Mosquito-borne Diseases in Ohio
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.
Wear 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
Check 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.
Pack 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
Don'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.
Stop 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).
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.
Estimated Distribution of Aedes albopictus in Ohio, 2017-2022
| County | Percent of Aedes albopictus Among Non-Culex spp. Mosquitoes |
| Adams | > 50% |
| Allen | 0% |
| Ashland | < 10% |
| Ashtabula | 0% |
| Athens | < 10% |
| Auglaize | 0% |
| Belmont | < 10% |
| Brown | 10 – 50% |
| Butler | 10 – 50% |
| Carroll | < 10% |
| Champaign | < 10% |
| Clark | 10 – 50% |
| Clermont | 10 – 50% |
| Clinton | < 10% |
| Columbiana | 0% |
| Coshocton | 0% |
| Crawford | < 10% |
| Cuyahoga | < 10% |
| Darke | 10 – 50% |
| Defiance | 0% |
| Delaware | < 10% |
| Erie | 0% |
| Fairfield | 10 – 50% |
| Fayette | < 10% |
| Franklin | 10 – 50% |
| Fulton | 0% |
| Gallia | > 50% |
| Geauga | 0% |
| Greene | 10 – 50% |
| Guernsey | 0% |
| Hamilton | 10 – 50% |
| Hancock | < 10% |
| Hardin | 0% |
| Harrison | 0% |
| Henry | 0% |
| Highland | < 10% |
| Hocking | 10 – 50% |
| Holmes | 0% |
| Huron | 0% |
| Jackson | 10 – 50% |
| Jefferson | 0% |
| Knox | 0% |
| Lake | < 10% |
| Lawrence | > 50% |
| Licking | < 10% |
| Logan | 0% |
| Lorain | < 10% |
| Lucas | < 10% |
| Madison | 10 – 50% |
| Mahoning | < 10% |
| Marion | 0% |
| Medina | 0% |
| Meigs | 10 – 50% |
| Mercer | 0% |
| Miami | < 10% |
| Monroe | < 10% |
| Montgomery | 10 – 50% |
| Morgan | 10 – 50% |
| Morrow | 0% |
| Muskingum | < 10% |
| Noble | < 10% |
| Ottawa | < 10% |
| Paulding | 0% |
| Perry | < 10% |
| Pickaway | 10 – 50% |
| Pike | 10 – 50% |
| Portage | < 10% |
| Preble | < 10% |
| Putnam | 0% |
| Richland | 0% |
| Ross | 10 – 50% |
| Sandusky | 0% |
| Scioto | 10 – 50% |
| Seneca | 0% |
| Shelby | 0% |
| Stark | < 10% |
| Summit | < 10% |
| Trumbull | 0% |
| Tuscarawas | < 10% |
| Union | < 10% |
| Van Wert | 0% |
| Vinton | < 10% |
| Warren | < 10% |
| Washington | 10 – 50% |
| Wayne | < 10% |
| Williams | 0% |
| Wood | < 10% |
| Wyandot | 0% |
Source: Ohio Department of Health mosquito surveillance data.
Last updated November 8, 2022.
Eastern treehole mosquito
Name: 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).
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).
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).
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.