keds, biting midges, sand flies, lice

keds adaptations for parasitism

dorsoventrally flattening

are keds solenophages or telonophages?

solenophages (directly into the blood vessel)

keds life cycle

larviparous - a single egg is passed to the uterus where is embryonates and hatches, then dropped closer to host and glued, adult fly will emerge after a period of several weeks to several months - 2 larval instars in uterus (nourished by accesssory glands)

sheep keds - life

females may live for 4 months and produce 10-12 larvae, males will live 2-3 months

when do female sheep keds mate?

females mate within a day of ecolsion and will mate with multiple males if present

when do sheep ked feed?

about every 24-36 hours, increasing to 2-day intervals in older keds for 5-10 minutes

what can sheep keds vector?

bluetongue virus

Heavy sheep ked infestations can lead to:

back loss which can lead to death by ewes rolling onto their backs to relieve irritation (animals become stuck and suffocate due to interbal organ pressure against diaphragm)

How do sheep keds spread?

newborn lambs become infested with keds directly from their mothers after birth (sheep to sheep transfer)

Treatment of sheep keds?

sheering prior to lambing reduces population by 70%
treat with organic pesticides is effective (dipping sheep)

Deer keds wings

wings are deciduous (lose wings within 48 hours of reaching host)

sand flies habitats/breeding sites

terrestrial (on land), highly orangic soils or decomposed manure, adults can be found in tree hollows, rock piles, animal burrows, and animal enclosures such as poultry houses and pigsties.

what sexes of sand flies feed?

only females feed

where do sand flies feed?

exposed skin areas (ear, nose, neck, undersides, feet, tail)

what do sand flies transmit?

leishmaniasis (ecology varies depending on geographic zone)

three presentations of leishmaniasis disease:

cutaneous leishmaniasis - skin surface

visceral leishmaniasis - internal organs

mucocutatneuous leishmaniasis - mouth

life cycle of leishmania

cycloproagative

vector - pathogen paring of leishmania

cutting action of sandfly mouthparts recruit macrophages, leishmania parasites first stop in vertebrate host in macrophages

what determines leishmaniasis severity?

immune response of host

two veterinary forms of leishmaniasis

canine leishmaniasis
feline leishmaniasis

leishmaniasis in the US

canine leishmaniasis has been reported from texas, oklahoma, kansas, and Ohio

vectors are unknown

spread by vertical (dog-dog) transmission

outcomes of leishmaniasis

rarely curative, relapses are common, potential zoonotic transmission of organisms

control of sand flies - chemical

insecticides (pyrethroids) for residual spraying of dwellings and animal shelters, space-spraying, impregnated dog collars (repellants may be more effective)

ecomonic impact of lice:

cause anemia, dermatitis, allergic responses, hair loss, restlessness, low weight gain, low milk yeild, hide or fleece damage, skin crusting or scabbing, and lameness

two groups of lice:

sucking lice and chewing (biting) lice

sucking lice

blood feeders (obligate hemotophagous ectoparasites), look for a tapered head

chewing (biting) lice

look for wider head, feeds on the fur or feathers

how do chewing lice feed?

bitng or scraping action of the mandibles to sever small pieces of fur or feathers, can also feed on skin debris and secretions

How do sucking lice feed?

solenophages (directly from blood vessels)

sucking lice are vectors for what?

pathogens that will replicate in red blood cells

morphology of lice

wingless (transmitted through direct contact), dorsoventrally flattened (top to bottom)

lice eggs

eggs are glued to the hair or father shaft (eggs are resisant to chemicals)

When do lice populations peak?

winter

do lice have host specificity?

yes

do lice show site specificity?

many chewing lice do which leads to morphological changes

kinds of lice of cattle

1 chewing and 3 sucking

3 sucking lice that infect cattle

longnosed cattle louse
little blue cattle louse
shortnosed cattle louse

lice in horses

horse biting louse (avoids coarse hair), horse sucking louse

Lice in swine

hog louse (blood feeder) - large species of sucking lice

lice in sheep

sheep biting louse, african blue louse, face and body louse, sheep foot louse

lice in goats - 2 biting, 2 chewing

goat biting louse, angora goat biting louse, goat sucking louse, african blue louse

lice of cats and dogs

cat biting louse, dog biting louse, dog sucking louse

Lice of domestic fowl (chicken)

at least nine species of chewing lice

lice surveillance

healthy animals should not have high lice burdens, for cattle examine 10-15 animals

cultural control of lice

grooming, keep animals healthy and well nourished, inspect new aniamls coming into a herd

insecticide treatment for lice

animals need to be treated at least twice, most prevalent in winter, insecticide application can cause stress and chilling

Injectable or oral treatment of lice

will kill sucking lice but not chewing lice
macrocylic lactones cannot be used later in winter if not used in the fall) non-systematic pour-ons are safer but must give two treatments

biting midges feeding type

telonophagy - causes skin reactions in horses, known as equine allergic dermatitis

what sexes of biting midges blood feed?

only females

biting midge life cycle

female needs a blood meal to develop eggs, eggs are laid in aquatic or semi-aquatic environments high in organic matter (manure) - 4 larval instars

sweet itch in horses

biting midges (propagative transmission) - aka seasonal equine dermatitis, allergic response to saliva of culicoides midges, horse IgE antibodies bind to the midge saliva proteins to cause immune cascade, produce histamine, and other inflammatory cytokines

biting midges as vectors

vectors of more than 35 arboviruses that infect domestic animals (only few of these viruses cause significant clinical disease), cattle, sheep, and horses most seriously affected

bluetongue disease

biting midges (propagative transmission) - caused by bluetongue virus, biting midges are the only vector, infects ruminants mainly sheep and cattle.

what does bluetongue infection look like?

hunched posture trying to take pressure of painful hooves, lesions on coronary band, between claws, and in or around mouth

bluetongue dieases occurs……..

venereally - via semen of infected ranms and bulls (can occur inadvertently), virus can survive indefinitely when frozen

Epizootic hemorrhagic disease

biting midges (propagative transmission) - similar presentation to bluetongue (crouched stance, painful hooves, tongues swollen hanging out of mouth, head hanging), found in wild ruminants (deer)

vesticular stomatitis virus

biting midges (propagative transmission) - causes acute, febrile (fever), weakening viral disease, affects horses, cattle, swine, and sometimes sheep and goats (presents similar to foot and mouth disease virus)

how is vesticular stomatitis virus transmitted?

through biting midges, humans, and equipment infected

african horse sickness virus

biting midges (propagative transmission) - disease of horses, donkeys, and mules, highly fatal in susceptible animals, infected horses aften get a swollen head (dikkop), vaccine available but does not protect against all variants

cultural control of biting midges

remove standing and shallow water where possible

physical/mechanical control of biting midges

stalling horses during dusk and dawn, fans can blow midges off animals, baited traps can remove many midges but mainly used for surveillance not control, use fly sheets on horses with allergic dermatitis

chemical control of biting midges

short contact time so insecticidal control is difficult, botanical extract may show promise as repellants