Logan, James

Lorenz, Lena

Maia, Marta

Moore, Sarah J

Ogoma, Sheila

Okumu, Fredros

Sangoro, Peter

English

Digital Library of the Tanzania Health Community

Vector Control Product Evaluations Collaborative Group 
Sheila Ogoma, Fredros Okumu, Peter Sangoro, James Logan, Marta Maia, Lena Lorenz and Sarah J Moore 
A outside  
A  C 
C 
C 
We are a group focused on 
development and evaluation vector 
control tools with a special interest 
in new tools designed for control of  
Outdoor Biting Outdoor Resting 
(OBOR) mosquitoes   
Experimental Hut Evaluations 
The experimental hut work  shown in this poster is made possible by the generous support of the American people through the United States Agency for International Development (USAID). The contents are the responsibility of Sarah J Moore and do not necessarily reflect the views of USAID or the United States Government. 
LSHTM repellent testing group 
Spatial repellent assays 
• The consumer market for repellents and coils was $2Billion in 2006 
•  Assays for evaluation of these products are mainly defined by toxicity end-points 
whereas repellent and feeding inhibition end points are the most desirable for the 
user 
• Spatial repellents have been shown to lower the incidence of falciparum 
malaria by 77%  in a randomised control trial where vectors bite early in the 
evening and rest outdoors Hill et al in preparation 
• The assay exploits mosquito taxis to rapidly, accurately and safely measure 
excito-repellency - oriented movement away from an attractive stimulus (human) 
due to irritation induced by insecticide vapour 
Right a schematic of mosquito taxis response to an attractive (+ positive) and  
repellent (- negative) stimulus, and the taxis index used to quantify taxis. 
Below left the taxis response of Anopheles gambiae s.s. to 
spatial repellents (transfluthrin 0.03%, metofluthrin 0.00625% coils) 
used in the presence of a human over a distance of 20 metres.  
A negative value denotes repellency. Contrast this with the  
response of An. arabiensis to attractants over 100 metres (below right) 
-0.4 
-0.3 
-0.2 
-0.1 
0 
0.1 
0.2 
5  10  15  20  Human 
Transfluthrin 
Metofluthrin 
-0.05 
0 
0.05 
0.1 
0.15 
0.2 
10  30  70  100 
CO2 
Blend 
Human 
Bottom: The Ifakara semi-field tunnel seen 
from the outside. The tunnel is 110m long, 
2m wide and 2.5m high. The SFT is 
supported by a 2.5 cm steel frame overlaid 
with PVC coated woven fibreglass mosquito 
netting (TENTEX®) that is highly durable 
and UV resistant. In order to protect the 
SFT from the sun and rain a traditional palm 
leaf thatch roof was constructed. The floor 
of the structure is concrete with an external 
water-filled moat to prevent the invasion of 
ants.    
Top left: taxis boxes in the tunnel with a 
human stimulus at one end (circled). A 
spatial repellent is situated 1 metre to the 
side of the person, used to repel the 
mosquitoes away  
Top right taxis boxes used in parallel to 
increase power and throughput of studies. 
They are opened from a distance (circled) to 
prevent human odours interfering with the 
mosquito response 
•  Designed to allow mosquitoes to behave as normally as 
possible – mosquitoes can easily leave huts into eave and 
window traps and are collected 3 times per night so that they are 
not held close to insecticide 
•  Baffles maximise catches without preventing mosquito hut entry 
(Okumu et al submitted PLoS One) 
•  Inner surfaces made of removable mud panels for ease of 
disposal within Stockholm Convention guidelines for Persistent 
Organic Pesticides 
•  A variety of surfaces may be evaluated – mud, plaster, wood, 
thatch roof or steel roof 
•  Year round high density (>40 / hut / night) pyrethroid and OC 
susceptible An. arabiensis. Seasonal high densities of    
susceptible An. gambiae s.s. and An. funestus s.s.   
•  Semi-field experimental hut evaluations planned to accurately   
and safely measure feeding inhibition without exposing   
volunteers to wild mosquitoes 
•  Evaluation of indoor vector control interventions 
•  Long Lasting Insecticidal Nets and Indoor Residual Spraying  
Fredros Okumu, et al  (2011) A modified experimental hut design for studying behavioural and physiological 
responses of disease-transmitting mosquitoes to vector control interventions: the Ifakara Experimental Huts 
submitted PloS One 
•  House Screening  
 Sheila Ogoma et al., (2010) Blocking and or screening mosquito house entry points as a potential tool for 
the integrated control of endophagic vectors of malaria, filariasis and arboviruses PloS NTD 4(8): e773 
•  Synthetic mosquito attractants 
 Fredros Okumu et al (2010). Trapping malaria vectors using synthetic odors that are more attractive than 
humans. PloS One 10.1371/journal.pone.0008951 
• Laboratory assays and room tests conducted at LSHTM using standard strains of all major vector 
mosquito species contact James.Logan@lshtm.ac.uk 
• Provides a thorough and accurate repellent testing service to Good Experimental Practice Standard 
(GEP) for topical repellents, consumer products, impregnated clothing and new tools 
• Semi-field and full field evaluations are conducted with An. gambiae and An. arabiensis at Ifakara 
Health Institute, Tanzania 
Far Left exposure free repellent testing with 
laboratory reared mosquitoes under 
ambient conditions in the IHI semi-field 
system. Left results from the SFS and right 
results from the field site close to Ifakara 
using the same repellents demonstrating 
the accuracy of the SFS for standard 
repellent evaluation. Data represent model 
estimated mean An. arabiensis landings per 
person per hour with 95% CI, n=18 nights / trial 
  Easy-to-sample 
traps that  
improve 
accuracy 
• Similar dimensions to local houses giving representative 
house volume, surface area and “degree of openness” for 
representative mosquito entry and air flow 
• Traps and entry points on on all four sides to remove bias 
and maximise mosquito hut entry 
 Entomological practices designed to maximize data 
quality to Good Experimental Practice (GEP) standard 

Vector Control Product Evaluations Collaborative Group

http://ihi.eprints.org/1106/1/IVCC_poster_low_res.pdf

Vector Control Product Evaluations Collaborative Group

Abstract

Similar works

Full text

Available Versions

Digital Library of the Tanzania Health Community