September 2000 volume 16 number 9 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. - Graphics 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) 657-2608 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 West Nile Virus and West Nile Encephalitis West Nile virus (WNV) emerged in the Western Hemisphere during 1999 when it caused an outbreak of encephalitis among humans, horses, and wild birds in the New York City (NYC) area. The mosquito-borne flavivirus is blamed for 62 cases of human encephalitis (including 7 fatalities), 25 cases of equine encephalitis (including 9 fatalities), and the death of hundreds of wild birds, which were mostly crows, during the summer and fall of 1999. This year, hundreds of birds that succumbed to WNV infection have been found throughout the northeastern region of the United States and WNV positive mosquito pools have been identified in NY, NJ, CT, and MA. As of August 28, 2000 the currently known geographic distribution of WNV has expanded south to Baltimore, MD (where an infected crow was found in 1999), north to Clinton County, NY (which borders Canada and VT), east to Boston, MA, and west to Buffalo, NY. Five human cases of West Nile encephalitis have been identified this year through August 28, 2000. All five individuals are over 60 years of age and live in close proximity to areas where positive birds and mosquito pools were identified earlier this season. The emergence of WNV in the northeastern United States has demonstrated the ease with which infectious diseases may be introduced to and established within new geographic areas. The 1999 outbreak also demonstrated that cooperation between medical, veterinary, public health, laboratory, and wildlife biology professionals is crucial to quickly detect and effectively respond to emerging diseases. Due to concern that the virus has spread via migrating birds and will establish itself in new geographic areas, federally funded surveillance is now being conducted in 21 states or jurisdictions along the Atlantic and Gulf Coasts. This issue of the Georgia Epidemiology Report (GER) provides clinical and epidemiologic information about West Nile virus and West Nile encephalitis, and details the surveillance activities that are being conducted in Georgia. Up-to-date information about WNV and surveillance for WNV in Georgia may be found on the public health website at http://health.state.ga.us. Agent: WNV is a flavivirus. It belongs to the Japanese encephalitis complex, which includes West Nile virus, St. Louis encephalitis, Japanese encephalitis, Murray Valley, and Kunjiin. Reservoir and Mode of Transmission: Wild birds are the primary reservoir hosts. The virus is transmitted from infected birds to other birds or mammals by mosquitoes. Culex ssp. are probably the principal mosquito vectors; however, WNV positive pools of Aedes japonicus and Aedes triseriatus have also been found this season near the epicenter of the 1999 outbreak. Aedes japonicus and Aedes triseriatus are both active during the day, so measures to prevent mosquito bites should be taken at all times while outdoors. Humans and animals other than birds are dead end hosts; they do not play a role in the natural transmission of the virus. Direct human-to-human or bird-to-human transmission is not known to occur. Occurrence: Historically, WNV has caused human encephalitis sporadically and in outbreaks in parts of Africa, West Asia, Eastern Europe, and the Middle East. The virus was identified in the Western Hemisphere for the first time in 1999 when it caused an outbreak of human encephalitis in the New York City area. Seroprevalence rates in endemic areas overseas have ranged from 10% to 50%. The 1999 New York strain has been sequenced and found to be most similar to a strain first isolated from a goose in Israel in 1998. the United States. The Georgia Department of Human Resources, Incubation Period: Usually 6 days (range 5 to 15 days) after the bite of Division of Public Health received almost $200,000 to boost laboratory an infected mosquito. capacity and oversee surveillance for West Nile virus in humans, horses, and wild birds. Symptoms: In endemic areas overseas, asymptomatic infections and milder illnesses are more common than central nervous system (CNS) Human Surveillance: disease. The ratio of symptomatic to asymptomatic cases ranges from Active surveillance for viral encephalitis in humans is being 1:140 to 1:300. Milder illnesses have usually been characterized by fever, conducted in 49 counties in South Georgia and coastal Georgia headache, myalgias, arthralgias, lymphadenopathy, and a maculopapular (Valdosta, Albany, Savannah, Waycross, and Brunswick Health or roseolar rash affecting the trunk and extremities. Pancreatitis, Districts). Diagnostic support is being offered to physicians hepatitis, and myocarditis have occasionally been reported. CNS treating hospitalized patients with symptoms of encephalitis when involvement is rare and predominantly affects older patients. A a bacterial etiology and herpes simplex virus have been ruled out. serosurvey conducted at the epicenter of the 1999 NYC outbreak revealed Acute- and convalescent-phase sera and CSF may be submitted for 19 seropositive individuals (of 677 surveyed) who exhibited mild a panel of tests (to be performed by the Florida Department of symptoms or no symptoms. Seroprevalence in the surveyed area was Public Health Laboratory Services) that includes screening for estimated at 2.6%. WNV and other arboviruses. Enhanced passive surveillance for arboviral infections in humans is Special Diagnostic Clues for West Nile Encephalitis: Arboviral conducted throughout the state. Appropriate clinical samples may encephalidites typically cannot be distinguished without specific labora- be submitted to the Georgia Public Health Laboratory (GPHL) for tory testing. However, viral encephalitis associated with severe, diffuse an arbovirus panel that will include screening for WNV. Samples muscle weakness (characterized by flaccid paralysis and/or an axonal neuropa- are being sent to the Centers for Disease Control and Prevention thy by EMG testing) was a unique characteristic of the West Nile encepha- (CDC) laboratory at Fort Collins, Colorado for testing now; litis cases that occurred during the 1999 outbreak. Neurologic illness however, GPHL will have the capacity to perform an arbovirus (including both encephalitis and meningitis) is more common among older panel in the future. Health care providers are reminded that WN adults infected with WNV; therefore testing for West Nile virus should encephalitis cannot be clearly distinguished from other arboviral also be considered for adult patients hospitalized with aseptic meningi- encephalidites based on clinical information alone. EEE, SLE, tis. This is in contrast to children with aseptic meningitis, who are more and LaCrosse encephalitis should be considered for residents of likely to have enteroviral infection, especially in the late summer and early Georgia who present with an illness that is clinically compatible fall. For this reason, West Nile viral testing is less likely to be positive with an arboviral infection. Therefore, screening for WNV alone among patients aged 16 and younger who present with aseptic meningi- will not be performed; rather, a panel of tests that includes EEE tis. Physicians might also consider WNV infection in the differential and SLE will be performed on all submissions. diagnosis of Guillain-Barr syndrome, especially when associated with fever, altered mental status or pleocytosis. Serologic testing for patients Equine Surveillance: who have milder symptoms (such as fever and headache only), are asymp- Enhanced passive surveillance for equine encephalitis is being tomatic, or have simply been bitten by mosquitoes is not necessary or conducted statewide. Large animal veterinarians are encouraged to recommended. The likelihood of WNV infection among these patients seek diagnostic support from Tifton Veterinary Diagnostic is extremely low, especially in the absence of an outbreak. Laboratory or Athens Veterinary Diagnostic Laboratory for all horses with clinical CNS disease manifestations. Testing will be Differential Diagnoses: (1) EEE, SLE, and LaCrosse encephalitis are provided free of charge for horses exhibiting clinical signs of endemic to Georgia and should be considered for any illness that is encephalitis and will include screening for WNV and other clinically compatible with an arboviral infection. (2) Enteroviruses arboviruses after rabies virus is ruled out as an etiology. circulate widely during the late summer and early fall and should especially be considered for patients aged 16 years and younger with Avian Surveillance: encephalitis or aseptic meningitis. A polymerase chain reaction (PCR) Active surveillance for arboviruses in wild birds is being performed test or viral culture of cerebrospinal fluid (CSF) may be used to diagnose by the Southeastern Cooperative Wildlife Diseases Study enteroviral infection. (3) Herpes simplex viruses may be considered in (SCWDS) at the University of Georgia College of Veterinary patients with encephalitis and clinical signs and symptoms such as Medicine. Targeted and non-targeted collection of several species bizarre behavior, speech disturbances, olfactory hallucinations, focal of resident and migratory birds is being conducted in Coastal, seizures, or EEG changes localized to the temporal lobes. A PCR test or Coastal Plain and Piedmont regions of the state. Blood is viral culture of CSF can be diagnostic. (4) Varicella should be considered collected and tested for antibodies to arboviruses including WNV. in patients with encephalitis and a vesicular rash. As of August 28, 2000, 1357 birds have been collected throughout Georgia. Nearly half have been tested by virus isolation techniques Treatment: There is currently no known effective antiviral therapy or with no evidence of arboviral infection. vaccine for WNV. Milder illnesses do not require therapy. In more severe cases, intensive supportive therapy is indicated. Passive surveillance for dead or ill birds is being conducted statewide. Birds with no obvious causes of death or signs of trauma are being reported to county health departments. Dead Surveillance for West Nile virus in crows and bluejays that have been dead for less than 24 hours and Georgia: are in good condition, as well as individuals from bird die-offs are Georgia is one of the 21 jurisdictions that received federal funding to monitor the spread and geographic distribution of West Nile virus in submitted to SCWDS for necropsy and WNV testing. As of August 28, 2000, 33 dead birds have been submitted and of the 26 birds for which results are available, none have shown evidence of -2 - arboviral infection. Identification of WNV as the cause of the 1999 outbreak: Unusual bird die-offs were observed in the NYC area during the summer of 1999, before recognition of any human cases of encephalitis. The avian morbidity and mortality, which primarily affected crows, was attributed to an unknown encephalitic infection. While veterinarians and wildlife biologists suspected that the avian epidemic was somehow related to the human outbreak of encephalitis, they were convinced that the birds were not dying of EEE or SLE because the zoos flock of emus (which are excellent sentinels for EEE) was healthy and SLE has never been known to be fatal to birds. Their suspicions were confirmed when WNV was isolated from affected humans and crows. Because crows are particularly susceptible to WNV, and the vast majority of infected crows die, they are considered an important early warning sign that infection could be present in a specific area. In fact, the discovery of WNV-positive dead crows in the NYC area this year preceded the identification of positive mosquito pools by 6 weeks, the first human case by 8 weeks, the first horse case by 12 weeks and the seroconversion of a sentinel chicken by 12 weeks. Dead bird surveillance will continue to be an important component of surveillance for WNV in Georgia during 2001. If evidence of WNV or other arboviruses is found in Georgia, the public will be alerted and encouraged to eliminate mosquito breeding habitats from around their homes and to protect themselves and their families from mosquito exposure. Adult and/or larval mosquito control may be conducted at the discretion of local health authorities. How to Avoid Exposure to Arboviruses The best way to prevent infections with West Nile virus and other mosquito-borne diseases is to avoid getting mosquito bites. Other viruses that are transmitted by mosquitoes, including those that cause St. Louis Encephalitis (SLE) and Eastern Equine Encephalitis (EEE), already exist in Georgia and the following precautions should be taken to prevent mosquito bites: Minimize time spent outdoors when mosquitoes are most active. If you go outdoors while mosquitoes are active, cover up by wearing shoes, socks, long-sleeved shirts, and long pants. Consider using a mosquito repellant that contains DEET (N, N-diethyl-methyl-metatoluamide) on exposed skin. Use products containing 10% or less DEET for children and no more than 30% for adults. Do NOT use products containing DEET on infants. Carefully read and follow directions on the container and wash treated skin when mosquito exposure has ended. Make sure your home, porch, and patio have tight-fitting screens that keep mosquitoes out. All mosquitoes need standing water for the first stages of development. To eliminate stagnant water around your home where mosquitoes can lay eggs: Dispose of old tin cans, jars, tires, plant pots, and any other container that can hold water. Store wheelbarrows, buckets, boats, etc. upside down so that water cannot accumulate in them. Inspect rain gutters and downspouts and remove any leaves and other debris. Empty stagnant bird baths, lily ponds, small wading pools, etc. at least once a week. Properly maintain and treat backyard swimming pools. Cover any pool not in use so rainwater and leaves do not accumulate in it. Be sure the cover does not hold pockets of water. Additional Reading 1. Tsai TF, Popovici F, Cernescu C, Campbell GL, Nedelcu NI. West Nile encephalitis epidemic in southeastern Romania. Lancet. 1998;352:767-771. 2. Hubalek Z, Halouzka, J. West Nile fevera reemerging mosquito-borne viral disease in Europe. Emerg Infect Dis. 1999;5:643-650. 3. Han LL, Popovici F, Alexander JP Jr, et al. Risk factors for West Nile virus infection and meningoencephalitis, Romania, 1996. J Infect Dis. 1999;179:230-233. 4. Lanciotti RS, Roehrig JT, Deubel V, et al. Origin of the West Nile virus responsible for an outbreak of encephalitis in the northeastern United States. Science. 1999:286:2333-2337. 5. Jia XY, Briese T, Jordan I, et al. Genetic analysis of West Nile New York 1999 encephalitis virus. Lancet. 1999;354:1971-1974. 6. Cunha BA. West Nile encephalitis. Infect Dis Practice. 1999;23:85-90. 7. Cernescu C, Nedelcu NI, Tardei G, Ruta S, Tsai T. Continued transmission of West Nile virus to humans in southeastern Romania, 1997-1998. J Infect Dis. 2000;181:710-712. MMWR: 1999;48:845-49. 8. CDC. Update: surveillance for West Nile virus in overwintering mosquitoesNew York, 2000. MMWR. 2000;49:178-179. 9. CDC. Update: West Nile Virus isolated from mosquitoes New York, 2000. MMWR. 2000;49:211. 10. CDC. Outbreak of West Nile-like viral encephalitisNew York, 1999. MMWR. 1999;48:845-849. 11. CDC. Update: West Nile-like viral encephalitisNew York, 1999. MMWR. 1999;48:890-892. 12. CDC. Update: West Nile virus encephalitisNew York, 1999. MMWR. 1999:48:944-946, 955. 13. CDC. Guidelines for surveillance, prevention, and control of West Nile virus infectionUnited States. MMWR. 2000;49:2528. 14. CDC. West Nile Virus Activity New York and New Jersey, 2000. MMWR. 2000;49:640-642. 15. CDC. Update: West Nile Virus Activity Northeastern United States, January-August 7, 2000. MMWR. 2000;49:714717. This article was written by Catherine Rebmann, M.P.H. -3 - The Georgia Epidemiology Report Epidemiology Branch Two Peachtree St., NW Atlanta, GA 30303-3186 Bulk Rate U.S. Postage Paid Atlanta, Ga Permit No. 4528 September 2000 Volume 16 Number 9 Reported Cases of Selected Notifiable Diseases in Georgia Profile* for June 2000 Selected Notifiable Diseases Total Reported for June 2000 2000 Previous 3 Months Total Ending in June 1998 1999 2000 Previous 12 Months Total Ending in June 1998 1999 2000 Campylobacteriosis 80 Chlamydia genital infection 2382 Cryptosporidiosis 5 E. coli O157:H7 6 Giardiasis 101 Gonorrhea 1579 Haemophilus influenzae (invasive) 7 Hepatitis A (acute) 27 Hepatitis B (acute) 24 Legionellosis 2 Lyme Disease 0 Meningococcal Disease (invasive) 4 Mumps 0 Pertussis 2 Rubella 0 Salmonellosis 200 Shigellosis 17 Syphilis - Primary 11 Syphilis - Secondary 26 Syphilis - Early Latent 47 Syphilis - Other** 45 Syphilis - Congenital 1 Tuberculosis 45 205 219 191 5889 9686 7175 24 33 26 30 7 11 245 244 261 4845 6056 4314 13 27 24 209 131 78 50 48 62 3 0 4 2 0 0 19 23 13 1 1 0 15 10 8 0 0 0 312 423 379 383 58 62 29 22 30 68 54 69 207 174 132 239 158 130 5 1 4 158 186 181 849 17932 116 51 1075 17205 52 848 276 7 12 106 2 26 0 1377 1397 141 291 959 991 17 622 830 28850 194 60 1288 21188 87 753 170 5 1 80 2 37 0 2023 672 123 243 789 767 17 630 623 30043 146 50 1377 20361 80 339 263 11 0 65 5 61 0 1895 284 148 314 637 733 20 657 * 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. Report Period Latest 12 Months: 7/99 - 6/00 Five Years Ago: 7/94 - 6/95 Cumulative: 7/81 - 6/00 Total Cases Reported* Percent Female AIDS Profile Update Risk Group Distribution (%) MSM IDU MSM&IDU HS Blood Unknown 1296 26.6 30.1 12.5 3 14.9 1.5 38 2308 19 46 22.2 6.2 14.5 1.9 9.3 22011 16.3 49.3 18.7 5.7 13 1.9 11.4 MSM - Men having sex with men IDU - Injection drug users HS - Heterosexual * Case totals are accumulated by date of report to the Epidemiology Section - 4 - Race Distribution (%) White Black Other 19.8 77.2 3 34.5 63.5 2 36.4 61.5 2.1