Yes - it is to check for communicable diseases. Tuberculosis, black plague, leprosy, smallpox, yellow fever, polio, and more, including HIV. It's to make sure the diseases are treated before the immigrant infects the local population where they end up. There were doctors and a quarantine/ treatment center at Ellis Island when shiploads of immigrants were coming from Europe over 100 years ago, so it's not some new hurdle the evil feminists have thrown up. I'd wager the UK has a very similar requirement - Japan sure does.