Methodology

Establishment of a large semi-field system for experimental study of African malaria vector ecology and control in Tanzania

Heather M Ferguson^1,2 , Kija R Ng'habi^2,5 , Thomas Walder³ , Demetrius Kadungula³ , Sarah J Moore^2,4 , Issa Lyimo^1,2 , Tanya L Russell^2,4 , Honorathy Urassa² , Hassan Mshinda² , Gerry F Killeen^2,4 and Bart GJ Knols⁵

¹Division of Infection and Immunity, University of Glasgow, G12 8TA, Glasgow, UK

²Public Health Entomology Unit, Ifakara Health Institute, Ifakara, P.O Box 53, Tanzania

³Maintenance Unit, Tanzanian Training Centre for International Health, Ifakara, P.O. Box 39, Tanzania

⁴School of Biology Sciences, University of Durham, DH1 3LE, Durham, UK

⁵Laboratory of Entomology, Wageningen University and Research Centre, P.O. Box 8031, 6700 EH, Wageningen, The Netherlands

author email corresponding author email

Malaria Journal 2008, 7:158doi:10.1186/1475-2875-7-158

Published:	20 August 2008

Abstract

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.

Conclusion

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.