week 1 Flashcards
what mosquito behaviours indoors can we investigate
- behaviour at a LLIN
- house entry
- movement in d space
- resting
- arrival at the host
what sorts of mosq movements happen at a net
- swooping-dont contact net
- occasional visiting to the net
- frequenct bouncing contacts
- resting on the net
what part of a net are mosqs attracted to and why
top of net- attracted to CO2
how does an ITN work
human baited trap, mosq has brief contact with net above occupants torso
velocity measurements show mosqs detect nets even unbaited untreated nets, and decelerated prior to contact, to avoid collisions
do female aedes aegypti have preferred routes through a home?
aedes attracted to dark colours (simple stimulus)
what is a barrier bednet
add barriers near roof of net, different designs.
could expand range of insecticides used on nets
also could be cheaper than PBO nets
could be used on pyrethroid nets with an OP barrier or untreated net with OP barrier
what are the limitations of lab tests (cones tubes tunnels)
- not always representative of true LLIN action
- limited insight into slow acting insecticides
- sublethal or delayed (>24hr) effects missed
- behavioural effects not measured
what tests can evaluate AIs and LLINs
video cone test
thumb test
room scale tracking
what is an emerging VBD
a vbd that spreads into new areas, naive individuals may move to endemic areas, vectors change host preference or new interactions between parasites and hosts develop
what is a re-emerging VBD
VBD that reappears in locations it has been controlled in
what needs to be shown to associate a vector with disease
- Demonstration of feeding or other effective contact with the host under natural conditions
- A convincing biological association in time and/or space of the suspected arthropod species and occurrence of clinical or subclinical infection (asymptomatic) in the host
- Repeated demonstrations that the arthropod, under natural conditions, harbors the infectious agent in the infective stage. 4.Transmission of the agent under controlled conditions
how can you show there is effective contact between vector and host (1)
Evidence of bites- identify all poss vectors, are they zoophilic or anthropophilic
Collect major vectors using traps
Bloodmeal analysis using PCR
How to associate vector and host infection (2)
Identify pathogen in patient
Does the disease correspond with reports of increase in vector activity
how to show the vector harbours the infection agent in its infective stage
- dissection
- presence of parasites in faeces (triatomines)
- ELISA
- PCR
how to show transmission of agent under controlled conditions
- naturally or experimentally infected animal fed on by arthropods
- arthropods forced to feed on uninfected animals after extrinsic incubation period
define vector competence
the ability of a vector to transmit a disease: infect, maintain and transmit a pathogen
define vectorial capacity
the total number of potentially infectious bites that would arise from all the mosquitoes biting a single perfectly infectious human on a single day
what factors affect vectorial capacity
- pathogen receptivity in the vector
- contact with the host
- does vector live long enough to allow full intrinsic incubation of parasite
- freq of feeding
- mobility
- density big enough to sustain transmission
- physiological and behavioural plasticity
- susceptibility to control measures
