Experimental hut sites are located 15km from KCM College and 800m above sea level in an area between the Masai savannah and 5,896m high Mount Kilimanjaro. The surrounding area is dominated by agriculture and irrigated rice farming is the major activity close to the experimental huts. Japanese aid in this area of semi-arid savannah began in 1978 and has resulted in a system of irrigation canals and agricultural training. Paddy fields cover an area of more than 1,100 hectares. The irrigated fields are a major breeding site for the predominant malaria vector species in the area Anopheles arabiensis.

Fig. 1 Experimental huts located next to irrigated rice fields (with Mt. Kilimanjaro behind) which provide ideal breeding sites for An. arabiensis

The nuisance biting and filariasis vector Culex quinquefasciatus is also present at certain times of the year, breeding mainly in latrines and a sewage disposal plant situated approximately 1km away. Anopheles arabiensis are largely susceptible to most insecticide classes but show pyrethroid tolerance (as defined by WHO 80-100% mortality in susceptibility tests), due to metabolic mechanisms, and resistance to dieldrin. Culex quinquefasciatus in the area show resistance to pyrethroids, carbamates, and dieldrin.

Rainfall is concentrated in March-May accounting for 60% of the annual total 800mm in Moshi town (10km North). The remainder falls during October-December. Between the two rainy seasons are a hot, dry season January-February and a cool, dry season June-September. Rice is grown in 2 cycles with the sowing being done in mid-June, and November. Irrigation of rice fields during the early growing season coincide with peak An. arabiensis populations. Lower Moshi area is hyperendemic for falciparum malaria.

Fig. 2 Seasonal population dynamics of An. arabiensis at Mabogini field site. Showing mean number caught in the untreated control hut p/night.

Fig. 3 Seasonal population dynamics of Cx. quinquefasciatus at Mabogini field site. Showing mean number caught in the untreated control hut p/night.

Community localities for Phase 3 Trials

At present, two localities (Msitu-wa-Tembo & Babati) have been surveyed and prepared for Phase 3 evaluations. They have abundant An.arabiensis and Cx.quinquifasciatus population.

Fig 4 & 5. Peak Anopheles arabiensis breeding season with early stage transplanted rice.
Early morning mosquito collections from experimental hut window traps.

Laboratory facilities

Specialized spray equipment for WHO phase 1 laboratory & Phase 2 small-scale field trials of IRS.

Spray apparatus includes;

1. Potter Tower
2. Spinning disc conveyor sprayer
3. Hudson sprayer

Fig. 6 Potter tower insecticide sprayer

Laboratory equipped for mosquito bloodmeal analysis, speciation by PCR, resistance mechanism assays icluding kdr & enzyme ELISA.

Indoor Labolatory Bioassay
Residual Spraying (IRS)

Long Lasting Insecticidal Nets (LLINs)