Historical Outbreaks Year 2 Pop Block 3

5 phases of investigation

• describe outbreak

• collect and analyze data

• implement ontrol

• follow-up

• communication

epidemiologic triad

• agent

• host

• environment

West Nile Virus

• 1999

• Bronx Zoo

• Dr. Tracey McNamara

• zoonotic

New World Screworm

• cochliomyia hominivorax

• parasitic fly native to Western Hemisphere

• larvae cause obligate myiasis

• larvae feed on living tissue of warmblooded animals

• historically one of most economically important livestock pests in US

New World Screwworm Lifecycle

• females generally only mate once

• female search for open wound or orifice on host

• female fly lays eggs on wound

• eggs hatch in 12-24 hours

• larval stage for 5-7 days

• L-3 larvae drop from wound or orifice and burrow into soil to pupate

• larvae transition to pupae for 6-8 days then emerge as flies

How is New world screwworm transmitted?

• adult female flies attracted to wounds and susceptible boy sites

• females lay eggs along edges of wounds or body openings

• wounds can be very small, even a tick bite

• common sites include

  • traumatic or surgical wounds

  • umbilicus of newborn animals

  • nose, mouth, eyes, and ears

  • genitalia

• eggs hatch and larvae burrow into living tissue to feed

What animals does new world screwworm infect?

any warm-blooded animal, including birds and humans

diagnosis and next steps for new world screwworm

• contact state animal health official

• confirm and submit samples as directed for identification

  • collect larvae from deep within wound

• treat and remove larvae and clean wound

Was NWS once endemic in US?

• Yes was major livestock pest across southern US

• since mid 1800s in southwest

• significant problem in southeast in 1930s

• persistent infestations continued through 1950s

What is the intervention for NWS?

• sterile insect technique

• developed in 1950s as population-level strategy to eradicate NWS

What made eradication possible in US?

• recognition of NWS as distinct, live-tissue-dependent species

• mass-rearing flies

• understanding mating behavior

• sterile insect technique concept

• large-scale sterilization

Critical response activities for NWS

• epidemiologic investigation and tracing

• information management

• communication and coordination

• public eradication

• quarantine and movement control

• control area (or other zone) designations

• sterile insect technique → eradication

virulent newcastle disease

• agent: avian orthoavulavirus 1

• family: paramyxoviridae

• strains vary in virulence

  • lentogenic = low virulence

  • mesogenic = virulent

  • velogenic = highly virulent

• hosts = avian species

• transmission - inhalation or ingestion (direct and indirect transmission)

• incubation = 2-15 days

clinical presentation of vND

• respiratory = coughing, sneezing, gasping/dyspnea

• GI = diarrhea, hemorrhagic disease

• neurologic = tremors, paralysis, torticollis, circling

• reproductive = decreased egg production, abnormal eggs

• sudden death, up to 100% morbidity and mortality

What is the intervention for newcastle?

• depopulation

  • no treatment

  • highly contagious

• stamping out

  • rapid depopulation of infected poultry and exposed/contact poultry

critical response activities for nVD

• surveillance

• communication and coordination

• public education

• quarantine and movement control

• control area designations

• depopulation

• carcass disposal/cleaning and disinfection

common themes for outbreaks

• surveillance

• investigation

• communication and collaboration

• public education

• quarantine and movement control

• control zones