Establishment of a large semi-field system for experimental study of African malaria vector ecology and control in Tanzania.
BACKGROUND
Medical entomologists increasingly recognize that the ability to make inferences between laboratory experiments of vector biology and epidemiological trends observed in the field is hindered by a conceptual and methodological gap occurring between these approaches which prevents hypothesis-driven empirical research from being conducted on relatively large and environmentally realistic scales. The development of Semi-Field Systems (SFS) has been proposed as the best mechanism for bridging this gap. Semi-field systems are defined as enclosed environments, ideally situated within the natural ecosystem of a target disease vector and exposed to ambient environmental conditions, in which all features necessary for its life cycle completion are present. Although the value of SFS as a research tool for malaria vector biology is gaining recognition, only a few such facilities exist worldwide and are relatively small in size (< 100 m2).


METHODS
The establishment of a 625 m2 state-of-the-art SFS for large-scale experimentation on anopheline mosquito ecology and control within a rural area of southern Tanzania, where malaria transmission intensities are amongst the highest ever recorded, is described.


RESULTS
A greenhouse frame with walls of mosquito netting and a polyethylene roof was mounted on a raised concrete platform at the Ifakara Health Institute. The interior of the SFS was divided into four separate work areas that have been set up for a variety of research activities including mass-rearing for African malaria vectors under natural conditions, high throughput evaluation of novel mosquito control and trapping techniques, short-term assays of host-seeking behaviour and olfaction, and longer-term experimental investigation of anopheline population dynamics and gene flow within a contained environment that simulates a local village domestic setting.


CONCLUSIONS
The SFS at Ifakara was completed and ready for use in under two years. Preliminary observations indicate that realistic and repeatable observations of anopheline behaviour are obtainable within the SFS, and that habitat and climatic features representative of field conditions can be simulated within it. As work begins in the SFS in Ifakara and others around the world, the major opportunities and challenges to the successful application of this tool for malaria vector research and control are discussed.
Ferguson
Heather M
HM
Division of Infection and Immunity, University of Glasgow, G128TA Glasgow, UK. H.Ferguson@bio.gla.ac.uk
Ng'habi
Kija R
KR
Walder
Thomas
T
Kadungula
Demetrius
D
Moore
Sarah J
SJ
Lyimo
Issa
I
Russell
Tanya L
TL
Urassa
Honorathy
H
Mshinda
Hassan
H
Killeen
Gerry F
GF
Knols
Bart Gj
BG
D000818:Animals; D000852:Anopheles / Q000254:growth & development* / Q000469:parasitology*; D017753:Ecosystem; D006801:Humans; D007303:Insect Vectors; D008288:Malaria / Q000517:prevention & control* / Q000635:transmission*; D009032:Mosquito Control / Q000379:methods*; D012107:Research Design; D013636:Tanzania