List of West Nile virus outbreaks

Global distribution of West Nile virus.(2006)

• United States: From 1999 through 2001, the CDC confirmed 149 West Nile virus infections, including 18 deaths. In 2002, a total of 4,156 cases were reported, including 284 fatalities. Thirteen cases in 2002 were contracted through blood transfusion. The cost of WNV-related health care in 2002 was estimated at $200 million. The first human West Nile disease in 2003 occurred in June, and one West Nile-infected blood transfusion was also identified that month.^[1]

In the 2003 outbreak, 9,862 cases and 264 deaths were reported by the CDC. At least 30% of those cases were considered severe, involving meningitis or encephalitis. In 2004, only 2,539 cases and 100 deaths were reported. In 2005, there was a slight increase in the number of cases, with 3,000 cases and 119 deaths reported. Cases increased in 2006, with 4,269 cases and 177 deaths. In 2007, the number of cases reported decreased to 3,623 and the number of deaths dropped to 124. In 2007, 1,227 cases of WNV neuroinvasion disease and 117 deaths occurred.^[2]

In 2008, West Nile surveillance data reported to CDC, a total of 28 states have reported 236 cases of human WNV illness. A total of 137 cases for which such data were available occurred in males, median age patients was 48 years. Dates of illness onset ranged from January 17 to August 14: Two cases were fatal.^[3]

In 2009, 663 cases were reported; of these, 335 were encephalitis or meningitis infections, a reaction to the virus that approximately one in 150 people who get the virus will show. Three hundred and two cases were filed for West Nile fever, the most likely symptom of the virus; 26 cases were unspecified. The state of Texas had the most cases, with 104 total. The total mortality rate for 2009 was 32 deaths of the 663 reported serious cases, a 4.5% casualty rate, but only of the severe infections. Approximately 80% of cases have no symptoms, so the total casualty rate would be less than 1% of total infections in the U.S. These and earlier years data are available from the Centers for Disease Control and Prevention.^[4]

Dallas County, Texas health officials announced in the second week of August 2012 a death toll of nine so far in the county. County Judge Clay Jenkins declared a public health emergency for the county on August 9, 2012, due to the West Nile virus outbreak in the area.^[5][6] North Texas has been hit the hardest in 2012, with approximately 663 human cases and 18 deaths, as of August 23, 2012. During the same time, the CDC reported 1,118 human cases and 41 deaths nationwide.^[7]

• Canada: One human death occurred in 1999. In 2002, ten human deaths out of 416 confirmed and probable cases were reported by Canadian health officials. In 2003, 14 deaths and 1,494 confirmed and probable cases were reported. Cases were reported in 2003 in Nova Scotia, Quebec, Ontario, Manitoba, Saskatchewan, Alberta, British Columbia, and the Yukon. In 2004, only 26 cases were reported and two deaths; however, 2005 saw 239 cases and 12 deaths. By October 28, 2006, 127 cases and no deaths had been reported. One case was asymptomatic and only discovered through a blood donation. In 2007, 445 Manitobans had confirmed cases of WNV and two people died with a third unconfirmed but suspected.^[8] Summer of 2012 saw widespread viral penetration in Canada, coast to coast.^[9] 17 people have either tested positive or are suspected of having the virus in Saskatchewan, and only one person has tested positive in Alberta.^[10]Saskatchewan has reported 826 cases of WNV plus three deaths.^[11] The spread of West Nile Virus infected mosquitoes to British Columbia for the first time was reported in 2009^[12]
• Israel: In the year 2000, the CDC found 417 confirmed cases with 326 hospitalizations; 33 of these people died. The main clinical presentations were encephalitis (57.9%), febrile disease (24.4%), and meningitis (15.9%).^[13]
• Romania: In 1996–1997, about 500 cases occurred in Romania with a fatality rate of nearly 10%. In 2010, 34 cases were confirmed, with 3 fatalities.^[14]
• Greece: In the summer of 2010, several cases were reported mainly in northern Greece, a countrywide total of 262 diagnosed cases and 35 fatalities.^[15] In 2011 the virus spread to central Greece but with fewer cases, 101 diagnosed and 9 fatalities.^[16] In 2012, 44 were diagnosed and 3 died.^[17] The total number of people in Greece infected by the virus is estimated to 1,800.^[18] In 2013, 35 diagnosed and 1 died.^[19]

References