At a glance
Babesiosis is a disease caused by microscopic parasites that infect red blood cells. Many different species (types) of Babesia parasites have been found in animals, only a few of which have been found in people. Babesia microti—which usually infects white-footed mice and other small mammals—is the main species that has been found in people in the United States. Occasional cases caused by other Babesia species have been detected.
Annual Summaries
- Surveillance for Babesiosis – United States, 2020 (February 6, 2023)
- Surveillance for Babesiosis – United States, 2019 (August 12, 2021)
- Surveillance for Babesiosis – United States, 2018 (April 22, 2019)
- Surveillance for Babesiosis – United States, 2017 (June 27, 2019)
- Surveillance for Babesiosis – United States, 2016 (June 27, 2019)
- Surveillance for Babesiosis – United States, 2015 (June 27, 2019)
- Surveillance for Babesiosis – United States, 2014 (February 29, 2016)
Number and incidence of reported cases of Babesiosis
Number and incidence of reported cases of babesiosis, by state and year, 2014–2020*
|
2014 |
2015 |
2016 |
2017 |
2018 |
2019 |
2020 |
||||||||
| State† |
No. |
Rate |
No. |
Rate |
No. |
Rate |
No. |
Rate |
No. |
Rate |
No. |
Rate |
No. |
Rate |
| Alabama |
1 |
<0.1 |
2 |
<0.1 |
0 |
0.0 |
1 |
<0.1 |
0 |
0 |
0 |
0 |
0 |
0 |
| Alaska§ |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
| Arizona |
— |
— |
— |
— |
— |
— |
— |
— |
0 |
0 |
0 |
0 |
0 |
0 |
| Arkansas |
— |
— |
0 |
0.0 |
1 |
<0.1 |
0 |
0.0 |
2 |
<0.1 |
1 |
<0.1 |
0 |
0 |
| California |
3 |
<0.1 |
5 |
<0.1 |
3 |
<0.1 |
4 |
<0.1 |
6 |
<0.1 |
2 |
<0.1 |
1 |
<0.1 |
| Colorado§ |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
| Connecticut |
205 |
5.7 |
328 |
9.1 |
322 |
9.0 |
309 |
8.6 |
248 |
6.9 |
323 |
9.0 |
151 |
4.2 |
| Delaware |
1 |
0.1 |
1 |
0.1 |
2 |
0.2 |
4 |
0.4 |
3 |
0.3 |
3 |
0.3 |
4.0 |
0.4 |
| District of Columbia |
— |
— |
— |
— |
— |
— |
— |
— |
2 |
0.3 |
0 |
0.0 |
0 |
0 |
| Florida |
— |
— |
— |
— |
— |
— |
9 |
<0.1 |
19 |
<0.1 |
24 |
<0.1 |
2 |
<0.1 |
| Georgia |
— |
— |
— |
— |
— |
— |
— |
— |
0 |
0 |
1 |
<0.1 |
0 |
0 |
| Hawaii§ |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
| Idaho§ |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
| Illinois |
1 |
<0.1 |
3 |
<0.1 |
2 |
<0.1 |
0 |
0.0 |
1 |
<0.1 |
1 |
<0.1 |
5 |
<0.1 |
| Indiana |
0 |
0.0 |
0 |
0.0 |
0 |
0.0 |
1 |
<0.1 |
1 |
<0.1 |
0 |
0.00 |
1 |
<0.1 |
| Iowa |
— |
— |
— |
— |
— |
— |
2 |
0.1 |
0 |
0 |
0 | 0 |
1 |
<0.1 |
| Kansas |
— |
— |
— |
— |
— |
— |
— |
— |
0 |
0 |
0 |
0 |
0 |
0 |
| Kentucky |
— |
— |
0 |
0.0 |
0 |
0.0 |
0 |
0.0 |
0 |
0 |
0 |
0 |
0 |
0 |
| Louisiana |
0 |
0.0 |
1 |
<0.1 |
0 |
0.0 |
1 |
<0.1 |
1 |
<0.1 |
0 |
0 |
0 |
<0.1 |
| Maine |
42 |
3.2 |
55 |
4.1 |
82 |
6.2 |
118 |
8.8 |
101 |
7.5 |
138 |
10.3 |
66 |
4.8 |
| Maryland |
2 |
<0.1 |
4 |
0.1 |
6 |
0.1 |
5 |
<0.1 |
7 |
0.1 |
7 |
0.1 |
9 |
<0.1 |
| Massachusetts |
535 |
7.9 |
444 |
6. |
517 |
7.6 |
591 |
8.6 |
527 |
7.6 |
636 |
9.2 |
580 |
8.3 |
| Michigan |
2 |
<0.1 |
3 |
<0.1 |
2 |
<0.1 |
3 |
<0.1 |
1 |
<0.1 |
1 |
<0.1 |
0 |
0 |
| Minnesota |
49 |
0.9 |
45 |
0.8 |
50 |
0.9 |
60 |
1.1 |
49 |
0.9 |
55 |
1.0 |
— |
— |
| Mississippi§ |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
| Missouri |
— |
— |
— |
— |
1 |
<0.1 |
0 |
0.0 |
0 |
0 |
1 |
<0.1 |
0 |
0 |
| Montana |
0 |
0.0 |
0 |
0.0 |
1 |
0.1 |
0 |
0.0 |
0 |
0 |
0 |
0 |
0 |
0 |
| Nebraska |
0 |
0.0 |
0 |
0.0 |
1 |
0.1 |
0 |
0.0 |
0 |
0 |
0 |
0 |
0 |
0 |
| Nevada§ |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
| New Hampshire§ |
42 |
3.2 |
53 |
4.0 |
13 |
1.0 |
78 |
5.8 |
37 |
2.7 |
63 |
4.6 |
28 |
2.0 |
| New Jersey |
159 |
1.8 |
281 |
3.1 |
174 |
1.9 |
193 |
2.1 |
247 |
2.8 |
236 |
2.6 |
237 |
2.6 |
| New Mexico§ |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
| New York |
471 |
2.4 |
581 |
2.9 |
430 |
2.2 |
696 |
3.5 |
641 |
3.3 |
663 |
3.4 |
461 |
2.3 |
| North Carolina§ |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
| North Dakota |
0 |
0.0 |
3 |
0.4 |
1 |
0.1 |
0 |
0.0 |
1 |
0.1 |
0 |
0.0 |
0 |
0.0 |
| Ohio |
1 |
<0.1 |
2 |
<0.1 |
— |
— |
1 |
<0.1 |
4 |
<0.1 |
4 |
<0.1 |
1 |
<0.1 |
| Oklahoma§ |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
| Oregon |
1 |
<0.1 |
2 |
<0.1 |
2 |
<0.1 |
5 |
0.1 |
2 |
<0.1 |
2 |
<0.1 |
4 |
0.1 |
| Pennsylvania§ |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
— |
| Rhode Island |
172 |
16.3 |
190 |
18.0 |
155 |
14.7 |
161 |
15.2 |
165 |
15.6 |
158 |
14.9 |
193 |
17.6 |
| South Carolina |
3 |
0.1 |
2 |
<0.1 |
2 |
<0.1 |
2 |
<0.1 |
1 |
<0.1 |
0 |
0 |
0 |
0 |
| South Dakota |
1 |
0.1 |
0 |
0.0 |
0 |
0.0 |
0 |
0.0 |
0 |
0 |
0 |
0 |
1 |
<0.1 |
| Tennessee |
0 |
0.0 |
1 |
<0.1 |
1 |
<0.1 |
1 |
<0.1 |
1 |
<0.1 |
1 |
<0.1 |
1 |
<0.1 |
| Texas |
1 |
<0.1 |
1 |
<0.1 |
1 |
<0.1 |
0 |
0.0 |
2 |
<0.1 |
2 |
<0.1 |
3 |
<0.1 |
| Utah |
0 |
0.0 |
0 |
0.0 |
0 |
0.0 |
1 |
<0.1 |
1 |
<0.1 |
0 |
0 |
0 |
0 |
| Vermont |
3 |
0.5 |
9 |
1.4 |
15 |
2.4 |
22 |
3.5 |
21 |
3.4 |
34 |
5.4 |
16 |
2.5 |
| Virginia |
— |
— |
— |
— |
— |
— |
0 |
0.0 |
5 |
<0.1 |
1 |
<0.1 |
3 |
<0.1 |
| Washington |
4 |
0.1 |
2 |
<0.1 |
0 |
0.0 |
1 |
<0.1 |
0 |
0 |
1 |
<0.1 |
0 |
0 |
| West Virginia |
0 |
0.0 |
0 |
0.0 |
0 |
0.0 |
1 |
0.1 |
1 |
<0.1 |
0 |
<0.1 |
0 |
0 |
| Wisconsin |
43 |
0.7 |
56 |
1.0 |
68 |
1.2 |
88 |
1.5 |
64 |
1.1 |
58 |
1.0 |
57 |
1.0 |
| Wyoming |
0 |
0.0 |
0 |
0.0 |
0 |
0.0 |
0 |
0.0 |
0 |
0 |
0 |
0 |
1 |
<0.1 |
| Total¶# |
1,742 |
0.8 |
2,074 |
0.9 |
1,909 |
0.8 |
2,358 |
0.9 |
2,161 |
0.77 |
2,418 |
0.86 |
1,827 |
0.65 |