Final answer:
The developed world is largely free from many devastating infectious diseases thanks to public health measures, antibiotics, and vaccinations. Smallpox has been eradicated, and diseases like measles and polio have been drastically reduced, although infectious diseases remain a challenge in developing countries.
Step-by-step explanation:
Most of the developed world is now largely free from many infectious diseases that once had devastating effects on human populations. This level of control over communicable diseases is attributable to advancements in public health, sanitation, the use of antibiotics and vaccines, as well as international efforts in disease prevention and control. For instance, diseases like smallpox have been eradicated, polio is near eradication, and diseases such as measles have seen drastic reductions in developed nations. In the 1950s, measles cases in the United States were as high around 700,000 a year, but by the late 1990s, this number dropped practically to zero. Vaccination programs, alongside improved nutrition and vector control, have been pivotal in achieving these health milestones. However, infectious diseases still pose significant challenges in developing countries, where access to these health advancements may be limited.