EID Weekly Updates:
Emerging and Reemerging Infectious Diseases, Region of the Americas
Vol. 1, No. 14—9 October 2003
United States, 9 October 2003: Since the first human case of WNV was detected on 9 July 2003, 6,613 human cases and 139 deaths have been reported to the Centers for Disease Control and Prevention of the United States (CDC). The number of new cases reported for this week is 792, though most cases occurred during August and September (see graph to the left). Even though cases are continuously being reported, cooler weather has decreased the mosquito population. This year, 42 of the 50 states have reported human cases. The District of Columbia reported its first four human cases this week. Three states have detected viral activity in animals or mosquitoes, though no human cases have been detected to date. The most affected state continues to be Colorado, with 2,090 human cases and 38 deaths. For more information, see the CDC West Nile Virus page.
Source: Division of Vector-Borne Infectious Diseases: West Nile Virus, Centers for Diseases Control and Prevention (CDC), USA.
Canada: Up to 7 September, 276 human cases were confirmed (236 in Alberta, 19 in Saskatchewan and 14 in Manitoba), with 9 deaths. There are currently 860 cases under study. Five provinces have reported probable cases of native origin: Québec, Ontario, Alberta, Saskatchewan, and Manitota; up to 8 October, these same five provinces detected viral activity in horses and birds. For more information, see the Health Canada West Nile Virus Surveillance Information page: English | français.
Source: West Nile Virus Surveillance Information, Health Canada.
Mexico: Up to 2 October, 480 persons were serologically tested in 20 states. Four people have shown positive results, 3 in Chihuahua and one in Sonora. Out of 20 states, 15 have detected equine WNV activity. The states with the highest equine WNV infection rates are Chiapas (61%), Quintana Roo (59%), and Jalisco (57%). Eight states have carried out testing for the detection of WNV in birds, five of which have detected viral activity. Tabasco is the state with the highest WNV infection rate (9%). For more information, see the WNV page of the Program of Action for Vector-Borne Disease Prevention and Control, Secretary of Health, Mexico.
Source: Programa de Acción para la Prevención y Control de las Enfermedades Transmitidas por Vector, Secretaría de Salud, México (Action Program for the Prevention and Control of Vector-Borne Diseases, Secretary of Health, Mexico).
Additional note: Besides the United States, Canada, and Mexico, there has been native circulation of WNV in