenKeep repellents out of reach of children Don’t allow children to apply repellents to themselvesDon’t allow children to apply repellents to themselves Rub repellent on skin of child; do not sprayRub repellent on skin of child; do not spray Use small amounts of repellent on children and follow label instructions carefullyUse small amounts of repellent on children and follow label instructions carefully Do not apply to the hands of young childrenDo not apply to the hands of young children American Academy of Pediatrics recommends 10% DEET for childrenAmerican Academy of Pediatrics recommends 10% DEET for children

48 2/26/03 SAS Fight the Bite MSDH Objectives Promote public cooperation to reduce mosquito breeding sitesPromote public cooperation to reduce mosquito breeding sites Help individuals reduce their risk of being bitten by mosquitoesHelp individuals reduce their risk of being bitten by mosquitoes Educate providers about WNVEducate providers about WNV Enlist media to present accurate representations of WNVEnlist media to present accurate representations of WNV Focus on high-risk populationsFocus on high-risk populations

49 2/26/03 SAS Fight the Bite MSDH Objectives Call the MSDH if you have any questions at: WNV Hot lineWNV Hot line 1 – WST – NILE Division of EpidemiologyDivision of Epidemiology 601 – 576 – 7725 Public Health LaboratoryPublic Health Laboratory

50 2/26/03 SAS Fight the Bite MSDH Objectives Or visit the web site at: or the CDC web site at:


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