Arboviral Surveillance in Maryland, 2003 Kimberly C. Mitchell, MPH West Nile Virus Coordinator January 29, 2004

Contents of Presentation Review of 2003 Maryland arboviral surveillance season Discussion Q & A

Maryland WNV Human Surveillance: June 1, October 31, 2003 Over 900 blood/CSF samples from patients tested at DHMH Laboratories Administration 73 cases reported in 13 jurisdictions: Anne Arundel, Baltimore City, Baltimore County, Carroll, Caroline, Charles, Frederick, Harford, Howard, Montgomery, Prince Georges, Queen Anne’s, and Washington counties 5 fatalities

Maryland WNV Human Surveillance, 2003  Median age: 58 years; Range: years  Onset date range: July 22 to October 25, out of 73 (6.8%) died due to WNV (age range: 63 to 83 years; median age: 77 years)

Human WNV Cases by Disease (n=73)

Maryland WNV Mosquito Surveillance: June 1, October 31, 2003 Over 190,000 mosquitoes tested 62 pools in 14 jurisdictions positive for WNV (Allegany, Anne Arundel, Balt. City, Baltimore County, Caroline, Carroll, Charles, Dorchester, Frederick, Prince George’s, Somerset, Talbot, Wicomico, Worcester) Mostly C. salinarius; also C. species, C. perturbans, and A. vexans.

WNV Mosquito Surveillance in Maryland, 2003 (as of 12/10/03)

Maryland WNV Equine Surveillance Horse exhibits clinical signs Blood, CSF, and/or brain samples from horses are submitted for arboviral testing at a laboratory facility: –DHMH Laboratories Administration –Cornell Diagnostic Laboratory –Pennsylvania Animal Diagnostic Laboratory System –Other private labs

Maryland WNV Equine Surveillance Clinical signs of WNV infection in equines include: –fever –ataxia (staggering gait) –recumbency –facial paralysis –muscle fasciculations (contractions) –lip twitching –head tilt –lethargy

Maryland WNV Equine Surveillance Date of onset Vaccination history Travel history Age Breed Vital Status (Alive/Fatal)

Maryland Equine Surveillance June 1, October 31, horses positive for WNV in 20 jurisdictions: –Anne Arundel, Baltimore Co., Calvert, Caroline, Carroll, Cecil, Charles, Dorchester, Frederick, Harford, Howard, Kent, Montgomery, Prince George’s, Queen Anne’s, St. Mary’s, Somerset, Talbot, Washington, Worcester Clinical information available on 232 of total 233 cases: –74 of 232 (32%) were fatal cases –47 horses of 232 (20%) current on WNV vaccinations –18 of 47 (38%) currently vaccinated horses were fatal cases –21 of 232 (9%) had unknown vaccination history

WNV Equine Cases in Maryland, 2003 (as of 12/10/03)

Maryland WNV Avian Surveillance, 2003 (as of 11/14/03) Maryland DHMH discontinued dead bird surveillance in 2003 season due to endemic nature of WNV. Continue to receive and report avian surveillance results from Dept. of Natural Resources (DNR) and Dept. of Defense (DoD)

Maryland WNV Avian Surveillance, 2003: DNR Results 11 birds in 5 jurisdictions tested positive for WNV Jurisdictions: –Cecil –Dorchester –Queen Anne’s –Wicomico –Worcester

Eastern Equine Encephalitis (EEE) Mosquito-borne disease Primary vectors in Maryland: C. melanura; bridge vectors: C. perturbans, A. vexans Symptoms: mild flu-like illness to encephalitis (inflammation of the brain), coma and death Estimated 35% of people who survive EEE will have mild to severe neurologic deficits Case fatality rate in humans is ~35%

Maryland Mosquito Surveillance: Eastern Equine Encephalitis (as of Nov. 13, 2003) 10 mosquito pools in 2 jurisdictions tested positive for Eastern equine encephalitis (EEE)* –3 pools of C. melanura mosquitoes in Wicomico County –7 pools of C. melanura mosquitoes in Worcester County *One pool of C. melanura collected in Worcester County on August 12 tested positive for both WNV and EEE.

Maryland Equine Surveillance: Eastern Equine Encephalitis (as of Nov. 13, 2003) Three horses in Worcester County tested positive for EEE: –Two horses in Pocomoke City area –One horse in Whaleyville area All were fatal cases None had any history of EEE vaccine

Maryland EEE Surveillance: Other Species (as of Nov. 13, 2003) In mid-September, 1 emu (ratite) tested positive for EEE infection in Salisbury area of Wicomico County In ratites, EEE disease can cause severe illness and death.

Department of Defense (DoD) Arboviral Surveillance in MD, 2003 Mosquito surveillance is conducted at 9 military installations in Maryland; testing is performed at USACHPPM (Fort Meade). As of 12/1/03, 53 mosquito pools in 3 jurisdictions tested positive for WNV: –Harford County (Aberdeen Proving Ground) –Montgomery County (National Naval Medical Center, Naval Surface Warfare Center) –Prince George’s County (Andrews Air Force Base)

Department of Defense (DoD) Arboviral Surveillance in MD, 2003 Avian surveillance: sampling and testing of select dead birds at designated military installations Of 32 birds collected for testing to date, 11 birds tested positive for WNV in 5 jurisdictions: Anne Arundel, Frederick, and Harford, Montgomery, and Prince Georges Counties Mostly corvids

Baltimore Zoo Surveillance: January 1 - December 31, avians tested by serum neutralization and/or PCR 21 birds tested antibody positive Positive species included: –Bald Eagle –Black-footed penguin –Domestic chicken –Goldeneye –Lesser flamingo

Comparison of 2002 and 2003 Maryland Arboviral Surveillance

Summary West Nile Virus (WNV) –73 human WN cases; 5 fatalities –115 positive mosquito pools –45 positive birds –233 positive horses Eastern Equine Encephalitis (EEE) –10 positive mosquito pools –3 positive horses Other Arboviruses: –1 positive mosquito pool (Melao Complex virus)

Conclusions Accomplishments  Successful monitoring and reporting of WNV and other arboviral activity in Maryland  Greater understanding of WNV epidemiology and ecology in Maryland Future Directions  Refinement of resources and methods for tracking WNV and other arboviruses of public health significance  Continued education for veterinarians and other health care professionals