Jul 2, 2004 (CIDRAP News) Arizona continues to bear most of the current burden of West Nile virus (WNV) infections, with 38 of the 57 human cases reported nationwide, according to figures from the Centers for Disease Control and Prevention (CDC).
One of the Arizona cases was fatal. Cases in other states included 10 in California, 3 in New Mexico, 2 in Florida, and 1 each in Michigan, Nebraska, South Dakota, and Wyoming, the CDC reports in today's Morbidity and Mortality Weekly Report. The numbers were cases reported to the CDC as of Jun 29.
The CDC classified 35 of the 57 cases as neuroinvasive disease, meaning severe infections involving meningitis or encephalitis, according to the agency's WNV Web site. Nineteen cases were listed as West Nile fever, and three cases were unclassified.
The case numbers reported by the CDC are lower in some cases than the numbers reported by states on their health department Web sites. For example, the Arizona Department of Health Services today reports 57 human WNV cases, rather than 38. Colorado, which is not mentioned in the MMWR report, is reporting seven cases.
CDC spokesman Llelwyn Grant said there can be a lag between when the states report cases and when the CDC compiles and publishes the numbers. The states report cases through the ArboNet electronic surveillance system. "It's not atypical for the states to be a little ahead of this system," Grant told CIDRAP News. "They often will announce cases ahead of CDC and then we'll eventually reflect them in the ArboNet case count system."
Grant said the CDC is updating its WNV case count once a week in this early stage of the WNV season. Later in the season the agency typically updates the numbers more often, so the numbers will probably track more closely what the states announce, he said.
The total of 57 cases reported by the CDC this week is an increase of 25 since last week. The number of blood donors with evidence of WNV in their blood remained at 13, the same as last week. Twelve of the donors were in Arizona and one was in New Mexico.
The CDC says 23 states have reported a total of 760 dead crows and 85 other dead birds with WNV infection, and 11 states have reported 42 WNV infections in horses.
CDC. West Nile virus activityUnited States, June 23-29, 2004. MMWR 2004;53(25):563 [Full text]
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