The West Nile Virus – A Global and Local Concern Amleto A. Pucci, Jr. Ph.D. P.E. Director, Bureau of Environmental Health Bucks County Department of Health Add Corporate Logo Here

Outline Global Extent United States Program Science –Vectors, hosts –Transmission cycle Surveillance & Control NYC Case study Bucks County Data

West Nile Outbreaks Uganda (first diagnosed case)Uganda (first diagnosed case) Israel , 1957, 2000Israel , 1957, 2000 France , 2000France , 2000 South Africa South Africa Romania – 1996Romania – 1996 Italy 1998Italy 1998 Russia Russia United States – United States – Modified from

West Nile Fever: Classical Clinical Description Asymptomatic or mild dengue fever-like illness Fever, headache, abdominal pain, vomiting, rash, conjunctivitis Fever, headache, abdominal pain, vomiting, rash, conjunctivitis Incubation period usually 3 to 15 days Incubation period usually 3 to 15 days CNS involvement and death in minority of cases CNS involvement and death in minority of cases Modified from

West Nile Virus in the US Some Possible Pathways of Introduction Infected human hostInfected human host Human-transported vector(s) (agent)Human-transported vector(s) (agent) Human-transported vertebrate host (carrier)Human-transported vertebrate host (carrier) –Legal –Illegal Storm-transported vertebrate host (bird)Storm-transported vertebrate host (bird) Intentional introduction (terrorist event)Intentional introduction (terrorist event)

Partnerships for West Nile Virus in the United States Centers for Disease Control and PreventionCenters for Disease Control and Prevention U.S. Department of AgricultureU.S. Department of Agriculture U.S. Geological SurveyU.S. Geological Survey Department of DefenseDepartment of Defense Environmental Protection AgencyEnvironmental Protection Agency State and Local Health DepartmentsState and Local Health Departments State and Local VeterinariansState and Local Veterinarians State and Local Wildlife BiologistsState and Local Wildlife Biologists

New York City Philadelphia Houston Los Angeles Washington, D.C. Jurisdictions Funded for Enhanced WN Surveillance First Round $$ Second Round $$

West Nile Fever: Background and Epidemiology Basic transmission cycle involves mosquitoes feeding on birds infected with the West Nile virus Basic transmission cycle involves mosquitoes feeding on birds infected with the West Nile virus Infected mosquitoes then transmit West Nile virus to humans and animals when taking a blood meal Infected mosquitoes then transmit West Nile virus to humans and animals when taking a blood meal Modified from

Virus Virus uses birds as amplifier hosts, with vectors that feed on birds. Virus strain is highly infectious for North American birds, causing mortality and high viremia. Virus does not transmit from infected mosquito to next mosquito generation. Virus overwinters in some mosquitoes.

Vectors Examples of vectors which affect many of one kind of bird (epizootic) within in a limited range (enzootic) Culex pipiens, Culex restuans, others Examples of vectors that can infect many individual mammals at one time (epidemic), such as humans Culex pipiens, Culex restuans, others? Other mosquito species as accessory vectors? Yes!

West Nile Virus Transmission Cycle Modified from

Estimated Sensitivity of West Nile Virus Surveillance Methods Human cases Veterinary cases Mosquitoes, Dead bird Time Disease Activity Surveillance method sentinel hosts

Integrated Mosquito Management Surveillance –Bird –Mosquito –Human Larval Mosquito Control –Source reduction –Appropriate response to the need Adult Mosquito Control –Targeted Approach – based on field data Education - Outreach

Mosquito Trap methods used by West Nile Virus Program Bucks County Department of Health, Gravid Trap ABC Mosquito Light Trap Modified Aspirator

Types of Mosquito Control used in the Bucks County West Nile Virus Program Bti (Bacillus thuringiensis isrealensis) – naturally occurring soil bacteria which disrupts the gut of the larvae –Essentially nontoxic to humans –Does not effect wildlife and non-target species Methoprene “Altocid” -- chemical growth regulator –Low toxicity to mammal, birds, and fish. –Some invertebrates are sensitive to it therefore strictly controlled. –Not unreasonable risk to the environment. Breaks down quickly.

1999 WN virus activity in NYC area Mosquitoes Birds Humans

Bucks County West Nile Virus Positive Dead Birds in 2001 per Twp Sq. Mi ( through 10/17/01 ) Bensalem Township Bristol Township Bristol Borough Falls Township Lower Southampton Township Morrisville Borough Upper Southampton Township Middletown Township Lower Makefield Township Northampton Township Warminster Township Warrington Township Doylestown Township Chalfont Borough Buckingham Township Municipality in Bucks County, PA Dead Birds Tested Positve for WNV/Sq. Mile Dead Birds perTownship Sq. Mi. in 2001 Municipality series is approximately from southeast towards nortwest within Bucks County

Select West Nile Virus Research Priorities Virus persistence mechanisms (disease reservoir) Vector (mosquito species) relationships and range –Mosquito biology and behavior Vertebrate host (birds) relationships and range –Bird migration as dispersal mechanism Current & future geographic WNV distribution Development of preventative strategies –Improved lab diagnostic tests –Clinical studies of human infections –Vaccine development

Key Messages Best thing is to eliminate places where mosquitoes breed. Public Health is working hard to reduce mosquito populations in Bucks County. If you have questions call West Nile Virus Hotline (1-877-PAHEALTH), and contact your physician.