West Nile Virus Summary 2016 West Nile virus (WNV) is a mosquito-borne virus that can cause mild flu-like symptoms or severe neurological infections. WNV was first recognized in the U.S. in 1999 in the state of New York. In 2002, North Dakota had its first confirmed human cases of WNV. Laboratory testing also detected WNV in birds, horses and mosquitoes. There have been human cases of WNV in North Dakota every year since 2002. On June 1, 2016, the North Dakota Department of Health (NDDoH) West Nile virus (WNV) surveillance program initiated its fourteenth season of human arboviral surveillance. The NDDoH Division of Laboratory Services conducted free WNV testing on human specimens from June 1 until October 1. Commercial and private laboratories also performed testing and reported results to the NDDoH. A total of 85 human cases were identified (Figure 1). Of the 85 reported cases, 22 (25%) met the case definition of West Nile neuroinvasive disease and 63 (75%) cases were classified as West Nile fever. Twenty-eight of the cases were hospitalized. Two cases were fatal. Five asymptomatic North Dakota blood donors with WNV infections were also reported to the NDDoH in 2016. Table 1. Human WNV Cases by Age Group, North Dakota, 2016 Twenty-eight of the cases were female and 57 were male. Fifty (59%) cases were age 50 or older (Table 1). The North Dakota Veterinary Diagnostic Laboratory (NDVDL) tested 26 horses for WNV infection. Of those, 5 (19%) tested positive for WNV. One squirrel also tested positive for WNV. Figure 1. WNV Human Disease Cases by County, North Dakota, 2016. In 2016, dead bird collection focused on raptors and birds from the corvid family. The corvid family includes crows, jays, magpies, and ravens. Raptors include birds of prey such as hawks, eagles, falcons, and owls. Four dead birds were collected and tested for WNV at the NDVDL. Two (50%) of the birds tested positive. Numerous birds were also tested by local vector control agencies throughout the state, and four additional positive birds were identified (Table 2). Statewide mosquito monitoring was conducted weekly from June through August using New Jersey light traps stationed around the state. Female Culex tarsalis counts peaked during the first week in August (Figure 2). Age Group Cases Age <10 2 Ages 10-19 2 Ages 20-29 9 Ages 30-39 12 Ages 40-49 10 Ages 50-59 17 Ages 60 and older 33 The North Dakota Department of Health (NDDoH) monitors WNV activity in the state through surveillance activities that include reporting and testing sick horses and other animals, trapping and testing mosquitoes, reporting and testing dead birds, and monitoring illness in humans. Dead bird surveillance is an indicator of transmission of WNV and can play a role in predicting human risk of infection. The NDDoH’s dead bird surveillance for WNV involves collecting reports of dead bird sightings and testing dead birds for WNV. In North Dakota, 60-70 mosquito traps are set up each season, with at least one trap in every county. The traps are emptied once per week and mosquitoes are sent to the NDDoH Division of Laboratory Services for counting and identification. Visit www.ndhealth.gov/wnv to find additional information about WNV in North Dakota. Division of Disease Control 800.472.2180
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
West Nile Virus Summary 2016
West Nile virus (WNV) is a mosquito-borne virus that can cause mild flu-like symptoms or severe
neurological infections. WNV was first recognized in the U.S. in 1999 in the state of New York. In
2002, North Dakota had its first confirmed human cases of WNV. Laboratory testing also detected
WNV in birds, horses and mosquitoes. There have been human cases of WNV in North Dakota every
year since 2002.
On June 1, 2016, the North Dakota
Department of Health (NDDoH) West Nile
virus (WNV) surveillance program initiated
its fourteenth season of human arboviral
surveillance. The NDDoH Division of
Laboratory Services conducted free WNV
testing on human specimens from June 1
until October 1. Commercial and private
laboratories also performed testing and
reported results to the NDDoH. A total of 85
human cases were identified (Figure 1).
Of the 85 reported cases, 22 (25%) met the
case definition of West Nile neuroinvasive
disease and 63 (75%) cases were classified
as West Nile fever. Twenty-eight of the
cases were hospitalized. Two cases were
fatal. Five asymptomatic North Dakota
blood donors with WNV infections were
also reported to the NDDoH in 2016.
Table 1. Human WNV Cases by Age Group, North Dakota, 2016
Twenty-eight of the cases were female and
57 were male. Fifty (59%) cases were age 50
or older (Table 1).
The North Dakota Veterinary Diagnostic
Laboratory (NDVDL) tested 26 horses for
WNV infection. Of those, 5 (19%) tested
positive for WNV. One squirrel also tested
positive for WNV.
Figure 1. WNV Human Disease Cases by
County, North Dakota, 2016.
In 2016, dead bird collection focused on
raptors and birds from the corvid family. The
corvid family includes crows, jays, magpies,
and ravens. Raptors include birds of prey
such as hawks, eagles, falcons, and owls.
Four dead birds were collected and tested for
WNV at the NDVDL. Two (50%) of the
birds tested positive. Numerous birds were
also tested by local vector control agencies
throughout the state, and four additional
positive birds were identified (Table 2).
Statewide mosquito monitoring was
conducted weekly from June through August
using New Jersey light traps stationed
around the state. Female Culex tarsalis
counts peaked during the first week in
August (Figure 2).
Age Group Cases
Age <10 2
Ages 10-19 2
Ages 20-29 9
Ages 30-39 12
Ages 40-49 10
Ages 50-59 17
Ages 60 and older 33
The North Dakota
Department of Health
(NDDoH) monitors WNV
activity in the state through
surveillance activities that
include reporting and testing
sick horses and other
animals, trapping and testing
mosquitoes, reporting and
testing dead birds, and
monitoring illness in humans.
Dead bird surveillance is an
indicator of transmission of
WNV and can play a role in
predicting human risk of
infection. The NDDoH’s
dead bird surveillance for
WNV involves collecting
reports of dead bird sightings
and testing dead birds for
WNV.
In North Dakota, 60-70
mosquito traps are set up
each season, with at least one
trap in every county. The
traps are emptied once per
week and mosquitoes are sent
to the NDDoH Division of
Laboratory Services for
counting and identification.
Visit www.ndhealth.gov/wnv
to find additional information
about WNV in North Dakota.
Division of Disease Control
800.472.2180
Table 2. WNV Activity by County, North Dakota, 2016.
Culex tarsalis, the mosquito species that transmits
WNV, typically reaches its peak numbers at the end of
July or beginning of August. Increases in the number
of Culex tarsalis pose a higher risk for human WNV
infection.
Figure 2. Total Number of Mosquitoes and Female Culex tarsalis from Surveillance Traps, North Dakota, 2016.
West Nile Virus in the United States
Final national WNV data for 2016 is pending.
Figure 3. Provisional WNV Activity Reported by
County, United States, 2016.
County Human Horse Bird Other Vet
Adams
Barnes 3
Benson 1
Billings
Bottineau
Bowman 2
Burke
Burleigh 7 1 Cass 21 2 1
Cavalier Dickey 3 Divide
Dunn 1
Eddy
Emmons 1
Foster 1
Golden Valley
Grand Forks 5 3
Grant Griggs 1
Hettinger
Kidder
LaMoure
Logan
McHenry 1
McIntosh 3
McKenzie
McLean 1 1
Mercer 2
Morton 5 1
Mountrail
Nelson
Oliver Pembina
Pierce 1
Ramsey 2
Ransom 1
Renville
Richland 2 1
Rolette Sargent 2
Sheridan 1
Sioux 1 1
Slope
Stark Steele
Stutsman 1
Towner
Traill 2
Walsh 1
Ward 6
Wells 4 Williams 2
1884
17134
34227
17281
1039811105
4689
2521528592
40699
21511
25248
47872
17809
737 59 109153153
147159
364
22142189
558585 691
0
500
1000
1500
2000
2500
3000
05000
10000150002000025000300003500040000450005000055000
6/5
/20
16
6/1
2/2
01
6
6/1
9/2
01
6
6/2
6/2
01
6
7/3
/20
16
7/1
0/2
01
6
7/1
7/2
01
6
7/2
4/2
01
6
7/3
1/2
01
6
8/7
/20
16
8/1
4/2
01
6
8/2
1/2
01
6
8/2
8/2
01
6
9/4
/20
16
Fem
ale
C. t
ars
ali
s
Tota
l Mo
squ
ito
es
Total Mosquito Count Female Culex tarsalis Count
Related Documents
