Changes

=====Vectors=====

=====Vectors=====

Vectors transmit viral particles between sylvatic hosts when takin ga blood meal.  If the virus can peentrate the gut of the vector, then it may pass throhg the haemolymph to the oral glands, multiply and subsequntrly be shed in the saliva and other oral secretions.  If th eblood meal octnains adequate numbers of viral particles, multiplication may not be rrequired for transmission.  It is likely tha the mosquito remians infected for life.  The most significant disease vectors for each serotype are:

During a blood meal, mosquito vectors transmit viral particles between wild animal hosts.  Viruses that are able to penetrate the mosquito's gut can pass via the haemolymph to the oral glands.  Here, viral replication is followed by the shedding of viral particles into the saliva and other oral secretions.  Viral multiplication may not be necessary for transmission if the original blood meal contained sufficient numbers of viral particles.  It is thought that the mosquito remains permanently infected.   

The most significant disease vectors for each viral serotype are:

*Eastern EEV: ''Aedes'' spp.

*Eastern EEV: ''Aedes'' spp.

*Western EEV: ''Culex tarsalis''

*Western EEV: ''Culex tarsalis''

*Venezuelan EEV: ''Culex melanconium'', ''Aedes'' spp., ''Phosphora'' spp.

*Venezuelan EEV: ''Culex melanconium'', ''Aedes'' spp., ''Phosphora'' spp.

''Culiseta melanura'' is another vector for Eastern EEV.  It feeds mostly on swamp birds, completing an enzootic cycle of viral transmission.  ''C.melanura'' is thus an inhabitant of freshwater swamps and is not usually found in areas densely populated by equids.  Epizootics and epidemics of Eastern EEV disease are propagated by ''Aedes'' spp.  Western EEV persists in an enzootic cycle with passerine birds, transmitted by ''C.tarsalis''.  Other vectors or overwintering hosts for this serotype may include ''Dermacentor andersoni'' ticks, ''Triatoma sanguisuga'' (the assassin bug), and the cliff swallow bug (''Oeciacus vicarius'').  Several species of mosquitoes from at least 11 geerna have been determined ot be naturally infected with epidemic strains of VEE virus.  Ticks may also be capable of viral trasnmission.

''Culiseta melanura'' is another vector for Eastern EEV.  It feeds mostly on swamp birds, completing an enzootic cycle of viral transmission.  ''C.melanura'' is thus an inhabitant of freshwater swamps and is not usually found in areas densely populated by equids.  Epizootics and epidemics of Eastern EEV disease are propagated by ''Aedes'' spp.  Western EEV persists in an enzootic cycle with passerine birds, transmitted by ''C.tarsalis''.  Other vectors or overwintering hosts for this serotype may include ''Dermacentor andersoni'' ticks, ''Triatoma sanguisuga'' (the assassin bug), and the cliff swallow bug (''Oeciacus vicarius'').  Epidemic strains of Venezuelan EEV have infected mosquito species from several genera and this viral serotype may also be transmitted by ticks.