Where do most cases of anaplasmosis occur in the United States?
Blacklegged ticks infected with A. phagocytophilum have been reported in New England, the Midwest, and southeastern states while western blacklegged ticks infected with A. phagocytophilum have been found along the pacific coast and in some southwestern states (see map below). Most human cases of anaplasmosis occur where the infected ticks are present. Occasionally someone who does not live in a tick-endemic area will become ill with anaplasmosis, possibly having been bitten by an infected tick during travel. If you traveled during the 3 weeks prior to becoming ill, you should tell your doctor. About 600-800 cases of anaplasmosis are reported to CDC each year. States reporting the highest incidence of anaplasmosis in 2006 were Minnesota, Wisconsin, New York, New Jersey, and Connecticut.
