Identifying, tracking and trying to stop the spread of infectious and chronic diseases is the charge of the disease detectives at the Centers for Disease Control and Prevention, the nation’s premier public health agency.
At the 25th Annual USF Health Research Day, keynote speaker Dr. David Swerdlow of the CDC talked about how lessons learned from the work of disease detectives investigating previous outbreaks –the influenza A (H1N1) virus and Middle East Respiratory Syndrome (MERS) – could be applied to Ebola.
USF Health Research Day 2015 keynote speaker Dr. David Swerdlow, an infectious diseases specialist, helped lead the CDC’s emergency responses to the Influenza A (H1N1) and MERS outbreaks.
Dr. Swerdlow, a medical epidemiologist and associate director for science at the CDC’s National Center for Immunization and Respiratory Diseases, has plenty of experience leading emergency responses at the front lines of emerging infectious diseases. During the H1N1 flu pandemic in 2009 he co-led the field investigation determining how the new virus spread, its severity and causes of death. He also coordinated the CDC’s response to the deadly MERS virus when the first U.S case was identified in 2014.
During the H1N1 pandemic, the CDC periodically produced estimates of the total disease burden associated with infection by the swine-origin virus.
“Rapid epidemiological field investigations are critical for helping answer questions about emerging infectious diseases,” Dr. Swerdlow said. “We found that the severity of H1N1 was much less than that of the 1918 flu pandemic – probably more similar to seasonal influenza.”
Early recognition by the CDC that the highest rates of disease and complications affected younger people in the United States (rather than those 65 and older) was critical to creating pandemic vaccine policies, focusing surveillance strategies, and communicating risks to the public and health care professionals.
The first case of MERS arose in Saudi Arabia in 2012 and spread to other places in the Middle East before the first of two cases hit the U.S. in 2014. The illness, which had a high fatality rate (25-30 percent) and no known treatment, raised global concern.
Led by Dr. Swerdlow, the CDC applied the lessons learned from Severe Acute Respiratory Syndrome, or SARS, to the emergency response operation for MERS. SARS was another respiratory illness, and close cousin of the MERS virus, that caused more than 8,200 illnesses and about 800 deaths when it arose in China in 2002.
Those lessons included rapid surveillance for identifying cases, making sure patients identified were isolated, quarantines of at-risk health care workers exposed to the MERS virus, and good infection control measures.
“With MERS, we found clear evidence of some person-to-person spread, but not sustained. Camels were likely a source of exposure, but it’s unknown what proportion of cases has camel exposure,” Dr. Swerdlow said. “We also found many people were getting sick by exposure to health care workers, so there was an amplification of illness from this population.”
Finally, speaking about the recent Ebola epidemic, “the largest of its kind in history,” Dr. Swerdlow said most cases were and still are confined to Guinea, Liberia and Sierra Leone.
To help contain the epidemic, the CDC worked with international partners and focused on providing technical assistance in surrounding African countries identified by the World Health Organization as being at increased risk of Ebola. Among its activities, the agency enhanced entry screening at airports, tracked travelers from the three highest-risk countries who came to the U.S., and tightened infection control guideline for health care workers.
The number of new Ebola infections in West Africa has declined sharply since late last year, but Dr. Swerdlow and others tracking the outbreak are hesitant to say the deadly hemorrhagic disease is done.
“Everyone is thrilled the Ebola cases have decreased dramatically, but getting to zero is going to be more difficult,” he said. “There are challenges, largely because of an overburdened health care system in these West African countries – unpaid health care workers, insufficient treatment centers, medical supplies and personal protective equipment.”
Dr. Swerdlow concluded that epidemiological research is vital for understanding how to help prevent geographic spread of epidemics and effectively respond to future global health security threats.
“The risk remains,” he said.” We live in a very interconnected world where diseases are only a flight away.”
Photo by Eric Younghans, USF Health Communications
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