Georgia epidemiology report, Vol. 25, no. 3 (Mar. 2009)

March 2009

volume 25 number 03

Mosquito-Borne Viruses in Georgia, 2008

Human Arbovirus Surveillance West Nile virus (WNV) is a mosquito-borne viral pathogen that was introduced into the United States in 1999. Within four years following its initial detection in New York, WNV was detected in states from the East and West coasts as well as in Mexico and Canada. In Georgia, the virus was first identified in 2001. WNV is now considered endemic in most parts of the U.S., including Georgia.

Figure 1. Human Arboviral Cases, by Month of Onset, Georgia 2008

ArbAorbvoirvuirsusCCaasseessinin GGeeoorrggiiaabbyyMMonotnhthofoOfnOsents2e0t0, 82008

5

LaCrosse Encephalitis

Dengue Fever

4

West Nile Virus

3

Number of Cases

West Nile virus is maintained in birds. It occasionally infects humans who are bitten by mosquitoes that have been feeding on birds. Most people (approximately 80%) infected with WNV do not develop symptoms. About one in five infected persons experiences a mild illness, often termed "West Nile Fever" (WNF), characterized by fever, headache, muscle weakness or myalgia, arthralgia, and sometimes rash. Less than one percent of persons infected with WNV develop neurologic illness ("West Nile Neurologic Disease"

2

1

0

January

February March

April

May

June

July

Month of Onset

August

September October

November December

Table 1. Arbovirus Cases by County of Residence, Georgia 2008

Arbovirus

Month of Onset

County of Residence

Clinical Syndrome

Fatality

DENGUE January

Gwinnett Fever

No

DENGUE March

Cobb

Fever

No

LAC

July

Lowndes Encephalitis

No

LAC

August

Forsyth

Encephalitis

No

WNV WNV WNV WNV WNV WNV WNV WNV

July July August August August September September September

Lee Dougherty Fulton Floyd Cobb Dougherty Floyd Bibb

Fever

No

Fever

No

Altered Mental Status No

Encephalitis

No

Encephalitis

No

Fever

No

Meningitis

No

Encephalitis

No

WNV*

September Gwinnett Asymptomatic

No

WNV*

September Lee

Asymptomatic

No

WNV*

September DeKalb

Asymptomatic

No

WNV*

October

Forsyth

Asymptomatic

No

or WNND) in the form of meningitis, encephalitis, or possibly acute flaccid paralysis. Approximately three to fifteen percent of WNND cases are fatal. Risk of WNND is associated with increasing age and the presence of underlying medical conditions.
Nationwide, 1,338 cases of WNV illness (both WNF and WNND) and 43 deaths were reported to CDC in 2008 (as of February 13, 2009). In Georgia, an acute arboviral infection is a reportable condition; however, the majority of cases of arboviral infection remain undetected if moderate or severe illness does not develop. In 2008, Georgia reported 8 confirmed cases of WNV. Four positive viremic blood donors were also identified, but are not counted as any of the 8 confirmed cases. 5 (62%) of the 8 cases experienced WNV neurologic illness (Altered mental status, encephalitis, and/or meningitis) and 3 (38%) were diagnosed with WNV fever. The four viremic blood donors remained asymptomatic. The average age of cases was 54 years (range 23-76). The average age of those with WNV neurologic illness was 66 years (range 58-76). 7 (88%) of the 8 cases were male. As in past seasons, the majority of cases were reported in August and September (Figure 1). Dougherty and Floyd Counties both reported two WNV cases, followed by Bibb, Cobb, Fulton and Lee Counties which each reported 1 case. See Table 1 for the counties of residence of each case.

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Other Mosquito-Borne Viruses in Georgia West Nile virus is one of several mosquito-borne viruses, also called arboviruses (arthropod-borne viruses) that circulate in Georgia. Other identified arboviruses include Eastern Equine Encephalitis virus (EEE), LaCrosse virus (LAC), and rarely St. Louis encephalitis virus (SLE), which is closely related to WNV. West Nile virus is the most commonly reported arbovirus in Georgia, although LAC infection is probably under-recognized because it usually causes only a mild clinical illness. EEE is the most severe of the arboviral infections, leading to death in 30-50% of symptomatic cases and often leaving survivors permanently disabled.

In addition to the 8 cases of WNV discussed previously, two confirmed cases LaCrosse Encephalitis were reported in Georgia in 2008.

All acute arbovirus infections are reportable in Georgia, including those that are not acquired within the United States. The Georgia Division of Public Health requires all acute arboviral infections to be reported because species of mosquitoes thrive in Georgia that are competent vectors for exotic diseases such as Dengue, Chikungunya and Yellow Fever. Although the risk of local transmission is low, it does exist. There were two internationally acquired cases of Dengue reported in 2008. Please see Table 2 for country of origin.

Table 2. Internationally Acquired Arbovirus Infections in Georgia Residents, by Country of Origin

Arbovirus Infections

Country of Origin

DENGUE

St Barts-Saint Barthelemy

DENGUE

India

Human Testing for WNV and other Arboviruses Commercial tests to detect WNV and other arbovirus antibodies are readily available at most commercial laboratories. During 2009, GDPH recommends that diagnostic testing for human arbovirus infections be performed at commercial laboratories. The Georgia Public Health Laboratory (GPHL) can perform testing for serologic evidence of infection with each of the arboviruses that circulate in Georgia. GPHL does not charge for WNV and arbovirus panel tests, but due to decreased funding for arboviral testing, specimens should only be submitted to GPHL in situations of extreme need. Specimens will not be tested by GPHL unless they meet the criteria as listed below. Please call the Georgia Division of Public Health (404-657-2588) or the appropriate District Health Office before submitting specimens for arboviral testing to assure that the criteria are met for testing

at GPHL. If needed, specimens positive for WNV or other arboviruses at commercial laboratories can be retested at GPHL to verify the results. Please do not submit specimens unless testing criteria are met; ineligible specimens will not be tested.
Table 3. GPHL Arbovirus Testing Criteria for 2009
Adults: To qualify for testing at GPHL, persons must be 18 years or older and meet at least one of the following clinical criteria:
Meningitis, OR Encephalitis, OR Acute onset of profound muscle weakness or acute flaccid
paralysis (including Guillian-Barre syndrome), OR Fever (greater than 100.4F) and at least 2 of the following:
o Headache o Malaise o Arthralgia o Fatigue o Eye Pain Children: To qualify for testing at GPHL, persons must be 17 years or younger and meet at least one of the following clinical criteria: Fever (greater than 100.4F) with ataxia or extrapyramidal signs, OR New onset seizures or increased seizure activity in children with pre-existing seizure disorders, OR Encephalitis, OR Acute onset of profound muscle weakness or acute flaccid paralysis (including Guillian-Barre syndrome)
Note: Because meningitis due to other causes is rather frequent among children during arbovirus transmission season, children with meningitis will not be tested unless they meet additional criteria described above, or after other bacterial and viral causes have been ruled out.
For more information regarding arbovirus activity in Georgia, please visit http://health.state.ga.us/epi/vbd/mosquito.asp or call 404-657-2588.
Arbovirus Surveillance in Sentinel Species In addition to surveillance for human disease caused by arboviruses in Georgia, GDPH and its partners conduct surveillance for arboviruses in horses, birds, and mosquitoes in an effort to determine local risk of human disease. However, decreased funding will make it less likely that arboviral surveillance programs will be sustainable. Below is a summary of arbovirus surveillance results in 2008.
Bird Surveillance The number of birds being submitted for testing has continued to decrease, and dead bird surveillance appears to be losing ground as a surveillance tool, especially where mosquito surveillance is being done. In areas where no mosquito

Division of Public Health http://health.state.ga.us
S. Elizabeth Ford, M.D., M.B.A., F.A.A.P. Acting Director, State Health Officer
Acting Deputy Director Health Information, Policy, Strategy, &
Accountability

John M. Horan, M.D., M.P.H. State Epidemiologist
Director, Epidemiology Section http://health.state.ga.us/epi
Cherie Drenzek, D.V.M., M.S. Director, Acute Disease Epi Section

Georgia Epidemiology Report Editorial Board
Carol A. Hoban, M.P.H., Ph.D. Editor Kathryn E. Arnold, M.D.
Cherie Drenzek, D.V.M., M.S. John M. Horan, M.D., M.P.H. S. Elizabeth Ford, M.D., M.B.A., F.A.A.P. Angela Alexander - Mailing List Jimmy Clanton, Jr. - Graphic Designer

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Georgia Department of Human Resources
Division of Public Health

Two Peachtree St., N.W. Atlanta, GA 30303-3186 Phone: (404) 657-2588
Fax: (404) 657-7517
Please send comments to: gaepinfo@dhr.state.ga.us

surveillance occurs, bird surveillance can be useful in predicting increased risk of human disease. It is also useful for providing a trigger for public health messages concerning personal protection measures to take to lower the risk of mosquito-borne diseases.
Horse Surveillance No horses had laboratory confirmed WNV infections in 2008. Twenty-three horses and 1 dog had laboratory confirmed EEE infections, indicating an elevated risk for EEE locally. Horse surveillance has been useful in rural counties where bird and mosquito surveillance resources are few. However, reduced disease reporting for horses, due to increased immunity, increased vaccination, and decreased interest in testing, makes this surveillance system less useful as a sentinel for determining increasing human disease risk.

WNV is now considered to be endemic throughout Georgia (Figure 2). However, lack of funding needed to collect mosquito population data and test vector species makes it difficult to predict human risk for any of the arboviruses currently found in Georgia or to help detect any newly introduced arboviruses. Continued monitoring of mosquitoes is our best course of action for reducing the incidence of arboviral diseases in Georgia. Information obtained from these surveillance efforts should lead to responsible and informed decisions about mosquito control as well as public education about reducing mosquito breeding in yards and neighborhoods and prevention of mosquito bites.
For more information regarding arbovirus activity in Georgia, please visit http://health.state.ga.us/epi/vbd/mosquito.asp or call 404-657-2588.

Like humans, horses are incidental hosts for WNV and other arboviral infections. Reports of positive horses in an area indicate increased human risk because mammal-biting mosquitoes are transmitting virus. Public health contacts the owners of arboviral-positive horses to educate them about their personal risk of disease and risk-reduction measures they can take on their farm to prevent future cases.

Figure 2: WNV-Positive Counties, 2001-2008, Georgia

Mosquito Surveillance Mosquito surveillance is conducted to detect the presence of arboviruses in potential vectors and to help guide and evaluate mosquito control programs. Some level of mosquito surveillance was conducted in 28 of 159 Georgia counties in 2008. In addition, the U.S. Army Center for Health Promotion and Preventive Medicine South (USA-CHPPM) conducted mosquito surveillance on military bases in Georgia, sharing those data with GDPH. Intensive mosquito surveillance was conducted in fewer than 10 counties. Five counties reported WNV-positive mosquito pools. The first positive mosquitoes were detected in metro Atlanta in early July. The last positive pool was collected in metro Atlanta in October, with peaks in numbers of positive pools occurring in August.

Culex quinquefasciatus, our primary WNV vector in Georgia, is a container-breeding mosquito that flies only a short distance

2001- human horse mosquito positive

2008 cases case

pool

bird

from its breeding site when searching for a blood meal.

total 227 303

628

1889

Personal protection measures are ways in which the public

mean 28.4 37.9

78.5 236.1

can help reduce the risk of WNV for themselves and in their

community. These include: Wearing repellent. Dumping out standing water at least once a week. Keeping grass cut, leaves raked, and vegetation trimmed.

Counties in Georgia with labotory confirmed infections in WNV+ mosquitoes, birds, horses, or human cases reported between 2001-2008 (in blue).

Applying larvicide to areas of standing water that cannot Counties with no reported positives (in white) have done little

be dumped out or drained.

to no surveillance; WNV is considered endemic in Georgia.

Keeping gutters clear of debris.

Picking up trash in yards and neighborhoods. Removing saucers from under outdoor potted plants. Keeping window screens repaired.

Authors: Meghan M. Weems, M.P.H.; Rosmarie Kelly, Ph.D., M.P.H.

Removing or covering all containers that may hold

water.

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The Georgia Epidemiology Report Epidemiology Branch Two Peachtree St., NW Atlanta, GA 30303-3186
Providers can contact Public Health IMMEDIATELY 24 hours a day, 7 days a week, by calling: 1-866-PUB-HLTH (1-866-782-4584) to report immediately notifiable diseases and public health emergencies

PRESORTED STANDARD U.S. POSTAGE
PAID ATLANTA, GA PERMIT NO. 4528

March 2009

Volume25Number03

Reported Cases of Selected Notifiable Diseases in Georgia, Profile* for December 2008

Selected Notifiable Diseases
Campylobacteriosis Chlamydia trachomatis Cryptosporidiosis E. coli O157:H7 Giardiasis Gonorrhea Haemophilus influenzae (invasive) Hepatitis A (acute) Hepatitis B (acute) Legionellosis Lyme Disease Meningococcal Disease (invasive) Mumps Pertussis Rubella Salmonellosis Shigellosis Syphilis - Primary Syphilis - Secondary Syphilis - Early Latent Syphilis - Other** Syphilis - Congenital Tuberculosis

Total Reported for December 2008
2008 37 2913 22 0 55 1190 21 4 18 5 0 0 0 0 0 132 40 15 72 31 75 1 34

Previous 3 Months Total Ending in December

2006 2007 2008

129

147

116

9270

0

8955

81

47

75

6

14

8

174

202

167

4611

0

3632

35

35

39

12

13

12

44

37

51

14

16

11

1

3

2

6

5

2

0

0

0

7

3

7

0

0

0

458

611

542

597

458

219

30

0

33

130

0

185

93

0

110

236

0

275

3

0

2

126

115

99

Previous 12 Months Total Ending in December

2006 2007 2008

580

693

689

40010

0

42399

281

240

263

43

49

44

679

708

702

20402

0

16184

123

128

149

56

69

57

198

157

187

38

43

43

8

11

35

20

24

18

4

0

3

31

15

26

0

0

0

1840

2033

2301

1382

1647

1103

124

0

150

482

0

763

385

0

557

1019

0

1342

10

0

11

507

473

478

* The cumulative numbers in the above table reflect the date the disease was first diagnosed rather than the date the report was received at the state office, and therefore are subject to change over time due to late reporting. The 3 month delay in the disease profile for a given month is designed to minimize any changes that may occur. This method of summarizing data is expected to provide a better overall measure of disease trends and patterns in Georgia.
** Other syphilis includes latent (unknown duration), late latent, late with symptomatic manifestations, and neurosyphilis.
AIDS Profile Update

Report Period
Latest 12 Months

Disease

Total Cases Reported*

Classification <13yrs

>=13yrs Total

HIV, non-AIDS 13

2,964

2,977

Percent Female MSM

26

31

Risk Group Distribution %

IDU

MSM&IDU HS

Unknown Perinatal White

2

1

4

62

<1

22

Race Distribution %

Black

Hispanic Other

73

4

1

2/08-01/09 AIDS

1

1,897

1,898

25

30

2

1

6

61

<1

23

70

5

<1

Five Years Ago:**

HIV, non-AIDS 92

1,862

1,954

36

30

9

3

15

42

<1

20

76

3

1

02/04-01/05 AIDS

8

1,463

1,471

28

32

7

3

15

44

<1

18

77

4

<1

Cumulative: HIV, non-AIDS 226

13,356

13,582

31

29

6

2

10

53

<1

21

74

4

1

07/81-01/09 AIDS

239

33,817

34,056

20

43

14

5

14

24

<1

30

67

3

<1

Yrs - Age at diagnosis in years

MSM - Men having sex with men

IDU - Injection drug users

HS - Heterosexual

* Case totals are accumulated by date of report to the Epidemiology Section ** Due to a change in the surveillance system, case counts may be artificially low during this time period

***HIV, non-AIDS was not collected until 12/31/2003

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