Figure 3.

F. tularensis possible localizations inside mosquitoes and corresponding modes of transmission to humans. Mechanical contamination cycle via mosquito dejection: F. tularensis is ingested during a blood meal in an infected host ①, the bacterium ingested is located in the mosquito midgut ②, Francisella tularensis is then digested, crosses the Malpighian tube to be rejected onto a new host dermis during a blood meal ③. Mechanical contamination cycle via mosquito saliva: F. tularensis is ingested during a blood meal in an infected host ①, the bacterium stays hooked inside mosquito’s proboscis (i.e., the elongated appendage from the head), and then is reinjected to a new host via the contaminated saliva during a new blood meal ⑤. Biological contamination cycle: F. tularensis is ingested during a blood meal in an infected host ①, the bacterium migrates to the salivary glands and undergoes several multiplications ④, the bacterium is then injected into a new host via the contaminated saliva during a new blood meal ⑤.