HD cases were reported from 30 U.S. states and Puerto Rico in 2005 (Table 1). A ten year summary of reported cases is shown in Table 1b, and a graphical representation with comparison to the ten year trend is shown in Figures 4 and 5 respectively. California, Louisiana, Massachusetts, New York and Texas contributed the largest number of cases in 2005, and collectively accounted for 60% (100/166) of the cases registered. The predominance of these states is in keeping with the ten year trend in reporting, which also would identify Florida, Hawaii, Pennsylvania, Puerto Rico and Washington as the most likely U.S. locations to report HD.

Autochthonous foci of HD transmission are recognized in Hawaii, Puerto Rico and on the U.S. mainland in the region of the western Gulf of Mexico. Some speculate that it also may occur in California. In 2005, a total of 9 cases were reported from Hawaii and 10 from Puerto Rico. Reporting from both of these locations generally exceeds their
historical trend. Hawaiian cases were almost exclusively among immigrants and about half the increased number seen from Puerto Rico were among late reporting cases diagnosed before 2004.

A total of 45 cases were reported from Texas (24) and Louisiana (21). Though somewhat higher than usual, the combined number of cases is consistent with the historical norms from these states and about half of the cases reported were native born U.S. citizens with no residence history outside the U.S.. Inspection of the Louisiana data also suggests that there is some late reporting of cases that had been diagnosed in earlier years. This may reflect an increasing awareness of disease in the state. The consistency of this trend and the potential long term impact of disruptions caused by recent hurricanes on disease awareness and reporting merits additional consideration.