Flies & Vectors of Veterinary Importance

Question 1

what problems do dipteran flies cause

Answer 1

fly worry

Economic losses due to reduced grazing and reduced weight gain

parasitic

Blood feeders

Myiasis

Question 2

what are the two ways flies act as vectors

Answer 2

mechanical

biologic transmission

Question 3

what is mechanical transmission

Answer 3

Simple carriage of pathogen between host

• Fly body/mouthparts become contaminated while feeding
• Transfer pathogen to subsequent feeding site (animal or potential food source) without amplification or development

Question 4

what is biological transmission and what are the types

Answer 4

Propagative transmission:

Cyclo-propagative transmission:

Cyclo-development transmission:

Vertical and direct transmission:

Question 5

what is propagative transmission

Answer 5

Propagative transmission:

Undergoes simple replication within vector (various viruses)

Question 6

what is cyclo-propagative transmission

Answer 6

Undergoes developmental cycle as well as replication (ex. Leishmaniasis)

Question 7

what is cyclodevelopmental transmission

Answer 7

Undergoes developmental cycle but NO replication (ex. Filariasis)

Question 8

what is vertical and direct transmission

Answer 8

Pathogen is passed from parent flies to offspring (various disease)

Question 9

what are non biting dipteran flies

Answer 9

house fly

face fly

head fly

fruit fly

Question 10

what are biting dipteran flies

Answer 10

stable fly

horn fly

black flies

midges

tsetse fly

sand flies

mosquitos

Question 11

how do non biting flies act as disease vectors

Answer 11

Mouthparts adapted for sponging

Obvious only during feeding

Mouthparts have rasping device

• Cannot puncture skin
• Feeding increases the size of existing wounds
• Prevents wound healing

Pick up pathogens when feeding on feces or rotting food

• Contaminate host while feeding (secretions from eyes, mouth, nose
• Open sores
• Contaminate foodstuff

Question 12

what type of transmission is summer sores caused by nematode roundworms

Answer 12

non biting flies

biological transmssion

cyclo-developmental

Question 13

what type of transmission is summer bleeding disease

Answer 13

Question 14

what type of transmission is thelazie spp and meatode roundworms

Answer 14

Question 15

what is the pathogenic significance of stable biting flies

Answer 15

Both male and females feed on blood

Takes 2-5 mins to feed to engorged

Abundant around farm buildings and stables in late autumn

Large numbers cause signifiant annoyance

• Reduced grazing
• Up to 20% loss in meat and milk production

Long feeding period and frequent bites allows transmission of

• Trypanosoma evensi (mechanical transmission)
• Besnoitia spp (mechanical transmission)
• Habronema (cyclo-developmental transmission)

Question 16

what can black flies transmit

Answer 16

Parasites

• Cyclo-developmental transition
  
  • Bovine onchocerciasis
  • Human onchocerciasis
  • Leukocytozoon (protozoan — malaria like disease affecting turkeys, geese and ducks)

Viruses

• Propagative transmission
  
  • Vesicular stomatitis virus

Question 17

what diseases can tabanids transmit

Answer 17

Viruses

• Equine infectious anemia
• Vesicular stomatitis
• Classical swine fever

Bacteria

• Anaplasma marginale
• Bacillus anthraces
• Pasteurella multocida
• Francisella tularensis
• Brucella spp
• Listeria monocytogens

Protozoa

• Trpyanosoma evensi
• T. equiperdum
• T. congolense
• T. brucei spp
• Besnoitia besnoitis

Question 18

what parasites do culicoides transmit

Answer 18

biological transmission; cyclodevelopmental

Onchocerca cervicalis (filaria nematode)

Cutaneous equine onchocerciasis

Equine ventral midline dermatitis

Equine nuchal disease

Uveitis

Question 19

what are arthropod borne viruses (arboviruses)

Answer 19

Question 20

how do culicoides transmit schmallenberg virus (SBV)

Answer 20

Biological transmission; propagative

Adult

• Transitory infection lasting a few days
• Inappetance, diarrhea, fever, loss of body condition, reduced milk yield
• Sheep & goats— no clinical signs

Transplacental infection can lead to severe congenital malformations

• Arthrogryposis
• Vertebral column
• Skull
• Brain
• Spinal cord

Question 21

how do culicoides transmit bluetongue virus

Answer 21

Biological transmission; propagative

Enormous impaction in sheep production

Question 22

how do culicoides transmit african horse sickness

Answer 22

Biological transmission; propagative

Question 23

what human diseases do moquites transmit

Answer 23

Chikungunya

Dengue

Zika

Yellow fever

Malaria

Question 24

what animal disease do mosquitos transmit

Answer 24

Paraistes

• Dirofilaria immitis
• Dirofilaria repens
• Dirofilaria roemeri
• Numerous viruses:

Viruses:

• Bunyaviridae; Phlebovirus - Rift Valley Fever (RVF)
• Togaviridae; Alphavirus — Eastern Equine Encephalitis (EEE), WEEV, VEEV
• Flaviviridae; Flavivirus — Japanese Encephalitis (JE), West Nile virus (WNV)

Question 25

how is rift valley fever transmitted

Answer 25

Mixed mode: propagative and vertical RFV Multiplies in the adult mosquito and is passed to the next generation of flies transovarially

Question 26

how is RFV enzootically transmitted

Answer 26

Low level of virus in wildlife and small mosquito population Mosquito eggs require water to hatch and develop through larval stages Normal rainfall mosquito numbers remain low

Question 27

what is the RVF epidemic-epizootic transmission cycle

Answer 27

Heavy rainfall induced spike in mosquito numbers Increased numbers of infected mosquitos leads to increased wildlife infections and livestock become infected Livestock amplification hosts and secondary bridge vectors increase disease occurrence Human infection detected

Question 28

what are the mosquito alphaviruses (propagative and vertical)

Answer 28

Question 29

what type of transmission is japanese encephlitis virus

Answer 29

Question 30

what type of transmission is west nile virus

Answer 30

Question 31

what type of transmission is dirofilaria immitis

Answer 31

Question 32

what does phlebotomine sandlifes transmit

Answer 32

Leishmania spp

Question 33

what is the leishmania lifecycle

Answer 33

Question 34

what are the clinical signs of canine leishmaniasis

Answer 34

Asymptomatic dog Generalized non-pruritic alopecia and multiple other dermatological abnormalities Popliteal lymphadenopathy Bilateral blepharitis and extensive muzzle involvement with marked exfoliative ulcerative lesions Ulcerative lesions at the bony prominences of hind limb leg Onychogryphosis Is a disorder of nail plate growth

Question 35

what do glossina spp transmit

Answer 35

Ttsete flies Sub-Saharan Africa Nagana: * Tsetse transmitted animal African trypanosomiasis (AAT) * T. congolense * T. vivax * T. brucei spp Trypanosome spp Biological transmission; cyclo-propagative

Question 36

how is non-tsetse transmitted animal trypanosomiasis transmitted

Answer 36

T. vivax, T. evansi, T. equiperdum no longer have a life cycle that requires transitioning through tsetse gut Spread by mechanical transmission * T. vivax -- Nagana * T. evansi -- Surra Sexual transmitted disease in equids (Dourine) * T. equiperdum (not vector borne)