How disease detectives track deadly bugs today

Given how fast two entirely new and deadly viruses—the H7N9 influenza strain in China and the MERS coronavirus in Saudi Arabia—were picked up by disease surveillance experts, we’ve been pondering how the tools and technologies we take for granted today might have altered the course of HIV and AIDS if they’d been available when AIDS blipped on the public health radar.

It was 32 years ago last month that the US Centers for Disease Control and Prevention issued a report of an unusual spate of pneumocystis carinii pneumonia, among “five, gay, otherwise healthy men.”  

This matter-of-fact report, as we now know, signaled the emergence of a new and terrifying epidemic. It would take researchers another two years to isolate the virus behind the deadly disease, at the time thought to be a concern mainly of gay men and drug users. By then, the disease was already on its way to becoming one of the worst pandemics in human history. 

Genetic tools have since revealed that the very first cases of HIV transmission likely occurred during the late 1800s and early 1900s in central or western Africa, when the virus jumped from apes to humans. Our understanding of HIV, its transmission and pathogenesis has since evolved at a furious pace—we probably know more about this virus than we do about any other. 

But virologists didn’t have PCR machines in 1983, and epidemiologists lacked much of the surveillance infrastructure and technology that might have led to a quicker and more coordinated response, says Ray Arthur, who leads the 5-year-old Global Disease Detection (GDD) Operations Center of the US Centers for Disease Control and Prevention (CDC), which prepares an annual watch list of pathogens on the move.  

There was no global Internet around to capture and spread word of new illnesses as they occurred, much less social media platforms on which folks could share such news in real time. There were no smartphones sending signals and gathering rumors from remote communities. And lab diagnostics that could swiftly identify entirely novel pathogens like MERS—identified by Dutch scientists last fall, within four months of the first reported case—were, at best, a glimmer in some inventor’s eye.
 
Arthur noted that the GDD Program—authorized by the US Congress in 2004—has enabled low-income countries in particular to build such capacity, the aim being to rapidly detect, identify and contain emerging disease and bioterrorist threats before they become a global problem. 

In fact, it was the spread of severe acute respiratory syndrome (SARS)—a coronavirus that erupted in Asia in 2002 and moved rapidly along international trade and travel routes—that motivated public health authorities to establish the GDD, and lawmakers to fund the initiative. 

The GDD’s Operations Center is modeled after the World Health Organization’s alert and response operations, which monitor global public health events using event-based surveillance. 

The CDC also has public health experts stationed in GDD regional centers in 10 countries across all WHO regions. These experts provide technical assistance and training in field epidemiology and laboratory methods.

Arthur said syndromic surveillance has enabled health workers to pinpoint several species of Bartonella, bacteria transmitted by rodents, as the cause of an acute febrile illness in Thailand. Work by the GDD and its collaborators also helped identify novel viruses, including coronaviruses in bats in Guatemala. These viruses are being studied to see if they cause disease in humans. 

Currently, the CDC is helping Indian researchers get to the bottom of a mysterious brain illness that appears every year in mid-May and afflicts children. The often fatal disease, known officially as acute brain encephalitis, surfaced in 1995 and seems to be spreading.  

Arthur said the impetus for creating the GDD was to respond rapidly to the next pandemic. “If we had had a multi-center systematic approach to responding to enigmatic disease events, it could have changed the face of the [AIDS] epidemic, at least for the Western world,” said Arthur. 

Just imagine how quickly HIV might have been addressed by rudimentary public health measures if the earliest cases of AIDS, in Africa, had been detected and marked for further surveillance. (For that matter, imagine how the gay rights movement might have looked today if that had happened.) 

Kira Christian, a veterinary medical officer and analyst at the GDD operations center in Atlanta, said the Internet has had a profound impact on how information about global diseases is shared today. This is particularly true in developing countries that lack a robust case-reporting system. 

“What happens in those particular parts of the world is that reporters and journalists are often the first to pick up these stories,” said Christian. “It could be an increase of cases of any type of syndrome at a hospital, noticed by reporters.” 

The job of the GDD Operations Center and its partners, of course, is to look into the veracity of these reports, and frame an appropriate public health response. While the GDD Operations Center monitors between 30 and 40 public health threats at any given time, it most closely watches those of concern to the global public health community and which have the potential of turning into an international emergency. 

In 2012, the five top infectious disease threats were the highly pathogenic H5N1 virus, cholera, polio, a polio-like illness known as enterovirus-71 and extensively drug-resistant tuberculosis. The GDD added H7N9 and MERS as an addendum to the 2012 list, which was published this month in Emerging Health Threats. 

Arthur said the appearance of two global public health threats in a single year is not unprecedented. “You have to expect the unexpected,” he said, noting that last year was an unusually quiet period for the GDD Operations Center.  “We kept saying it was the quiet before the storm, and it turns out we were right.” 

Fortunately, the GDD Operations Center is around to watch its gathering clouds.

If you enjoyed this article, you might like IAVI Report's 30-year-timeline tracking HIV vaccine science.

For a more technical story about what mathematical modeling and computational biology can tell us about HIV evolution, see IAVI Report's The Math of HIV.