Dramatic decreases of malaria transmission intensities in Ifakara, south-eastern Tanzania since early 2000s

Malaria Journal

Table 6 Comparative estimates of annual PfEIR using the two different methods [13], for malaria mosquitoes collected: indoors versus outdoors, in wet versus dry seasons, using different trapping methods, and in the different geographical zones of the study area

Attributes	Category	No. mosquitoes caught	No. trap nights (no. traps per night * no. nights)	Biting rate (no. mosquitoes/no. nights)	No. sporozoites positive	Sporozoite positive rate	PfEIR by standard method^a	PfEIR by alternative method ^a
Location	Indoors	3801	1792	2.12	0	0	0	0
Location	Outdoors	4394	1780	2.47	1	0.00023	0.205	0.205
Season	Wet (December–May)	7604	1786	4.26	0	0	0	0
Season	Dry (June–November)	591	1786	0.33	1	0.00169	0.204	0.204
Temperature	Cool (June–September)	706	1190	0.59	1	0.00142	0.307	0.307
Temperature	Hot (October–May)	7489	2382	3.14	0	0	0	0
Zones	North and Western area (Viwanja Sitini and Ifakara Mjini)	853	1427	0.60	0	0	0	0
	South and central areas (Lipangalala and Mlabani)	2379	1427	1.67	0	0	0	0
	Eastern peri-urban areas (Katindiuka)	4963	714	6.95	1	0.00020	0.511	0.511
Trapping method	HLC	5197	1200	4.33	1	0.00019	0.304	0.304
	CDC light trap	1894	1192	1.59	0	0	0	0
	Suna trap	1104	1180	0.94	0	0	0	0
Overall		8195	3572	2.29	1	0.000122	0.102	0.102

^aThe standard method calculates PfEIR as a product of sporozoites rates and human-biting rates; i.e., C*(Number of sporozoite positive mosquitoes/Number of mosquitoes tested) × (Number of mosquitoes collected/Number of trap nights) × 365(46), where, C is the relative efficiency coefficient for the relationship between CDC-light trap catches and human landing catches. The alternative method calculates PfEIR the ratio of sporozoite positive mosquitoes and number of nightly catches; i.e., C*(no of sporozoite positive mosquitoes/number of trap nights) × 365(14). Though the sporozoite rates are varied, the PfEIR estimates are same, primarily because all An. gambiae and An. funestus were analysed

ISSN: 1475-2875