Surveillance Report 2020-2021

What to know

This page features accessible versions of tables in the 2020-2021 Legionnaires’ Disease Surveillance Summary Report.

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Tables and figures

Section 1: National Notifiable Diseases Surveillance System (NNDSS)

Figure 1. Crude incidence rates of reported confirmed cases of Legionnaires’ disease by year—NNDSS, United States, 2000–2021
Figure 2. Number of reported confirmed cases of Legionnaires’ disease by month and year—NNDSS, United States, 2020 and 2021
Figure 3a. Crude incidence rates of reported confirmed cases of Legionnaires’ disease by jurisdiction of residence—NNDSS, United States, 2020
Figure 3b. Crude incidence rates of reported confirmed cases of Legionnaires’ disease by jurisdiction of residence—NNDSS, United States, 2021
Table 1. Number of reported confirmed cases of Legionnaires’ disease by jurisdiction of residence and year—NNDSS, United States, 2020 and 2021
Table 2. Number, percent, and crude incidence rates of reported confirmed cases of Legionnaires’ disease by demographic characteristics and year—NNDSS, United States, 2020 and 2021

 

Section 2: National Notifiable Diseases Surveillance System comparison with Supplemental Legionnaires’ Disease Surveillance System (SLDSS)

Figure 4a. Percent of reported confirmed cases of Legionnaires’ disease by age group and year—NNDSS and SLDSS, United States, 2020 and 2021
Figure 4b. Percent of reported confirmed cases of Legionnaires’ disease by sex and year—NNDSS and SLDSS, 2020 and 2021
Figure 4c. Percent of reported confirmed cases of Legionnaires’ disease by race and year—NNDSS and SLDSS, United States, 2020 and 2021
Figure 4d. Percent of reported confirmed cases of Legionnaires’ disease by ethnicity and year—NNDSS and SLDSS, United States, 2020 and 2021

 

Section 3: Supplemental Legionnaires’ Disease Surveillance System

Figure 5a. Reported confirmed cases of legionellosis by syndrome and completeness of jurisdictional reporting—SLDSS, United States, 2020
Figure 5b. Reported confirmed cases of legionellosis by syndrome and completeness of jurisdictional reporting—SLDSS, United States, 2021
Figure 6a. Number of reported confirmed cases of Legionnaires’ disease by exposure category—SLDSS, complete reporting jurisdictions, 2020
Figure 6b. Number of reported confirmed cases of Legionnaires’ disease by exposure category—SLDSS, complete reporting jurisdictions, 2021
Table 3. Number of reported confirmed cases of Legionnaires’ disease by exposure category and year— SLDSS, complete reporting jurisdictions, 2020 and 2021
Table 4a. Number of reported confirmed cases of Legionnaires’ disease by demographic characteristics and exposure category—SLDSS, complete reporting jurisdictions, 2020
Table 4b. Number of reported confirmed cases of Legionnaires’ disease by demographic characteristics and exposure category—SLDSS, complete reporting jurisdictions, 2021
Table 5a. Number of reported confirmed cases of healthcare-associated Legionnaires’ disease by healthcare facility type and healthcare exposure certainty—SLDSS, complete reporting jurisdictions, 2020
Table 5b. Number of reported confirmed cases of healthcare-associated Legionnaires’ disease by healthcare facility type and healthcare exposure certainty—SLDSS, complete reporting jurisdictions, 2021
Table 6. Number of reported confirmed cases of Legionnaires’ disease by hospitalization and exposure category—SLDSS, complete reporting jurisdictions, 2020 and 2021
Table 7. Number of reported confirmed cases of Legionnaires’ disease by outcome and exposure category—SLDSS, complete reporting jurisdictions, 2020 and 2021
Figure 7. Percent of reported confirmed cases of Legionnaires’ disease that were treated in hospital by age group and year—SLDSS, complete reporting jurisdictions, 2020 and 2021
Figure 8. Percent of reported confirmed cases of Legionnaires’ disease resulting in death by age group and year—SLDSS, complete reporting jurisdictions, 2020 and 2021
Table 8. Number of reported confirmed cases of Legionnaires’ disease by diagnostic testing method and year—SLDSS, United States, 2020 and 2021

Figure 1. Crude incidencea rates of reported confirmed cases of Legionnaires’ diseaseb by yearc—
NNDSS,d,e United States, 2000–2021.

Figure 1. Crude incidence rates of reported confirmed cases of Legionnaires’ disease by year—NNDSS, United States, 2000–2021
aCrude incidence of cases per 100,000 population (number of confirmed Legionnaires' disease cases reported that year divided by postcensal population estimate for that year times 100,000 population).
bCases of disease due to Legionella are reported to NNDSS as legionellosis, which includes Legionnaires’ disease, Pontiac fever, and extrapulmonary legionellosis, but are referred to as Legionnaires’ disease in this figure (because almost all legionellosis cases reported in the United States are Legionnaires’ disease cases).
cBased on year the case was reported to CDC.
dNational Notifiable Diseases Surveillance System (NNDSS).
eJurisdictions may report cases of any case status to NNDSS but only confirmed cases of Legionnaires’ disease from the 50 U.S. states, the District of Columbia, and New York City are included in this figure, with the exceptions noted below. National case counts published in the MMWR use the same criteria and exceptions.
2000, 2002, and 2003: Legionnaires’ disease cases with probable, suspect, and unknown case status were also included.
2001: Legionnaires’ disease cases with probable and unknown case status were also included.
2000–2001: Legionnaires’ disease cases were not reportable in Oregon and West Virginia.
2004–2012: Legionnaires’ disease cases with unknown case status reported from California were also included.
2011–2012: Legionnaires’ disease cases were not reportable in the District of Columbia.

Figure 2. Number of reported confirmed cases of Legionnaires’ diseasea by monthb and yearc—NNDSS,d United States, 2020 and 2021.

Figure 2. Number of reported confirmed cases of Legionnaires’ disease by month and year—NNDSS, United States, 2020 and 2021
aCases of disease due to Legionella are reported to NNDSS as legionellosis, which includes Legionnaires’ disease, Pontiac fever, and extrapulmonary legionellosis, but are referred to as Legionnaires’ disease in this figure (because almost all legionellosis cases reported in the United States are Legionnaires’ disease cases).
bMonth is based upon Morbidity and Mortality Weekly Report year and week (available at https://ndc.services.cdc.gov/wp-content/uploads/2021/02/MMWR_Week_overview.pdf).
cBased on year the case was reported to CDC.
dNational Notifiable Diseases Surveillance System (NNDSS).

Figure 3a. Crude incidencea rates of reported confirmed cases of Legionnaires’ diseaseb by jurisdiction of residencec—NNDSS,d United States, 2020.e,f

Figure 3a. Crude incidence rates of reported confirmed cases of Legionnaires’ disease by jurisdiction of residence—NNDSS, United States, 2020

State Crude incidence rates
Alabama 1.21
Alaska 0.27
Arizona 1.25
Arkansas 1.29
California 0.96
Colorado 1.30
Connecticut 2.29
Delaware 1.41
District of Columbia 1.04
Florida 1.98
Georgia 1.35
Hawaii 0.96
Idaho 0.92
Illinois 2.57
Indiana 2.28
Iowa 1.07
Kansas 1.70
Kentucky 1.64
Louisiana 1.12
Maine 0.81
Maryland 2.95
Massachusetts 1.99
Michigan 3.75
Minnesota 1.65
Mississippi 1.12
Missouri 1.75
Montana 0.64
Nebraska 0.81
Nevada 0.83
New Hampshire 2.32
New Jersey 2.60
New Mexico 0.85
New York 3.25
New York City 3.71
North Carolina 1.24
North Dakota 0.77
Ohio 4.55
Oklahoma 0.66
Oregon 1.22
Pennsylvania 2.70
Rhode Island 3.28
South Carolina 1.11
South Dakota 1.13
Tennessee 2.22
Texas 1.08
Utah 0.97
Vermont 1.24
Virginia 2.37
Washington 0.88
West Virginia 2.74
Wisconsin 4.09
Wyoming 0.87

aCrude incidence of cases per 100,000 population (number of confirmed Legionnaires' disease cases reported that year divided by postcensal resident jurisdiction population estimate for that year times 100,000 population).

bCases of disease due to Legionella are reported to NNDSS as legionellosis, which includes Legionnaires’ disease, Pontiac fever, and extrapulmonary legionellosis, but are referred to as Legionnaires’ disease in this figure (because almost all legionellosis cases reported in the United States are Legionnaires’ disease cases).
cJurisdiction of the patient’s “usual residence” at the time of disease onset.
dNational Notifiable Diseases Surveillance System (NNDSS).
eBased on year the case was reported to CDC.
fShading represents quintiles of incidence rates.

Figure 3b. Crude incidencea rates of reported confirmed cases of Legionnaires’ diseaseb by jurisdiction of residencec—NNDSS,d United States, 2021.e,f

Figure 3b. Crude incidence rates of reported confirmed cases of Legionnaires’ disease by jurisdiction of residence—NNDSS, United States, 2021

State Crude incidence rates
Alabama 1.80
Alaska 0.41
Arizona 1.54
Arkansas 1.49
California 1.18
Colorado 1.86
Connecticut 3.27
Delaware 2.39
District of Columbia 0.45
Florida 2.30
Georgia 1.36
Hawaii 0.90
Idaho 1.05
Illinois 4.12
Indiana 4.04
Iowa 1.38
Kansas 1.60
Kentucky 2.57
Louisiana 1.53
Maine 2.83
Maryland 3.45
Massachusetts 4.06
Michigan 5.75
Minnesota 2.27
Mississippi 1.22
Missouri 2.71
Montana 1.36
Nebraska 2.24
Nevada 0.79
New Hampshire 4.18
New Jersey 2.65
New Mexico 1.04
New York 5.39
New York City 4.29
North Carolina 1.55
North Dakota 0.64
Ohio 7.34
Oklahoma 0.80
Oregon 1.53
Pennsylvania 3.49
Rhode Island 7.93
South Carolina 1.68
South Dakota 2.34
Tennessee 2.34
Texas 1.19
Utah 1.17
Vermont 2.01
Virginia 1.88
Washington 1.10
West Virginia 3.36
Wisconsin 3.83
Wyoming 1.21
aCrude incidence of cases per 100,000 population (number of confirmed Legionnaires' disease cases reported that year divided by postcensal resident jurisdiction population estimate for that year times 100,000 population).
bCases of disease due to Legionella are reported to NNDSS as legionellosis, which includes Legionnaires’ disease, Pontiac fever, and extrapulmonary legionellosis, but are referred to as Legionnaires’ disease in this figure (because almost all legionellosis cases reported in the United States are Legionnaires’ disease cases).
cJurisdiction of the patient’s “usual residence” at the time of disease onset.
dNational Notifiable Diseases Surveillance System (NNDSS).
eBased on year the case was reported to CDC.
fShading represents quintiles of incidence rates.

Table 1. Number of reported confirmed cases of Legionnaires’ diseasea by jurisdiction of residenceb and yearc—NNDSS,d United States, 2020 and 2021.

2020
(Total=6,310)		 2021
(Total=8,442)
Jurisdiction N % N %
ALABAMA 61 1.0 91 1.1
ALASKA 2 0.0 3 0.0
ARIZONA 90 1.4 112 1.3
ARKANSAS 39 0.6 45 0.5
CALIFORNIA 380 6.0 460 5.5
COLORADO 75 1.2 108 1.3
CONNECTICUT 82 1.3 118 1.4
DELAWARE 14 0.2 24 0.3
DISTRICT OF COLUMBIA 7 0.1 3 0.0
FLORIDA 428 6.8 502 6.0
GEORGIA 145 2.3 147 1.7
HAWAII 14 0.2 13 0.2
IDAHO 17 0.3 20 0.2
ILLINOIS 329 5.2 523 6.2
INDIANA 155 2.5 275 3.3
IOWA 34 0.5 44 0.5
KANSAS 50 0.8 47 0.6
KENTUCKY 74 1.2 116 1.4
LOUISIANA 52 0.8 71 0.8
MAINE 11 0.2 39 0.5
MARYLAND 182 2.9 213 2.5
MASSACHUSETTS 139 2.2 284 3.4
MICHIGAN 378 6.0 577 6.8
MINNESOTA 94 1.5 130 1.5
MISSISSIPPI 33 0.5 36 0.4
MISSOURI 108 1.7 167 2.0
MONTANA 7 0.1 15 0.2
NEBRASKA 16 0.3 44 0.5
NEVADA 26 0.4 25 0.3
NEW HAMPSHIRE 32 0.5 58 0.7
NEW JERSEY 241 3.8 246 2.9
NEW MEXICO 18 0.3 22 0.3
NEW YORK 369 5.9 614 7.3
NEW YORK CITY 324 5.1 363 4.3
NORTH CAROLINA 130 2.1 164 1.9
NORTH DAKOTA 6 0.1 5 0.1
OHIO 537 8.5 864 10.2
OKLAHOMA 26 0.4 32 0.4
OREGON 52 0.8 65 0.8
PENNSYLVANIA 351 5.6 454 5.4
RHODE ISLAND 36 0.6 87 1.0
SOUTH CAROLINA 57 0.9 87 1.0
SOUTH DAKOTA 10 0.2 21 0.3
TENNESSEE 154 2.4 163 1.9
TEXAS 317 5.0 353 4.2
UTAH 32 0.5 39 0.5
VERMONT 8 0.1 13 0.2
VIRGINIA 205 3.3 163 1.9
WASHINGTON 68 1.1 85 1.0
WEST VIRGINIA 49 0.8 60 0.7
WISCONSIN 241 3.8 225 2.7
WYOMING 5 0.1 7 0.1
Total 6,310 100.0 8,442 100.0
aCases of disease due to Legionella are reported to NNDSS as legionellosis, which includes Legionnaires’ disease, Pontiac fever, and extrapulmonary legionellosis, but are referred to as Legionnaires’ disease in this table (because almost all legionellosis cases reported in the United States are Legionnaires’ disease cases).
bJurisdiction of the patient’s “usual residence” at the time of disease onset.
cBased on year the case was reported to CDC.
dNational Notifiable Diseases Surveillance System (NNDSS).

Table 2. Number, percent, and crude incidencea rates of reported confirmed cases of Legionnaires’ diseaseb by demographic characteristics and yearc—NNDSS,d United States, 2020 and 2021.

Characteristic 2020 2021
N % Ratea N % Ratea
Age
0–9 12 0.2 0.03 9 0.1 0.02
10–19 6 0.1 0.01 16 0.2 0.04
20–29 110 1.7 0.25 131 1.6 0.30
30–39 362 5.7 0.80 460 5.5 1.01
40–49 746 11.8 1.82 955 11.3 2.34
50–59 1,363 21.6 3.18 1,814 21.5 4.27
60–69 1,614 25.6 4.14 2,377 28.2 6.00
70–79 1,300 20.6 5.36 1,675 19.8 6.66
80–84 378 6.0 6.14 491 5.8 7.78
85+ 417 6.6 6.88 509 6.0 8.43
Not stated 2 0.0 N/A 5 0.1 N/A
Sex
Female 2,326 36.9 1.39 3,090 36.6 1.84
Male 3,960 62.8 2.41 5,316 63.0 3.23
Not stated 24 0.4 N/A 36 0.4 N/A
Race
American Indian/Alaska Native 23 0.4 0.47 28 0.3 0.57
Asian/Pacific Islander 87 1.4 0.38 117 1.4 0.51
African American/Black 1,301 20.6 2.73 1,836 21.8 3.84
White 3,976 63.0 1.55 5,381 63.7 2.10
Othere 440 7.0 N/A 491 5.8 N/A
Not stated 483 7.7 N/A 589 7.0 N/A
Ethnicity
Hispanic 441 7.0 0.71 577 6.8 0.92
Non-Hispanic 4,590 72.7 1.70 6,509 77.1 2.42
Not stated 1,279 20.3 N/A 1,356 16.1 N/A
Total 6,310 100.0 1.90 8,442 100.0 2.54
aCrude incidence of cases per 100,000 population (number of confirmed Legionnaires' disease cases reported that year divided by postcensal population estimate for that year times 100,000 population)
bCases of disease due to Legionella are reported to NNDSS as legionellosis, which includes Legionnaires’ disease, Pontiac fever, and extrapulmonary legionellosis, but are referred to as Legionnaires’ disease in this table (because almost all legionellosis cases reported in the United States are Legionnaires’ disease cases).
cBased on year the case was reported to CDC.
dNational Notifiable Diseases Surveillance System (NNDSS).
eOther race includes individuals that did not identify with races listed.

Figure 4a. Percent of reported confirmed cases of Legionnaires’ diseasea by age group and yearb—NNDSSc and SLDSS,d United States, 2020 and 2021.

Figure 4a. Percent of reported confirmed cases of Legionnaires’ disease by age group and year—NNDSS and SLDSS, United States, 2020 and 2021
aCases of disease due to Legionella are reported to NNDSS as legionellosis, which includes Legionnaires’ disease, Pontiac fever, and extrapulmonary legionellosis, but are referred to as Legionnaires’ disease in this figure (because almost all legionellosis cases reported in the United States are Legionnaires’ disease cases). SLDSS data are limited to cases of Legionnaires’ disease in this figure.
bBased on year the case was reported to CDC in NNDSS and year of symptom onset in SLDSS. If onset date was not stated in SLDSS, case year for confirmed cases was determined by the earliest of the following dates: positive laboratory date; date patient was hospitalized during treatment for Legionnaires’ disease; or date case was first reported to public health at any level.
cNational Notifiable Diseases Surveillance System (NNDSS).
dSupplemental Legionnaires’ Disease Surveillance System (SLDSS).

Figure 4b. Percent of reported confirmed cases of Legionnaires’ diseasea by sex and yearb—NNDSSc and SLDSS,d United States, 2020 and 2021.

Figure 4b. Percent of reported confirmed cases of Legionnaires’ disease by sex and year—NNDSS and SLDSS, 2020 and 2021
aCases of disease due to Legionella are reported to NNDSS as legionellosis, which includes Legionnaires’ disease, Pontiac fever, and extrapulmonary legionellosis, but are referred to as Legionnaires’ disease in this figure (because almost all legionellosis cases reported in the United States are Legionnaires’ disease cases). SLDSS data are limited to cases of Legionnaires’ disease in this figure.
bBased on year the case was reported to CDC in NNDSS and year of symptom onset in SLDSS. If onset date was not stated in SLDSS, case year for confirmed cases was determined by the earliest of the following dates: positive laboratory date; date patient was hospitalized during treatment for Legionnaires’ disease; or date case was first reported to public health at any level.
cNational Notifiable Diseases Surveillance System (NNDSS).
dSupplemental Legionnaires’ Disease Surveillance System (SLDSS).

Figure 4c. Percent of reported confirmed cases of Legionnaires’ diseasea by raceb and yearc—NNDSSd and SLDSS,e United States, 2020 and 2021.

Figure 4c. Percent of reported confirmed cases of Legionnaires’ disease by race and year—NNDSS and SLDSS, United States, 2020 and 2021
aCases of disease due to Legionella are reported to NNDSS as legionellosis, which includes Legionnaires’ disease, Pontiac fever, and extrapulmonary legionellosis, but are referred to as Legionnaires’ disease in this figure (because almost all legionellosis cases reported in the United States are Legionnaires’ disease cases). SLDSS data are limited to cases of Legionnaires’ disease in this figure.
bIn NNDSS, Other includes American Indian/Alaska Native, Asian/Pacific Islander, and individuals that did not identify with either race in NNDSS. In SLDSS, Other includes American Indian/Alaska Native, Asian, Hawaii/Pacific Islander, and individuals that identified with multiple races.
cBased on year the case was reported to CDC in NNDSS and year of symptom onset in SLDSS. If onset date was not stated in SLDSS, case year for confirmed cases was determined by the earliest of the following dates: positive laboratory date; date patient was hospitalized during treatment for Legionnaires’ disease; or date case was first reported to public health at any level.
dNational Notifiable Diseases Surveillance System (NNDSS).
eSupplemental Legionnaires’ Disease Surveillance System (SLDSS).

Figure 4d. Percent of reported confirmed cases of Legionnaires’ diseasea by ethnicity and yearb—NNDSSc and SLDSS,d United States, 2020 and 2021.

Figure 4d. Percent of reported confirmed cases of Legionnaires’ disease by ethnicity and year—NNDSS and SLDSS, United States, 2020 and 2021
aCases of disease due to Legionella are reported to NNDSS as legionellosis, which includes Legionnaires’ disease, Pontiac fever, and extrapulmonary legionellosis, but are referred to as Legionnaires’ disease in this figure (because almost all legionellosis cases reported in the United States are Legionnaires’ disease cases). SLDSS data are limited to cases of Legionnaires’ disease in this figure.
bBased on year the case was reported to CDC in NNDSS and year of symptom onset in SLDSS. If onset date was not stated in SLDSS, case year for confirmed cases was determined by the earliest of the following dates: positive laboratory date; date patient was hospitalized during treatment for Legionnaires’ disease; or date case was first reported to public health at any level.
cNational Notifiable Diseases Surveillance System (NNDSS).
dSupplemental Legionnaires’ Disease Surveillance System (SLDSS).

Figure 5a. Reported confirmed cases of legionellosisa by syndrome and completeness of jurisdictional reportingb—SLDSS,c United States, 2020.d

Figure 5a. Reported confirmed cases of legionellosis by syndrome and completeness of jurisdictional reporting—SLDSS, United States, 2020
aLegionellosis includes Legionnaires’ disease, Pontiac fever, and extrapulmonary legionellosis.
b47 complete reporting jurisdictions in 2020: Alabama, Alaska, Arkansas, Arizona, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Iowa, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York (state), New York City, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.
cSupplemental Legionnaires’ Disease Surveillance System (SLDSS).
dBased on year of symptom onset in SLDSS. If onset date was not stated in SLDSS, case year for confirmed cases was determined by the earliest of the following dates: positive laboratory date; date patient was hospitalized during treatment for Legionnaires’ disease; or date case was first reported to public health at any level.
eLegionnaires’ disease.

fCFR: Case fatality rate calculated as the number of reported confirmed case deaths divided by the number of patients with a known outcome.

gPontiac fever.
hExtrapulmonary legionellosis.
iComplete reporting

Figure 5b. Reported confirmed cases of legionellosisa by syndrome and completeness of jurisdictional reportingb—SLDSS,c United States, 2021.d

Figure 5b. Reported confirmed cases of legionellosis by syndrome and completeness of jurisdictional reporting—SLDSS, United States, 2019
aLegionellosis includes Legionnaires’ disease, Pontiac fever, and extrapulmonary legionellosis.
b49 complete reporting jurisdictions in 2021: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York (state), New York City, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.
cSupplemental Legionnaires’ Disease Surveillance System (SLDSS).
dBased on year of symptom onset in SLDSS. If onset date was not stated in SLDSS, case year for confirmed cases was determined by the earliest of the following dates: positive laboratory date; date patient was hospitalized during treatment for Legionnaires’ disease; or date case was first reported to public health at any level.
eLegionnaires’ disease.
fCFR: Case fatality rate calculated as the number of reported confirmed case deaths divided by the number of patients with a known outcome.
gPontiac fever.
hExtrapulmonary legionellosis.
iComplete reporting.

Figure 6a. Number of reported confirmed cases of Legionnaires’ disease by exposure categorya—SLDSS,b complete reporting jurisdictions,c 2020.d

Figure 6a. Number of reported confirmed cases of Legionnaires’ disease by exposure category—SLDSS, complete reporting jurisdictions, 2020
Cases
(Total = 6,014)
Exposure category N %
Any Healthcare 857 14.3
Presumptive 178 3.0
Possible 679 11.3
Any Travel 585 9.7
Any Assisted or senior living 148 2.5
None of these 4,553 75.7

aExposure categories are not mutually exclusive. A patient may report multiple exposures in the 14 days before date of symptom onset. Exposure categories:

Healthcare: A patient who visited, worked in, or stayed in a healthcare setting in the 14 days before date of symptom onset.
Travel: A patient with a history of spending at least one night away from home in the 14 days before date of symptom onset, not including nights spent in a healthcare facility.
Assisted or senior living facility: A patient who visited, worked in, or stayed in a senior or assisted living facility in the 14 days before date of symptom onset.
None of these: A patient without reported healthcare setting, travel, or senior or assisted living facility exposure in the 14 days before date of symptom onset.

bSupplemental Legionnaires’ Disease Surveillance System (SLDSS).

c47 Complete reporting jurisdictions in 2020: Alabama, Alaska, Arkansas, Arizona, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Iowa, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York (state), New York City, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.
dBased on year of symptom onset in SLDSS. If onset date was not stated in SLDSS, case year for confirmed cases was determined by the earliest of the following dates: positive laboratory date; date patient was hospitalized during treatment for Legionnaires’ disease; or date case was first reported to public health at any level.

Figure 6b. Number of reported confirmed cases of Legionnaires’ disease by exposure categorya—SLDSS,b complete reporting jurisdictions,c 2021.d

Figure 6b. Number of reported confirmed cases of Legionnaires’ disease by exposure category—SLDSS, complete reporting jurisdictions, 2021
Cases
(Total = 7,837)
Exposure category N %
Any Healthcare 1,198 15.3
Presumptive 159 2.0
Possible 1,039 13.3
Any Travel 1,227 15.7
Any Assisted or senior living 146 1.9
None of these 5,503 70.2

aExposure categories are not mutually exclusive. A patient may report multiple exposures in the 14 days before date of symptom onset. Exposure categories:

Healthcare: A patient who visited, worked in, or stayed in a healthcare setting in the 14 days before date of symptom onset.
Travel: A patient with a history of spending at least one night away from home in the 14 days before date of symptom onset, not including nights spent in a healthcare facility.
Assisted or senior living facility: A patient who visited, worked in, or stayed in a senior or assisted living facility in the 14 days before date of symptom onset.
None of these: A patient without reported healthcare setting, travel, or senior or assisted living facility exposure in the 14 days before date of symptom onset.

bSupplemental Legionnaires’ Disease Surveillance System (SLDSS).

c49 Complete reporting jurisdictions in 2021: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York (state), New York City, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.
dBased on year of symptom onset in SLDSS. If onset date was not stated in SLDSS, case year for confirmed cases was determined by the earliest of the following dates: positive laboratory date; date patient was hospitalized during treatment for Legionnaires’ disease; or date case was first reported to public health at any leve.

Table 3. Number of reported confirmed cases of Legionnaires’ disease by exposure categorya and yearb—SLDSS,c complete reporting jurisdictions,d 2020 and 2021.

2020
(Total = 6,014)		 2021
(Total = 7,837)
Exposure category N % N %
Healthcare 857 14.3 1,198 15.3
Healthcare facility type
Hospital 304 35.5 410 34.2
Long-term care facility 178 20.8 174 14.5
Clinic 226 26.4 393 32.8
Multiple 84 9.8 103 8.6
Other 32 3.7 65 5.4
Not stated 33 3.9 53 4.4
Healthcare exposure type
Inpatient 331 38.6 317 26.5
Outpatient 322 37.6 583 48.7
Visitor 37 4.3 67 5.6
Employee 60 7.0 91 7.6
Multiple 46 5.4 63 5.3
Not stated 61 7.1 77 6.4
Travel 585 9.7 1,227 15.7
Any public accommodation 370 63.2 728 59.3
Hotel/motel/resort 369 N/A 724 N/A
Cruise ship 4 N/A 6 N/A
All private accommodations 165 28.2 287 23.4
Unknown travel accommodation type 50 8.5 212 17.3
Assisted or senior living 148 2.5 146 1.9
Assisted or senior living facility type
Assisted living facility 75 50.7 71 48.6
Senior living facility 54 36.5 56 38.4
Both 3 2.0 3 2.1
Not stated 16 10.8 16 11.0
Assisted or senior living exposure type
Resident 107 72.3 106 72.6
Visitor 14 9.5 11 7.5
Employee 13 8.8 13 8.9
Multiple 1 0.7 1 0.7
Not stated 13 8.8 15 10.3
None of these 4,553 75.7 5,503 70.2
aExposure categories (categories are not mutually exclusive):
Healthcare: A patient who visited, worked in, or stayed in a healthcare setting in the 14 days before date of symptom onset.
Travel: A patient with a history of spending at least one night away from home in the 14 days before date of symptom onset, not including nights spent in a healthcare facility. Cases may occur in patients with multiple travel locations during the exposure period. If any exposure to a public accommodation occurs, the case is categorized as public travel. Private travel represents exposure to private accommodations only. If a patient has exposure to both private and unknown accommodations, the case is categorized as unknown travel.
Assisted or senior living: A patient who visited, worked in, or stayed in a senior or assisted living facility in the 14 days before date of symptom onset.
None of these: A patient without reported healthcare setting, travel, or senior or assisted living facility exposure in the 14 days before date of symptom onset.
bBased on year of symptom onset in SLDSS. If onset date was not stated in SLDSS, case year for confirmed cases was determined by the earliest of the following dates: positive laboratory date; date patient was hospitalized during treatment for Legionnaires’ disease; or date case was first reported to public health at any level.
cSupplemental Legionnaires’ Disease Surveillance System (SLDSS).
d47 complete reporting jurisdictions in 2020: Alabama, Alaska, Arkansas, Arizona, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Iowa, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York (state), New York City, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.
49 complete reporting jurisdictions in 2021: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York (state), New York City, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.

Table 4a. Number of reported confirmed cases of Legionnaires’ disease by demographic characteristics and exposure categorya—SLDSS,b complete reporting jurisdictions,c 2020.d

Exposure category
Healthcare
(Total = 857)		 Travel
(Total = 585)		 Assisted or senior living
(Total = 148)		 None of these
(Total = 4,553)
Characteristic N % N % N % N %
Median Age (years) 67 N/A 60 N/A 75 N/A 62 N/A
Age
0–9 3 0.4 1 0.2 0 0.0 1 0.0
10–19 4 0.5 2 0.3 0 0.0 1 0.0
20–29 14 1.6 13 2.2 2 1.4 80 1.8
30–39 40 4.7 32 5.5 6 4.1 273 6.0
40–49 71 8.3 91 15.6 6 4.1 559 12.3
50–59 128 14.9 148 25.3 13 8.8 1,032 22.7
60–69 209 24.4 145 24.8 26 17.6 1,176 25.8
70–79 200 23.3 117 20.0 36 24.3 914 20.1
80–84 95 11.1 23 3.9 19 12.8 252 5.5
85+ 93 10.9 12 2.1 40 27.0 264 5.8
Not stated 0 0.0 1 0.2 0 0.0 1 0.0
Sex
Female 387 45.2 218 37.3 85 57.4 1,592 35.0
Male 466 54.4 362 61.9 63 42.6 2,942 64.6
Not stated 4 0.5 5 0.9 0 0.0 19 0.4
Race
American Indian/Alaska Native 3 0.4 1 0.2 0 0.0 16 0.4
Asian 12 1.4 3 0.5 0 0.0 53 1.2
Black or African American 159 18.6 95 16.2 24 16.2 955 21.0
Native Hawaiian/Other Pacific Islander 1 0.1 1 0.2 1 0.7 9 0.2
White 581 67.8 404 69.1 107 72.3 2,940 64.6
Multiple 2 0.2 2 0.3 0 0.0 7 0.2
Not stated 99 11.6 79 13.5 16 10.8 573 12.6
Ethnicity
Hispanic 69 8.1 31 5.3 8 5.4 385 8.5
Non-Hispanic 646 75.4 453 77.4 117 79.1 3,388 74.4
Not stated 142 16.6 101 17.3 23 15.5 780 17.1

aExposure categories (categories are not mutually exclusive):

Healthcare: A patient who visited, worked in, or stayed in a healthcare setting in the 14 days before date of symptom onset.
Travel: A patient with a history of spending at least one night away from home in the 14 days before date of symptom onset, not including nights spent in a healthcare facility.
Assisted or senior living: A patient who visited, worked in, or stayed in a senior or assisted living facility in the 14 days before date of symptom onset.
None of these: A patient without reported healthcare setting, travel, or senior or assisted living facility exposure in the 14 days before date of symptom onset.
bSupplemental Legionnaires’ Disease Surveillance System (SLDSS).
c47 complete reporting jurisdictions in 2020: Alabama, Alaska, Arkansas, Arizona, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Iowa, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York (state), New York City, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.
dBased on year of symptom onset in SLDSS. If onset date was not stated in SLDSS, case year for confirmed cases was determined by the earliest of the following dates: positive laboratory date; date patient was hospitalized during treatment for Legionnaires’ disease; or date case was first reported to public health at any level.

Table 4b. Number of reported confirmed cases of Legionnaires’ disease by demographic characteristics and exposure categorya—SLDSS,b complete reporting jurisdictions,c 2021.d

Exposure category
Healthcare (Total = 1,198) Travel (Total = 1,227) Assisted or senior living (Total = 146) None of these (Total = 5,503)
Characteristic N % N % N % N %
Median Age (years) 65 N/A 61 N/A 73 N/A 62 N/A
Age
0–9 0 0.0 0 0.0 0 0.0 5 0.1
10–19 3 0.3 0 0.0 0 0.0 9 0.2
20–29 20 1.7 23 1.9 1 0.7 86 1.6
30–39 51 4.3 72 5.9 3 2.1 314 5.7
40–49 88 7.3 167 13.6 8 5.5 664 12.1
50–59 231 19.3 289 23.6 17 11.6 1,188 21.6
60–69 335 28.0 370 30.2 33 22.6 1,525 27.7
70–79 288 24.0 221 18.0 34 23.3 1,071 19.5
80–84 80 6.7 41 3.3 13 8.9 325 5.9
85+ 102 8.5 38 3.1 37 25.3 314 5.7
Not stated 0 0.0 6 0.5 0 0.0 2 0.0
Sex
Female 526 43.9 445 36.3 79 54.1 1,924 35.0
Male 671 56.0 776 63.2 67 45.9 3,557 64.6
Not stated 1 0.1 6 0.5 0 0.0 22 0.4
Race
American Indian/Alaska Native 2 0.2 3 0.2 0 0.0 27 0.5
Asian 17 1.4 7 0.6 1 0.7 77 1.4
Black or African American 276 23.0 231 18.8 24 16.4 1,234 22.4
Native Hawaiian/Other Pacific Islander 1 0.1 0 0.0 0 0.0 6 0.1
White 766 63.9 833 67.9 108 74.0 3,542 64.4
Multiple 3 0.3 5 0.4 0 0.0 7 0.1
Not stated 133 11.1 148 12.1 13 8.9 610 11.1
Ethnicity
Hispanic 88 7.3 74 6.0 9 6.2 465 8.4
Non-Hispanic 971 81.1 979 79.8 114 78.1 4,287 77.9
Not stated 139 11.6 174 14.2 23 15.8 751 13.6

aExposure categories (categories are not mutually exclusive):

Healthcare: A patient who visited, worked in, or stayed in a healthcare setting in the 14 days before date of symptom onset.
Travel: A patient with a history of spending at least one night away from home in the 14 days before date of symptom onset, not including nights spent in a healthcare facility.
Assisted or senior living: A patient who visited, worked in, or stayed in a senior or assisted living facility in the 14 days before date of symptom onset.
None of these: A patient without reported healthcare setting, travel, or senior or assisted living facility exposure in the 14 days before date of symptom onset.

bSupplemental Legionnaires’ Disease Surveillance System (SLDSS).

c49 complete reporting jurisdictions in 2021: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York (state), New York City, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.
dBased on year of symptom onset in SLDSS. If onset date was not stated in SLDSS, case year for confirmed cases was determined by the earliest of the following dates: positive laboratory date; date patient was hospitalized during treatment for Legionnaires’ disease; or date case was first reported to public health at any level.

Table 5a. Number of reported confirmed cases of healthcare-associateda Legionnaires’ disease by healthcare facility type and healthcare exposure certaintyb—SLDSS,c complete reporting jurisdictions,d 2020.e

Healthcare exposure certainty
Presumptive Possible Total
Facility type N % N % N %
Hospital 33 18.5 271 39.9 304 35.5
Long-term care facility 108 60.7 70 10.3 178 20.8
Clinic 3 1.7 223 32.8 226 26.4
Multiplef 17 9.6 67 9.9 84 9.8
Otherg 2 1.1 30 4.4 32 3.7
Not stated 15 8.4 18 2.7 33 3.9
Total 178 679 857
aHealthcare–associated Legionnaires’ disease includes both presumptive and possible cases in patients who worked in, visited, or stayed in a healthcare setting for any amount of time in the 14 days preceding symptom onset.
bHealthcare exposure certainty defined as:
Presumptive case of healthcare–associated Legionnaires’ disease was defined as laboratory-confirmed legionellosis in a patient with ≥10 days of continuous stay at a healthcare facility during the 14 days before onset of symptoms.
Possible case of healthcare–associated Legionnaires’ disease was defined as laboratory-confirmed legionellosis in a patient who spent a portion of the 14 days before date of symptom onset in one or more healthcare facilities but does not meet the criteria for a presumptive healthcare-associated case.
cSupplemental Legionnaires’ Disease Surveillance System (SLDSS).
d47 complete reporting jurisdictions in 2020: Alabama, Alaska, Arkansas, Arizona, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Iowa, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York (state), New York City, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.
eBased on year of symptom onset in SLDSS. If onset date was not stated in SLDSS, case year for confirmed cases was determined by the earliest of the following dates: positive laboratory date; date patient was hospitalized during treatment for Legionnaires’ disease; or date case was first reported to public health at any level.
fMultiple indicates more than one type of healthcare facility.
gOther facility includes locations such as outpatient laboratories and pharmacies.

Table 5b. Number of reported confirmed cases of healthcare-associateda Legionnaires’ disease by healthcare facility type and healthcare exposure certaintyb—SLDSS,c complete reporting jurisdictions,d 2021.e

Healthcare exposure certainty
Presumptive Possible Total
Facility type N % N % N %
Hospital 40 25.2 370 35.6 410 34.2
Long-term care facility 80 50.3 94 9.0 174 14.5
Clinic 2 1.3 391 37.6 393 32.8
Multiplef 22 13.8 81 7.8 103 8.6
Otherg 5 3.1 60 5.8 65 5.4
Not stated 10 6.3 43 4.1 53 4.4
Total 159 1,039 1,198
aHealthcare–associated Legionnaires’ disease includes both presumptive and possible cases in patients who worked in, visited, or stayed in a healthcare setting for any amount of time in the 14 days preceding symptom onset.
bHealthcare exposure certainty defined as:
Presumptive case of healthcare–associated Legionnaires’ disease was defined as laboratory-confirmed legionellosis in a patient with ≥10 days of continuous stay at a healthcare facility during the 14 days before onset of symptoms.
Possible Possible case of healthcare–associated Legionnaires’ disease was defined as laboratory-confirmed legionellosis in a patient who spent a portion of the 14 days before date of symptom onset in one or more healthcare facilities but does not meet the criteria for a presumptive healthcare-associated case.
cSupplemental Legionnaires’ Disease Surveillance System (SLDSS).
d49 complete reporting jurisdictions in 2021: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York (state), New York City, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.
eBased on year of symptom onset in SLDSS. If onset date was not stated in SLDSS, case year for confirmed cases was determined by the earliest of the following dates: positive laboratory date; date patient was hospitalized during treatment for Legionnaires’ disease; or date case was first reported to public health at any level.
fMultiple indicates more than one type of healthcare facility.
gOther facility includes locations such as outpatient laboratories and pharmacies.

Table 6. Number of reported confirmed cases of Legionnaires’ disease by hospitalizationa and exposure categoryb—SLDSS,c complete reporting jurisdictions,d 2020 and 2021.e

Exposure category 2020 2021
Number of cases with known hospitalization status Number of hospitalizations Hospitalization rate Number of cases with known hospitalization status Number of hospitalizations Hospitalization rate
All cases 5,410 5,257 97.2 7,565 7,340 97.0
Healthcare 790 754 95.4 1,184 1,147 96.9
Travel 564 545 96.6 1,201 1,157 96.3
Assisted or senior living 139 133 95.7 145 140 96.6
None of these 4,041 3,945 97.6 5,270 5,124 97.2
aWhere status of hospitalization for treatment of Legionnaires’ disease was known (2020: 5,410/6,014 cases (90.0%); 2021: 7,565/7,837 cases (96.5%)).
bExposure categories (categories are not mutually exclusive):
Healthcare: Legionnaires' disease in a patient who visited, worked in, or stayed in a healthcare setting in the 14 days before date of symptom onset.
Travel: Legionnaires' disease in a patient with a history of spending at least one night away from home in the 14 days before date of symptom onset, not including nights spent in a healthcare facility.
Assisted or senior living: Legionnaires' disease in a patient who visited, worked in, or stayed in a senior or assisted living facility in the 14 days before date of symptom onset.
None of these: A patient without reported healthcare setting, travel, or senior or assisted living facility exposure in the 14 days before date of symptom onset.
cSupplemental Legionnaires’ Disease Surveillance System (SLDSS).
d47 complete reporting jurisdictions in 2020: Alabama, Alaska, Arkansas, Arizona, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Iowa, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York (state), New York City, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.
49 complete reporting jurisdictions in 2021: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York (state), New York City, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.
eBased on year of symptom onset in SLDSS. If onset date was not stated in SLDSS, case year for confirmed cases was determined by the earliest of the following dates: positive laboratory date; date patient was hospitalized during treatment for Legionnaires’ disease; or date case was first reported to public health at any level.

Table 7. Number of reported confirmed cases of Legionnaires’ disease by outcomea and exposure
categoryb—SLDSS,c complete reporting jurisdictions,d 2020 and 2021.e

Exposure category 2020 2021
Number of cases with known outcome Number of deaths Case fatality rate Number of cases with known outcome Number of deaths Case fatality rate
All cases 5,111 506 9.9 6,494 627 9.7
Healthcare 756 131 17.3 990 154 15.6
Presumptive 157 46 29.3 120 44 36.7
Possible 599 85 14.2 870 110 12.6
Travel 507 26 5.1 1,080 57 5.3
Assisted or senior living 137 25 18.2 130 16 12.3
None of these 3,820 340 8.9 4,503 417 9.3

aWhere outcome was known (2020: 5,111/6,014 cases (85.0%); 2021: 6,494/7,837 cases (82.9%)).

bExposure categories (categories are not mutually exclusive):
Healthcare: Legionnaires' disease in a patient who visited, worked in, or stayed in a healthcare setting in the 14 days before date of symptom onset.
Travel: Legionnaires' disease in a patient with a history of spending at least one night away from home in the 14 days before date of symptom onset, not including nights spent in a healthcare facility.
Assisted or senior living: Legionnaires' disease in a patient who visited, worked in, or stayed in a senior or assisted living facility in the 14 days before date of symptom onset.
None of these: A patient without reported healthcare setting, travel, or senior or assisted living facility exposure in the 14 days before date of symptom onset.
cSupplemental Legionnaires’ Disease Surveillance System (SLDSS).
d47 complete reporting jurisdictions in 2020: Alabama, Alaska, Arkansas, Arizona, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Iowa, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York (state), New York City, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.
49 complete reporting jurisdictions in 2021: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York (state), New York City, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.
eBased on year of symptom onset in SLDSS. If onset date was not stated in SLDSS, case year for confirmed cases was determined by the earliest of the following dates: positive laboratory date; date patient was hospitalized during treatment for Legionnaires’ disease; or date case was first reported to public health at any level.

Figure 7. Percent of reported confirmed cases of Legionnaires’ disease that were treated in hospitala by age groupb and yearc—SLDSS,d complete reporting jurisdictions,e 2020 and 2021.

Figure 7. Percent of reported confirmed cases of Legionnaires’ disease that were treated in hospital by age group and year—SLDSS, complete reporting jurisdictions, 2020 and 2021
aWhere status of hospitalization for treatment of Legionnaires’ disease was known (2020: 5,410/6,014 cases (90.0%); 2021: 7,565/7,837 cases (96.5%)).
bDue to small case counts (N≤12), hospitalization rates may be unstable in age groups 0–9 and 10–19, and where age is missing; therefore, caution should be used when interpreting these rates.
cBased on year of symptom onset in SLDSS. If onset date was not stated in SLDSS, case year for confirmed cases was determined by the earliest of the following dates: positive laboratory date; date patient was hospitalized during treatment for Legionnaires’ disease; or date case was first reported to public health at any level.
dSupplemental Legionnaires’ Disease Surveillance System (SLDSS).
e47 complete reporting jurisdictions in 2020: Alabama, Alaska, Arkansas, Arizona, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Iowa, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York (state), New York City, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.
49 complete reporting jurisdictions in 2021: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Hawaii,
Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, Nevada, New Hampshire, New
Jersey, New Mexico, New York (state), New York City, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee,
Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.

Figure 8. Percent of reported confirmed cases of Legionnaires’ disease resulting in deatha by age groupb and yearc—SLDSS,d complete reporting jurisdictions,e 2020 and 2021.

Figure 8. Percent of reported confirmed cases of Legionnaires’ disease resulting in death by age group and year—SLDSS, complete reporting jurisdictions, 2020 and 2021
aWhere outcome was known (2020: 5,111/6,014 cases (85.0%); 2021: 6,494/7,837 cases (82.9%)).
bDue to low case counts (N≤10), CFRs may be unstable in age groups 0–9 and 10–19, and where age is missing; therefore, caution should be used when interpreting these rates.
cBased on year of symptom onset in SLDSS. If onset date was not stated in SLDSS, case year for confirmed cases was determined by the earliest of the following dates: positive laboratory date; date patient was hospitalized during treatment for Legionnaires’ disease; or date case was first reported to public health at any level.
dSupplemental Legionnaires’ Disease Surveillance System (SLDSS).
e47 complete reporting jurisdictions in 2020: Alabama, Alaska, Arkansas, Arizona, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Iowa, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York (state), New York City, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.
49 complete reporting jurisdictions in 2021: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York (state), New York City, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.

Table 8. Number of reported confirmed cases of Legionnaires’ disease by diagnostic testing methoda and yearb—SLDSS,c United States, 2020 and 2021.

2020 2021 Total
Diagnostic testing method N % N % N %
Urinary antigen test 5,843 95.7 7,762 96.0 13,605 95.9
Serology 2 0.0 3 0.0 5 0.0
Culture 271 4.4 322 4.0 593 4.2
Culture site
Respiratory secretiond 177 65.1 218 67.7 395 66.5
Lung biopsy 12 4.4 11 3.4 23 3.9
Pleural fluid 6 2.2 15 4.7 21 3.5
Blood 0 0.0 2 0.6 2 0.3
Other 16 5.9 28 8.7 44 7.4
Not stated 61 22.4 48 14.9 109 18.4
Culture species
L. pneumophila 148 54.4 194 60.2 342 57.6
Serogroup 1 69 N/A 100 N/A 169 N/A
Serogroup 2 1 N/A 2 N/A 3 N/A
Serogroup 6 1 N/A 1 N/A 2 N/A
Serogroup 3 0 N/A 1 N/A 1 N/A
L. longbeachae 6 2.2 8 2.5 14 2.4
L. anisa 6 2.2 2 0.6 8 1.3
L. bozemanii 2 0.7 6 1.9 8 1.3
L. micdadei 1 0.4 6 1.9 7 1.2
L. dumoffii 1 0.4 0 0.0 1 0.2
L. feeleii 1 0.4 0 0.0 1 0.2
Serogroup 1 1 N/A 0 N/A 1 N/A
L. wadsworthii 0 0.0 1 0.3 1 0.2
Not stated 107 39.3 105 32.6 212 35.7
Nucleic Acid Amplification Test (NAAT) 170 2.8 298 3.7 468 3.3
NAAT site
Respiratory secretiond 106 61.6 204 65.8 310 64.3
Pleural fluid 4 2.3 30 9.7 34 7.1
Lung biopsy 6 3.5 6 1.9 12 2.5
Blood 4 2.3 4 1.3 8 1.7
Other 11 6.4 9 2.9 20 4.1
Not stated 41 23.8 57 18.4 98 20.3
NAAT species
L. pneumophila 59 34.3 147 47.4 206 42.7
Serogroup 1 13 N/A 29 N/A 42 N/A
L. micdadei 2 1.2 2 0.6 4 0.8
L. bozemanii 1 0.6 1 0.3 2 0.4
L. longbeachae 1 0.6 0 0.0 1 0.2
Not stated 109 63.4 160 51.6 269 55.8

aMore than one type of test might apply. Laboratory criteria for diagnosis include the following for confirmed cases:

Urinary antigen test: detection of Legionella pneumophila serogroup 1 antigen in urine using validated reagents.
Serology: 4-fold or greater rise in specific serum antibody titer to L. pneumophila serogroup 1 using validated reagents detected 3–6 weeks apart.
Culture: isolation of any Legionella organism from respiratory secretions, lung tissue, pleural fluid, or other normally sterile site.
NAAT: detection of any Legionella species from lower respiratory secretions, lung tissue, pleural fluid, or extrapulmonary site by a validated nucleic acid amplification test
bBased on year of symptom onset in SLDSS. If onset date was not stated in SLDSS, case year for confirmed cases was determined by the earliest of the following dates: positive laboratory date; date patient was hospitalized during treatment for Legionnaires’ disease; or date case was first reported to public health at any level.
cSupplemental Legionnaires’ Disease Surveillance System (SLDSS).
dRespiratory secretions include sputum, bronchial wash, bronchoalveolar lavage.
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Content Source:
National Center for Immunization and Respiratory Diseases; National Center for Environmental Health