Table 1. Infection experiment in which homogenates of mosquitoes exposed in the larval stage to fully virulent F. t. holarctica, unexposed mosquitoes, and a positive control (F. t. holarctica FSC200, 17 cfu) were used to infect mice. Mice injected i.p. were monitored for signs of disease for 24 days and the bacterial load of F. t. holarctica in spleens were determined. p.i.: post infection, n.a.: not applicable, n.d.: not detected.

	Mosquito pools (pool size)	Mice	Diseased mice (days p.i.)	Bacterial load in spleen bacteria/ml
Mosquito batch 1	4 (4–5)	5	2 (5, 5)	2.3 and 2.1 × 108
Mosquito batch 2	3 (3)	3	1 (4)	2.5 × 108
Unexposed mosquitoes	4 (5)	4	n.d.	n.d.
F. t. holarctica	n.a.	3	3 (5, 5, 5)	3.2, 3.1 and 6.0 × 108