Public Health IPM
Insects, Mosquitos & Ticks in Public Health
Mosquito-Borne Disease Update for New Hampshire
Oct 15, 2014: DHHS has announced a third human case of EEE in New Hampshire, this time from Manchester. The victim appears to have been exposed at the end of August. This should not affect the risk now, which continues in many southern NH spots, because they have not had a killing frost.
Oct 6, 2014: A horse from Nottingham has tested positive for EEE. In addition, 5 mosquito batches tested positive for EEE; one each from Newton, Derry, Candia, Kingston and Raymond. In response, officials have raised the EEE threat level a bit in Nottingham, Lee, Barrington, Epping and Northwood. We have had light scattered frost in the area, but not a heavy enough frost to kill adult mosquitoes. When we do, the disease risk for this year will plummet. Elsewhere in the state, risk levels remain the same as they were before this discovery.
Sept 30, 2014: Three more EEE-positive mosquito batches have been detected from Candia, Derry and Newton. All were a bird-biting species, Culiseta melanura. These are within the usual geographic range for EEE, so the department of Health & Human Services has not altered the risk maps. A hard frost will greatly reduce the risk of acquiring EEE, and two hard frosts should totally end the risk for this year.
Sept 23, 2014: A batch of Aedes cinereus mosquitoes from Hampstead has tested positive for EEE. This in the area where we have traditionally had EEE activity, and isn’t much of a surprise for this time of year. A. cinereus is a mammal-biting species. Also we learned of the first positive West Nile virus batch this year, a bird-biting species from Greenland. Overall, this week’s report doesn’t change the risk picture too much. When we get a really hard frost (maybe two) the risk will end for the year.
Sept 17, 2014: Again the EEE risk has risen slightly, which is typical for this time of year. Three additional batches of mosquitoes have tested positive for EEE. They were from Amherst, Londonderry and Portsmouth. All were Culiseta melanura, a bird-biting species. To see NH DHHS’s map of positive results and regional risk, follow this link http://www.dhhs.nh.gov/dphs/cdcs/arboviral/results.htm
This makes a total of 9 EEE-positive mosquito batches for this year, out of 3393 batches tested. Positive batches came from Candia (2), Derry (2), Londonderry (2), Danville (1), Amherst (1), and Portsmouth (1). One mule (Candia) and two humans (Hopkinton, Conway) were detected. The Conway report is well outside of what we typically think of as the higher EEE-risk region of NH, and the Hopkinton case is close to the edge of that “typical” higher risk region of Rockingham County and eastern Hillsborough county.
It is wise to limit your exposure to biting mosquitoes, especially if you are in one of the areas of elevated risk shown on the 2014 map. This period of elevated risk will continue until we get one (more likely, two) hard freeze in the areas of elevated risk. Reducing the area of exposed skin, and using repellants are two ways to significantly reduce your risk of becoming a victim. It may help to avoid areas with lots of mosquitoes, especially within two hours of sunset.
September 11, 2014 - EEE Risk Continues; no WNV indicators Yet: September is typically the time of highest risk from mosquito-borne diseases in New Hampshire. A second human case of Eastern Equine Encephalitis has been found, this time from Hopkinton. No additional mosquito batches have tested positive for EEE, and we still have found no positive West Nile Virus mosquito batches this year.
It is a wise precaution to reduce your risk of getting bitten by wearing clothing that minimized exposed skin, avoiding mosquito-prone places (especially within an hour or two of sunset) and consider using repellants.
August 25, 2014 - EEE Risk Has Risen in New Hampshire:
On August 22, the New Hampshire Department of Health and Human Services announced several new Eastern Equine Encephalitis (EEE) indicators in New Hampshire. One was a human case from Conway. This underlines the fact that EEE could show up almost anywhere in the state.
There are no communities in the Conway area that routinely trap mosquitoes and submit them for testing, so we don’t have a good idea how prevalent the virus is in mosquitoes from that region.
Four batches of mosquitoes from Candia and Derry tested positive for EEE. Three batches were of a bird-biting species. One was a mammal biting species, so that is a bit higher concern than positive bird-biters. These positive finds are in the area of southeastern New Hampshire that frequently shows an elevated risk of EEE. Based on past patterns, the risk is likely to go higher, and typically is highest in September, until a killing frost shuts down mosquito activity.
You can reduce the chances of becoming a victim by reducing the odds of being bitten. That could include covering up exposed skin, using repellants, and reducing outdoor activity within an hour or two of dusk, when mosquito biting peaks.
For more information about mosquito-borne diseases in New Hampshire, visit the DHHS website.
To learn more about insect repellants, see my publication.
To learn more about mosquito management options, see my publication
—Dr. Alan Eaton, UNH Cooperative Extension Entomology specialist
Blacklegged Ticks in New Hampshire, Updated Map 2014
This map is the result of 25 years of active and passive surveillance on blacklegged tick (BLT) in New Hampshire. In the beginning, there were just three published records of this species in New Hampshire. This map compiles over 700 records, through late November 2013.
The NH Division of Health & Human Services has information and maps on Lyme disease and blacklegged tick.
Ticks can transmit several human diseases, and New Hampshire is home to many species of ticks. Learn what ticks look like, how they live, the diseases they spread, how to manage tick problems, and how to protect yourself from tick-borne diseases.
The NH Division of Health & Human Services has information & maps on mosquito-spread diseases in NH.
Eastern Equine Encephalitis (EEE) is a disease that is transmitted by mosquitos. Learn about Eastern Equine Encephalitis (EEE) and how it spreads, what types of mosquitos transmit EEE, and how to protect yourself from this disease.
Insect repellents can help you protect yourself from insect-borne diseases. Learn about the various types of insect repellents available and their efficacy.