The Ohio Department of Health (ODH) Zoonotic Disease Program, in partnership with ODH Laboratory, local public health partners, and sanitary district partners, conducts statewide vectorborne disease surveillance which includes monitoring for human and veterinary cases.

We will monitor for diseases transmitted by mosquitoes and ticks throughout the summer and fall and will report positive results and summary statistics on this website, updated each Friday at noon.  Please download the attached document for a more detailed summary of mosquito and tick surveillance in Ohio.

2022 Numbers-At-A-Glance

As of January 9, 2023

2022 Mosquito-borne diseases

West Nile virus

Mosquito surveillance

• 453,586 Culex spp. from 64 agencies in 51 counties pooled into 14,067* samples.
• 946 West Nile virus positive mosquito samples.

* Testing agencies: Ohio Department of Health using RT-PCR assay = 9,917 pools reported, Franklin County Public Health using RAMP assay = 1,358 pools reported, Columbus Public Health using VecTOR assay = 555 pools reported, Columbus Public Health using RAMP assay = 602 pools reported, Licking County Health Department using RAMP assay = 118 pools reported, Toledo Area Sanitary District using qPCR = 1,517.

Human surveillance

• 7 West Nile virus cases: 3 females and 4 males, median age 52 years, from 3 counties – Cuyahoga (2), Franklin (2), and Montgomery (3).
• 2 West Nile virus asymptomatic viremic blood donors.
• 0 West Nile virus asymptomatic viremic organ donors.

Veterinary surveillance

• 3 West Nile virus equine cases.
• Reported by the Ohio Department of Agriculture Animal Disease Diagnostic Laboratory.

La Crosse/California encephalitis virus

Human surveillance

• 13 La Crosse virus disease cases: 5 females and 8 males, median age 9 years, from 10 counties – Coshocton (2), Franklin (1), Knox (1), Muskingum (3), Perry (1), Richland (1), Ross (1), Stark (1), Tuscarawas (1), and Vinton (1).
• 0 unspecified California virus cases.

Travel-associated mosquito-borne diseases

Human surveillance

• 2 chikungunya virus cases: 1 female and 1 male, median age 26 years, traveled to – India (1) and Tanzania (1).
• 4 dengue virus cases: 1 female and 3 males, median age 31 years, traveled to – El Salvador (1), Guatemala (1), Nepal (1), and multiple countries (1).
• 0 Zika virus cases.
• 76 malaria cases: 29 females and 47 males, median age 39 years, traveled to – Cameroon (4), Central African Republic (1), Chad (3), Cote d'Ivoire (2), Democratic Republic of the Congo (4), Gambia (1), Ghana (5), Guinea (7), Kenya (2), Liberia (1), Madagascar (1), Mali (1), Nigeria (4), Pakistan (1), Senegal (2), Sierra Leone (22), South Sudan (2), Tanzania (1), Uganda (5), and unknown countries (7).

* Ohioans traveling to areas where local transmission is occurring should be aware of the ongoing situation and make every effort to avoid mosquito bites.  Additional information can be found from the Centers for Disease Control and Prevention (CDC)'s Travelers' Health and Pan-American Health Organization websites.

2022 Tickborne diseases

Lyme disease, anaplasmosis, babesiosis

Tick surveillance

• 1,272 blacklegged ticks, Ixodes scapularis, identified from 66 counties – Allen (1), Ashland (3), Ashtabula (21), Athens (23), Belmont (19), Brown (1), Butler (2), Carroll (8), Champaign (1), Clark (1), Clermont (5), Columbiana (153), Coshocton (108), Cuyahoga (37), Defiance (1), Delaware (2), Erie (5), Fairfield (3), Franklin (187), Gallia (65), Geauga (18), Greene (1), Guernsey (63), Hamilton (20), Harrison (1), Henry (1), Highland (15), Hocking (190), Holmes (5), Huron (3), Jackson (2), Jefferson (15), Knox (13), Lake (30), Licking (10), Lorain (9), Lucas (2), Mahoning (9), Medina (8), Meigs (2), Mercer (1), Miami (1), Monroe (4),  Montgomery (3), Morrow (1), Muskingum (3), Noble (1), Ottawa (1), Perry (1), Pickaway (17), Pike (23), Portage (15), Richland (6), Ross (16), Scioto (1), Stark (13), Summit (42), Trumbull (9), Tuscarawas (5), Vinton (4), Warren (1), Washington (3), Wayne (17), Williams (2), Wood (5), Wyandot (13), and unknown counties (1).

Human surveillance

• 519 Lyme disease cases: 193 females and 325 males, median age 26 years, from 53 counties – Allen (2), Ashland (4), Ashtabula (1), Athens (2), Belmont (46), Brown (2), Butler (3), Carroll (11), Champaign (1), Clark (1), Clermont (15), Columbiana (23), Coshocton (14), Cuyahoga (28), Delaware (3), Fairfield (20), Franklin (36), Gallia (6), Geauga (6), Guernsey (4), Hamilton (19), Hancock (1), Harrison (8), Highland (1), Holmes (34), Jackson (13), Jefferson (10), Knox (10), Lake (5), Licking (9), Lucas (1), Madison (1), Mahoning (8), Marion (2), Medina (6), Monroe (1), Morgan (2), Morrow (1), Muskingum (18), Noble (2), Pickaway (1), Pike (1), Portage (9), Richland (11), Ross (17), Scioto (3), Stark (27), Summit (16), Trumbull (18), Tuscarawas (28), Warren (4), Washington (1), and Wayne (3).
• 11 anaplasmosis cases: 4 females and 7 males, median age 64 years, from 7 counties – Columbiana (1), Franklin (3), Gallia (1), Greene (1), Jackson (2), Stark (1), and Warren (2).
• 4 babesiosis cases: 2 females and 2 males, median age 52 years, from 4 counties – Athens (1), Hamilton (1), Montgomery (1), and Stark (1).

Rocky Mountain spotted fever

Tick surveillance

• 1,158 American dog ticks, Dermacentor variabilis, identified.

Human surveillance

• 40 Rocky Mountain spotted fever cases: 19 females and 21 males, median age 44 years, from 15 counties – Athens (2), Butler (1), Clermont (1), Cuyahoga (1), Delaware (1), Gallia (5), Hamilton (1), Jackson (18), Lucas (1), Meigs (2), Montgomery (1), Muskingum (1), Pike (2), Ross (1), Stark (1), and Warren (1).

Ehrlichiosis

Tick surveillance

• 300 Lone star ticks, Amblyomma americanum, identified.

Human surveillance

• 15 ehrlichiosis cases: 6 females and 9 males, median age 53 years, from 12 counties – Athens (2), Butler (1), Fairfield (1), Gallia (3), Hamilton (1), Hocking (1), Madison (1), Meigs (1), Portage (1), Preble (1), Ross (1), and Stark (1).

2021 Numbers-At-A-Glance

As of December 7, 2021

2021 Mosquito-borne diseases

West Nile virus

Mosquito surveillance

• 544,582 Culex spp. from 60 agencies in 49 counties pooled into 15,561 samples.
• 1,286 West Nile virus positive mosquito samples.

Human surveillance

• 13 West Nile virus cases: 7 females and 6 males, median age 68 years, from 12 counties – Clark (2), Cuyahoga (1), Fulton (1), Hardin (1), Jefferson (1), Lucas (1), Mahoning (1), Mercer (1), Montgomery (1), Richland (1), Summit (1), and Wood (1).
• 1 West Nile virus asymptomatic viremic blood donor.
• 0 West Nile virus asymptomatic viremic organ donors.

Veterinary surveillance

• 1 West Nile virus equine case.
• Reported by the Ohio Department of Agriculture Animal Disease Diagnostic Laboratory.

La Crosse/Unspecified California encephalitis virus

Human surveillance

• 17 La Crosse virus cases: 5 females and 12 males, median age 6 years, from 12 counties – Franklin (1), Geauga (1), Holmes (1), Knox (4), Marion (1), Morrow (2), Preble (1), Stark (1), Summit (1), Trumbull (1), Tuscarawas (1), and Wayne (2).
• 1 unspecified California virus case: 1 male, aged 9 years.

Travel-associated mosquito-borne diseases

Human surveillance

• 0 chikungunya virus cases.
• 3 dengue cases: 2 females and 1 male, median age 33 years, traveled to – Ecuador (1), India (1), and Mexico (1).
• 0 Zika virus cases.
• 62 malaria cases: 25 females and 37 males, median age 33 years, traveled to – Cameroon (6), Chad (1), Cote d'Ivoire (2), Gambia (1), Ghana (4), Guinea (8), Kenya (4), Liberia (2), Mali (1), Nigeria (4), Senegal (2), Sierra Leone (10), Sudan (2), Togo (1), Uganda (1), and unknown countries (13).

* Ohioans traveling to areas where local transmission is occurring should be aware of the ongoing situation and make every effort to avoid mosquito bites.  Additional information can be found from the Centers for Disease Control and Prevention (CDC)'s Travelers' Health and Pan-American Health Organization websites.

2021 Tickborne diseases

Lyme disease, anaplasmosis, babesiosis

Tick surveillance

• 659 blacklegged ticks, Ixodes scapularis, submitted from 50 counties – Ashland (62), Ashtabula (9), Athens (37), Belmont (1), Butler (1), Champaign (1), Clark (2), Clermont (1), Clinton (1), Columbiana (7), Coshocton (214), Cuyahoga (3), Delaware (7), Erie (19), Fairfield (8), Fayette (9), Franklin (7), Gallia (1), Geauga (3), Greene (2), Guernsey (2), Hamilton (3), Highland (8), Hocking (7), Jackson (1), Jefferson (1), Knox (56), Lake (4), Lawrence (1), Licking (30), Lorain (4), Lucas (1), Madison (9), Medina (4), Meigs (2), Mercer (2), Monroe (13), Morrow (8), Muskingum (1), Ottawa (1), Portage (6), Richland (63), Ross (2), Stark (8), Summit (9), Trumbull (5), Tuscarawas (2), Vinton (1), Warren (4), and Wayne (6).

Human surveillance

• 542 Lyme disease cases: 215 females and 327 males, median age 40 years, from 59 counties – Allen (1), Ashland (1), Ashtabula (1), Belmont (42), Carroll (6), Clark (3), Clermont (8), Columbiana (8), Coshocton (19), Cuyahoga (27), Delaware (9), Erie (3), Fairfield (6), Franklin (23), Gallia (2), Geauga (4), Guernsey (3), Hamilton (8), Hardin (1), Harrison (23), Henry (1), Hocking (4), Holmes (10), Jackson (11), Jefferson (32), Knox (23), Lake (3), Lawrence (1), Licking (27), Logan (1), Lorain (1), Lucas (2), Madison (1), Mahoning (10), Mercer (3), Monroe (3), Montgomery (8), Morrow (1), Muskingum (16), Noble (10), Ottawa (2), Paulding (1),  Perry (1), Pickaway (1), Pike (2), Portage (15), Richland (9), Ross (6), Sandusky (1), Scioto (1), Seneca (2), Stark (42), Summit (28), Trumbull (16), Tuscarawas (38), Union (1), Warren (3), Wayne (5), and Wood (2).
• 2 anaplasmosis cases: 0 females and 2 males, median age 57 years, from 2 counties – Delaware (1) and Henry (1).
• 3 babesiosis cases: 3 females and 0 males, median age 63 years, from 3 counties – Cuyahoga (1), Medina (1), and Scioto (1).

Rocky Mountain spotted fever

Tick surveillance

• 1,400 American dog ticks, Dermacentor variabilis, submitted.

Human surveillance

• 29 Rocky Mountain spotted fever cases: 9 females and 20 males, median age 50 years, from 14 counties – Athens (1), Cuyahoga (1), Erie (1), Franklin (1), Gallia (2), Hamilton (2), Jackson (13), Knox (1), Meigs (1), Montgomery (2), Pike (1), Vinton (1), Warren (1), and Wayne (1).

Ehrlichiosis

Tick surveillance

• 564 Lone star ticks, Amblyomma americanum, submitted.

Human surveillance

• 8 ehrlichiosis cases: 5 females and 3 males, median age 54 years, from 7 counties – Athens (1), Butler (1), Clermont (1), Franklin (1), Gallia (1), Hamilton (1), and Jackson (2).