Flies & Vectors of Veterinary Importance Flashcards
what problems do dipteran flies cause
fly worry
Economic losses due to reduced grazing and reduced weight gain
parasitic
Blood feeders
Myiasis
what are the two ways flies act as vectors
mechanical
biologic transmission
what is mechanical transmission
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
what is biological transmission and what are the types
Propagative transmission:
Cyclo-propagative transmission:
Cyclo-development transmission:
Vertical and direct transmission:
what is propagative transmission
Propagative transmission:
Undergoes simple replication within vector (various viruses)
what is cyclo-propagative transmission
Undergoes developmental cycle as well as replication (ex. Leishmaniasis)
what is cyclodevelopmental transmission
Undergoes developmental cycle but NO replication (ex. Filariasis)
what is vertical and direct transmission
Pathogen is passed from parent flies to offspring (various disease)
what are non biting dipteran flies
house fly
face fly
head fly
fruit fly
what are biting dipteran flies
stable fly
horn fly
black flies
midges
tsetse fly
sand flies
mosquitos
how do non biting flies act as disease vectors
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
what type of transmission is summer sores caused by nematode roundworms
non biting flies
biological transmssion
cyclo-developmental
what type of transmission is summer bleeding disease
what type of transmission is thelazie spp and meatode roundworms
what is the pathogenic significance of stable biting flies
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)
what can black flies transmit
Parasites
- Cyclo-developmental transition
- Bovine onchocerciasis
- Human onchocerciasis
- Leukocytozoon (protozoan — malaria like disease affecting turkeys, geese and ducks)
Viruses
- Propagative transmission
- Vesicular stomatitis virus
what diseases can tabanids transmit
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
what parasites do culicoides transmit
biological transmission; cyclodevelopmental
Onchocerca cervicalis (filaria nematode)
Cutaneous equine onchocerciasis
Equine ventral midline dermatitis
Equine nuchal disease
Uveitis
what are arthropod borne viruses (arboviruses)
how do culicoides transmit schmallenberg virus (SBV)
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
how do culicoides transmit bluetongue virus
Biological transmission; propagative
Enormous impaction in sheep production
how do culicoides transmit african horse sickness
Biological transmission; propagative
what human diseases do moquites transmit
Chikungunya
Dengue
Zika
Yellow fever
Malaria
what animal disease do mosquitos transmit
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)
how is rift valley fever transmitted
Mixed mode: propagative and vertical
RFV Multiplies in the adult mosquito and is passed to the next generation of flies transovarially
how is RFV enzootically transmitted
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
what is the RVF epidemic-epizootic transmission cycle
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
what are the mosquito alphaviruses (propagative and vertical)
what type of transmission is japanese encephlitis virus
what type of transmission is west nile virus
what type of transmission is dirofilaria immitis
what does phlebotomine sandlifes transmit
Leishmania spp
what is the leishmania lifecycle
what are the clinical signs of canine leishmaniasis
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
what do glossina spp transmit
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
how is non-tsetse transmitted animal trypanosomiasis transmitted
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)
