Health Canada
http://www.hc-sc.gc.ca/english/index.htm
A searchable site covering all health issues in Canada.
Center for Disease Control
http://www.cdc.gov/
This vast and complete site covers almost all aspects of disease. In addition to information on any from a full list of diseases, numerous CDC publications are available.
Society for Medical Anthropology
http://www.medanthro.net/
Human Biology Association
http://www.humbio.org/