week 3 Flashcards
aedes transmit…
YF, dengue, chikungunya, zika
why is dengue on the rise
increased urbanisation migration inadequate water supplies no vaccine/prophylaxis ineffective/unsustainable vector control
which mosq eggs can withstand temperate climates
aedes albopictus
problems with detecting dengue cases
- dengue shows unpredictable dynamics
- dengue freq misdiagnosed
- virus rates in adult aedes often too low to detect
dengue control methods
fogging outdoors larviciding house screening insecticide treated material irs RIDL SIT wolbachia atsb
how an mathematical models aid vector control?
- identify which organisms/ life stages we need to target
- level of coverage
- likely time scale of impact
- strategies for managing resistance
- impact on health and productivity
- identify most cost effective methods
main tsetse control methods
ground spraying
aerial spraying
traps and targets
insecticide treated cattle
pros and cons of ground spraying
pros: highly effective
cons: ineffective against reinvasion, labour intensive, logistically demanding
what is sequential aerosol technique
timing of insecticide applications is based on larval and pupal periods.
first cycle kills adults, flies emerge and next application is timed to kill the young flies before they deposit their first larva
pros and cons of sequential aerosol spraying
pros: rapid, effective, does not require large labor force
cons: expensive, technically demanding, susceptible to reinvasion, not poss in broken terrain
pros and cons of insecticide treated cattle
cheap
practicable for farmers
environmentally safe
effective against tsetse and ticks
cons?
pros and cons of SIT
pros: definitive solutions, cost justified in long term, environmentally friendly
cons: expensive, not effective if more than 1 species, requires prev tsetse suppression, after suppression is SIT still needed, released males might transmit the disease, requires external expertise
what is the most widespread mosq borne arbovirus
dengue fever- affects 390 mill people a year
why is dengue increasing?
increased urbanisation (aedes found in urban and peri-urban environments)
migration
inadequate water supplies
no vaccine or prophylaxis
ineffective or unsustainable vector control
biting and breeding habits of aedes?
breed near humans
bite mostly humans
bite in and out and during day
eggs withstand drying for months and albopictus can withstand cold
what are main methods of dengue control
- early diagnosis of cases
- prevent breeding by using larvicide or eliminating potential breeding sites
- fogging/space spraying
- house screening
- maybs targeted IRS?
- maybs comm based environmental management- more studies needed
why is dengue difficult to control
- it is cyclic- there are 4 serotypes that increase at certain times and it is difficult to predict when they’ll come
- dengue cases frequently misdiagnosed
- virus rates in aedes typically too low to detect
what are latest aegypti control methods?
target larval stages..
- more efficient control of breeding by targeting key containers
- use pyriproxyfen (stops pupal development and adults can also rest, pick up insecticide and kill own eggs)
adults. .. - house screening with ITM
- IRS
how can dengue morbidity be reduced?
- implementing improved outbreak prediction and detection through coordinated epi and ento surveillance
- IVM
- local vector control-household water management
which parameters govern tsetse population dynamics?
adult mortality
pupal mortality
duration of pupal and larval periods
what may a mathematical model not take into account?
numerous rounds of control or reinvasion from other populations
what tsetse stages should we control and why
adults on ly ones vulnerable, modest mortality of 3% a day is effective
kill them by ground or aerial spraying
how to control savannah tsetse?
- odour baited targets
2. blue/black traps and targets
how to control riverine tsetse?
not attracted to host odours
1. tiny targets
triatomine control
improved housing
irs - resistance seen
anti-parasitic drugs to dogs to stop tranmission
why should we treat dogs for t.cruzi
they could facilitate entry of cruzi into sylvatic strains- cruzi has many mammal hosts
eg of pemanent ectoparasite
periodic
temporary
lice and mites
ticks
sandflies tsetse
stimuli used in host-seeking
physical-heat and texture
visual-shape and size and colour
chemical-co2(siginifies host)
body odours
what is an olfactory sensillum
variety of structures capturing odour molecule (proboscis,antennae, palps)
molecule diffuses, causes action potentials
what are kairomones
host odours such as co2
causes a behavioural or physiological response in another species that is favourabe for that species, but not itself#
can direct feeding behaviour
eg. of kairomones
co2, lactic acid, ketones, octenol, cCOOH
what do sanflies transmit
Bartonella bacilliformis a
arboviruses
leismania
describe some of the ways to incriminate a sandfly with disease
parasite seen in mg
bites hosts
xenodiagnosis-experimental transmission
mathematical modelling looking at disease incidnece and fly density
control methods for leishmania
deltamethrin dog collars-community wide deployment
case detection and drug treatent
reservoir host culling
vector control-needs mnay methods together
dog and human vaccines in development
how to improve leish control
better estimations of where females bite hosts, ento inoculation rates for parous females
human blood index for females
rapid vector identification
how can transmission modelling be used in lesihmania
identifies vectors that are a public health priority
effective modelling requires use of EIR
