Georgia epidemiology report, Vol. 20, no. 4 (Apr. 2004)

April 2004

volume 20 number 4

Division of Public Health http://health.state.ga.us
Kathleen E. Toomey, M.D., M.P.H. Director
State Health Officer
Epidemiology Branch http://health.state.ga.us/epi
Paul A. Blake, M.D., M.P.H. Director
State Epidemiologist
Mel Ralston Public Health Advisor
Georgia Epidemiology Report Editorial Board
Carol A. Hoban, M.S., M.P.H. - Editor Kathryn E. Arnold, M.D.
Paul A. Blake, M.D., M.P.H. Susan Lance-Parker, D.V.M., Ph.D. Kathleen E. Toomey, M.D., M.P.H.
Angela Alexander - Mailing List Jimmy Clanton, Jr. - Graphic Designer
Georgia Department of Human Resources
Division of Public Health Epidemiology Branch
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
The Georgia Epidemiology Report is a publication of the Epidemiology Branch,
Division of Public Health, Georgia Department of Human Resources

Mosquito-Borne Viruses in Georgia 2003
West Nile virus (WNV) is a mosquito-borne viral pathogen introduced into the United States in 1999. Within four years after its initial detection in New York, WNV was detected in states on the East and West coasts as well as in Mexico and Canada. The virus was first identified in Georgia in 2001. WNV is now considered endemic in most parts of the U.S., including Georgia.
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 persons infected experience 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" 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 with the presence of underlying medical conditions.
Nationwide, 9175 cases of WNV illness and 230 deaths were reported to CDC in 2003. In Georgia, an acute arboviral infection is a reportable condition; however, the majority of cases of arboviral infection remain undetected when moderate or severe illness does not develop. In 2003, the Georgia Division of Public Health (GDPH) reported 55 residents infected with WNV, four of whom developed fatal illness. The first human case occurred in Bartow county in June. The last human case reported in Georgia in 2003 occurred in Telfair county in December. Twenty-nine (53%) cases were diagnosed with WNND while 21 (38%) developed WNF. Five (9%) of the reported WNV infections did not develop any symptoms of illness. The average age of all persons infected was 51 years (range 5 83 years). The average age of fatal cases was 65 years (range 51 83 years). Thirty-seven (67%) of the 55 cases were male. The majority of cases occurred in September.
Clinical Guidance
Due to its broad spectrum of illness, WNV can be difficult to identify clinically. In 2003, healthcare providers were asked to complete a case report form that assessed whether a variety of signs and symptoms were associated with the acute WNV cases they treated. The most commonly reported signs and symptoms included fever (93% of cases), headache (67%), fatigue (67%), malaise (54%), nausea (50%), vomiting (37%), anorexia (35%), muscle weakness (35%), arthralgia (30%), myalgia (30%), rash (22%), and eye pain (22%). WNF cases reported some symptoms (fatigue, headache, arthralgia, myalgia, eye pain) much more frequently than WNND cases, presumably due to the inability of some persons with acute neurologic illness to report subjective symptoms.
WNV-Associated Morbidity
Anecdotal reports have indicated that WNV infection can lead to prolonged morbidity in some persons. In an effort to assess the duration and extent of WNV-associated morbidity in affected Georgia residents, symptomatic WNV cases reported to GDPH in 2003 were interviewed at one, three, and six months following acute onset of illness. Interviews were conducted to inquire about the presence and persistence of certain signs and symptoms that were not present before acute WNV illness. Interviews are still being conducted; as of 3/1/04, 63 interviews have been conducted (33 one-month, 26 three-month, and 4 six-month interviews), representing 36 cases. Preliminary data from the one-month (average 37 days after acute onset) and three-month (average 105 days) interviews are displayed in Table 1. The P value assesses the significance of the difference between the frequencies reported at one and three months. P value < 0.05 is considered statistically
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significant (in italics). The high proportions of persons reporting symptoms during the interviews, in conjunction with the lack of significant differences between the frequency of symptoms reported at one and three months, indicates that many persons do not quickly recover from WNV-associated morbidity.

years' criteria will be re-instituted. For this reason, please call the Georgia Division of Public Health (GDPH) before submitting specimens for arboviral testing (404-657-2588). As in past years, all specimens positive for WNV or other arboviruses at commercial laboratories will be retested at GPHL to verify the results.

Table 1. Percentage of Cases Reporting Persistent Symptoms Following Acute WNV Illness, Georgia, 2003

Sign/Symptom Fatigue Muscle Weakness Sleepiness Weight Loss Difficulty Walking Poor Appetite Difficulty Remembering Muscle Pain Headache Confusion Insomnia Irritability Balance Problems Tremors Shortness of Breath Disoriented Depression Blurred Vision Eye Pain

One Month (%) 70 58 55 55 52 48 45 45 42 39 39 33 33 33 33 27 27 24 24

Three Months (%) 54 54 35 15 27 15 35 35 31 27 27 19 31 23 23 19 19 12 12

P Value 0.2113 0.7745 0.1271 0.0020 0.0563 0.0077 0.4001 0.4001 0.3580 0.3151 0.3151 0.2264 0.8342 0.3878 0.3878 0.4710 0.4710 0.3162 0.3162

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 St. Louis Encephalitis virus (SLE), which is closely related to WNV. WNV is the most commonly reported arbovirus in Georgia, although LAC infection is probably under-recognized because it usually causes only mild clinical illness. EEE is the most severe arboviral infection, leading to death in 30-50% of symptomatic cases and often leaving survivors permanently disabled. In 2003, two human cases of EEE were reported in Georgia. One case was fatal. In addition, one non-fatal case of LaCrosse meningitis was reported. No cases of SLE infection were reported.
Testing for WNV and other Arboviruses
While commercial tests to detect WNV antibodies are readily available, submitting specimens to the Georgia Public Health Laboratory (GPHL) is preferable in that all specimens submitted are tested for serologic evidence of infection with each of the arboviruses that circulate in Georgia. GPHL does not charge for WNV and arbovirus panel tests. Criteria for testing at GPHL were instituted in 2001 to conserve limited laboratory resources and were intended primarily to detect neurologic manifestations of arboviral infections. The criteria have been modified to encourage healthcare providers in Georgia to use GPHL for testing. Figure 1 displays the criteria for testing in 2004. Should submissions exceed the laboratory's capacity, then the previous

Arbovirus Surveillance
In addition to surveillance for human disease caused by arboviruses in Georgia, GDPH and its partners conduct surveillance for arboviruses in birds, horses, and mosquitoes. Below is a summary of arbovirus surveillance results in 2003.
Horse Surveillance
Like humans, horses are incidental hosts for WNV and other arboviral infections. Detection of arboviral infection in horses provides a valuable means to recognize foci of viral activity. Reports of positive horses in an area indicate increased human risk because mammal-biting mosquitoes are transmitting virus.
Georgia reported only about one-third as many equine cases of WNV in 2003 as in 2002. This decrease may be attributable to natural immunity or increased vaccination. Sixty cases of WNV were reported in equines in 36 counties in 2003. Fifty-two (87%) cases had onsets from August through October, although onsets ranged from mid-May through the end of November. Twenty-seven percent of cases were fatal (including those euthanized), a figure similar to case fatality rates in other states. Twenty percent of Georgia's WNV positive horses were reportedly vaccinated in 2003. It is likely that most of these represent cases where the vaccine had been handled or stored improperly, the horse was due for a booster, or the vaccine was given too late and did not have time to become effective before actual infection. Thus, not all "vaccinated" horses may have truly been vaccinated according to label. For the vaccine to be most effective, it must be given in two doses, 3 to 6 weeks apart, with the last dose given 4 weeks before the beginning of the mosquito season. An annual booster is needed.

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Figure 1. Criteria for Arbovirus Testing at Georgia Public Health Laboratory

Adults To qualify for testing at GPHL, persons must be 18 years or older and meet at least one of the following criteria:



Meningitis, OR



Encephalitis, OR



Acute onset of profound muscle weakness or acute flaccid paralysis (including Guillain-Barr 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 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 Guillain-Barr 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.

EEE was at least as important as WNV in causing morbidity and mortality among horses in Georgia in 2003. There were 81 confirmed cases of EEE in 47 counties in 2003. Onsets were reported from January through December. The case fatality rate was 85% (including those euthanized), which is consistent with historical case fatality rates of up to 90%. This is notably higher than the average case fatality rate for WNV. Twenty-five percent of horse owners reported having vaccinated their horses for EEE before onset of illness. It is likely that the vaccine was either not given early enough to prevent disease, or the vaccine was handled or administered improperly in most of these cases. It is important that horse owners in Georgia vaccinate for both WNV and EEE before the 2004 mosquito season begins (usually in April, or earlier if weather is mild).
Bird Surveillance
Bird mortality surveillance in Georgia remains a sensitive tool to determine the geographic range and extent of WNV and other arbovirus activity in the state and to predict risk of human disease. In 2003, 2131 birds were submitted from 114 counties; 479 WNV-positive birds were found in 65 of those counties. The first positive bird in 2003 was submitted for testing on 1/8/03, but the second WNV-positive bird was not submitted until 4/24/03. The last positive bird was submitted on 11/23/03. While more than 120 species of birds were submitted for testing, blue jays, American crows, and mourning doves made up 43% of the birds submitted. Only about 1% of the mourning doves submitted tested positive, but 68% of the crows and 55% of the blue jays submitted were positive for WNV.
Nineteen birds tested positive for EEE in 12 counties. The first EEEpositive bird was submitted on 4/25/03 and the last was submitted on 11/24/03.

Mosquito Surveillance
Mosquito surveillance is conducted to detect arboviruses in potential vectors and guide mosquito control programs. Some level of mosquito surveillance was conducted in 28 counties in 2003. 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 surveillance was conducted in fewer than 10 counties. Seven counties reported WNV positive mosquito pools. These positive mosquitoes were collected in May in south Georgia, and starting in July throughout the rest of Georgia. The last positive pool was collected at the end of September, with a peak in number of positive pools at the end of August. Seventy-five percent of the positive pools collected were Culex quinquefasciatus, the southern house mosquito, which is a primary WNV vector in Georgia. An additional 21% were unspeciated Culex, most of which were likely to be Culex quinquefasciatus.
EEE was isolated from 4 mosquito pools, 3 collected in June and 1 collected in July. One pool testing positive for EEE was Culex salinarius; the rest of the positive mosquitoes were Culiseta melanura, a bird-biting species that maintains the EEE virus in birds.
One human case was the only evidence of LAC activity was detected in Georgia in 2003. One pool of Cx quinquefasciatus collected in south Georgia in late September tested positive for both SLE and WNV. Surveillance data in recent years indicate that EEE activity may be high again in Georgia in 2004, so Georgians may continue to be at risk for severe human illness.
For more information regarding arbovirus activity in Georgia, please visit http://health.state.ga.us/epi/vbd/mosquito.shtml or call 404-657-2588.

Surveillance indicates there is some level of transmission occurring almost year-round. Although bird submissions drop off considerably in October, currently available data suggest that detectable transmission occurs from April or May of one year until January or February of the next, depending on meteorological conditions.

Authors: Katherine Bryant, M.P.H., Rosmarie Kelly, Ph.D., M.P.H. and Laurel E. Garrison, M.P.H.

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The Georgia Epidemiology Report Epidemiology Branch Two Peachtree St., NW Atlanta, GA 30303-3186

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

April 2004

Volume 20 Number 4

Reported Cases of Selected Notifiable Diseases in Georgia Profile* for January 2004

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 January 2004 34 353 16 1 56 219 7 42 58 0 1 3 0 0 0 85 48 8 16 34 25 0 13

Previous 3 Months Total

Ending in January

2002

2003 2004

106

154

92

8049

8675

2243

27

23

39

9

7

3

183

212

174

4666

4472

1209

41

22

23

153

146

125

94

149

145

2

5

1

0

1

1

16

8

13

1

0

0

4

6

6

0

0

0

333

334

384

460

604

151

30

28

30

61

95

81

204

178

108

193

191

123

4

3

1

162

122

105

Previous 12 Months Total

Ending in January

2002

2003

2004

642

673

598

32925

35148

29650

159

120

132

48

46

27

942

936

828

18514

18814

14676

112

78

83

918

515

783

418

504

682

11

21

31

1

6

10

52

32

36

7

2

3

24

31

32

0

0

0

1699

1957

2060

832

1901

1053

99

109

126

303

355

435

693

717

678

864

787

745

22

15

9

551

559

502

* 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.

Note: Due to activities to ensure completeness and timeliness of reporting, STD data in this edition of the GER are not current. STD data will be updated and

complete in the next GER.

AIDS Profile Update

Report Period
Latest 12 Months: 04/03-03/04 Five Years Ago: 04/99-03/00 Cumulative: 07/81-03/04

Total Cases Reported* <13yrs >=13yrs Total

5

2,053 2,058

12

1,597 1,609

216

27,993 28,209

Percent Female
27.0
26.3
18.5

Risk Group Distribution (%) MSM IDU MSM&IDU HS Blood Unknown

34.0

6.6

1.6

14.4

1.6

41.9

33.8

14.0

3.7

20.5

1.7

26.4

46.7

16.6

5.2

14.3

1.9

15.3

Race Distribution (%) White Black Other

21.4 74.7

3.9

19.5 77.9

2.6

32.8 64.6

2.6

MSM - Men having sex with men

IDU - Injection drug users

HS - Heterosexual

* Case totals are accumulated by date of report to the Epidemiology Section

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