Using a participatory approach to characterize HPAI outbreaks in Indonesian village poultry
-
Upload
ilri -
Category
Technology
-
view
265 -
download
0
Transcript of Using a participatory approach to characterize HPAI outbreaks in Indonesian village poultry
Jost, C, Walker, P, Bett , B, Poole, J , Azar, M, Murahman, J , Daju, D, McLaws, M, Schoonman, L, Unger, F, Mariner, J
USING A PARTICIPATORY APPROACH TO
CHARACTERIZE HPAI OUTBREAKS IN
INDONESIAN VILLAGE POULTRY
Reproduction number (R) The number of new individuals that will become infected from a single infected individual
TRANSMISSIBILITY
Risk factors
Variables associated with an increased risk for infection
Relative risk
The probability of infection occurring in an exposed group versus a non-exposed group
RISK
Mass vaccination efficacy study:
One-year mass vaccination program
Control neighborhoods
Sampling: 16 districts on Java
All H5N1 outbreaks diagnosed by VS
1-3 randomly selected outbreaks
Infection tree reconstruction
Susceptible-infected-recovered (SIR) model
METHODS
Affected Neighborhood (RT): Focus group interview
Mapping
Transect walk
Geo-referencing
1-5 Affected Households: Individual interview
Timeline
2 Adjacent Neighborhood Transect walk
Rapid interviews
PE TOOLS
Epidemiological relationships
Housing
Husbandry
Bird contacts
Risk factors
FOCUS GROUP INTERVIEWS
All households
Species of poultry in each household
Households affected
Species affected in each household
Spread of the outbreak
Timing of each household affected
MAPPING
Triangulation interview info
Geo-referencing
Index household
Closest unaffected household
2nd household affected
TRANSECT WALK AND GEO-REFERENCING
Morbidity, mortality, slaughter and sale rates
Key outbreak events
Husbandry characteristics
TIMELINE
Commercial poultr y
Present in the village in ½ of outbreaks
Involved in only 7.3% of outbreaks
Relative r isk for presence in outbreak household:
Muscovy ducks
Backyard chickens
Broilers
Geese
But not pigeons or ducks!
Top r isk factor for introduction: New bird entry into household flocks (24.4%)
Top r isk factor for spread: Bird contact between households (73.2%)
RESULTS
Within Flock R*
Vaccinated areas: 2.23, 95% credible interval (1.96-2.51)
Unvaccinated areas: 2.79, 95% CrI (2.52-3.10)
Vaccination coverage: 11% (5%-19%)
Between Flock R
Vaccinated areas: 1.9, 95 % CrI (1.59,2.26)
Unvaccinated areas: 2.07, 95% CrI (1.82,2.35)
Vaccination coverage: 14% (5%-27%)
RESULTS
*decisive according to Jeffrey’s scale of evidence (Bayes factor (BF)> 100)
Backyard poultr y on Java provide the necessary condit ions for indefinite transmission
Level of population immunity necessary to interrupt transmission:
64.2% (+60.3-67.7%) of birds in household flocks
51.7% (+41.5-57.4%) of households in neighborhood
Incidence study: moderate levels of f lock protection reduced HPAI-compatible disease incidence by 46%
Cost > 1 million USD
PE is a cost ef fective and simple tool for assessing the epidemiological impact of disease control measures
Cost ~ 90,000 USD
LESSONS LEARNT
MoA Indonesia
District VS
Imperial College London
USAID and the World Bank
ACKNOWLEDGEMENTS