Distribution of the Vectors of Equine Encephalomyelitis in Massachusetts

Abstract

A state-wide survey of the mosquitoes was made during 1939, following the occurrence of an outbreak of equine encephalomyelitis in man in 1938. About 275,000 specimens of 21 spp. were collected. Of these, 6 (all Aedes) had been demonstrated to be able to transmit this disease and these 6 represented 76.4% of the Aedes collected and 6.4% of the total collections. The peak of abundance of the known vectors was late in Aug., just before the peak of the 1938 outbreak of encephalomyelitis. Three of the vectors[long dash]Aedes vexans, A. cantator and A. sollicitans[long dash]constituted, respectively, 25.1%, 22.5% and 20.4% of the total Aedes. More than 60% of the spp. caught on man were vectors but < 6% of those taken inside houses were of this group.