West Nile Virus Maricopa County, 2005 Figure 1. West Nile Virus Incidence in Humans and Mosquito Pools in Maricopa County 3/1/2005 To 11/30/2005 Weekly 25 20 15 Human Mosquito 10 5 3/ 63/ 12 3/ 20 -3 /2 6 4/ 34/ 4/ 9 17 -4 /2 3 5/ 15/ 5/ 15 7 -5 /2 1 5/ 29 -6 /4 6/ 12 -6 /1 8 6/ 26 -7 /2 7/ 10 -7 /1 6 7/ 24 -7 /3 0 8/ 78/ 13 8/ 21 -8 /2 7 9/ 49/ 10 9/ 18 -9 / 10 24 /2 10 -10 /8 /1 610 /2 10 2 /3 011 11 /5 /1 311 /1 11 9 /2 712 /3 0 ƒ ƒ ƒ One human case was not included in the epi-curve due to questionable date of onset. Human data are based on date of symptom onset; if onset is missing date used is earliest available: date of diagnosis, date of lab specimen or date of report to public health. Mosquito data are based on specimen lab delivery date. -1- Figure 2. West Nile Virus Cases by Gender and Disease Classification Maricopa County, 2005 Case Classification # Male # Female Total # Cases Encephalitis 11 7 18 Meningitis 5 4 9 Viremic Donor Encephalitis Viremic Donor Meningitis Paralysis Syndrome 3 3 6 Neuroinvasive Disease-Cumulative 19 14 33 Fever 21 19 40 Viremic Donor Fever 3 3 6 Fever-Cumulative 24 22 46 Unknown - Total Cumulative Viremic Donors Asymptomatic ƒ ƒ % 23% 11% 0% 0% 8% 42% 51% 8% 58% 0% # Deaths 4 4 - 43 36 79 100% 4 - - 6 - - The initial WNV testing methodology for Viremic Donors is a nucleic acid amplification test (NAT), which measures viral DNA. Viremic donors who did not become symptomatic are not included in case numbers. Case classifications: West Nile Fever: A non-specific, self-limited, febrile illness caused by infection with West Nile virus. Typical cases are characterized by the acute onset of fever, headache, arthralgias, myalgias, and fatigue. Maculopapular rash and lymphadenopathy are generally observed in less than 20% of cases. A confirmed case is a clinically compatible illness that is West Nile virus laboratory confirmed. (Arizona Department of Health Services case definition; for more information, see Arizona Administrative Code R9-6-304). ƒ Meningitis: Arboviral meningitis is characterized by fever, headache, stiff neck, and pleocytosis. A confirmed case is a clinically compatible illness that is West Nile virus laboratory confirmed. (http://www.cdc.gov/ncidod/dvbid/westnile/clinicians/surveillance.htm#casedef) ƒ Encephalitis: Arboviral encephalitis is characterized by fever, headache, and altered mental status ranging from confusion to coma with or without additional signs of brain dysfunction (e.g., paresis or paralysis, cranial nerve palsies, sensory deficits, abnormal reflexes, generalized convulsions, and abnormal movements). A confirmed case is a clinically compatible illness that is West Nile virus laboratory confirmed. http://www.cdc.gov/ncidod/dvbid/westnile/clinicians/surveillance.htm#casedef ƒ Paralysis syndrome: No CDC or ADHS case definition for this syndrome exists at the present time. The criteria applied to Maricopa County cases are: 1-laboratory confirmed acute WNV-infection AND 2-Physician documented acute paralysis. -2- Figure 3. West Nile Virus % of Total Cases by Disease Classification Maricopa County, 2005 Meningitis (9) 11% Paralysis Syndrome (6) 8% West Nile Fever (46) 58% Encephalitis (18) 23% -3- Figure 5. West Nile Virus Case Rates in Maricopa County Cities, 2005 † City Tempe Scottsdale Chandler Other³ Phoenix Mesa Total As of December 31, 2005 Cases Population ¹ 7 160,735 8 223,835 7 231,785 6 250,385 21 1,452,825 7 452,355 79 3,648,545 Rate/City ² 4.35 3.57 3.02 2.40 1.45 1.55 2.17 ¹ Population statistics obtained from Arizona Department of Economic Security July 1, 2005 ² Rate per 100,000 population = (N/population) * 100,000 ³ Unincorporated areas – Laveen, Higley, Sun City, and Sun City West; and Gila River Indian Community † Table only includes cities with 5 or more cases of WNV Figure 6. West Nile Virus Cases by Age Maricopa County, 2005 Age 0-17 18-29 30-39 40-49 50-59 60-69 70-79 80-89 90-99 TOTAL Neuroinvasive 1 1 7 4 9 5 3 3 0 33 ¹ Includes Viremic Donor Fever classification -4- Fever¹ 3 3 8 16 10 6 0 0 0 46 WEST NILE VIRUS SURVEILLANCE INDICATORS Maricopa County, 2005 3/5/05 5/26/05 -5Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 5/14/05 6/1/05 4/20/05 Dates of first positive findings in a mosquito pool, human, equine, bird, and sentinal chicken flock.