Florida Mosquito Control Association

 

Arbovirus Surveillance Reports - 2006

May 2006

In May there were no seroconversions due to alphaviruses (Eastern Equine Encephalitis virus (EEE) and Highlands J virus(HJ)).  May activity has not been this low since May 1999. There were three new HAI flavivirus positive sentinel (St Louis Encephalitis virus (SLE) antigen used in the HAI assay) during Maay.  These were confirmed as WN+ by IgM Elisa or Serum Neutralization for a seroconversion rate of 0.2%, which is not significantly different from the mean statewide rate for May. 

Figures 1A and 1B depict the seroconversion rates for EEE and to WN for the January through May in 2005 and 2006.  The effect of this year’s spring drought is most noticeable for EEE seroconversions.

Sera from 165 live wild birds were screened by HAI in May.  Table 1 lists submissions and results by county for EEE.  Table 2 lists submissions and results by county for WN.

Table 1.  EEE positive live wild birds


county

# birds

total EEE+

blue jay

black bird

cardinal

cow bird

dove

grackle

hawk

sparrow

thrasher

tit mouse

Pinellas

1

0

 

 

 

 

 

 

0+/1

 

 

 

Okaloosa

38

4

3+/8

0+/2

1+/14

0+/1

 

0+/11

 

 

0+/1

0+/1

Santa Rosa

34

7

6+/15

 

1+/12

 

0+/1

0+/5

 

 

0+/1

 

Walton (North)

47

1

0+/8

 

0+/27

 

 

 

 

1+/12

 

 

Washington

45

1

0+/6

0+/4

1+/26

 

 

0+/3

 

0+/6

 

 

totals

165

13

9+/37

0+/6

3+/79

0+/1

0+/1

0+/19

0+/1

1+/18

0+/2

0+/1

* # + / # submitted

Table 2.  WN positive live wild birds


county

# birds

total WN+

blue jay

black bird

cardinal

cow bird

dove

grackle

hawk

sparrow

thrasher

tit mouse

Pinellas

1

1

 

 

 

 

 

 

1+/1

 

 

 

Okaloosa

38

0

0+/8

0+/2

0+/14

0+/1

 

0+/11

 

 

0+/1

0+/1

Santa Rosa

34

6

4+/15

 

1+/12

 

1+/1

0+/5

 

 

0+/1

 

Walton (North)

47

2

0+/8

 

2+/27

 

 

 

 

0+/12

 

 

Washington

45

4

0+/6

1+/4

0+/26

 

 

0+/3

 

3+/6

 

 

totals

165

13

4+/37

1+/6

3+/79

0+/1

1+/1

0+/19

1+/1

3+/18

0+/2

0+/1

* # + / # submitted

There were 43 dead birds submitted for arbovirus assay during May.  Virus was not detected.  Brain tissues from four equines in May were submitted for arbovirus testing; all were negative for arbovirus.   

Table 3.  Numbers of dead birds submitted by county


county

birds

mammal

March

submitted

EEE positive

WN positive

submitted

EEE positive

WN positive

Alachua

1

 

 

 

 

 

Dade

30

 

 

 

 

 

Duval

 

 

 

1

 

 

Hernando

2

 

 

 

 

 

Levy

1

 

 

 

 

 

Marion

 

 

 

1

 

 

Okeechobee

 

 

 

1

 

 

Orange

4

 

 

 

 

 

Osceola

 

 

 

1

 

 

Volusia

5

 

 

 

 

 

Totals-Jan

43

0

0

4

0

0

Table 3. Numbers of dead birds submitted by species.


Species

May

Blackbird

4

Bluejay

1

Catbird

1

Crow

4

Cuckoo

1

Dove

9

Duck

2

Grackle

4

Kingbird

1

Mockingbird

3

Moorhen

1

Parakeet

1

Thrush

5

Warbler

6

total

43

During March, one traditional mosquito pools from Pinellas and 26 from Sarasota counties were assayed.  California group viruses were detected in one pool of Anopheles crucians from Sarasota County (50 mosquitoes each, collected 4/5/06).   

HAI May 2006

March 2006, April 2006

Numbers of submitted sera and submitting counties are beginning to increase in preparation for the coming season.

In March there were five seroconversions due to alphaviruses, all to Eastern Equine Encephalitis virus (EEE), resulting in a seroconversion rate of 0.6%, similar to the mean for EEE historical activity during March.  During April there were 2 seroconversions to EEE (0.2% seroconversion rate) and none to HJ.  This is similar to historical means. 

There were no new HAI flavivirus positive sentinel (St Louis Encephalitis virus (SLE) antigen used in the HAI assay) during March and three were detected in April.  These were confirmed as WN+ by IgM Elisa or Serum Neutralization for a seroconversion rate of 0.2%, which is not significantly different from the mean statewide rate for those months. 

Sera from 192 live wild birds were screened by HAI in March and 158 birds were screened in April.  Table 1 lists submissions and results by county for EEE.  Table 2 lists submissions and results by county for WN.

Table 1.  EEE positive live wild birds


March
county

# birds

total EEE+

blue jay

black-bird

card-inal

cow-bird

finch

grackle

mocking-bird

star-ling

spar-row

thra-sher

Okaloosa

48

5

1+/4

0+/2

2+/10

0+/2

0+/1

1+/1

0+/1

0+/1

1+/25

0+/1

Santa Rosa

47

1

 

 

1+/17

0+/2

 

0+/4

 

 

0+/24

 

Walton(North)

51

8

0+/2

 

3+/17

 

 

 

 

 

5+/32

 

Washington

46

4

2+/3

0+/1

2+/10

 

 

0+/1

 

 

0+/31

 

totals

192

18

3+/9

0+/3

8+/54

0+/4

0+/1

1+/6

0+/1

0+/1

6+/112

0+/1

April
county

# birds

total EEE+

blue jay

cardinal

cowbird

grackle

mocking-bird

sparrow

thrasher

Okaloosa

54

10

8+/11

1+/13

0+/3

0+/12

 

0+/11

1+/4

Santa Rosa

47

4

1+/4

0+/9

0+/1

1+/4

1+/2

0+/26

1+/1

Walton(North)

30

1

0+/1

0+/15

 

 

 

1+/12

0+/2

Washington

27

2

0+/1

1+/14

 

0+/1

0+/1

1+/10

 

totals

158

17

9+/17

2+/51

0+/4

1+/17

1+/3

2+/59

2+/7

* # + / # submitted

Table 2.  WN positive live wild birds


March
county

# birds

total WN+

blue jay

black-bird

card-inal

cow-bird

finch

grackle

mocking-bird

star-ling

spar-row

thra-sher

Okaloosa

48

0

0+/4

0+/2

0+/10

0+/2

0+/1

0+/1

0+/1

0+/1

0+/25

0+/1

Santa Rosa

47

0

 

 

0+/17

0+/2

 

0+/4

 

 

0+/24

 

Walton(North)

51

4

0+/2

 

1+/17

 

 

 

 

 

3+/32

 

Washington

46

4

0+/3

1+/1

0+/10

 

 

0+/1

 

 

3+/31

 

totals

192

8

0+/9

1+/3

1+/54

0+/4

0+/1

0+/6

0+/1

0+/1

6+/112

0+/1

April
county

# birds

total WN+

blue jay

cardinal

cowbird

grackle

mocking-bird

sparrow

thrasher

Okaloosa

54

1

1+/11

0+/13

0+/3

0+/12

 

0+/11

0+/4

Santa Rosa

47

1

1+/4

0+/9

0+/1

0+/4

0+/2

0+/26

0+/1

Walton(North)

30

0

0+/1

0+/15

 

 

 

0+/12

0+/2

Washington

27

0

0+/1

0+/14

 

0+/1

0+/1

0+/10

 

totals

158

2

2+/17

0+/51

0+/4

0+/17

0+/3

0+/59

0+/7

* # + / # submitted

There were 37 dead birds were submitted for arbovirus assay during March and 36 during April.  Virus was not detected.  Brain tissues from three equines in March and from two in April were submitted for arbovirus testing.  EEE was detected in a Levy County horse that died in March. 

Table 3.  Numbers of dead birds submitted by county


county

birds

mammal

March

submitted

EEE positive

WN positive

submitted

EEE positive

WN positive

Alachua

1

 

 

 

 

 

Dade

19

 

 

 

 

 

Duval

1

 

 

 

 

 

Hernando

2

 

 

 

 

 

Hillsborough

4

 

 

 

 

 

Jackson

1

 

 

 

 

 

Levy

1

 

 

1

1

 

Madison

2

 

 

 

 

 

Marion

 

 

 

1

 

 

Martin

1

 

 

 

 

 

Orange

3

 

 

 

 

 

Palm Beach

1

 

 

 

 

 

Suwannee

 

 

 

1

 

 

Walton

1

 

 

 

 

 

Totals-Jan

37

0

0

3

1

0

April

 

 

 

 

 

 

Alachua

1

 

 

 

 

 

Dade

29

 

 

 

 

 

Dixie

1

 

 

 

 

 

Hillsborough

2

 

 

 

 

 

Indian River

1

 

 

 

 

 

Jackson

1

 

 

 

 

 

Jefferson

 

 

 

1

 

 

Marion

 

 

 

1

 

 

Orange

1

 

 

 

 

 

Totals-Feb

36

0

0

2

0

0

Table 3. Numbers of dead birds submitted by species.


Species

March

April

Blackbird

 

2

Bluejay

1

 

Cardinal

6

1

Chicken

2

 

Crow

1

1

Dove

6

8

Duck

5

 

Finch

 

1

Flycatcher

 

1

Gallinule

 

1

Grackle

1

 

Hawk

2

3

Limpkin

1

 

Hummingbird

 

1

Mockingbird

 

2

Ostrich

1

 

Owl

1

 

Parula

 

2

Rail

1

 

Sandpiper

2

 

Scrubjay

1

 

Sparrow

2

1

Swan

1

 

Turkey

 

2

Warbler

2

3

Whip-poor-will

1

1

Wren

 

1

total

37

36

During March, three traditional mosquito pools from Pinellas and 49 from Sarasota counties were assayed.  California group viruses were detected in three pools of Anopheles crucians from Sarasota County (50 mosquitoes each, collected 2/23/06, 3/2/06 and 3/22/06.   During April, 24 traditional pools from Sarasota, 7 from St. Johns and 54 from Volusia counties were assayed for arboviruses by real-time RT-PCR and cell culture inoculation.  All were negative. 

HAI March 2006, HAI April 2006

January 2006, February2006

Total numbers of submitted sera remain at low to moderate levels as some counties have stopped their surveillance programs until spring.

In January there were eight seroconversions due to alphaviruses, six to Eastern Equine Encephalitis virus (EEE) and two to Highlands J virus (HJ), resulting in seroconversion rates of 0.8% and 0.3% respectively..  The rate for EEE activity is similar to the mean for EEE historical activity during January.  During February there were 13 seroconversions to EEE (1.6% seroconversion rate) and none to HJ.  This is the highest February rate since 1999.  Testing prior to 2004 did not distinguish between these two alphaviruses, thus making direct comparisons with rates reported prior to 2004 problematic. 

There were 3 new HAI flavivirus positive sentinel (St Louis Encephalitis virus (SLE) antigen used in the HAI assay) confirmed as WN+ by IgM Elisa or Serum Neutralization during January, for a rate of 0.4% and 2 such seroconversions in February (rate, 0.2%). These rates are not significantly different from the mean statewide rate for those months. 

Sera from 112 live wild birds were screened by HAI in January and 183 birds were screened in February.  Table 1 lists submissions and results by county for EEE.  Antibody to WN was not detected in the January birds.  WN antibody was detected in two sparrows collected in February, one from North Walton county and one from Okaloosa county.

Table 1.  EEE positive wild birds


January    county

# birds

total EEE+

blue jay

cardinal

finch

sparrow

thrasher

titmouse

Hillsborough

0

0

 

 

 

 

 

 

Okaloosa

32

4

3+/5

0+/5

0+/4

1+/15

0+/1

0+/2

Santa Rosa

25

0

0+/1

1+/8

 

0+/16

 

 

Walton (North)

30

0

 

0+/1

 

0+/29

 

 

Washington

25

0

 

0+/2

 

3+/23

 

 

totals

112

4

3+/6

1+/16

0+/4

4+/83

0+/1

0+/2

 

 

 

 

 

 

 

 

 

February    county

# birds

total EEE+

blue jay

Black bird

cardinal

cowbird

dove

sparrow

Hillsborough

0

0

 

 

 

 

 

 

Okaloosa

46

6

1+/2

0+/2

2+/12

 

0+/1

3+/29

Santa Rosa

44

1

0+/1

 

1+/15

0+/6

0+/1

0+/21

Walton (North)

53

3

 

 

2+/18

 

 

1+/35

Washington

40

3

0+/2

2+/2

1+/11

 

 

0+/25

totals

183

13

1+/5

2+/4

6+/56

0+/6

0+/2

4+/109

* # + / # submitted

Ten dead birds were submitted for arbovirus assay during January and 13 during February.  Virus was not detected.  Brain tissues from two equines in January and from four in February were submitted for arbovirus testing.  EEE was detected in a Duval County horse that dies in early February. 

Table 2.


county

birds

mammal

January

submitted

EEE positive

WN positive

submitted

EEE positive

WN positive

Alachua

 

 

 

1

 

 

Dade

3

 

 

 

 

 

Hillsborough

4

 

 

1

 

 

Madison

1

 

 

 

 

 

Marion

1

 

 

 

 

 

Orange

1

 

 

 

 

 

Totals-Jan

10

0

0

2

0

0

February

 

 

 

 

 

 

Broward

 

 

 

2

 

 

Citrus

6

 

 

 

 

 

Dade

4

 

 

 

 

 

Duval

 

 

 

1

1

 

Hernando

1

 

 

 

 

 

Hillsborough

1

 

 

 

 

 

Orange

1

 

 

 

 

 

Polk

 

 

 

1

 

 

Totals-Feb/

13

0

0

4

1

0

During January, seven traditional mosquito pools from Manatee county and during February, one from Pinellas county were assayed for arboviruses by real-time RT-PCR and cell culture inoculation.  All were negative. 

HAI January 2006, HAI February 2006
© 2006 Florida Mosquito Control Association.