VECTORS AND VECTOR-BORNE DISEASE IN THE SAINT LOUIS REGION
JAMES SAYERS
VECTOR CONTROL PROGRAM SUPERVISOR
SAINT LOUIS COUNTY DEPARTMENT OF PUBLIC HEALTH AGENDA
Biology and Ecology of Common Vectors
Integrated Pest Management (IPM)
Vector Surveillance
Vector Abatement Activities MOSQUITO BIOLOGY MOSQUITO LIFE CYCLE: 4 STAGES
Egg Laid directly on water or on ground in flood prone areas Larva Feeding stage with 4 stages of development (Instars) Pupa Resting Stage Adult MOSQUITO EGGS LARVAL STAGE MOSQUITO LARVAE IN ACTION
*Note: When disturbed, the larvae head for the bottom. PUPAL STAGE ADULT STAGE COMMON MOSQUITO VECTORS OF SAINT LOUIS COUNTY
56+ SPECIES OF MOSQUITO IDENTIFIED IN SAINT LOUIS COUNTY
• ONLY A FEW ARE IMPLICATED IN THE TRANSMISSION OF DISEASE CULEX PIPIENS: THE NORTHERN HOUSE MOSQUITO
Our main vector WNV SLE
Prefer water rich in organics or pollution, but can be found breeding in most anything
Active only at night (and dusk and dawn)
Prefer to feed on birds Humans are incidental hosts AEDES ALBOPICTUS: THE ASIAN TIGER MOSQUITO
Came to the US from Asia via a tire shipment.
Arrived in St. Louis around the mid 1980’s
Now very common, especially during the months of July, August, and September. AEDES ALBOPICTUS: THE ASIAN TIGER MOSQUITO
Considered mainly a nuisance mosquito, however… WNV Zika Dengue Chikungunya
Small container breeders
Vicious daytime biters
Very short flight range- often coming from own yard or neighbor’s AEDES AEGYPTI
Vector of public health significance Main Vector of Zika Virus, Chikungunya, and Dengue
Lives in close proximity to and prefers to feed on humans
Has not been identified in St. Louis County CULISETA MELANURA: EASTERN EQUINE ENCEPHALITIS
Responsible for maintaining EEE mosquito-bird transmission cycle Found in swamps and primarily feeds on birds EEE transmission to humans requires a bridge vector Aedes Coquillettidia Culex INTRODUCTION TO MO TICKS BIOLOGY
Arachnids – 8 legs Except Larva – 6 legs
Ectoparasitic Mite Feed on blood of host
3 Species of public health significance in MO All 3 are members of Ixodidae (Hard Ticks) Family TICK LIFE CYCLE HABITAT
Occur Statewide
Found in woodlands, tall grasses, weeds, brushy areas, edges of paths and game trails
Most common in areas with abundant wildlife (host animals) FEEDING
Only feed on blood
Hold onto brush with back legs and hold out front legs and wait for host to pass “Questing”
Sense Carbon dioxide as well as vibrations and changes in light TICKS AS ARBOVIRAL DISEASE VECTORS IN SAINT LOUIS COUNTY
Majority of arboviral disease cases in Saint Louis County and statewide tend to be tick-borne Amblyomma americanum (Lone Star Tick) Dermacentor variabilis (American Dog Tick) Ixodes scapularis (Black Legged Tick) MAJOR VECTOR OF DISEASE AMBLYOMMA AMERICANUM: LONE STAR TICK
Brown with distinctive white dot on scutem LONE STAR TICK
Found mostly in woodlands with dense undergrowth Aggressive human biters Will actively seek hosts as apposed to questing. Active April through November Nymphs and adults transmit Ehrlichiosis Tularemia DERMACENTOR VARIABILIS: AMERICAN DOG TICK
Brown with gray mottling on upper surface/scutem AMERICAN DOG TICK
Predominantly found in grassy fields and scrubland Walking Trails
Active April through November
Adults transmit Rocky Mountain Spotted Fever Tularemia IXODES SCAPULARIS: BLACK LEGGED TICK (DEER TICK)
Legs and scutem are black BLACK LEGGED TICK
Prefer leaf litter in forested areas
Active as long as temps are above freezing
All stages transmit Lyme Disease Anaplasmosis Babesiosis AMBLYOMMA MACULATUM: GULF COAST TICK GULF COAST TICK
Normally inhabit grasslands and woodland edges
Range extends into extreme Southern MO, however, 2 specimens identified from Saint Louis County this summer
Transmit Rickettsia parkeri to humans HAEMAPHYSALIS LONGICORNIS: ASIAN LONGHORNED TICK ASIAN LONGHORNED TICK
Invasive species with multiple populations found in the US Not identified in MO, yet…
Predominately found in meadows, grassy areas, and livestock pastures near wooded areas
Capable of transmitting several pathogens to humans and livestock PREVENTION
Avoid tick-infested areas
Wear protective clothing
Use insect repellent
Remove ticks as soon as possible
Tick Removal Tool or Forceps INTEGRATED PEST MANAGEMENT (IPM) WHY IS VECTOR CONTROL IMPORTANT?
Public Health: Over 1 million human deaths worldwide every year from mosquitoes
Quality of Life Nuisance Mosquitoes VECTOR CONTROL PROGRAM: PURPOSE
Protect public health by decreasing the risk of arboviral disease transmission within Saint Louis County
Accomplish this by reducing the disease carrying mosquito, tick, and rodent population on public property using Integrated Pest Management (IPM) methods. VECTOR CONTROL PROGRAM: INTEGRATED PEST MANAGEMENT
What is Integrated Pest Management (IPM)?
A science-based strategy that focuses on long-term prevention of target organisms through a combination of control techniques that are practical and effective to protect public health, as well as the environment.
Aim to reduce targeted pest populations while minimizing impacts to non-target species, beneficial organisms, human health, and the environment VECTOR CONTROL PROGRAM: INTEGRATED PEST MANAGEMENT
Key Points:
Surveillance Allows us to concentrate efforts and allocate resources where they are needed most Provide the data to justify the need to make pesticide applications Pesticide applications occur only after surveillance results indicate they are warranted VECTOR CONTROL PROGRAM: INTEGRATED PEST MANAGEMENT
Key Points:
Utilization of multiple control methods Larviciding Adulticiding Biological Controls Source Reduction Public Education SURVEILLANCE SURVEILLANCE HELPS US TO:
Focus treatment on the areas that need it most
Higher numbers of disease carrying mosquitoes are located
Where mosquitoes are testing positive for disease ADULT MOSQUITO SURVEILLANCE
230+ permanent traps sites
Trapping starts in May and runs through late September or October
On average: Up to 16 traps set 5 nights per week during the season Gravid Sentinel 2 VECTOR CONTROL PROGRAM: TRAP SITES TICK SURVEILLANCE
Dragging or Flagging cloth through tick habitat to pick up questing ticks
CO2 Traps mounted to plywood surrounded by double-sided tape TICK SURVEILLANCE
Tick surveillance and abatement can be logistically difficult and is underfunded nationwide
Vector Control provides education to residents on how to protect from tick bites
Product used for barrier applications in some county parks for mosquito control is also labeled for control of ticks Samples taken back to Vector lab where we: Sort out non-vectors Identified by sex and species Counted (by hand…) Mosquito samples tested for presence of arboviral disease
Surveillance data is shared with: DPH, local, state, and federal agencies MOSQUITO CONTROL ACTIVITIES LARVICIDING
Larviciding
Treatment of known mosquito breeding sites on public property
Currently monitor and treat 6000+ sites throughout Saint Louis County LARVICIDING
Most effective and cost efficient control method
Control mosquitoes before they emerge as adults
Component of Integrated Pest Management Biological larvicide targets only mosquito larvae
Document known breeding sites on public property allowing for systematic surveillance and treatment Sites are regularly monitored for breeding activity and treated as needed MOSQUITO BREEDING SITES
Sewers / Ditches Catch Basins
Detention Basins MOSQUITO BREEDING SITES
Ponds Swamps
Standing Creeks Water BREEDING SITES AROUND YOUR HOME
Bird Baths Ornamental Ponds Drains
Gutters Flower Pots Corrugated Pipe NEGLECTED SWIMMING POOLS LARVICIDES
Summit B.t.i. Vectolex WSP Fourstar Briquets Briquets MOSQUITO ADULTICIDING MOSQUITO ADULTICIDING
Ultra Low Volume (ULV) Spraying Use truck mounted or hand held ULV machines to dispense mosquito control product to the air County roads, public streets, parks Barrier Applications Use truck mounted skid sprayers backpack sprayers to apply barrier sprays in public areas County parks, sports fields, playgrounds, etc. WHY IS ADULT MOSQUITO CONTROL UTILIZED?
Reduce the number of adult mosquitoes to help prevent the spread of disease ULV applications determined by surveillance data
Only way to control adult mosquitoes
Adulticiding is just another facet of the Integrated Pest Management (IPM) approach to mosquito control QUESTIONS?