West Nile Virus Background and Ecology First

West Nile Virus: Background and Ecology • First isolated in West Nile district, Uganda, 1937 • Commonly found in humans and birds and other vertebrates in Africa, Eastern Europe, West Asia, and the Middle East, but has not previously been documented in the Western Hemisphere • 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

West Nile Virus Outbreaks u Israel – 1951 -1954, 1957, 2000 u France – 1962, 2000 u South Africa – 1974 u Romania – 1996 u Italy – 1997 u Russia – 1999 u U. S. A. – 1999 -2002

Spread of West Nile Virus in the U. S. 7/30/02 1999 2000 2001 2002 Humans

WNV Case-Patient Demographics & Mortality United States, 1999 -2001 1999 - 2000 83 2001 66 65 5 - 90 68 19 - 90 Males 54% 65% CFR 11% 14% Number Age (yr) median range

Date of Symptom Onset, West Nile Virus United States, 1999 -2001 2000 1999 25 20 15 10 5 Week ending 3 12 /2 4 11 /2 7 10 /2 29 9/ 1 9/ 4 8/ 7 0 7/ Number of cases 30

Clinical Epidemiology u Incubation u 20% u 1 period 3 - 14 days develop “West Nile fever” in 150 develop meningoencephalitis – Advanced age primary risk factor for severe neurological disease and death

West Nile Fever: Classic Clinical Description • Mild flu-like illness of sudden onset • Duration 3 - 6 days • Fever, swollen lymph nodes, headache, abdominal pain, vomiting, rash, conjunctivitis, eye pain, anorexia • Symptoms of West Nile fever in contemporary outbreaks not fully studied

Symptoms of Hospitalized Patients with West Nile Virus Fever Weakness Nausea Vomiting Headache Change in mental status Diarrhea Rash Swollen Lymph Nodes 90% 56% 53% 51% 47% 46% 27% 19% 2%

West Nile Virus

Mosquitoes u Usually Culex Genus Pipiens or Restuans species are most common carriers in this area u Only the females bite u Males feed on nectar u Normally only ¼ “ long u “Huge” mosquitoes are really crane flies u

Mosquito Lifecycle u Egg raft Ø Up to 300 eggs Ø Hatch within 3 days u Larvae Ø Wigglers u Pupae Ø Tumblers Ø Become adults within a few days u Adult Ø Males Live one week Ø Females live one month Ø Flight range up to ½ mile

West Nile Virus Transmission Cycle u Mosquito infects bird while taking a “blood meal” u Other mosquitoes pick up the virus from the infected bird u Humans and animals (horses) get the virus from infected mosquitoes u ONLY MOSQUITOES CAN SPREAD WEST NILE VIRUS

West Nile Virus Transmission Cycle

Dead Birds u Virus found in over 100 species of birds u Predominant species: – Hawks – Owls – Crows – Blue jays u Call 1 -877 -PA HEALTH u Only five birds are tested weekly

Hawks u u u Length: 18 inches Wingspan: 48 inches Short, dark, hooked beak Large, broad-winged, broad-tailed hawk Immatures have notably narrower wings and tail, and appear slimmer Dark patagial mark on underwing, present on all ages and races, is unique

Owls u u u Length: 8 inches Wingspan: 22 inches Small, nocturnal, predatory bird Large, rounded head with ear tufts Yellow eyes Dense streaking on underparts with finer barring Some birds have rusty plumage, others dark gray

Bluejays u u u u Length: 10 inches Black sturdy bill Blue crest and upperparts Black eyeline and breastband Grayish-white throat and underparts Bright blue wings with black bars and white patches Long blue tail with black bars and white corners Dark legs

Crows u u Length: 17 inches Entirely black plumage Squared-off tail Very common in urban and agricultural areas

Washington County WNV Program u Surveillance of known problem areas u Surveillance of citizen complaints u Samples sent to PA DOH for analysis u Positive areas are treated u Heavily infested areas are treated u Purpose is not to eradicate the mosquito population

West Nile Virus Surveillance Dead Bird Reports Dead Bird Testing Live Bird Testing Mosquito Testing Equine Cases Human Cases

Gravid Trap u Lactalbumin water is an attractant u Draws mosquitoes into trap from the bottom u Easier to use u More effective than light traps

Gravid Trap

Light Trap Carbon dioxide and light used as attractants u Color u Collection bin hangs from the bottom u

West Nile Virus – Human Cases PREVENTION Mosquito Control Personal Protection

Personal Protection Clothing ØAvoid black and white ØWear long sleeves ØWear long pants

Personal Protection Avoidance • Home needs to be “Bug Tight” • Stay indoors at dusk and dawn • Use insecticides at dusk and dawn • Use white incandescent lights • Vitamin “B”, “Bug Zappers”, and “ultrasonic” devices are ineffective

Personal Protection • Repellant ØDeet ØBite Blocker ØAvon Skin So Soft • Read and understand label directions • Apply lightly to skin and clothing

Mosquito Control

Mosquito Control Habitat Elimination Adulticiding Larviciding

Adulticiding u Malathion Ø Organophosphate Ø Applied in “Ultra Low Volume” Ø Can be toxic to humans u Originally, only done for positive test areas u Will be done for heavy infestations

Larviciding Preferred method of control u Microbial – BTI, CG, and WDG u Naturally occurring bacteria Ø Non-toxic to humans and animals Ø u Methoprene Growth regulating hormone Ø Applied to ditches, ponds, marshes Ø u Temephos Organophosphate pesticide Ø Can pose a human health hazard Ø u Monomolecular films & Oils Causes larvae and pupae to drown Ø Poses little risk to humans, wildlife, and the environment Ø

Natural Predators u Purple Martins u Bats u Mosquito fish u Other breeds of mosquitoes u. Mosquitoes of choice are not the meal

Habitat Catch basins u Clogged bodies of water u Construction depressions u Flooded Flower pots u Public dumps u Birdbaths u Unfiltered swimming pools u Cemetery urns u Clogged rain gutters u Boats u Rain barrels u Hoof prints u Swamps u Tree holes u Tin cans u Tires u

Control Breeding Sites u Turn over pools and wheel barrows u Dispose of things that can hold water i. e. tires, tin cans, broken toys, etc. u Drill holes in permanent containers u Clean clogged roof gutters u Empty accumulated water from boats u Keep outdoor water fresh u Landscape your property u Keep grass cut and weeds pulled

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