By Richard Rupp and Bridget Hawkins
Dear VaccineSmarts,
The media is abuzz with enterovirus D68 (EV-D68), Middle East Respiratory Syndrome (MERS) and Ebola. Why are there so many frightening diseases going around? Are we close to having vaccines for these diseases?
Tyson
League City
Dear Tyson,
There are probably several reasons why we are hearing a lot more about so-called “new and emerging diseases.” One reason is that a slew of advances in science and technology make the identification and tracking of diseases much easier. These illnesses would have likely remained unexplained or have gone unrecognized in the past.
Another reason is that our world is changing. Seven billion people inhabit the globe. Many live in crowded conditions that accelerate the spread of disease. Modern transportation enables diseases to rapidly jump from continent to continent regardless of natural barriers. Expanding cities and towns encroach on natural habitats placing humans in close contact with wildlife that may harbor disease-causing germs. Additionally, shifts in climate allow these germs to thrive in regions where they could not before.
The diseases that you mentioned help illustrate these points. Enteroviruses are a very common cause of illness in humans. There are about 70 known and they cause a wide range of human diseases, everything from mild cold symptoms through paralytic polio. This year, unusually high numbers of children suffered from respiratory illnesses that were sometimes severe and even life-threatening.
EV-D68 is the culprit in many of these cases. EV-D68 is also suspected in several cases of paralysis that developed in clusters of children. Although, EV-D68 has been with us for years, its role in this outbreak became known only because of new testing capabilities.
We still have a lot to learn about MERS. As its name implies, the first cases were discovered in the Middle East. It causes a respiratory illness that often results in pneumonia. About a quarter of those identified with the disease die. It does not transmit well from person to person. Camels and maybe bats are the probable source of the virus.
Travelers account for the couple of cases that have occurred in the United States. Fruit bats in Africa are likely a natural host of the Ebola virus. Ebola is introduced into human populations through close contact with the blood, organs or other bodily fluids of infected rain forest animals such as chimpanzees, gorillas, forest antelope and porcupines. Humans catch Ebola by butchering and eating sick or dead forest animals. The disease then spreads from person to person quite readily through body secretions. We are all quite aware that Ebola arrived in Dallas from a traveler from Liberia.
EV-D68, MERS and Ebola demonstrate our current limitations. Medical treatment for all three is limited to supportive care. Targeted treatments are in experimental phases only. These diseases demonstrate the shortcomings of screenings, travel bans and quarantines. Vaccines overcome many of the weaknesses of such strategies. Unfortunately, vaccines for these viruses are not close at hand. We still have a lot to learn about interplay between the immune system and diseases. Once armed with such knowledge, we should be able to rapidly and safely produce vaccines in response to these types of diseases.
In the meantime, it is important that everyone follow the current vaccine recommendations. For example, everyone should get the flu vaccine. All three of these diseases can initially be confused with the flu. Health care providers face a daunting task distinguishing these relatively rare illnesses from common diseases like the flu. Furthermore, public health officials should not be squandering their time or precious resources dealing with vaccine-preventable disease outbreaks such as the measles, whooping cough or measles. They already have their hands full.