In 1830, an influenza epidemic was raging around the world, affecting populations in Asia, Europe and North America. It hit Native Americans in British Columbia particularly hard, wiping out large portions of their population. It also spread through territories now known as Oregon and California. There were also reports of the influenza epidemic hitting the populations of Wisconsin quite hard.
European settlers traveling West sparked smallpox epidemics among the native populations. In 1830, the Plains Indians contracted smallpox from deckhands in an American Fur Company steamboat. This outbreak caused thousands of deaths and is attributed to wiping out nearly all of the Mandan in the Upper Missouri region. It was also in this period that some European settlers intentionally spread smallpox by giving blankets infected with the virus to Native Americans. In 1832, Dr. Douglass Houghton and Henry Schoolcraft traveled among the Chippewa tribe and gave out 2,000 smallpox vaccinations.
Between 1830 and 1833 there were a number of malaria outbreaks in Oregon that were deadly to the native population. The first occurred in August 1830 near Fort Vancouver. Mosquitoes spread malaria that affected white and native populations. However, because of the differing immune systems, white people tended to just get sick while malaria killed Native Americans. According to one report, in October 1830, the Oregon malaria outbreak killed 75 percent of the Native population. When the epidemic ended, it had claimed the lives of 90 percent of the Native Americans who lived in lower Columbia and in the Willamette Valley.
A cholera epidemic took place shortly after 1830, in the winter of 1831 that was devastating to the Choctaw nation. U.S. President Andrew Jackson forced the tribe to move West, threatening to exterminate them if they did not. They were the first to travel what would become known as the Trail of Tears. The government promised to provide supplies, but the supplies never showed. Amid hardships caused by weather and the lack of food, an epidemic of cholera broke out.