ARBOVIRUS AVTIVIY IN MASSACHUSETTS: 2011 SEASON SUMMARY

M. Cynthia Stinson

Massachusetts Department of Public Health

Hinton State Laboratory Institute

305 South Street, Room 816

Jamaica Plain, MA 02130

cynthia.stinson@state.ma.us

ABSTRACT

2011 Arbovirus activity in Massachusetts included WNV and EEE mosquito isolates; EEE and WNV infection in humans, and one WNV equine infection. Arbovirus activity was identified in eleven counties within the Commonwealth.

A total of 4604 mosquito pools consisting of 131,158 mosquito specimens were tested for the season. 275 mosquito pools were confirmed as WNV (+) and 80 pools were confirmed as EEE (+). Of the 275 WNV mosquito pools, 224 were identified as Culex pipiens/restuans. The remaining WNV isolates were identified in Culex species (23), Coquillettidia perturbans (1), Culex salinarius (1), Culiseta melanura (24), Ochlerotatus canadensis (1) and Aedes vexans (1). Of the 80 EEEv mosquito pools, 58 were identified in the enzootic vector species, Culiseta melanura. The remaining isolates were identified in Coquillettidia perturbans (8), Culex pipiens/restuans (8), Ochlerotatus canadensis (4) and Aedes vexans (2). The Hinton State Laboratory Institute confirmed 1 human cases of EEE in a Massachusetts resident; a second EEE case was identified in a Missouri resident with infection acquired while in Massachusetts. Five human WNV cases were confirmed with clinical presentations ranging from fever to encephalitis. Mammal activity included one WNV positive horse identified in Hampshire County.