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Mosquito-borne Diseases in Ohio

Fight the Bite

Diseases spread by mosquitoes are a concern in Ohio each year.  Mosquito-borne diseases that may occur locally in Ohio include:

There are also several mosquito-borne diseases that Ohioans can acquire when traveling that could be brought back into Ohio:

Prevent mosquito bites

The most effective way to prevent mosquito-borne diseases is to prevent being bitten by mosquitoes.  In Ohio, mosquito-borne illnesses are most often transmitted during the warmest months, May through October.

Being aware of mosquito and mosquito-borne disease activity in your area allows you to take action to protect yourself and others: avoid mosquitoes and mosquito bites, plan ahead for mosquitoes while traveling, and stop mosquitoes from breeding in and around your home.

AVOID mosquitoes and mosquito bites

Use insect repellents when you go outdoors:

  • Apply repellents on exposed skin that are registered with the U.S. Environmental Protection Agency (EPA).  EPA-registered insect repellents are proven safe and effective, even for pregnant and breastfeeding women.
  • Applying insect repellentWear clothing treated with permethrin or another EPA-registered repellent for extra protection.
  • Use products according to label instructions to optimize safety and effectiveness.
  • Don't spray repellents on the skin under your clothing.

Take care during peak mosquito biting hours:

  • Take extra care to use repellents from dusk to dawn.
  • Wear light-colored clothing, long-sleeved shirts or jackets, and long pants to protect against mosquito bites.
  • Consider avoiding outdoor activities during peak mosquito biting hours.
  • Use mosquito netting when sleeping outdoors or in an unscreened structure.

PLAN ahead for mosquitoes while traveling

CDC Travels'  Health websiteCheck travel notices for mosquito-borne and other disease transmission updates:

  • Visit the Centers for Disease Control and Prevention (CDC)'s Travelers' Health website to search for the latest health notices for the country you're traveling to.

Speak to your healthcare provider regarding risks:

  • Talk to your healthcare provider about your travel plans and measures you can take to reduce your risk of mosquito-borne diseases.
  • Depending on which country(ies) you are visiting, malaria chemoprophylaxis or yellow fever vaccination may be recommended or required.  An International Certificate of Vaccination (ICV) may be required for travelers to gain entry into certain countries.

Packing insect repellentPack appropriately to protect yourself from mosquitoes:

  • Bring EPA-registered insect repellent to use when outdoors.
  • Consider bringing clothing treated with permethrin or another EPA-registered repellent for extra protection.
  • Pack light-colored clothing, long-sleeved shirts or jackets, and long pants to protect against mosquito bites.
  • Purchase mosquito netting to use when sleeping outdoors or in an unscreened structure.

STOP mosquitoes from breeding in and around your home

Dumping containersDon't let mosquitoes breed around your home:

  • Empty standing water from flowerpots, buckets, barrels, tarps/covers, and wheel barrows on a regular basis.
  • Discard trash such as tin cans, plastic containers and other water-holding containers that have accumulated on your property.
  • Dispose of discarded tires properly.  Drill holes in tire swings so water drains out.
  • Change the water in pet dishes frequently.
  • Replace the water in bird baths weekly.
  • Check and clean clogged roof gutters at least twice annually so they will drain properly.
  • Aerate ornamental pools or stock them with mosquito-eating fish.
  • Clean and chlorinate swimming pools, even those that are not being used.
  • Keep children's wading pools empty and on their sides when they aren't being used.
  • Consider using products containing Bacillus thuringiensis israelensis (Bti), available at many garden and home improvement stores, to control mosquito larvae in containers that are too large to empty.  Follow label instructions.

Screens on windowsStop mosquitoes from coming indoors:

  • Install or repair screens on windows and doors.
  • Use air conditioning, if you have it.

Support your community surveillance and control programs:

  • Mosquito control activities are most often handled at the local level, through county or city government.  The type of mosquito control methods used by a program depends on the time of year, the type of mosquitoes to be controlled and the habitat structure.  Methods can include elimination of mosquito larval habitats, application of insecticides to kill mosquito larvae or spraying insecticides from trucks or aircraft to kill adult mosquitoes.  Your local mosquito control program can provide information about the type of products being used in your area.  Check with your local health department for more information.
  • Report dead birds to local authorities.  Dead birds may be a sign that West Nile virus and other arboviruses are circulating between birds and the mosquitoes in an area.  By reporting dead birds to local health departments, you can play an important role in monitoring mosquito-borne diseases.  Local agencies have different policies for collecting and testing birds, so check with your local health department for more information.

Mosquitoes in Ohio

Each summer, mosquitoes are a familiar biting pest in backyards, parks, and campgrounds.  Most are merely a nuisance and not major vectors of disease.  In fact, only a few of the 59 species of mosquitoes in Ohio can transmit disease.  However, the diseases these mosquitoes can carry are very serious ones, such as encephalitis and malaria in humans and heartworm in dogs.  Therefore, it is always advisable to take preventive measures to protect yourself and your family against mosquito bites.

Asian tiger mosquito

Name:  Asian tiger mosquito (Aedes albopictus).Asian tiger mosquito, Aedes albopictus

Distribution:  Throughout the eastern United States.  In Ohio, it has been found in nearly all of the southern counties, but likely occurs in others.

Habitat:  Outdoors in vegetation.  Lays eggs in both natural and artificial containers including used tires, plastic containers, treeholes, and clogged gutters.

Hosts:  Opportunistic blood feeder on a variety of animals and humans.

Transmits:  Potential to transmit chikungunya, dengue, and Zika viruses.

Active:  Most active during the day in shady conditions.

Comments:  Aggressive biter.  Asian tiger mosquitoes were imported into the United States in the 1980s.  They have spread through the United States and become established because of their ability to survive temperate climates.

Map: Aedes albopictus distribution in Ohio

Estimated Distribution of Aedes albopictus in Ohio, 2016-2021

County Distribution
 Adams Identified
 Allen Not identified
 Ashland Identified
 Ashtabula Not identified
 Athens Identified
 Auglaize Not identified
 Belmont Identified
 Brown Identified
 Butler Identified
 Carroll Identified
 Champaign Identified
 Clark Identified
 Clermont Identified
 Clinton Identified
 Columbiana Not identified
 Coshocton Not identified
 Crawford Identified
 Cuyahoga Identified
 Darke Identified
 Defiance Not identified
 Delaware Identified
 Erie Not identified
 Fairfield Identified
 Fayette Identified
 Franklin Identified
 Fulton Not identified
 Gallia Identified
 Geauga Not identified
 Greene Identified
 Guernsey Not identified
 Hamilton Identified
 Hancock Identified
 Hardin Not identified
 Harrison Not identified
 Henry Not identified
 Highland Identified
 Hocking Identified
 Holmes Not identified
 Huron Not identified
 Jackson Identified
 Jefferson Not identified
 Knox Not identified
 Lake Identified
 Lawrence Identified
 Licking Identified
 Logan Not identified
 Lorain Identified
 Lucas Not identified
 Madison Identified
 Mahoning Identified
 Marion Not identified
 Medina Not identified
 Meigs Identified
 Mercer Not identified
 Miami Identified
 Monroe Identified
 Montgomery Identified
 Morgan Identified
 Morrow Not identified
 Muskingum Identified
 Noble Identified
 Ottawa Identified
 Paulding Not identified
 Perry Identified
 Pickaway Identified
 Pike Identified
 Portage Identified
 Preble Identified
 Putnam Not identified
 Richland Not identified
 Ross Identified
 Sandusky Not identified
 Scioto Identified
 Seneca Not identified
 Shelby Not identified
 Stark Identified
 Summit Identified
 Trumbull Not identified
 Tuscarawas Identified
 Union Identified
 Van Wert Not identified
 Vinton Identified
 Warren Identified
 Washington Identified
 Wayne Not identified
 Williams Not identified
 Wood Not identified
 Wyandot Not identified

Identified = Aedes albopictus identified.
Not identified = Mosquito surveillance conducted, no Aedes albopictus identified.

Source: Ohio Department of Health mosquito surveillance data.
Last updated Sep. 16, 2021.

Eastern treehole mosquito

Name:  Eastern treehole mosquito (Aedes triseriatus).Eastern treehole mosquito, Aedes triseriatus

Distribution:  Throughout Ohio.

Habitat:  Wooded areas, parks.  Lays eggs in artificial containers in trash dumps or backyards and the natural treeholes of silver maple, oak, and beech trees.

Hosts:  Mammals, particularly small mammals such as chipmunks and squirrels.

Transmits:  La Crosse virus.

Active:  Most active during the day in shady conditions.  Keeps near wooded areas to lay eggs in deciduous forests.

Comments:  Ohio has reported more cases of La Crosse virus disease than any other states in the United States, averaging about 20 cases per year.

Malaria mosquitoes

Name:  Common malaria mosquito (Anopheles quadrimaculatus), woodland malaria mosquito (Anopheles punctipennis).Common malaria mosquito, Anopheles quadrimaculatus

Distribution:  Throughout Ohio.

Habitat:  Lays eggs in permanent and semi-permanent bodies of water with vegetation such as ponds, marshes, and ditches.  The woodland malaria mosquito may also lay eggs in slow-moving streams with vegetation.

Hosts:  Humans.

Transmits:  Potential to transmit Plasmodium species parasites that cause malaria.

Active:  Most active at dusk and dawn and during the night.

Comments:  Malaria was eliminated from the United States in the early 1950s.  However, the potential for malaria to be transmitted in the United States still exists.

Northern house mosquito

Name:  Northern house mosquito (Culex pipiens).Northern house mosquito, Culex pipiens

Distribution:  Widespread throughout Ohio.

Habitat:  Weeds, shrubs, tall grass.  Lays eggs in catch basins, stagnant water in ditches, and containers of water with high organic matter (e.g., flowerpot saucers, clogged rain gutters).

Hosts:  Prefers to feed on birds.

Transmits:  St. Louis encephalitis and West Nile viruses.

Active:  Most active at dusk and dawn.

Comments:  West Nile virus was first identified in Ohio in 2001, and it is now established where cases occur each year and seasonal epidemics flare up under certain conditions in the summer and continue into the fall.

Yellow fever mosquito

Name:  Yellow fever mosquito (Aedes aegypti).Yellow fever mosquito, Aedes aegypti

Distribution:  Tropical and sub-tropical climates.  Found in the United States primarily in the southern tier states.

Habitat:  Urban areas near and inside homes.  Lays eggs in man-made containers, pools of fresh rainwater.

Hosts:  Humans.

Transmits:  Chikungunya, dengue, yellow fever and Zika viruses.

Active:  Most active during the day.

Comments:  This species is not established in Ohio.  It cannot survive below freezing temperatures.  However, it has rarely been collected in Ohio during the summer where it was likely transported by people in containers, such as used tires, plant pots, etc.

What time of year are you more likely to encounter mosquitoes?

Mosquitoes are active in Ohio during the warmest months, usually May through October.  Mosquito activity will cease after the first hard frost in the fall.