Transcript for Vital Signs Teleconference: Vector Borne Diseases

Press Briefing Transcript

Tuesday, May 1, 2018

Please Note: This transcript is not edited and may contain errors.

MICHELLE BONDS: We’re joined today by the CDC Director Robert Redfield, as well as, Dr. Lyle Peterson, Director of CDC’s Division of Vector-Borne Diseases. After his remarks, Dr. Redfield has to leave, however, we will be joined by Dr. Peterson, who will be available to answer questions during the Q&A portion of the briefing. I’d like to turn the call over to Dr. Redfield.

ROBERT REDFIELD: Thank you very much. Thank you all for joining us today. CDC works 24/7 to protect Americans against health threats. In each month’s CDC Vital Signs reports, we focus on one of the threats and what we can do — what can be done about it. Today the report contains new information about our nation’s growing burden of disease from mosquitos, ticks, and flea bites and the important role that the state and local departments and vector control organizations have in controlling them. As well as the important role that public at risk also plays. We’re specifically talking about vector-borne diseases such as dengue, Zika, West Nile, chikungunya, Lyme disease and plague. These are serious diseases that result when people are bitten by an infected mosquito, tick or flee. These vectors cause disease and sickness worldwide. Cases of these diseases have tripled in the United States with 640,000 cases reported between 2004 and 2016. There are several reasons why we’re seeing this increase. Mosquitos and ticks and infections are moving into new areas nationwide. Overseas travel and commerce are more common than ever before. A traveler can get infected from a mosquito borne disease like Zika in one country and then return home now infected, which then puts other people at risk. Finally, a number of new germs spread through mosquito and tick bites have been discovered or introduced here. In fact, nine new germs, seven of them spread by ticks, have been newly introduced or discovered in the United States since 2004. We know that mosquitos, ticks, and fleas are widespread and can be difficult to control. This growing burden has put increased demands on state and local health departments and vector control organizations. We must continue to provide the support to enhance their ability to combat these vector-borne diseases. Since Zika emerged in 2016, the resources that were provided for national response have helped strengthen the state of prevention and control capacity. Our nation is better prepared today than we were a year ago. So what more can be done to protect the public health of our nation? It will take all of us working together to prevent and control diseases from mosquitos, ticks, and fleas. And there is a role for everyone. For example, state and local health departments can strengthen their capacity to test and track diseases and control mosquito, tick and fleas that spread them. Health departments, universities and schools can educate people on how to protect themselves and their families and emphasize the critical role of vector control and preventing and stopping these diseases in their communities. Companies and researchers can develop new or better methods and products to kill mosquitos, ticks, fleas at every stage of life. Everyone can and should take steps to protect themselves from mosquito, ticks and fleas using an EPA registered insect repellant, and taking steps to prevent ticks and fleas on animal pets. We can also eliminate mosquito-breeding sites by emptying containers around the house, which hold small amounts of water, which can be a place for mosquitos to lay eggs. The bottom line is this: Illnesses from mosquitos, ticks, and flea bites continue to impact our nation. The threat of disease spread by mosquitos, ticks, and fleas are increasing. With the warm weather and summer travel rapidly approaching, we know that we are vulnerable to these diseases from both ticks and mosquitos. Protecting ourselves from this threat is possible. It will require improvements in vector control, public education on the best practices for prevention of insect bites, as well as supporting improved surveillance and reporting, better diagnostics and research for both better methods of vector control, as well as better methods of treating and preventing human infection when vector exposure occurs. It sounds ambitious, but I would encourage everyone to never underestimate the possible. It can be done if we work together and it’s time to do that. I’m now going to turn over today’s Vital Signs discussion to Dr. Lyle Peterson who will share the findings in the report.

LYLE PETERSON: Thank you, Dr. Redfield. In this Vital Signs, CDC collectively examined trends in data from 2004 to 2016 for all vector-borne diseases that are reported nationwide. Here’s what we learned. As Dr. Redfield pointed out, the number of reported vector-borne disease cases have tripled over the last 13 years. This includes a doubling of reported cases of tick — of diseases from ticks over this time period, which accounted for more than 60 percent of all reported vector-borne diseases. Keep in mind that many infections are not reported or recognized so it’s difficult to truly estimate the overall cost and burden. For example, we know that the number of Lyme disease cases that actually occur each year are approximately 300,000 or 10 times higher than what is nationally reported. Although Lyme disease accounts for 82 percent of all tick-borne cases, other diseases from ticks have also increased. Areas where we find these diseases now are expanding. Mosquito borne diseases are reported by all states and territories. West Nile Virus is the most common germ spread by mosquitos in the continental United States and epidemics strike every summer. Periodically, as in 2012 with West Nile Virus, large epidemics also occur. U.S. territories report the most cases and epidemics of mosquito-borne diseases like Zika and dengue. State and local health departments and vector control organizations are the nation’s main defense for preventing and controlling these diseases. Nationally, we have more than 1900 vector-control organizations. Each operates independently and sets its own standards for conducting vector control. Funding either comes from local taxes or government and most commonly from the local health department. In 2017, a survey conducted by CDC and the National Association of City and County Health Officials showed that 84 percent of vector control organizations report needing improvement in one of — in one or more of four core competencies such as monitoring and tracking mosquitos and ticks locally or conducting resistance testing. CDC is using two strategies to better prepare state and local health departments and vector control organizations to prevent and control these threats. First, we’re working to expand the number of effective and publicly accepted mosquito and tick prevention and control options to protect all of us. Second, CDC is working with state and local health departments to build or rebuild comprehensive vector programs that have eroded over time. By taking these steps and sustaining these efforts, we as a nation will become more resilient in the fight against these diseases. There is a role here for everyone to play from CDC to state, local, and vector control organizations. Now I’ll turn it back to the moderator.

MICHELLE BONDS:  Thank you, Dr. Peterson. Brandon, we’re ready for questions.

OPERATOR: Thank you. We will now begin the question and answer session. If you’d like to ask a question, please press star 1. You’ll be prompted to record your name. To withdraw your question, you may press star 2. Once again at this time if you would like to ask a question, please press star 1. One moment, please, for our first question. Our first question is from Mike Stobbe with the Associated Press. Your line is open.

MIKE STOBBE: Hi. Thank you for taking my call. Dr. Redfield said — is Dr. Redfield still on the phone?

LYLE PETERSON: No, he’s not.

MIKE STOBBE: He said something about we’re better prepared today than we were a year ago. Dr. Peterson, you were talking about the CDC NACCHO survey, which seems to suggest that we’re not very well prepared. I was wondering what Dr. Redfield was referring to. Could you let us know where did Dr. Redfield have to go? Thank you.

LYLE PETERSON: Dr. Redfield had another appointment. I can’t speak to where he is at this exact moment. But to answer your question over preparedness, over the last couple years certainly with the Zika epidemic, the funds that congress made available for — to respond to the Zika epidemic actually helped provide more resources to state and local health departments, as well as vector control organizations to help boost capacity. However, it’s important to note that improving the situation for vector-borne diseases is a long term effort that it needs to be a sustainable effort. It just can’t — the whole system, we’re dealing with 1900 vector control organizations — can’t all be improved in a one or two-year period. So I think with the Zika funding that enabled a good start to help us prepare for these kinds of diseases. But a long term effort is necessary.

MICHELLE BONDS: Next question please.

OPERATOR: Our next question is from Dennis Thompson with Health Day. Your line is open.

DENNIS THOMPSON: Thank you for taking my question. I have two questions. Number one, do you expect the tick and mosquito season ahead to be a bad one as it was in the most recent year noted here? And also, do we have any reasons why mosquito and tick areas are expanding? Does it have to do with global warming or other factors? Thanks.

LYLE PETERSON: Yeah. So to answer the first question about what might happen this summer, I certainly don’t have a crystal ball. I can’t predict with any accuracy what is going to happen this summer. These diseases are very complicated diseases in nature which — and many, many different factors promote epidemics or disease incidents. Making it very hard to make predictions. For example, these diseases are very weather dependent. I can’t predict what the weather is going to be line in July or August. So the main point is because these diseases are so unpredictable, we know that — I mean we just need to be prepared for whatever might occur. So preparedness is very important.

MODERATOR: Next question.

LYLE PETERSON: We have another question. The second part of the question was why mosquitos and ticks — why these diseases are increasing? As I mentioned, these are very complicated diseases in nature. And there are many, many different factors which effect where these diseases occur and how frequent they are. And so for the mosquito-borne diseases, in particular, they’re very sensitive to patterns of travel and trade and how we live. So, for example, the fact that Zika virus or Chikungunya viruses or the fact that West Nile Virus came to our shores in 1999, these are diseases that are spread by the movement of people, for example. Or the movements of animals or occasionally the movements of the vectors and the way we transport them. So right now we’re in a situation with the expanding global travel and trade that all these diseases are basically a plane flight away. And so because travel and trade has been increasing, the number of diseases coming into our shores has increased as well. At least the mosquito-borne diseases. For example, in West Nile Virus, it came in 1999. Another one came in 2014. Zika virus came in 2015. So there appears to be an accelerating trend. For the tick-borne diseases, they are many factors involved with those as well. Including the way we live. So, for example, there is many more deer in the area — areas where people live and with more deer you have more deer ticks and with more deer ticks you have more Lyme disease or a number of other diseases that spread. In addition, we know that temperature is very important. And so if you increase temperatures in general, what will happen is that the tick populations could move further north, expanding their range. As well as increasing the length of tick season which puts more people at risk for a longer period of time.

MICHELLE BONDS:  next question.

OPERATOR: our next question is from Allison Aubrey with NPR. Your line is open.

ALLISON AUBREY: What I hear you saying, Dr. Peterson is climate change does play a role here with the tick-borne disease?

LYLE PETERSON: What I can say is that any of these diseases are very sensitive to temperatures. And so when there is increasing temperatures, it promotes several things. One is the mosquito-borne diseases tend to get worse during heat waves. West Nile Virus major outbreaks have happened in the United States have all happened during heat waves. So temperatures tend to make mosquitos more infectious and infectious faster thus promoting outbreaks. For the tick-borne diseases as I previously mentioned, increasing temperatures will tend to expand the range of the ticks further north as well as increasing the length of tick season.

ALLISON AUBREY: I just have a follow up question to that. Separately. You mentioned that the number of Lyme disease cases might be closer to 300,000. I’m wondering, given the need for better reporting and surveillance, I’m wondering what it would take to get, say, what you’ve done with the flu, we don’t really know how many people get the flu. But we do know how many children, the cases that the child had deaths and pediatric cases reported, there is more requirements for reporting. What would it take to get better reporting requirements for something like Lyme disease for every time a hospital or doctor gets a positive test to report it to somebody?

LYLE PETERSON: Yeah. That’s important to know that the reporting to CDC is a function of the states. And the states control their own surveillance systems. We support those surveillance systems. But this is a state specific matter because public health is a matter of the states that we support. So one of the factors is we certainly need better surveillance. And we need better ways of simply monitoring the shear large number of cases that are occurring. So certain states like New York State, for example, has — they don’t try and count every case. But they use methods of estimating the number of cases that they have based on a sampling technique. So new methods are clearly needed to try and deal with the very heavy burden of cases in certain areas.

MICHELLE BONDS: Okay, go ahead. Go ahead.

ALLISON AUBREY:  Well, if New York State is an example of somebody doing it right, can you give us an example of where the reporting is just a mess or all over the map?

LYLE PETERSON: No, but, you know, I certainly think all the states are doing a good job. But I think what is necessary is that, you know, we need to make sure that states are adequately supported so that they can conduct surveillance as well as help people prevent tick bites from occurring.

MICHELLE BONDS:  Next, question, please.

OPERATOR: Our next question is from Gina Cherelus with Reuters News. Your line is open.

GINA CHERELUS: Hi, Dr. Peterson. So my question involves the sharp surges that we see in the years like 2005, 2007, ’12 and ’16. And I see that in 2015 it had eased off a bit. At 55 — over 55,000 and it jumped to 96,000. Can we expect a drop in 2017 from 2016? And can you also explain what caused that drop between those two years? I’m getting at any efforts that were being made in research at the centers and so on.

LYLE PETERSON: Right. It’s important to note that overall figures are really two distinct trends. One is the tick-borne disease that’s are steadily going up every year, year by year. And so that’s almost a monotonic increase in cases every year as the tick-borne diseases expand to new areas around the country and as the number of cases in areas where the tick has been established has gone up as well. For the mosquito-borne diseases, they tend to be more episodic. For example in, 2012, there was a large increase in West Nile cases because there was a large epidemic. In 2016, we had the Zika epidemic. Many cases associated with that. So the mosquito-borne diseases tend to be more episodic causing these numbers to fluctuate up and down whereas the tick-borne diseases are generally increasing year by year over time.

MICHELLE BONDS: Next question.

OPERATOR: Our next question is from Julia Edgar with WebMD.

JULIA EDGAR: Hi Dr. Petersen. Thank you for taking my call. You talked about the resources the federal government made available in the wake of Zika. You have said that the CDC is interested in supporting local efforts to combat tick-borne diseases in particular. What specifically does the government plan to do to help local public health departments to improve surveillance techniques, reporting and so forth? What are you talking about money? Please be specific.

LYLE PETERSON: Right. Certainly with regard to funding and support to state and local health departments, we understand that Congress and the administration have many difficult choices to make. We are grateful for the $12.255 million increase in our budget in FY-18. This money is able to fund up to nine states to enhance their vector-borne disease capacity.

MICHELLE BONDS: Next question.

OPERATOR: Our next question is from Suzanne Capatulo with WABE Radio Atlanta. Your line is open.

SUZANNE CAPATULO: Hello. Thank you so much for taking my call. I want to know do you have any state-by-state numbers somewhere we can access. And my other question is back to the temperatures. Are you saying that the high temperatures is due to, you know, high temperatures are due to climate change is causing more tick-borne diseases? Or are we taking those temperatures just as heat waves?

LYLE PETERSON: Yes, we — to answer the first question. We do have state-by-state figures. Some of them are in the MMWR. We have a fact sheet. We have state profiles that are available on the web. So the number of sources where you can get state-by-state data. As far as the increasing temperatures, as I mentioned previously, first of all, I can’t comment on why there is increasing temperatures. That’s the job of meteorologists. What I can tell you is that increasing temperatures have a number of effects on all of these vector-borne diseases. One effect as I mentioned previously is that from the tick-borne diseases, it enables the tick to expand to new areas. And where there are ticks, there comes the disease. It also increases the range of the length of tick season causing people to be at risk for longer periods of time potentially. For the mosquito-borne diseases, they’re very temperature sensitive. And so temperatures during the summer that are warmer tend to promote outbreaks because the mosquitos tend to become infectious a little bit faster after they’ve become infected. And the virus levels in the mosquitos tend to be higher causing them to become more infectious. So outbreaks of mosquito-borne diseases often like West Nile, for example, may occur when the temperatures are higher than normal.

MICHELLE BONDS: Final question, please.

OPERATOR: Our last question is from Jullia Belluz with VOX. Your line is open.

JULLIA BELLUZ Hi. Thanks so much for taking my question. I was just wondering about the undercount — you mentioned that, again, the number of Lyme disease cases may actually look more like 300,000. I was wondering if you could flesh that out a little bit more, like, why is there this undercounting in addition to the difficulties of detection? If you could just break that down.

LYLE PETERSON: Right. So one of the reasons that Lyme disease is undercounted is the fact that many Lyme disease cases are treated as outpatient. So people go to the local doctor to get treated. Diseases that are treated by local doctors, you know, particularly when the doctor sees many, many, many cases in a day, they all may not be reported. So as an outpatient disease like this, they’re typically underreported to a certain extent. But it’s important to note the other reason is that there are so many reports coming in to certain state health departments where it’s endemic that the state health department has a difficult time keeping up with the sheer number of case reports. But it’s also important to note that it’s not necessarily important — it’s not necessary that every single case is counted. For many of these diseases. You know, for example, you know, if you’re in rain storm, you don’t have to count every drop to know – to determine how much rain there actually is. What is important here is the actual trends. And the transfer of the tick-borne diseases are all going up over time. And so even though we don’t count every single case, we flow that the trend is towards a worsening in the United States where more tick-borne diseases are found in an increasingly wide area.

MICHELLE BONDS: Thank you, Dr. Redfield and Dr. Peterson for joining us today as well as all of the reporters. For more information about the vital signs, visit For follow up questions, call the press office at 404-639-3286 or send an e-mail to Thank you for joining us to day. This concludes our call.

OPERATOR: Thank you for participating in today’s conference. All lines may disconnect at this time.


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