Dr. Cahill believes that vaccines are the greatest contribution to medicine in the last century. Diseases like measles and polio were significant killers in the U.S. and are no longer a serious threat. Another example is Yellow Fever which is now only found in sub Saharan Africa and South America.
The disease was likely originally brought over from West African slave trade to Barbados and worked its way up to the United States. Yellow fever was such a problem in the United States that it contributed to the acquisition of the Louisiana Purchase.
Around 85 percent of Napoleon's Army in the United States succumbed to the disease and ultimately led to him selling the territory off. Yellow Fever was so prevalent it contributed to the decision to move the capital in the 1800's. A quarter of the population of Philadelphia died from the outbreak.
Dr. John D. Cahill, M.D. is a physician and medical educator who founded the Center for Global Collaboration & Health Initiatives. While studying abroad in medical school and after his postgraduate medical training at Brown University, Dr. Cahill spent time in Southeast Asia & Africa.