<unk> <unk>  occur around the world. Rates of infestations in developed countries while decreasing from the 1930s to the 1980s have increased dramatically since the 1980s. Previous to this they were common in the developing world but rare in the developed world. The increase in the developed world may have been caused by increased international travel, resistance to insecticides, and the use of new pest-control methods that do not affect<unk> <unk> . The fall in<unk>  bug populations after the 1930s in the developed world is believed to be partly due to the usage of DDT to kill cockroaches, which are a natural predator of the<unk>  bug. The invention of the vacuum cleaner and simplification of furniture design may have also played a role. Others believe it might simply be the cyclical nature of the organism.
Epidemiology of bed bugs
Epidemiology of snakebites
Epidemiology of measles
Epidemiology of syphilis
Epidemiology of herpes simplex
Epidemiology of motor vehicle collisions
Epidemiology of pneumonia
Epidemiology of HIV/AIDS