Arthropods Flashcards

Question

Culicoides

Answer 1

midges **Tiny flies** - can pass through insect wire screens Larvae in moist soil or water **FW, FBD in horses**, sometimes called **“sweet itch”** Transmits bluetongue in ruminants, some nematodes

Answer 2

Odd family of **bloodsucking flies**, no wings Adults usually have flat looking body In domestic animals: **sheep and goats “ked”**, not seen much in eastern US Most common species: Melophagus ovinus - **wingless** Family also contains “flat flies”, common on wild birds, deer, others

Answer 3

Mechanical * Window screens, doors * Fly sheets and masks for horses **Manure** * **Get rid of it** * Feed through pesticides * Parasitic wasps (parasitoid) **Pesticides** * Food animals: dust bags, back rubbers, ear tags (cattle), pour-on * Horses: Sprays, pour-on

Answer 4

Any infection due to the **invasion of the tissues or cavities** of the body by the **larvae** of dipterous insects. Two types: * **Cutaneous** myiasis: **fly strike, maggots** * **Internal** myiasis: **grubs, warbles, bots**

Answer 5

**myiasis** Caused by **larvae of blow flies** (Calliphorids) and some others Blow flies are filth flies, with a bright and metallic color (green, blue, bronze), house fly looking Larvae common called **maggots** Term also used for other filth fly larvae **Facultative parasites** (dont have to lay eggs in live animals) Life cycle * Eggs laid in **decaying organic material** * **Larvae feed on necrotic material** * **Pupate on ground**, adult flies emerge * Females also attracted by secretions from **wounds, fecal material,** etc. Diagnosis by finding maggots (Animal may be depressed from toxemia) **Treatment: remove maggots** Prevention * Wound spray in fly season * Castrate, dehorn, etc. before fly season Medical use of sterilized maggots for wound healing

Answer 6

**Cochliomyia hominivorax** **Obligate parasite: requires living tissue** Produces much more **severe disease** **Eradicated from the US** by sterile male release program **Notifiable disease:** if suspect, send sample to regulatory vets | IMPORTANT

Answer 7

Fly larvae called **bots, grubs and/or warbles** Adults hairy, **look like bees** Adults don’t feed, short life span Larva is **obligate internal parasite** Larva then leaves host, pupates in the environment

Answer 8

**horse bots**, Common equine parasite The adult has small, nonfunctional mouthparts and does not feed **Eggs laid on face or legs of equids** Eggs hatch, **move into mouth** Migrate in gums and tongue briefly **Move to stomach**, remain for 10-12 months **Pass out in manure, pupate in soil** Clinical signs * **Not very pathogenic** * No specific clinical signs associated with them * Rarely ulceration or perforation of stomach attributed to bots Diagnosis: See flies, eggs on legs Treatment * Typically annual treatment in fall * Eggs/larvae removal * Bot combs; warm water stimulates hatching

Answer 9

**rodent bot flies, internal myiasis** Parasites of rodents, rabbits **Eggs laid near burrows or along trails** **Larva picked up by rodent, rabbit** Develop in **subQ cyst** Pupate on ground Clinical signs * Lump observed, develops opening * May develop secondary infection * Occasional cases of abnormal migration **Treatment/Control: Remove carefully** Other animals * **Dogs/cats can pick up larvae** * Usually found on head and neck. Looks like boil (furuncle)

Answer 10

Major problem recently If house is infested, might see **bites on pets** Environmental control required

Answer 11

Transmit Chagas disease (**Trypanosoma cruzi**) Pretty common around here

Answer 12

ticks and mites

Answer 13

Mouthparts: important in tick ID (Gnathosoma or Capitulum) Everything else (Idiosoma) Leg numbers * Adults, nymphs * Larvae

Answer 14

**Skin disease** of domestic animals caused by several genera of **mites** * No characteristic lesion, other skin diseases could look similar * Alopecia, erythema, pruritus * May lead to pyoderma

Answer 15

Most similar to lice in many ways * **Host specific** * **All stages on host**, survive poorly off host * Short life cycle (a few weeks) * Transmitted by **direct contact, fomites** Usually **diagnose by skin scraping** (scrape periphery of lesion) - different from lice **MICROSCOPIC** Disease usually called **“mange”** Not specific terminology Can see wide range of clinical signs in animals, may have asymptomatic carriers

Answer 16

Sarcoptes Knemidocoptes Demodex

Answer 17

Otodectes Chorioptes Psoroptes

Answer 18

**subsurface mites** **Round bodies**: last 2 pairs of legs short **Burrowing mite, females lay eggs in tunnels in epidermis** Life cycle takes about 3 weeks **Easily transmitted between individuals** of host species

Answer 19

subsurface mites Separate varieties for dogs, pigs, cattle, horses (**Host specific**) * Common cause of **mange in dogs** * Uncommon to rare in **cattle (REPORTABLE)** and horses Mites like **hairless or thin haired areas**: lesions may appear first on face, ears, legs Intense **pruritus, alopecia, inflammation** Chronic sarcoptic mange: * **Alopecia, thickened, wrinkled skin** * **Pyoderma** * Self inflicted trauma May be difficult to find mites in skin scraping, scrape several areas Hypersensitivity reaction elicited by a few mites Treatment/Control * Several effective drugs available * Environmental treatment? Not important, mostly lives on host

Answer 20

**subsurface mite** “**Cigar with legs**” Very **host specific** species in domestic animals, humans, others Some animals have more than one species **Hair follicles or sebaceous glands** Common species can be thought of as part of **normal skin fauna** Transmission occurs shortly after birth from dam **cause demodicosis**

Answer 21

Demodex (sub surface mite) seen most often in **dogs** Clinical signs occur when mites proliferate beyond normal levels * Balance between mite and host immune response * **Non-contagious** * **NO pruritus** * Interfere with **follicle, gland function** * Can lead to inflammation, secondary infection Several treatments available

Answer 22

surface mites **Surface dwellers, not burrowers** Look like sarcoptic mites but **oval, not round, longer legs** Life cycle: minimum 2 weeks

Answer 23

**Surface mite** Worldwide parasite of the **ear canal of dogs, cats, ferrets** * Seen most often in cats, easily transmitted cat to cat * Not clear if easily transmitted across species Causes **otitis externa, can be intensely pruritic** * Exudate looks like **coffee grounds** in ear Diagnosis with swab of ear and microscope ID or with otoscope Treatment: clean, use **miticide**

Answer 24

Most common **large animal mite in** US but more common in cattle, **host specific** **Cattle** * **Tailhead** (common), back of udder and perineal region * Usually not very significant **Small ruminants and horses** * **Leg, lower body** * Feathered horses especially

Answer 25

**Ticks** Importance of ticks * Bite wounds * Blood loss * Tick paralysis * **Transmission of pathogens** * Red meat allergy Recently interest in tick control has become bigger issue * **Tick-borne disease more prominent** * Several ticks changing distribution patterns **acquired from the environment, not from other animals**

Answer 26

Two families of **ticks** * **Ixodidae**: **hard ticks, important ones** * Argasidae: soft ticks, look soft and squashy compared to ixodids * Regardless of family, ticks are **acquired from the environment, not from other animals **

Answer 27

**hard ticks**, important ones **Hard, shiny appearance** Mouthparts projected forward **Scutum** (hard plate) on the dorsal surface allows to distinguish **males and females**

Answer 28

Life stages * Egg * Larva (3 pairs of legs) * Nymph * Adult **One blood meal in each stage** **Molt between stages** All of our common ticks are **3-host ticks** (can be same animal) **Leave host after each blood meal** Molt in the environment **Female lays eggs in environment then die** Hatched larval tick called **“seed tick”** * Small, 6 legs * Often hard to identify genus * Find a host, feed a few days * 3-host ticks: leaves after feeding, molts

Answer 29

Male and female nymphs have **8 legs** **Lack genital opening** Takes a blood meal Feeds and drop off into environment (1 host tick stays on host) **Molts to adult stage**

Answer 30

Adult males and females have **8 legs and genital opening** Sex difference in scutum (shield on the dorsal surface) **Mate on the host**, some species in environment **Females drop off, lay eggs in environment, die**

Answer 31

Ticks do not immediately feed after attachment May **wander on host for several hours or days before attaching** Attachment occurs when tick **inserts armed hypostome into skin** **Cementing substance from salivary glands** may also be secreted Process of attachment means **not much feeding occurs for 24-26 hours**

Answer 32

Initial period of **slow feeding, can last for several days** **Followed by rapid feeding** **12-36 hours before tick detaches** Period of feeding variable Larval ticks for few days **Female ticks may be attached for a week**

Answer 33

Many **pharmacologically active substances** in ticks saliva * **Histamine blocking** agent * **Anticoagulant** * Cytolysins to enlarge feeding lesion * **Vasoactive** mediators that increase vascular permeability * Paralytic **toxins** that cause ascending motor paralysis * Red meat allergy?

Answer 34

**horizontal** tick picks up disease agent as larva or nymph and transmits it to subsequent hosts. Agent survive tick’s molt

Answer 35

**vertical** disease agent in **female tick passes into eggs** and is passed through subsequent stages

Answer 36

soft ticks Don’t transmit major diseases in the US