Download - Stevenson entomology at macha 19.07.13
Dr Jennifer StevensonLimonty Simubali
Dr Doug Norris
Macha, Choma – 1 site of southern Africa International Center of Excellence for Malaria Research (ICEMR
Collaboration with Johns Hopkins Bloomberg School of Public Health
Combined and complimentary studies on malaria epidemiology, vector biology and parasite genetics/genomics
ICEMR Vector Biology
◦ Basic vector biology/bionomics
◦ Vector behavior
◦ Response to interventions
◦ Vector genetics
◦ Insecticide resistance
parasitemia
gametocytemia
antibodies anemia
insecticide
treated nets
anopheline
vectors
ecological
risk factorsknowledge
and practices
CDC light traps - current
Pyrethrum spray catches
Human landing catches
Larval surveys
Mosquitoes are identified using guides based on their physical appearance
Identities are confirmed using molecular techniques – PCR
The source of the bloodmeal is indentified using PCR
Infection status is determined using ELISA
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Mean no. Anopheles per trap per night
Cross-sectional
Longitudinal
April 2012 - March 2013Total different households visited: 125Total traps set 267Total female Anopheles caught 847Mean catch per trap 3.17
175 anophelines
caught in one house, 70% arabiensis
=Household with
Anopheles
=Household without
Anopheles
Morphological identification
n=981An. gambiae
An. squamosus
An. coustani
An. rufipes
An. longipalpis
An. pretoriensis
An. funestus
An.longipalpis
An. dureni
Molecular identification
n= 103 An. arabiensis
An. coustani
An. leesoni
An. longipalpis
An. parensis
An. pretoriensis
An. quadriannulaus
An. rufipes
ITS2 = 300 bp
ITS2 = 350 bp
ITS2 = 450 bp
ITS2 = 300 bp
Colonies of An.arabiensis, original collections from Macha area
Used for
◦ bioassays – testing effectiveness of control measures e.g. nets, indoor spraying
◦ studying mosquito behaviour in the lab
◦ training
◦ supply for other insectaries
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January –March 2012Locality Species Insecticide Mean
Mortality
Macha An. arabiensisDeltamethrin
(F1)100% (27)
Namwala
An. rivulorum
Deltamethrin(Field and F1)
100 % (n=126)
DDT(Field and F1)
100 % (n=113)
Bendiocarb( F1)
100 % (n=78)
An. arabiensis
Deltamethrin (Field)
100 % (n=4)
Deltamethrin(F1)
80% (n=10)
Namwalinda An. arabiensisDeltamethrin
(F1)100 % (n=27)
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An. arabiensis colony: 100% mortality
F1 field mosquitoes: 88% mortality
Norris L & Norris D, Malaria Journal 2011, 10:254
LLIN efficacy
Collection of 19 nets from 16 households. Nets were
2 year old deltamethrin LLINs
Norris L & Norris D, Malaria Journal 2011, 10:254
Household ID
very small holes(<1 cm)
small holes(1-5 cm)
medium holes(5-15 cm)
large holes(15-30 cm)
very large holes (>30 cm)
HH1-H2 2 1
HH3-H5 2 1
HH3-H8 3
HH4-H5 7 1
HH5-H1 1
HH6-H2 4 3
HH12-H3
HH13-H2
HH16-H2
HH19-H7 10 2
HH55-H8 2 5 2 2
HH58-H1 2 1
HH70-H4 15 10 1
HH75-H4
HH75-H5
HH79-H1 9 2 4
HH81-H1 1
HH90-H1 1 1
HH90-H2 1
Indoor vs outdoor feeding
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Dec07 Jan08 Feb08 Mar08 Apr08 Dec08 Jan09 Feb09 Mar09 Apr09
Seasonality of An. arabiensis Caught by HLC Pairs during the
2007-2008 and 2008-2009 Rainy Seasons
Paired indoor and outdoor HLCs were conducted
2008 - 130 inside, 279 outside
2009 - 61 inside, 96 outside
HLCs outside
caught
roughly 1.7 x
as many as
indoors
An. arabiensis caught by HLC Pairs December to April
Indoor vs outdoor, Biting Times
2008 Season
2009 SeasonOutdoor Biting Indoor Biting
Outdoor Biting Indoor Biting
• Overall 14% of HLC collections occurred before 10pm
Entomological surveillance and behavioural studies as part of national activities aimed to make southern Zambia malaria-free
Further evaluation of effectiveness of nets and IRS
Training and support for external projects for molecular assays
Refurbishment of insectary to house a standard global reference strain
Construction of a new insectary for locally caught colonies
Proposal of development of a malaria sphere
Large insect-proof greenhouses
Mosquitoes released inside or
colonies maintained inside
Used to study:◦ behaviour of mosquitoes
◦ effect of interventions
The community of Choma
ICEMR Team
MRT Team
Funding: MRT& The Johns Hopkins Malaria Research Institute, NIH ICEMR Program