I'm applying as a visiting doctor to australia, where can I get an international health certificate?

? An international health certificate is a veterinarian certificate for taking an animal internationally. Perhaps what you meant is an international vaccination record? An infectious disease doc who specializes in travel med is your best bet.
Clarification needed. A global health certificate, a certificate educational program, is offered by many public health schools and even on-line. This certificate prepares you for work in international health, typically in developing countries. An international vaccination certificate is avaialble from your department of public health, a travel medicine provider (istm.Org), and sometimes your regular doctor.