How the CDC responds to global emerging infections: a conversation with Scott Dowell

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This is the second in a series of conversations with officials at the Centers for Disease Control and Prevention (CDC), discussing the CDC’s role in global health and connections with HIV and TB activities. The following interview is with Scott Dowell, MD, MPH.  Dr. Dowell is the Director of the Division of Global Disease Detection and Emergency Response at the CDC Center for Global Health.  The Global Disease Detection program is the CDC’s principal means of identifying and containing emerging infections around the world.

Scott Dowell, MD, MPH

When did you first start working at the CDC and what drew you to global health work in particular?
I started at the CDC in the Epidemic Intelligence Service (EIS) class of 1993. During med school I worked with a mentor who did public health in Haiti at Johns Hopkins who knew of EIS and highly recommended it. From that time I had the EIS program in the back of my mind. When I joined in 1993 I had no idea I would be here 18 years later but it’s been a good 18 years.

When I came to my first EIS conference after I was selected, I remember feeling like a kid in a candy story – there were so many great things for physicians to choose from. The idea of doing ID investigations, especially in other parts of the world, working with top-quality scientists at different parts of the CDC, there was just a lot to choose from and great projects to work from.

My first big international experience was when there was a major refugee crisis in Zaire (now the Democratic Republic of Congo) – when a million refugees fled Rwanda within a couple of days fearing reprisals from a civil war. When they arrived in Lake Kivu they were struck with cholera and dysentery. It was unprecedented mortality – among the highest ever reported – so there was a huge public health response to that crisis and it had a long standing impact on me.

Tell me about your work starting up the International Emerging Infections Program (EIP) in Thailand.
In 2001 I was sent to Thailand by the director of the National Center for Infectious Diseases at that time – Dr. Jim Hughes. He brought me out to the center to develop a global ID strategy for CDC, and in the course of writing that strategy we came to believe that one of the things we should do is develop sites for collaboration in developing countries. After considering a number of countries, we came to decide on Thailand.

Thailand was quite eager to have the EIP there, and 2001 to 2005 were very productive years in terms of ID in that part of the world. When SARS was first identified in 2003 in Hanoi, Vietnam by Dr. Carlo Urbani, we communicated with him in the first few days. When he got sick himself, he came to Bangkok and we took care of him as the epidemic spread from Vietnam to China and other parts of the world. That was a very intense three or four month period. Then we had a bit of a break, and then the outbreak of Avian Influenza in humans or H5N1 started up in ‘04 and ’05.

Does that program still exist or has it evolved into the Global Disease Detection (GDD) Program?
Yes to both. It still exists and it has evolved into the GDD program. So the international EIP became a model that was then applied in Kenya and several other countries. But beginning in 2004 with SARS and the H5N1, the U.S. Congress decided we ought to do a better job of this work and put money into picking up these new disease threats in other countries before they spread. So beginning in 2004 – about the time I was finishing up my second term in Thailand in 2005 – I came back to lead the GDD program.

The GDD program has a bit of a broader mandate than the EIP. The GDD program now has a field epidemiology training program as a part of its core program, and an influenza program. All fully functioning sites have those three pillars. The others are a zoonotic (human/animal interface) program, a risk communications and emergency response program, and a support/capacity building for laboratories program.

Now we have seven fully functioning GDD centers: Thailand, Kenya, Guatemala, Egypt, China, South Africa and India. Then we have two under development in Kazakhstan and Bangladesh.

What are some examples of diseases the GDD has uncovered and how the community was able to respond to the outbreak as a result?
There are two main ways that we respond:  From the regional centers themselves and from headquarters in Atlanta. The regional responses are for small to medium-sized outbreaks that the country or neighboring countries ask for help with. We’ve had about 600 regional responses in the four or five years since the GDD has been up and running. The broader responses, when CDC has to bring in experts from Atlanta, we do that less frequently, but there have been about 50 responses from HQ in that time.

The responses really run the gamut from support for the investigation of a small cluster of H5N1 infections to complex multidisciplinary responses to a pneumatic outbreak.

One example is unexplained liver disease in Ethiopia – where the Ethiopian government had asked the CDC for help with cases of abdominal swelling. The initial investigation ruled out parasites that infect the liver. Eventually we started looking at a possible plant toxin. That theory was confirmed this year – that when eaten, this plant that grows interspersed with the crops grown in that region, caused severe liver damage. As part of the harvesting process, animals walk over the grain to break it up, and the toxic plant got mixed into the grain that people then ate. It was a long investigation, but important to figure out.

If the family weeded their crops before they harvested them, we were hopeful they would be protected against this liver disease. Hopefully we will prevent this in other communities by communicating about the risk. We do have a number of these complicated, enigmatic outbreaks. They haven’t all ended with such a clear picture.

What do you think the response to HIV/AIDS would have looked like if the GDD were in place in the early 80s?
I think it could have been a much quicker response. It was clear for a long time in West Africa that there was this syndrome “Slim Disease” that people were identifying. But at that time there weren’t trained epidemiology teams that could do the standard description, case control study, approach. Even if that had been possible, there wasn’t the lab capacity there to identify opportunistic infections that were the signal that there was something wrong with patients with AIDS. A lot of that now should have changed in places that have lab capacity built by the GDD program.

As an example, we’ve been investigating a “nodding disease” in South Sudan and Uganda. It’s a clearly odd syndrome where kids aged five to 15 have head nodding. The kids definitely die with it – it’s not rapidly progressive, but it seems to take hold of them. The nodding is in fact a type of seizure and they do in fact have brain disease. It looks to us like an epidemic epileptic syndrome. The kids die of the things that kids with severe epilepsy die from – they fall into a fire, they die when they are bathing, they get opportunistic pneumonia, etcetera.  When we first started investigating five years ago, it was unclear what the origin was. Now we have learned a lot more about what it is and is not, although we don’t know the underlying cause.

What role does the GDD play in tuberculosis detection – including what is going on in India right now with the “extra-extensively drug resistant” TB strain identified recently.
We have collaborated on TB-related studies in a variety of places – although TB is not part of the pillars of the GDD sites, per se, at the moment. In most of the mature programs, a core part is population-based surveillance for pneumonia. There is a lot of information about TB and its burden in the population that’s gleaned through that surveillance information.

The form of extensively drug resistant TB in India has been reported from Mumbai, and our GDD center in India is based in Delhi. That center has been offering support as needed, but so far has not been asked to play and active role in that problem in Mumbai.

We have a technical support core as part of the GDD program – a core of scientists at CDC that have expertise in different areas that are available 24/7 for the GDD to call upon. Dr. Ken Castro, head of the TB branch at CDC, is a key member of that core. We do have an explicit link with the TB folks. Kazakhstan and South Africa I would identify as the centers that would be high-priorities for TB collaboration.

Kibera slums in Nairobi, Kenya (Photo: Science Speaks)

Tell me about the work that the GDD is doing in the Kibera slums in Kenya.
Kibera is one of the largest slums in the world and is very close to the GDD center in Kenya, which is located in Nairobi. From the beginning, when we went to Kenya to establish the GDD center, we had just come from experiences in Bangladesh with urban surveillance, and we had a strong feeling that was the way to go for the slum dwellers. The work in Kibera has allowed us to understand more about the specific ID problems in these slum settings, as compared to rural settings. They have a fantastic system of community health workers and clinic workers in Kibera that allows them to monitor the slum over time, including common diseases like upper respiratory infections that might not lead to hospitalizations but we still want to know about. Some of the earliest information we got in H5N1 spreading in Africa was from the surveillance in the Kibera slums. And some of the detailed information on influenza still comes from that ongoing study.

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What about the centers in Kenya and South Africa — how are they working with other U.S.-funded HIV and TB programs on the ground?
In South Africa, like all countries where CDC is working, there is now a single country office under a single country director. It’s all under one umbrella. Our GDD center is part of the broader CDC office. In South Africa in particular, the big bulk of funding goes toward HIV, as you may know. So their resources greatly outweigh the GDD resources.

We overlap a lot. For example in South Africa we have helped support a system called GERMS that picks up on some pathogens that are also opportunistic infections common in HIV-infected patients that the PEPFAR folks are interested in as well. So when you do pneumonia surveillance in a place like South Africa, a lot of those patients are co-infected with HIV, so there’s a lot of overlap.

Field epidemiologist training is also a priority for both the PEPFAR folks and our folks, so support for the field epidemiology training programs comes from both CDC and PEPFAR in that case.

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