Health: Pre-Contact
According to statistics, the population maintained itself throughout the years of Ancient Hawaii. The kahuna were experts in medicine and came up with ways to fight illness. However, because the people were so isolated, they did not develop any kind of immunity to foreign agents which led to the drastic decline in the population after Captain Cook's arrival.
Health: Post-Contact
After Captain Cook established contact with Hawaii, many of the foreigners brought diseases to the Hawaiians. Because of their isolationism, they did not have any immunity at all to the diseases that the foreigners brought, so many of the population quickly died off. Sexually transmitted infections also grew exponentially across Hawaii. Many Hawaiians also turned to alcoholism, and died from over-consumption of alcoholic beverages. One of the most notable cases of disease, however, was leprosy. People suffering from leprosy were sent to an area called kalawao on Moloka'i.
Modern Health
With our technology, we have found many cures for the diseases that killed off many of the native population. However, there are more and more unknown diseases that keep surfacing throughout the world and our pharmaceuticals are always finding different cures to the new diseases.
Health in the Future
As technology evolves, I believe that we will eventually find the cure to just about anything. Even the cure for cancer.