My dad received the Philippines liberation medal. He was on many islands. On his discharge papers it says Bismark Archipelago, New Guinea and Southern Phillipines. He mentioned that he was in Hawaii. I recall him mentioning dysentery. I don't know if he had it. He got polio in 1949 after the war. The leg ulcers you mention sound like Staph infection. I lived on Maui, Hawaii during the 1970's. Soon after moving there, my husband got numerous mosquito bites that turned into sores. He went to a clinic and they told him it was staph. When you get a bite and scratch it, then go into the ocean you get the staph sores. He had to take antibiotics and go to the clinic daily to have the sores scrubbed with a pad until they bled. It's the only cure and very painful. It is common with surfers and others. I never got staph. They also said that staph feeds on sugar. This cured him of drinking coffee with sugar. It could have been this, or some other tropical disease that your dad had.