West Nile virus and other arboviral activity -- United States, 2013 reported to ArboNET Tuesday, This update from the CDC Arboviral Diseases Branch includes provisional data reported to ArboNET for January 1 December 31, 2013 for nationally notifiable arboviruses other than dengue. Additional resources for ArboNET and arboviral diseases are provided on page 11. West Nile virus (WNV) activity in 2013 As of January 7 th, 1,256 counties in 48 states and the District of Columbia have reported WNV activity to ArboNET for 2013, including 46 states with reported WNV human infections (i.e., disease cases or viremic blood donors) and two additional states with reported WNV activity in non-human species only (i.e., veterinary cases, mosquito pools, dead birds, or sentinel animals). No WNV activity was reported to ArboNET for the period from December 4 December 31 [Figure 1]. Figure 1. West Nile virus (WNV) activity* reported to ArboNET, by time period and state United States, 2013 (as of ) *WNV human disease cases, presumptive viremic blood donors, veterinary disease cases, or infections in mosquitoes, birds, or sentinel animals Arboviral Diseases Branch, CDC Page 1 of 11
Reported WNV disease cases To date, 2,374 human cases of WNV disease have been reported from 46 states [Table 1]. Of all WNV disease cases reported, 1,205 (51%) were classified as neuroinvasive disease (e.g., meningitis, encephalitis, acute flaccid paralysis) [Figure 2] and 1,169 (49%) as nonneuroinvasive disease. Dates of illness onset for disease cases ranged from January November [Figure 3]. Additional demographic and clinical characteristics of reported cases are provided on page 10 [Table 6]. Presumptive viremic blood donors To date, 420 WNV presumptive viremic blood donors have been reported from 35 states [Table 1]. Of these, 68 (16%) developed clinical illness and are also included as disease cases. Arboviral Diseases Branch, CDC Page 2 of 11
Figure 2. WNV neuroinvasive disease incidence (per 100,000 population) reported to ArboNET, by state United States, 2013 (as of ) Figure 3. WNV disease cases reported to ArboNET, by week of onset United States, 2013 (as of ) Arboviral Diseases Branch, CDC Page 3 of 11
Table 1. West Nile virus infections in humans reported to ArboNET, 2013 Presumptive Human disease cases reported to CDC* viremic blood State Neuroinvasive Non-neuroinvasive Total Deaths donors Alabama 0 7 7 0 1 Arizona 31 10 41 5 6 Arkansas 16 2 18 1 6 California 233 135 368 15 63 Colorado 89 229 318 7 23 Connecticut 1 3 4 0 1 Delaware 3 0 3 0 0 District of Columbia 0 1 1 0 0 Florida 4 1 5 0 0 Georgia 2 4 6 0 3 Idaho 14 26 40 1 12 Illinois 85 31 116 11 21 Indiana 18 4 22 2 3 Iowa 24 20 44 0 12 Kansas 31 54 85 7 30 Kentucky 1 2 3 1 0 Louisiana 34 20 54 4 5 Maryland 11 5 16 1 1 Massachusetts 7 1 8 0 1 Michigan 24 12 36 2 4 Minnesota 31 48 79 3 26 Mississippi 27 18 45 5 5 Missouri 24 5 29 1 8 Montana 10 28 38 2 5 Nebraska 53 168 221 5 38 Nevada 8 3 11 1 5 New Hampshire 1 0 1 0 0 New Jersey 9 2 11 2 3 New Mexico 24 14 38 3 2 New York 13 13 26 0 9 North Carolina 3 0 3 1 0 North Dakota 60 63 123 2 15 Ohio 20 4 24 3 6 Oklahoma 59 26 85 7 18 Oregon 1 1 2 0 0 Pennsylvania 6 5 11 1 0 Rhode Island 1 0 1 0 0 South Carolina 3 4 7 0 2 South Dakota 57 92 149 3 26 Tennessee 17 7 24 2 0 Texas 105 67 172 13 39 Utah 4 3 7 0 5 Vermont 1 1 2 0 0 Virginia 6 0 6 0 0 Washington 0 1 1 0 1 Wisconsin 18 4 22 2 10 Wyoming 16 25 41 1 5 Totals 1,205 1,169 2,374 114 420 *Includes confirmed and probable cases; Of the 420 presumptive viremic blood donors, 68 (16%) developed clinical illness and are also included as Human disease cases reported to CDC. Arboviral Diseases Branch, CDC Page 4 of 11
Eastern equine encephalitis virus (EEEV) activity in 2013 As of January 7 th, a total of 142 counties in 22 states have reported EEEV activity in 2013, including five states with human disease cases and 17 additional states with reported EEEV activity in non-human species only [Figure 4 and Table 2]. Additional demographic and clinical characteristics of reported cases are provided on page 10 [Table 6]. Figure 4. Eastern equine encephalitis virus (EEEV) activity reported to ArboNET, by state United States, 2013 (as of ) *EEEV veterinary disease cases, or infections in mosquitoes, birds, or sentinel animals Table 2. Eastern equine encephalitis virus human disease cases reported to ArboNET, United States, 2013* State Neuroinvasive Non-neuroinvasive Total cases Deaths Arkansas 1 0 1 1 Florida 2 0 2 1 Georgia 1 0 1 0 Massachusetts 1 0 1 1 North Carolina 1 0 1 0 Totals 6 0 6 3 *Includes confirmed and probable cases. Arboviral Diseases Branch, CDC Page 5 of 11
Jamestown Canyon virus (JCV) activity in 2013 As of January 7 th, a total of 21 counties in seven states have reported JCV activity in 2013, including six states with human disease cases and one additional state with reported JCV activity in non-human species only [Figure 5 and Table 3]. Additional demographic and clinical characteristics of reported cases are provided on page 10 [Table 6]. Figure 5. Jamestown Canyon virus (JCV) activity reported to ArboNET, by state United States, 2013 (as of ) *JCV veterinary disease cases, or infections in mosquitoes, birds, or sentinel animals Table 3. Jamestown Canyon virus human disease cases reported to ArboNET, United States, 2013* State Neuroinvasive Non-neuroinvasive Total cases Deaths Idaho 0 1 1 0 Massachusetts 1 0 1 0 Minnesota 1 0 1 0 New Hampshire 1 0 1 0 New York 3 0 3 0 Wisconsin 3 6 9 0 Totals 9 7 16 0 *Includes confirmed and probable cases. Arboviral Diseases Branch, CDC Page 6 of 11
La Crosse virus (LACV) activity in 2013 As of January 7 th, a total of 60 counties in 10 states have reported LACV activity in 2013; all 10 states have reported human disease cases [Figure 6 and Table 4]. Additional demographic and clinical characteristics of reported cases are provided on page 10 [Table 6]. Figure 6. La Crosse virus (LACV) activity reported to ArboNET, by state United States, 2013 (as of )) *LACV veterinary disease cases, or infections in mosquitoes, birds, or sentinel animals Table 4. La Crosse virus human disease cases reported to ArboNET, United States, 2013* State Neuroinvasive Non-neuroinvasive Total cases Deaths Indiana 1 0 1 1 Minnesota 4 1 5 0 Mississippi 2 1 3 0 North Carolina 12 0 12 0 Ohio 14 2 16 0 South Carolina 1 0 1 0 Tennessee 23 0 23 0 Virginia 2 0 2 0 West Virginia 10 0 10 0 Wisconsin 4 4 8 1 Totals 73 8 81 2 *Includes confirmed and probable cases. Arboviral Diseases Branch, CDC Page 7 of 11
Powassan virus (POWV) activity in 2013 As of January 7 th, a total of 11 counties in five states reported human cases of POWV disease in 2013 [Figure 7 and Table 5]. Additional demographic and clinical characteristics of reported cases are provided on page 10 [Table 6]. Figure 7. Powassan virus (POWV) activity reported to ArboNET, by state United States, 2013 (as of ) Table 5. Powassan virus human disease cases reported to ArboNET, United States, 2013* State Neuroinvasive Non-neuroinvasive Total cases Deaths Minnesota 1 0 1 0 New Hampshire 1 0 1 0 New Jersey 1 0 1 1 New York 4 0 4 0 Wisconsin 3 2 5 0 Totals 10 2 12 1 *Includes confirmed and probable cases. Arboviral Diseases Branch, CDC Page 8 of 11
St. Louis encephalitis virus (SLEV) activity in 2013 As of January 7 th, a total of 15 counties in five states have reported SLEV activity in 2013; all five states have reported SLEV activity in non-human species only [Figure 8]. Figure 8. St. Louis encephalitis virus (SLEV) activity reported to ArboNET, by state United States, 2013 (as of ) *SLEV veterinary disease cases, or infections in mosquitoes, birds, or sentinel animals Arboviral Diseases Branch, CDC Page 9 of 11
Table 6. Characteristics of reported cases of arboviral disease, United States, 2013 WNV LACV JCV POWV EEEV (N=2,374) (N=81) (N=16) (N=12) (N=6) No. (%) No. (%) No. (%) No. (%) No. (%) Age group <20 years 116 (5) 71 (88) 3 (19) 1 (8) 2 (33) 20-39 years 426 (18) 1 (1) 4 (25) 1 (8) 0 (0) 40-59 years 887 (37) 6 (7) 7 (44) 4 (34) 1 (17) 60 years 945 (40) 3 (4) 2 (12) 6 (50) 3 (50) Male sex 1,376 (58) 46 (57) 13 (77) 9 (75) 4 (67) Onset of illness Jan Mar 5 (<1) 0 (0) 1 (6) 0 (0) 2 (33) Apr Jun 46 (2) 8 (10) 4 (25) 5 (42) 1 (17) Jul Sep 2,152 (91) 69 (85) 11 (69) 6 (50) 2 (33) Oct Dec 171 (6) 4 (5) 0 (0) 1 (8) 1 (17) Clinical syndrome Non-neuroinvasive 1,169 (49) 8 (10) 7 (44) 2 (17) 0 (0) Neuroinvasive Encephalitis 641 (27) 62 (76) 7 (44) 8 (66) 6 (100) Meningitis 460 (20) 7 (9) 2 (12) 2 (17) 0 (0) Acute flaccid paralysis 104 (4) 4 (5) 0 (0) 0 (0) 0 (0) Outcome Hospitalization 1,426 (60) 74 (91) 8 (50) 10 (83) 6 (100) Death 114 (5) 2 (3) 0 (0) 1 (8) 3 (50) WNV=West Nile virus; LACV=La Crosse virus; JCV=Jamestown Canyon virus; POWV=Powassan virus; EEEV=Eastern equine encephalitis virus 78 WNV disease cases classified as acute flaccid paralysis also had encephalitis or meningitis. Four LACV disease case classified as acute flaccid paralysis also had encephalitis. Arboviral Diseases Branch, CDC Page 10 of 11
About ArboNET ArboNET is a national arboviral surveillance system managed by CDC and state health departments. In addition to human disease, ArboNET maintains data on arboviral infections among presumptive viremic blood donors (PVDs), veterinary disease cases, mosquitoes, dead birds, and sentinel animals. As with other national surveillance data, ArboNET data has several limitations that should be considered in analysis, interpretation, and reporting [Box]. Box: Limitations of ArboNET data The following should be considered in the analysis, interpretation, and reporting of ArboNET data: 1. ArboNET is a passive surveillance system. It is dependent on clinicians considering the diagnosis of an arboviral disease and obtaining the appropriate diagnostic test, and reporting of laboratoryconfirmed cases to public health authorities. Diagnosis and reporting are incomplete, and the incidence of arboviral diseases is underestimated. 2. Reported neuroinvasive disease cases are considered the most accurate indicator of arboviral activity in humans because of the substantial associated morbidity. In contrast, reported cases of nonneuroinvasive arboviral disease are more likely to be affected by disease awareness and healthcare-seeking behavior in different communities and by the availability and specificity of laboratory tests performed. Surveillance data for nonneuroinvasive disease should be interpreted with caution and generally should not be used to make comparisons between geographic areas or over time. Additional resources For additional arboviral disease information and data, please visit the following websites: CDC s Division of Vector-Borne Diseases: http://www.cdc.gov/ncezid/dvbd/ National Notifiable Diseases Surveillance System: http://wwwn.cdc.gov/nndss/script/casedef.aspx?condyrid=616&datepub=1/1/2011% 2012:00:00%20AM U.S. Geological Survey (USGS): http://diseasemaps.usgs.gov/ AABB (American Association of Blood Banks): www.aabb.org/programs/biovigilance/pages/wnv.aspx Arboviral Diseases Branch, CDC Page 11 of 11