Helldorado (scanlation)

The time is the mid-seventeenth century, the location is a tropical island in the mid Atlantic Ocean - the conflict is between two communities familiar with human violence: the native Indians of the island (the Syyanas) and the Spanish conquistadors who have recently arrived. A mysterious, extremely virulent disease is spreading on both sides. The conquistadors feel it is imperative keep the disease contained within the island or it will endanger all humanity, so no one is allowed to leave. Ultimately, the island becomes a microcosm of the radical differences between two very different civilizations - violently crossing the lines of morality, religion and attitudes.