Table 1.

Parameter estimates used in calculations of vectorial capacity for WNV in Culex pipiens mosquitoes feeding on common grackles whereby MF enhancement is invoked (VC_YES) or not invoked (VC_NO)

Scenario	Biting rate (ma)a	Avian host preference (a)b	Vector competence (b)c	Daily Survival (P)d	EIP (T)e
VCYES	1.53	0.186	0.87	0.90	5 d
VCNO	1.53	0.186	0.17	0.90	12 d

^aBiting rate (no. bites/bird/night)—based on bird-baited mosquito traps (Darbro and Harrington 2006).

^bAvian host preference—based on bird blood index of 0.93 (Molaei et al. 2006) divided by gonotrophic value of 5 d (Reisen et al. 1992).

^cVector competence—based on experimental transmission rates of an unpassed isolate of WNV (Crow 397–99 strain) obtained from the brain of a crow that died in the epicenter (i.e., New York, NY) during the initial year of the WNV outbreak (i.e., 1999) and using Cx. pipiens reared from larvae collected 20 km away from the epicenter. Values for vector competence represent viral transmission rates of mosquitoes that were either orally exposed to WNV (VC_NO; i.e., 31/178) or were intrathoracially inoculated and/or had disseminated infections (VC_YES; i.e., 21/24) (data are combined from Turell et al. 2000, Turell et al. 2001).

^dDaily survival—based on mark-release-recapture with Cx. pipiens in Washington, DC (Jones et al. 2012). Mortality of Cx. pipiens because of ingestion of Ch. quiscali MF was assumed to be negligible (≈4%; see text).

^eExtrinsic incubation period (EIP)—the `normal' EIP (i.e., VC_NO) of 12 d is based on orally exposed Cx. pipiens held at 26°C where dissemination rate exceeded 15% (Dohm et al. 2002, Anderson et al. 2008). The MF-enhanced EIP (i.e., VC_YES) of 5 d was calculated as 42.4% of normal EIP, based on the avg reductions of EIP observed with dengue 1 virus development within Ae. aegypti fed blood that was either dually infected (virus + Brugia malayi MF) or singly infected (virus only) (Vaughan et al. 2009).