High risk statewide
The Rhode Island Department of Environmental Management (DEM) and Rhode Island Department of Health (RIDOH) are announcing one confirmed human case of West Nile Virus (WNV) and one probable human case of WNV. Both people are Providence County residents in their 70s.
These human cases of WNV are in addition to the one confirmed
human case of WNV, one probable human case of WNV, and first human case of
Eastern Equine Encephalitis (EEE) virus in 2024 announced last week. This brings Rhode
Island’s human WNV case count to four, with two confirmed cases and two
probable cases.
Additionally, the most recent mosquito samples tested by the Rhode Island State Health Laboratories (RISHL) has confirmed one positive finding of EEE virus. The mosquito sample testing positive for EEE virus was collected in Westerly. These results are from 89 samples collected from 24 traps set statewide by DEM on September 5 and 9.
All other samples tested negative
for EEE virus, WNV, or Jamestown Canyon Virus (JCV). RIDOH and DEM are
reminding the public that it is a particularly active mosquito season in
Southern New England and that mosquito testing and recent human cases of both
EEE virus and WNV indicate a high risk level statewide.
Last month, DEM, RIDOH, and the Mosquito Borne Disease
Advisory Group (MDAG) they convene recommended that members of the public, schools, and
communities consider “smart scheduling" of outdoor
activities during peak mosquito activity hours to help minimize the risk of
mosquito bites. It is important for all Rhode Islanders to take
precautions to limit exposure to mosquitoes and prevent mosquito bites,
including using an EPA-approved insect repellent and wearing long sleeves and
pants when outdoors.
Due to the high risk level statewide, RIDOH and DEM are
urging schools and organizations that have not yet implemented
“smart-scheduling” to consider rescheduling outdoor activities scheduled to
occur during early morning or dusk hours to earlier in the afternoon or
relocating them to an indoor venue. Although adult mosquitoes are not
killed until a hard frost (defined as three consecutive hours below 32
degrees), mosquitoes become less active at temperatures below 58 degrees and
they become largely inactive when temperatures fall below 50 degrees.
Last month, DEM conducted an aerial application of mosquito larvicide across 3,000 acres of Chapman Swamp in Westerly and Great Swamp in South Kingstown to reduce mosquito populations and related disease risk. As mosquito season continues, the MDAG will continue to evaluate the risk level statewide and will provide updates if any further mosquito control measures are planned.
DEM and RIDOH continue to urge Rhode Islanders to protect themselves and their loved ones from mosquito bites and the diseases they carry, including EEE virus and WNV. Weekly mosquito trap density and mosquito testing results are available on RIDOH’s arboviral surveillance data webpage.
Previously this season, Rhode Island has announced 17 EEE virus findings in mosquito samples, 14 WNV findings, one confirmed human case off EEE virus, one confirmed human case of WNV, and one probable human case of WNV.
The State of Connecticut has announced 56 EEE virus findings, 305 WNV findings, two JCV findings, three human cases of WNV, and an animal case of EEE virus in a deer, and the Commonwealth of Massachusetts has announced 322 WNV findings, 96 EEE findings, four human cases of EEE virus, two animal cases of EEE virus, and 11 human cases of WNV.
It is notable that EEE
virus and WNV have been detected in several Massachusetts and Connecticut towns
bordering Rhode Island, indicating a higher risk in bordering Rhode Island
communities.
Although extremely rare in humans, EEE virus is very serious
and has a much higher human mortality rate than WNV. Approximately 30% of
people with EEE virus die, and many survivors have ongoing neurological
problems. Unlike WNV, which is prevalent in Rhode Island every year, EEE virus
risk is variable, changing from year to year. For more information on EEE virus
and ways to prevent it, please visit www.health.ri.gov/eee.
WNV is the leading cause of mosquito-borne disease in the
continental United States and is much more prevalent than EEE virus. Cases of
WNV occur during mosquito season, which starts in the summer and continues
through fall. There are no vaccines to prevent or medications to treat WNV in
people. Fortunately, most people infected with WNV do not feel sick. About one
in five people who are infected develop a fever and other symptoms. About one
out of 150 infected people develop a serious, sometimes fatal, illness. For
more information about WNV, please visit www.health.ri.gov/wnv.
EEE virus and WNV are typically present in wild bird
populations. Birds are reservoirs of the diseases and mosquitoes transmit these
viruses among birds. During an active mosquito season, the viruses are
amplified in the environment with each generation of mosquitoes. At a certain
point, several mosquito species that bite both birds and mammals serve as a
bridge between infected birds and uninfected mammals. Most bridge species
are within the Aedes, Coquillettidia, and Culex genera.
Mosquito Control:
Residents can help control mosquitoes by removing backyard
mosquito breeding grounds. The Asian Tiger Mosquito has become
prevalent in Rhode Island urban environments, and it is expected to be common
again this season. It is notable as a daytime biter encountered in shaded
backyards. It has a striking black and white pattern evident to the naked eye.
It develops from eggs laid in artificial containers, so residents are urged to
remove standing water from containers such as buckets, pots, wheelbarrows,
boats, and pools. Clogged rain gutters and puddles formed on tarps also can
support the larvae of this species. The Asian tiger mosquito is known to
transmit several diseases, including WNV.
In addition to considering smart-scheduling, Rhode Islanders
should take the following measures to
protect themselves from mosquito bites and to help minimize
mosquito breeding:
Protect yourself!
- Put
screens on windows and doors. Fix screens that are loose or have holes.
- Consider
rescheduling outdoor activities that occur during the evening or early
morning at sunrise and sundown (when mosquitoes carrying the EEE virus are
most active). If you must be outside, wear long-sleeved shirts and pants
and use bug spray.
- Use EPA-approved bug spray with
one of the following active ingredients: DEET (20-30%
strength), picaridin, IR3535, and oil of lemon eucalyptus or
paramenthane. Always read the label and follow all directions and
precautions.
- Do not
use bug spray with DEET on infants under two months of age. Check the
product label to find the concentration of DEET in a product. The American
Academy of Pediatrics recommends that repellents contain no more than 30%
DEET when used on children. Children should be careful not to rub their
eyes after bug spray has been applied on their skin. Wash children’s hands
with soap and water to remove any bug spray when they return indoors.
- Put
mosquito netting over playpens and baby carriages.
Remove mosquito breeding grounds!
- Remove
items around your house and yard that collect water. Just one cup of water
can produce hundreds of mosquitoes; an unused tire containing water can
produce thousands of mosquitoes.
- Clean
your gutters and downspouts so that they can drain properly.
- Remove
any water from unused swimming pools, wading pools, boats, planters, trash
and recycling bins, tires, and anything else that collects water, and
cover them.
- Remove
or treat any shallow water that can accumulate on top of a pool cover.
Larvicide treatments, such as Mosquito Dunks can be applied to
kill immature mosquitoes. This environmentally friendly product is
available at many hardware and garden stores and online.
- Clean
and change water in birdbaths at least once a week.
Best practices for horse owners!
Horses are particularly susceptible to WNV and EEE virus.
Horse owners are advised to vaccinate their animals early in the season and
practice the following:
- Remove
or cover areas where standing water can collect.
- Avoid
putting animals outside at dawn, dusk, or during the night when mosquitoes
are most active.
- Insect-proof
facilities where possible and use approved repellents frequently.
- Monitor
animals for signs of fever and/or neurological signs (such as stumbling,
moodiness, loss of appetite) and report all suspicious cases to a
veterinarian immediately. If you are unsure if your horse is properly
vaccinated, consult your veterinarian.
Visit health.ri.gov/mosquito for additional
mosquito prevention tips, videos, and local data. DEM traps mosquitoes weekly
and tests them at the RIDOH State Health Laboratories. From June through
to the first hard frost of the season, which usually occurs in mid-October, DEM
issues advisories on test results, with additional reports as necessary.
Typically, positive test results trigger additional trapping to assess
risk.
For more information on DEM programs and initiatives,
visit www.dem.ri.gov. Follow DEM on Facebook, Twitter (@RhodeIslandDEM),
or Instagram (@rhodeisland.dem) for timely updates. Sign up here to receive the latest
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