A tale of two epidemics
James Curran was chief of the research branch of the Division of Sexually Transmitted Diseases at the Centers for Disease Control in Atlanta in 1981 when some unusual cases of fatal pneumonia were reported among gay men in California and New York. The mysterious disease, of course, would come to be known as AIDS. Now dean of Rollins and co-director of the Emory Center for AIDS Research, Curran reflects on the AIDS epidemic as compared with the recent Ebola epidemic.
What stands out in your mind from the early days of the epidemics?
When Ebola first appeared in what is now the Democratic Republic of Congo in 1976, it was relatively easy to identify the causal virus. It looked like other hemorrhagic viral illnesses, and it grew rapidly in the blood.
With HIV/AIDS, of course, the epidemic was identified based upon the unusual occurrence of rare cancers and fatal opportunistic infections, which were the outcomes of a damaged immune system. It took about two years to identify the virus, HIV, and prove it was the cause of AIDS.
What are the most striking similarities and differences between the viruses?
Both are newly discovered diseases. Both originated in Africa, and both came from non-human species to humans—bats with Ebola and chimpanzees with HIV.
The most significant difference is the incubation period. With Ebola, the period between infection and illness is seven to 21 days. Ebola is much easier to transmit than HIV, but there are very few human carriers because in six weeks after infection, the person either dies or their immune system wipes the virus out. There have been 26 previous Ebola outbreaks in Africa in the nearly 40 years since it was discovered. Each of the outbreaks, while devastating to individuals, was able to be contained with infection control procedures.
HIV, on the other hand, is mostly silent for many years after infection. A person may not show any symptoms for 10 years or more. So by the time the virus was first discovered in the early 1980s, there were already millions of people carrying it who could infect others, largely through sexual contact or exposure to blood. We have not been able to control its spread—about 50,000 people in the U.S. and nearly 2 million throughout the world become infected each year. As a result, we now have a hyperendemic situation with 25 to 30 million people currently infected in the world.
How would you describe the public health response to the epidemics?
Oftentimes with new public health problems, there is a period when the situation is ignored and there is complacency. With AIDS, since it was only occurring in New York and California in a handful of gay men, it was hard to get anyone’s attention—that’s the story of the book And The Band Played On. It really wasn’t until it became apparent that the epidemic was more widespread and that there could be heterosexual and bloodborne transmission that public interest picked up.
Ebola was also seen first as a problem only occurring among distant others, in this case, in small limited outbreaks in Africa. There was virtually no concern about Ebola epidemics from 1976 until 2014. The occurrence of cases in the U.S., including the transmission to health care workers here, and the widespread and less controllable nature of the current epidemic changed the scale of concern here to the more appropriate level.
How would you characterize other responses?
When you look at the scientific response, the big difference was that HIV/AIDS was discovered occurring in the United States and other developed countries even before it was recognized as being more common in Africa. The very high mortality rates and its spread within the U.S. caused the scientific infrastructure to build up around AIDS that you wouldn’t see with Ebola, which infected very few people in our country and was relatively short-run.
The public response to both epidemics was characterized by shunning and panic. In the early days of AIDS, people were afraid to go to restaurants with gay waiters, they were afraid to eat dinner with someone who had AIDS, and in many instances, providers were afraid to provide care for someone with the disease.
The hysteria happened more quickly with Ebola. Compared to when I started in public health, the world is an even smaller place. With social media and around-the-clock news, information about new infectious strains travels even faster than the people who might be carriers.
What do you see ahead for Ebola and for HIV/AIDS?
We have reason to be optimistic about Ebola. As fearful as it is, the virus triggers a human immune response that seems at least partially successfully among those who survive. The people who do survive are probably not infected by the same strain again, which means a vaccine should work. I feel optimistic that we will find an effective vaccine for Ebola. And since humans can’t carry the virus without symptoms and the infection runs its course so quickly, Ebola epidemics can be controlled with timely and suffcient infection control measures.
With HIV, of course, there is no completely successful human immune response, so developing a vaccine has been a real struggle. Worldwide HIV transmission has been reduced to slightly less than 2 million people per year. Great progress has been made in the discovery and application of effective therapy and prevention methods. But all persons currently on therapy will require lifelong treatment with antiretroviral drugs and millions more have yet to be diagnosed and treated. So, in the long run, HIV remains a very large continuing threat to mankind.
