Other Animal Species

Large and growing list of animals that have tested positive for WNV

Current list at U.S. Geological Survey’s National Wildlife Health Center website at:

www.nwhc.usgs.gov

Dogs

Small Study (4 animals)

Low levels of viremia induced

None clinical

(Unpublished data to date-Michel Bunning, CDC-DVBID)

CatsSmall study

Viremia a little higher and longer than dogs

Parenteral: mild temp for 2-3 days

no CNS signs

Oral: fed infected mice

same level of viremia, no illness

Therefore-could be source for mosquitoes

WNV Positive Humans

Positive HumanWNV Cases 2002

577 cases51 deaths

0

5

10

15

20

25

7/20/2

002

7/27/2

002

8/3/20

02

8/10/2

002

8/17/2

002

8/24/2

002

8/31/2

002

9/7/20

02

9/14/2

002

9/21/2

002

9/28/2

002

10/5/

2002

Onset Date

Nu

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f C

ases

Confirmed Probable

Onset Date of Symptoms Among Human West Nile Virus Cases in Michigan as of November 5th, 2002

Age Groups of WNV Cases Michigan 2002

0102030405060708090

0-10 21-30

41-50

61-70

81-90

AGE IN YEARS

# Cases

Michigan Case Statistics:

All Cases

Age range: 9mo-95yrs

Ave Age: 57.6

% Female: 45

% Male: 55

Deaths

Age range: 24-95 yrs

Ave Age: 74.5

% Female: 41

% Male: 59

Types of Illness

80% asymptomatic

20% have flu-like symptoms

<1% have meningo-encephalitis/flaccid paralysis/other serious sequelae

~10% of those with serious CNS signs die

West Nile Meningo-encephalitis

Fever, headache

Altered mental status AND/OR

Stiff neck with CSF pleocytosis or elevated protein

Flaccid paralysis (poliomyelitis-type)

Diagnosis of Human Cases

CSF is best specimen

IgM Capture ELISA

PRNT (measure of IgG)

Serum-need paired sera to document a rise in titer

SLE cross reaction-must run concurrently

New Modes of Transmission

Transplant

Transfusion

Breast milk

Trans-placental

Occupational

Bird Surveillance Goals:

Collect information about dead bird sightings

Collect specimens for laboratory testing

Predict level of risk for human infection

Target intervention/prevention measures

Methods of Bird Surveillance

Citizen reports of dead or sick birds via hotline and website.

Laboratory testing of appropriate bird specimens.

Bias: Requires a person to find the bird and report it or submit it. Larger population areas will have more birds reported.

West Nile Virus Hot Line

Started in 2001

Toll Free #: 888-668-0869

Citizens call in to report dead bird

We requested reports of dead corvids

Request address and day bird was found, as well as willingness to collect bird for testing

Received 9,279 phone reports in 2002

WNV Hotline Calls* 2002

0

5000

10000

15000

20000

25000

July August September

# calls

888/668-0869

* >35,000 calls in Aug & Sept

Web-based Reporting

Accessed via www.michigan.gov/mda

Pilot program with Michigan State University

Received 1350 reports via the web

0

50

100

150

200

250

300

350

4/17/2

002

5/1/20

02

5/15/2

002

5/29/2

002

6/12/2

002

6/26/2

002

7/10/2

002

7/24/2

002

8/7/20

02

8/21/2

002

9/4/20

02

9/18/2

002

10/2/

2002

Date of Call

Nu

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alls

Phone Reports of Dead Birds in Michigan as of November 26th, 2002

Bird Surveillance Totals

Logged over 10,500 reports of dead birds and other animals

About 13% of reports came via the web

65% of dead birds reported were corvids (these were requested)

0

50

100

150

200

250

300

350

0

5

10

15

20

25

Phone Calls Human Cases

Phone Reports of Dead Birds versus Human Cases in Michigan as of November 26th, 2002

Potential Problems for Bird Surveillance in 2003

Bird immunity-crows could be less sensitive indicator of WN activity

Lack of web-based reporting for local and state reporting of diseases

Monitoring of bird reporting is labor intensive without technological support

Need to share data amongst agencies

Prevention

Source reduction

Personal protection

Mosquito control

Vaccine-horses only at this time

What Happened in 2002?

Expansion of endemic area to 44 states in the US

Huge epizootic/epidemic-especially in the Great Lakes and southern states

New modes of transmission discovered

Over 4000 human cases with more that 260 deaths

What to Expect in 2003?

Complete spread to the 48 states in the continental U.S.?

Bird immunity?

Human herd immunity?

Sporadic occurrence?

???????