List of West Nile virus outbreaks

United States

Main article: West Nile virus in the United States

The first cases of West Nile disease in the United States occurred in 1999 in New York. In the first three years only a small number of human cases were diagnosed, all in the Eastern or Southern U.S. (149 cases and 19 deaths, 1999–2001). In 2002, the disease exploded to most of the lower 48 states, causing 4,156 diagnosed cases of which 284 died. The disease continued to spread, reaching all but three states by 2006. The first case detected in Maine occurred in 2012. The single cases detected in Hawaii in 2014 and in Alaska in 2018 were likely imported.

In the period from 1999 to 2018, the United States had 2,330 total deaths out of 50,830 diagnosed cases, giving a case fatality rate of 5%. The worst years were 2003 for the most cases with 9,862 and 2012 for the most deaths with 286. Most cases are thought to go undiagnosed. The WHO claims that about 80% of cases are asymptomatic. Half of all cases (48.5%) diagnosed in the U.S. lead to neuroinvasive symptoms. Over 90% of deaths occurred in cases with neuroinvasive disease. After several cases of West Nile disease transmitted by blood transfusion, the U.S. began testing all blood donations and dozens of presumed cases are found each year. Some West Nile cases resulted from organ transplants and some but not all organs/donors are tested.

As of 2020, the disease outbreak is considered ongoing and essentially endemic. As well as humans, countless birds and over 27,000 horses have been infected, providing additional reservoirs for the virus.

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. Summer of 2012 saw widespread viral penetration in Canada, coast to coast. 17 people have either tested positive or are suspected of having the virus in Saskatchewan, and only one person has tested positive in Alberta. Saskatchewan has reported 826 cases of WNV plus three deaths. The spread of West Nile Virus infected mosquitoes to British Columbia for the first time was reported in 2009.

Europe and Asia

• 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%).
• Romania: In 1996, more than 800 cases of neuroinvasive disease were reported, 393 of which were confirmed to be caused by West Nile virus. During the outbreak, 17 deaths were reported. In 2010 from July to October, an outbreak occurred with 57 cases and 5 deaths.
• Greece: In the summer of 2010, several cases were reported mainly in northern Greece, a countrywide total of 262 diagnosed cases and 35 fatalities. In 2011 the virus spread to central Greece but with fewer cases, 101 diagnosed and 9 fatalities. In 2012, 44 were diagnosed and 3 died. The total number of people in Greece infected by the virus is estimated to 1,800. In 2013, 35 diagnosed and 1 died.
• Italy: On 30 July 2018, a man died and 12 others were hospitalized after they contracted the virus.
• Spain: In the summer of 2020, seven people died and 31 were hospitalized, all of them in the Autonomous Community of Andalusia, after they contracted the virus in the worst outbreak of it in the history of the country.

References

References

1. [https://www.cdc.gov/westnile/statsmaps/cumMapsData.html#three Final Cumulative Maps & Data for 1999–2018], Centers for Disease Control and Prevention, [[National Center for Emerging and Zoonotic Infectious Diseases]] (NCEZID), Division of Vector-Borne Diseases (DVBD), Centers for Disease Control, October 9, 2019
2. [https://time.com/5648511/west-nile-diagnoses/ Mosquito-Borne West Nile Virus Soared in 2018, According to CDC Data], ''Time'', Jamie Ducharme, August 9, 2019
3. [https://health.hawaii.gov/docd/disease_listing/west-nile-virus/ West Nile Virus], Disease Outbreak Control Division, Department of Health, State of Hawaii, July 2018
4. [https://www.who.int/news-room/fact-sheets/detail/west-nile-virus West Nile virus], World Health Organization, 3 October 2017
5. [http://www.aabb.org/research/hemovigilance/Pages/wnv.aspx West Nile Virus Biovigilance Network], [[AABB]], accessed June 5, 2020
6. [https://www.cdc.gov/westnile/transmission/blood-organ.html West Nile Virus: Blood Transfusion and Organ Donation], Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Division of Vector-Borne Diseases (DVBD), December 10, 2018
7. [https://www.aphis.usda.gov/livestock-poultry-disease/equine West Nile Virus (WNV)], United States Department of Agriculture, Animal and Plant Health Inspection Service, Jun 2, 2020
8. "West Nile Virus | Province of Manitoba".
9. "CTV News | News Video – Top National News Headlines – News Videos".
10. (19 August 2007). "Scientists still working to understand spikes in West Nile virus numbers". myTELUS.
11. (August 24, 2007). "Sask. reports 339 cases of West Nile, one death".
12. (22 August 2009). "West Nile virus found in B.C. mosquitoes". CBC News.
13. (Jul–Aug 2001). "Clinical characteristics of the West Nile fever outbreak, Israel, 2000". Emerging Infectious Diseases.
14. (October 2010). "West Nile virus infection outbreak in humans in Romania". European Centre for Disease Prevention and Control.
15. (13 January 2011). "Outbreak of West Nile virus infection in humans, Romania, July to October 2010". Euro Surveill.
16. (2011). "Έκθεση: Επιδημία Λοίμωξης από τον Ιό του Δυτικού Νείλου, 2010". Hellenic Centre for Disease Control and Prevention (KEELPNO).
17. (2012-05-07). "Έκθεση επιδημιολογικής επιτήρησης – Έτος 2011". Hellenic Centre for Disease Control and Prevention (KEELPNO).
18. (2012-08-08). "Και τρίτος νεκρός από τον ιό του Δυτικού Νείλου". in.gr.
19. (2012-07-24). "1800 άνθρωποι μολύνθηκαν από τον ιό του Δυτικού Νείλου στην Ελλάδα". Rodos Info News.
20. (2013-08-21). "Στα 35 τα επιβεβαιωμένα κρούσματα – Πρώτος θάνατος από τον ιό του Δυτικού Νείλου στην Ελλάδα για το 2013". in.gr.
21. (July 30, 2018). "Zanzara West Nile: c'è un primo morto in Veneto e 12 casi confermati".
22. Agencias. (2020-08-25). "La Fiebre del Nilo llega a Sevilla Este".
23. (11 June 2017). "Annual Epidemiological Report – West Nile fever".
24. (11 June 2017). "Weekly updates: 2021 West Nile virus transmission season".
25. (2023-12-08). "Weekly updates: 2023 West Nile virus transmission season".