Exam II Flashcards
What country was able to eliminate river blindness?
Colombia
Top 2 important factors that make mosquitoes good disease vectors.
- Taking a blood meal - a major way to acquire a pathogen
- The vector has to live long enough to pass it to another susceptible host. This can be a week or more if the pathogen develops or multiplies in the vector.
Mechanical transmission
Carry physically on body or by interrupted feeding - no development
Transfer via legs, etc.
Biological transmission
Cyclodevelopmental - develops
Propagative - pathogen multiples
Cyclopropagative - develops and multiplies
Pathogens can get into the new host.
Penetrate vector gut wall, move to salivary glands
What are 7 characteristics of a good vector?
- Can acquire, maintain, and transmit pathogens
- Provides suitable internal environment
- Lives for some min. time
- Feeding pattern matches pathogen host range
- Feeds often for extended periods
- Ingest large amounts of blood
- Be able to disperse
Diptera represents
Two wings = “true flies”
Diptera adults have:
1 pair of wings
Variable mouthparts? None, piercing/sucking, slashing, sponging
Many ways to think about flies (3)
- Classification: 3 main taxonomic groups
- How they feed: piercing-sucking, sponging
- Where they breed: water, mud, manure
Diptera larvae
No legs, with/without distinct head
Soft, thin cuticle
Aquatic, semi-aquatic, moist habitats, in tissues
Female mosquitoes/gnats are ______. Males are _____.
Blood feeder; nectar feeders
Primitive mosquitoes and gnats have…
Long antennae: 8 segments
Host-finding: Long range
Host-specific odors
Host-finding: Medium range
Host odors + CO2
Host-finding: Close/Final decision
- Warmth - convection currents, vision / movement (Day biters)
- Specific attraction to host
- Olfactory (smell) receptors on antennae
- Noranal - volatile skin chemical given off from birds and humans aids in long range detection (+ CO2)
Lactic acid, CO2, ammonia, fatty acids
House mosquito shifts feeding preference from _____ to _____ in late _____ / early _____ – at time of robin dispersal/migration
birds to humans
summer; fall
3 Factors in host attractiveness
- Body odors – skin bacteria
- Dark colors : Pregnancy – 1 degree warmer, exhale 20% more CO2
- Blood type – O 2x > A
A person who eats human flesh
Anthropophagic
An organism that consumes animal matter
Zoophagic
An organism that consumes birds
Ornithophagic
Mosquito bites -
Stylets protected by sheath, Enter capillary
There are _____ proteins in saliva - anti-coagulants, vasodilators, numbing agents, suppress anti-viral response.
Stimulate _____
> 10
Stimulate antibody response
How to think about > 50 mosquito species in KY:
1) Oviposition sites / Larval habitats
2) Overwintering stage
3) Number of generations/year
1) Eggs/larvae
- Single, groups, floating “rafts”
- Desiccation resistant or not
- In/on: ground depressions, floodwater, natural or artificial containers – buckets, tree holes,
surface of “dirty” water, etc.
2) Overwintering stage
Eggs – resistant to _____, drying
Mated females – in _____
Larvae – _____ - a few in mild climates
Cold; shelter; rare
A genetically determined state of arrested development that allows arthropods to overwinter in cold climates
Diapause
Diapause is induced primarily by _____
decreasing shorter daylight
Diapause has different stages based on _____
species
Diapause: _____ in blood or freezing in spaces between cells
Antifreeze
3) Generations / year
One - _____ peak or extended emergence – _____;
2+ – _____
spring; univoltine; bivoltine or multivoltine
Generations can change with season – For example…
Warmer season, extra generation
2 main reasons for variation in mosquito populations
Rainfall and temperature
3 reasons why mosquitoes are a problem
- Nuisance/ annoyance
- Blood loss – can lead to anemia
- Vector human/animal diseases – zoonosis encephalitis
Example mosquito species:
- Inland floodwater mosquito _____
- House mosquito _____
- Asian tiger mosquito _____
Aedes vexans; Culex pipiens complex; Aedes albopictus
Inland floodwater mosquitoes are a serious nuisance species. 4 reasons why:
- Night biter
- Rests on vegetation during day
- Not an important disease vector
- Can fly 10+ miles to feed
1) Inland floodwater mosquito • Winter - eggs in \_\_\_\_\_ in low areas • Hatch when covered w/ \_\_\_\_\_ • Unshaded rain pools • Problem during rainy spring /early summer • Multivoltine
soil cracks; w/water and O2 drop;
2) House mosquito complex “dirty” water mosquitoes
Northern and southern house mosquito and hybrids – they can _____
• Live in urban and rural areas
• Feed on _____
• NHM have a stronger _____ preference
• Females winter in _____ sites - culverts and caves
interbreed; birds & mammals; NHM - bird; females - protected
House mosquito Culex pipiens complex
- Can return to larval breeding site to oviposit BUT can travel _____ to feed
- Commonly enters structures
- Prefers _____, will feed on mammals: humans, raccoons, horses
- Can carry (competent vector for) _____ viruses
1,500 yards/night; birds (robins, house sparrows); Encephalitis, Dog heartworm
4 Factors that affect mosquitoes as disease vectors
1) Abundance –enough numbers to encounter infected host
2) Longevity – live long enough after feeding for pathogen to reach salivary glands
3) Competent – able to carry enough pathogen to be infective, don’t become sick themselves
4) Strong host selection behavior – reliable, contact with susceptible hosts
Infectious disease transmitted between species (sometimes by a vector) from animals to humans
Zoonosis
About _____% of human-emerging infectious diseases are caused by zoonotic pathogens
75%
Encephalitis virus • Symptoms • Also called: Eastern equine, St Louis, Venezuelan, West Nile • Bird – mosquito cycle • Spillover into \_\_\_\_\_
Inflammation or swelling of the brain affects CNS
Spillover from birds to humans, livestock
First case in US: West Nile Virus
1999 NY
Transovarian transmisson in mosquitoes
Mosquitoes live 2 to 3 weeks; feed 3x to 4x
Incubation period in mosquitoes = _____ gut to salivary glands
Birds amplifying host - infective _____
Incubation period in horses _____ – ___% recovery
7-10 days; 5 days; 7-14 days with 65% recovery
