We have never had an outbreak of Asian-type H5N1 highly pathogenic avian influenza in the United States, and we do not have any cases now. We had low-pathogenic avian influenza as recently as 2004. The H5N2 outbreak in one flock was designated as highly pathogenic on the basis of a laboratory test, but a more definitive test failed to confirm high pathogenicity. The last confirmed outbreak of H5N2 (not H5N1) highly pathogenic avian influenza in the United States was in Pennsylvania in 1983 and 1984. No known human illness or infections resulted from the outbreak.