Are Outbreaks of Infectious Disease Accelerating Around the World?

11/09/2016 03:22 pm ET Updated Nov 10, 2017

By Drs. David Niesel and Norbert Herzog

It seems that every time we look up, we hear about another infectious disease threatening people somewhere in the world. We really pay attention to the exotic threats - like Ebola and Zika that tend to get heavy media coverage. But sometimes we forget some of the common diseases that occur periodically like outbreaks of measles or the yearly influenza outbreak.

Recently, the Zika virus spread throughout South and Latin America, Mexico and Puerto Rico with its devastating effects on the newborn. We are all holding our breath, as Zika has the potential to spread along the Gulf Coast and in the southern US. One explanation for these more frequent outbreaks is that outbreaks are more efficiently detected and reported by public health systems around the world. However, there are many factors that make the case for an increase in the spread of infectious diseases. Why is this happening and why now?

First, the world is becoming a smaller place. It wasn't all that long ago that Jules Verne's "Around the World in 80 Days" was considered fantastic. Today, from most cities around the world, a flight can connect you to any place on the globe within 24 hours. This allows infectious diseases access to susceptible populations anywhere in the world. Recently, a Liberian citizen named Thomas Duncan was infected with Ebola in Liberia and traveled to Dallas before showing symptoms of infection. In a Dallas hospital where he was treated, two healthcare workers became the first Americans infected by Ebola in this country.

Another factor is that more than half the world's people are now living in urban areas. Densely packed populations are a boon for the spread of infectious microbes. Concurrent with the movement to cities is the growth of slums. The conditions in these closely packed and hygiene compromised areas make this a fertile ground for the spread of infectious diseases.

Poverty can also make outbreaks worse. Poverty leads to unhygienic conditions where diseases thrive. Access to healthcare and the quality of the public health systems are usually minimal. In western countries, relatively few Ebola-infected people died because of the high quality of supportive medical care available. In contrast, more than 11,000 died in West Africa, which lacked advanced medicine and a public health infrastructure. The availability of quality healthcare and an effective public health response helps people withstand an infectious disease outbreak.

Finally, climate change is a factor that we sometimes overlook. An increase in temperature can change the geographic distribution of vectors (i.e. mosquitos) that spread disease, which can impact susceptible populations and increase outbreaks of infectious diseases worldwide.

There is not one answer to address the increasing spread of infectious diseases. We need to understand how diseases are spread, how they cause disease and conduct research that develops new diagnostics, therapeutics and vaccines.

Medical Discovery News is a weekly radio and print broadcast highlighting medical and scientific breakthroughs hosted by professor emeritus, Norbert Herzog, and professor, David Niesel, biomedical scientists at the University of Texas Medical Branch at Galveston. Learn more at www.medicaldiscoverynews.com.