Table 1. Classification of the Venezuelan equine encephalitis (VEEV) complex of alphaviruses^a.

Subtype	Variety	Species	Transmission pattern	Equine virulenceb	Location	Vector
I	AB	VEEV	Epizootic	virulent	Central, South, North America	Mammalophilic mosquitoes
	C	VEEV	Epizootic	virulent	South America	mammalophilic mosquitoes
	D	VEEV	Enzootic	avirulent	Central, South America	Culex (Mel.) ocossa, panocossa, pedroi, adamesi, vomerifer
	E	VEEV	Enzootic	variable	Central America, Mexico	Cx. (Mel.) taeniopus
	F	Mosso das Pedras	Enzootic	unknown	Brazil	unknown
II		Everglades	Enzootic	avirulent	Southern Florida	Cx (Mel.) cedecei
III	A	Mucambo	Enzootic	avirulent	South America	Cx (Mel.) portesi
	B	Tonate	Enzootic	unknown	South, North America	Unknown (Tonate), bug (Bijou Bridge strains from N. America)
	C		Enzootic	unknown	Peru	Unknown
IV		Pixuna	Enzootic	unknown	Brazil	Unknown
V		Cabassou V	Enzootic	unknown	French Guiana	Unknown
VI		Rio Negro	Enzootic	unknown	Argentina	Unknown

^aSource: The Arboviruses: Epidemiology and Ecology (9).
^bVirulent strains produce high viremia titers and generally >50% death rates in horses experimentally infected.