Anopheles mortality is both age- and Plasmodium-density dependent: implications for malaria transmission

Malaria Journal

Table 1 Summary statistics for cages of An. stephensi mosquitoes fed different estimated P. berghei ookinete densities

Experiment (date)	Estimated ookinete density fed (per μl)	Mean^‡ number of oocysts per mosquito on day 10* (range)	Mean^‡ sporozoite score^† per mosquito on day 22*	Total number of mosquitoes in each cage	Median survival (days) (95% C.I.)
1	0			442	32 (30, 34)
(August 2007)	100	46.4 (0-251)	2.4	399	ND (25, ND)
	400	141.8 (0-307)	3.0	645	26 (23, 31)
	2,000	259.6 (0-591)	3.7	562	21 (19, 24)
2	0			733	33 (32, 35)
(April 2008)	100	55.3 (0-212)	2.0	565	ND (ND, ND)
	400	83.1 (0-259)	2.6	662	34 (32, ND)
	2,000	138.4 (0-477)	1.8	502	30 (29, ND)
3	0			625	42 (41, ND)
(July 2008)	50	11.3 (0-47)	1.2	815	36 (35, 37)
	250	67.6 (0-121)	1.7	852	36 (34, 38)
	1,000	96.8 (0-200)	2.9	999	34 (32, 35)

^‡ Arithmetic mean parasite load in 20, randomly chosen surviving mosquitoes.
* Parasite densities presented from the dissections on days 10 and 22 as these are the standard days used in determining oocyst and salivary gland sporozoite density and therefore allow comparisons to be made with published studies, such as Sinden et al [47].
^† Sporozoites counted using a scoring system; 0, 0 sporozoites; 1, 1 to 10 sporozoites; 2, 11 to 100 sporozoites; 3, 101 to 1,000 sporozoites; 4, 1,001 to 10,000 sporozoites; 5, over 10,000 sporozoites.
ND, not determined as survival curve does not cross 0.5 and therefore the median survival cannot be calculated.

ISSN: 1475-2875