2016 Lyme disease conference breakout session 1: surveillance part 1

Conference to develop a federal framework on Lyme disease

May 15-17, 2016, Government of Canada Conference Centre, 111 Sussex Drive, Ottawa, ON

Conference day 2: Monday May 16, 2016, Rideau Falls room

Audio Recording


Alain: [00:35]

Just a reminder before we get underway, of course, we will have a questions and answer period after the break, and we welcome any questions in either of the official languages, and if you have not gathered and taken up a simultaneous interpretation receiver, they are available at the back of this room. Ladies and gentlemen, I'll repeat myself for the benefit of simultaneous translation. It is available, of course, and you can enjoy it purely if you have access to the headphones and [inaudible] receivers - sorry, the receivers and headphones that are available on the table at the back of the room. Well, of course, the question period is open for in both official languages. There's plenty of room at the front, come on down.

Ladies and gentlemen, let's get underway. Again, to introduce myself; Daniel, my colleague in the Algonquin room, the main room, has introduced me. I am Alain Rabeau, and I have the pleasure of being the moderator over the course of the afternoon. Again, I remind you of some of the conversation from this morning. Let's have these conversations with respect, let's be hard on the issue, let's be kind and caring to everybody in the room, just as a reminder, as we move forward. We will hear two presentations. We will take a short break, probably around 2:10 or so, and then we will come back to hear two more presentations, and the reason for this is that we want to get a full span of the story around surveillance before we then open it up for questions and discussions between yourselves and, of course, our speakers. With the last half hour, I am going to ask you a skill-testing question, which is the following: out of the conversation this afternoon, out of what you've heard, the questions and answers and the discussions that we have, what are some of the key points, salient points, that you want me to report on your behalf tomorrow morning in plenary? So, that's-I'm asking you to give me the key messages that sit with you from this afternoon's conversation.

So, that's the plan for this afternoon. I'm not going to delay any further. I'm going to invite Nick Ogden, who is a senior research scientist at the National Microbiology Laboratory for the Public Health Agency of Canada, to start off this afternoon with Lyme disease surveillance in Canada. Nick?

Nick: [03:47]

Thanks, and it's a pleasure to be here at this meeting. I'm going to talk about Lyme disease surveillance in Canada; what we've done, which may be different from where we go. Just so you know, I don't have anything to disclose, I don't think.

So, that's my outline of the talk; just a little bit about what we mean by surveillance, environmental risk, how it's changed in Canada, surveillance objectives and surveillance methods, and lastly, a bit about what we've been doing.

So, just so you know, the WHO definition of surveillance is, "The continuous systematic collection, analysis, interpretation of health-related data needed for the planning, implementation, and evaluation of public health practice." So, it's a little different from- it's not clinical management of patients, this is for public health practice, which is essentially prevention and control, and that's what we're aiming to do. And the objectives can be serving as early warning systems, documenting impact of interventions, tracking progress towards goals, monitoring, clarifying epidemiology of health problems, and allowing priorities to be set. So, I think what we've been doing speaks to at least, well, all of those, to some extent.

Just a word about this morning: this is a simplistic view about Lyme disease, many people in the room will consider. I will talk a little bit more about this and about the Lyme disease case definition that we've used, and we're not including any mention of the sort of post-treatment issues, and I'll maybe talk a little bit about that later.

It is a vector-borne zoonosis, it's maintained by wildlife out in nature, and we encounter this disease where all of the elements are together, or at least most of them are together. The bug, the tick, the rodents, the reservoirs for Borrelia burgdorferi, the deer that drive the tick populations, and those elements have to be there for the high-level risk in the endemic areas. I think we know what ticks look like.

The risk, on a continental scale, essentially, these are all maps from the CDC, as you can see bulleting what's happening in Canada on the top, because there isn't any sort of joined up surveillance across the border. Essentially, we're at the north end of the main risk areas on a continental scale, where Ixodes pacificus is the vector in the west and Ixodes scapularis in the east. Within Canada, again, southern BC is the main risk area over there, and then we've got, I guess, three main risk areas: southern Manitoba, northwestern Ontario, and then southern Ontario and Quebec, and the Maritimes.

The risk is predominantly in woodland areas and peri-woodland areas where the ticks survive. And when we're in the woods, they're not kind of falling off the trees, they are crawling up from the herbage towards us. And there are three main factors that control where the tick populations occur, and that is climate; it's got to be warm enough for them to complete their life cycle, there's got to be suitable habitat for them to survive the cold over winter, and heat and desiccation in the summer, and there's got to be enough of those hosts for the ticks, because the ticks are parasites all the way through their life cycle.

How we measure risk in the environment is really-it's how many ticks there are, multiplied by what proportion are infected with the bug in question, in this case, Borrelia burgdorferi. So, where pacificus occurs, Ixodes pacificus, the risk is low to moderate because the ticks are-they don't quest very high in the herbage, and they've got low prevalence. Dermacentor variabilis is-occasionally, you'll find ticks infected but the bug, once it gets from the gut, or tries to leave the gut of the tick to get to the salivary glands, is zapped by the tick's immune response, so the actual risk there-there's lots of ticks, people get bitten by these a lot. There are other bugs transmitted by this that (inaudible), and then Ixodes scapularis, when you've got lots of ticks out there, they're happy to bite us, there's a high prevalence.

We have known for quite some time there's a wide geographic area of ticks appearing in a passive surveillance system, most likely dispersed by migratory birds, which then- basically, half a continent worth of birds leaves and enters Canada every year, and when they come back, they come back when the nymphs are active, mostly, and so we end up with adventitious ticks. Now these, I think, are a problem for people diagnosing Lyme disease and also interpreting the risk. But the risk is much greater where we've got reproducing populations, because these are notional calculations, but it gives you an idea that where the tick populations are occurring, the adults, which can bite us, and be infected, there's many more of them, and also the nymphs of the tick, and there are many more of them in reproducing populations, they do ever get brought in by migratory birds. So, trying to find where the reproducing populations are appearing is important, and where those reproducing populations occur. We did some risk assessment of where this might happen, and when we started off designing surveillance, and that's what we expect for the future. And of course, we now know we're kind of on the way to seeing that.

So, our objectives ultimately are framed in two ways; kind of what's the biology behind this emerging zoonosis, and secondly, what can we do to it? Because if we're producing surveillance to identify risk that there will trigger something, some public health response. What can we do? Well, we've no vaccine, and all we can do is provide information to the public about personal protection, environmental control to reduce cases, and also try to make sure that any cases that occur are treated early by providing information to clinicians and to the public about what Lyme disease is and that it's coming to your neighbourhood soon.

So, the surveillance aims to identify the Canadian population at risk; where risk is occurring, which are the risk populations geographically, but also demographic groups, and so on, so that we can target information to those who are most in need, and also get information about the type of Lyme that's occurring, which might help practitioners, we hope, but also gives us an idea of how well we're doing about informing people.

So, tick surveillance, going out into the environment to try and find the risk, is actually early warning, because when the tick populations are starting off, they've usually got ticks in low abundance, and there's a lower proportion off the ticks infected. And that takes them years for that to build up. The gold standard method is a combination of this, which is rodent trapping, trapping those wild animal hosts, which are out there running around, picking up ticks for us, and getting infected. So, they're a good place to be identifying, collecting the ticks, and then testing the rodents and the ticks for the bug, for Borrelia burgdorferi. It's, in most cases, a sensitive way of detecting where the populations are, as I say, because the rodents are always out there in the environment, and it's also a good way of detecting for evidence of infection, because the rodents have been out there being bitten by ticks for weeks to months. The disadvantage is that it's not necessarily very immediate, it's very resource-intensive, and so you can't kind of do this kind of surveillance throughout the whole of Canada. One site visit takes two days, and so it's kind of tough work.

A slightly lighter version of that is drag sampling, which is that you take a blanket, like the lady at the top, and you drag it in the herbage, and if the ticks are out there, they will jump onto it, and you'll be able to turn the blanket over and have a look and see that there are ticks that are crawling around, which you can then take off. You can identify, you confirm what species they are, and then test them for the Borrelia burgdorferi. So, you get a fairly immediate result, and then a bit later, you'll get an idea of what's the sort of risk in terms of what proportions of ticks are infected. One of the disadvantages, it doesn't really work for Ixodes specificus, because they tend to quest very, very low in the environment.

Out of that, we have been able to bring together through collating studies-we don't necessarily do it ourselves as the Public Health Agency, usually it's partnership with provinces who are doing it, often themselves, and now we've collated the data into a national picture. So, we've produced these data to kind of inform what's happening at the moment.

We also have a passive tick surveillance system, which has been going for quite a long time. It involves ticks collected from patients at medical and veterinary clinics, and it's provided a long data set, good geographical coverage, but there's a problem with specificity because they pick up- particularly, dogs pick up those ticks, adventitious ticks, that are dispersed by the migratory birds. So, you find a tick on a dog, that doesn't mean that there's actually a reproducing population there. But we've worked on methods to make this a much more specific method, and there's continuing studies on using passive surveillance, they're ongoing at the moment.

And lastly, human case surveillance; it's based on kind of diagnostics. Obviously, the main-and it's clinical and serological diagnostics, because that's the main method used, and of course, within the case definition for those with Erythema migrans, and you don't need evidence, the person needs to have had some credible encounter with ticks to have that red ring, but no serological response needed. For a confirmed case, you need disseminated Lyme disease symptoms and laboratory results and exposure, but for a probable case, you don't need exposure.

And we are keeping this limited, and I must make it clear that the limitations to this is because the post-Lyme syndrome and other syndromes are maybe caused by Lyme disease, but they're caused by a lot of other things as well. What we're talking about with public health surveillance, and this is not a clinical surveillance case, and we actually make that very clear on the website and everything. So, what we're trying to do is be able to determine, from one place to the next, where Lyme disease is emerging, rather than being able to capture every single possible case of Lyme disease. And that has been our objective.

As we know that, by and large, the cases are occurring where we're finding environmental risk, but not always. So, human cases are identifying new emerging areas, and of course, we are seeing increasing numbers, and these are apparently, for 2015, an underestimate. We are identifying age groups that are affected, particularly children, five to fourteen, and then elderly people like me, 55 onwards, and we get an idea of what is the proportion of cases identified at different stages of Lyme disease, and it's suggesting that we've got a long way to go in getting information out to the public.

I'll probably end there, but just leave that slide up, which says that there's a lot more going on than just Borrelia burgdorferi emergence, so I'll leave it there.

Alain: Thank you, Nick. Éric, could we make sure we stay within 20 minutes per presentation, please? Okay, thank you. Thank you, Nick. We'll be back with questions and an opportunity to dialogue after the break. Our next speaker is Natalia Rudenko, who is at the Biology Centre at the Institute of Parasitology. Did I get that right? Thank you-of the Czech Academy of Science. Natalia, over to you.

Natalia: [18:57]

Before the slides will be changed, ladies and gentlemen, I would like to thank these organizers, for inviting me. I was a little bit surprised, and it's an honour to be here. I am a laboratory mouse, I have never, ever experienced something like I experienced yesterday, at night. I never saw Lyme disease from this angle. We were doing basic science, actually, that can change your point of view on Lyme disease on a causative (inaudible), but this amount of pain and suffering, it's like, my deepest sympathy and support to everyone who was hurt with this creature.

So, my name is Natasha Rudenko. I'm Ukrainian; I've worked and lived in the Czech Republic for 20 years. Unfortunately, neither English nor French are my native languages. I hope you will apologize my mistakes. My presentation will mirror, a little bit, some information that Nick presented, but I will try to present it from a European point of view.

So, what-okay, can we start? Yeah. As it was mentioned, Lyme disease system is extremely successful system, and it involves a couple of parts. Actually, it makes a triangle. This is biotic things that need to be in this triangle: Pathogen, you have to have pathogen, you have to have vector, and you have to have host. And actually, the interactions between three of those compounds make this disease, or this system, so successful. Actually, the intensitivity of interaction in this triangle make the Borrelia an elusive pathogen. Actually there is small information about it. Ticks are obligate, non-permanent blood feeders, and they can feed on any live animal, almost. Ticks are the vectors of more kinds of microorganism than any other (inaudible). The distribution is from Arctic to Antarctic. There are more than 900 tick species that are already known, and ten percent of them can have a really deep impact on human public health. And the most important genre of hard ticks are Amblyomma, Boophilus, Dermacentor, Haemaphysalis, Hyalomma, Ixodes, and Rhipicephalus. I name them because you have almost all of them in Canada.

Worldwide distribution, this is a known map. It shows you the distribution of four tick species of major medical importance: persulcatus ricinus in Eurasia, and scapularis pacificus in United States. But there are more tick species that can transmit Lyme disease spirochete and other tick-borne pathogens. They're called maintenance vectors and they represent another dozens of species. And in some areas, the maintenance vectors can play a more important role than bridge vectors. Bridge vectors are those that transmit spirochete from infected host to a human. Maintenance vectors normally don't bite humans, but they feed on the same host, and in this way, they are getting the same spirochete that actually can be transmitted to another host, and if the bridge vector feeds on that infected host, the spirochete can be easily transmitted.

In the laboratory test, actually, all the tick vectors that were analyzed showed some capacity of transmitting Lyme disease spirochete, but only two vectors, Ixodes ricinus Eurasia, and scapularis were able to transmit any Lyme disease species that were tested. To maintain spirochete in nature, you have to have a reservoir host present in an area. Efficient reservoir hosts of Borrelia burgdorferi sensu lato share several characteristics. They must be abundant in the area; you have to have a lot of them around. A large number of them is measured infected and they can serve as a host for numerous vector-competent ticks. They do not usually become resistant. What does it mean? It means that another generation of ticks, another generation of ticks, another generation of ticks, can feed on the same animal. And they're already infected and remain infected for their whole lives.

I had a case with a laboratory rat. It lived in the lab cage for 13 years, 13. It was taken perfect care of, believe me, much more than some human beings, and each and every year, we tested it for infectivity. It was still infected, and was able to transmit live, pathogenic spirochete to another host.

Reservoir hosts represent hundreds of species; mammals, rodent, birds, and lizards, but not-excuse me? Yeah, this one-but not each animal can serve as a competent reservoir host. What does it mean? The spirochete that infects an animal need a surrounding where it will be able to multiply and be transmitted, in infective stage, to another host. We did some laboratory experiments, just testing the response of zoo animals to three different spirochetes, the major causes of Lyme disease in Europe. The first column is sensu stricto (inaudible) garinii, and the last one is afzelii. That dark grey column shows you an animal that cannot be infected with any one spirochete, because the immune system responds so strongly that spirochete will be cleared. Rabbit, you will not be able to infect a rabbit with any spirochete except Borrelia andersonii. So, that different colours, light grey and dark grey, show you the animals that respond differently to different species like-sorry, change this one, and this one. It means that Borrelia burgdorferi sensu stricto has a chance to infect those animals, but garinii and afzelii will not. If you check this part, so actually, those are the animals that can be infected easily with any of spirochete from sensu lato complex. And carnivores are actually believed to be the best reservoir hosts. It's like, you can be surprised, but Siamese crocodile is one that can be infected with anything. But another thing is that the chance of crocodile to meet infected ticks is kind of low, especially in Canada.

So, when the first spirochete was isolated, it was just a success. So, the problem is solved? No, that was the beginning of the problem. You can see, over the years, how the number of recognized spirochete grew up. Recognize it means that a lot of samples with similar sequences was proven to exist in nature, and they were detected repeatedly, because a giant amount of spirochetes that were not named yet, because the number of (inaudible) is very low. Currently, 21 species from Borrelia burgdorferi sensu lato complex is known, and out of them, ten, in one or the other way, are involved in human Lyme disease. Borrelia afzelii, Borrelia burgdorferi sensu stricto, Borrelia garinii, everybody get used to these names. So, if you check the table,Borrelia bavariensis, Borrelia bissettii,kurtenbachii, lusitaniae, spielmanii,valaisiana, and the newcomer, this is a favourite of 2016, Borrelia mayonii. All of those spirochete were detected in patient of human being in different European countries.

The genome of spirochete from Borrelia burgdorferi sensu lato complex actually presents the most complex genome, as it includes a B chromosome and a set of plasmids, 21 plasmids, in general. It's linear and circular, and spirochete is shuttling between cold-blooded vector and hot-blooded host. Being in two completely different surroundings, not a single one of them is a favourite for her. This creature needs to survive somehow, and it is known that spirochete shuttling back and forth can lose some information. If two or more spirochete species are present in one host vector, it's possible that they will exchange this information, and in reality, to be able to survive, the spirochete alters expression of outer surface protein antigens to be able to adjust to the surrounding where it is in the moment. So actually, the adjustment can give you a population that you wouldn't expect to be present in that host in that moment.

The geographical distribution ten years ago, they might look very clean and very easy. Forget about Eurasia; let's check North America. It's sensu stricto and a little bit of bissettii. Five years ago, it's kind of a mess, but believe me, it's not as big a mess as it is right now. In addition to kurtenbachii, andersonii, californiensis, americana, and carolinensis, was detected in there. Separation of kurtenbachii showed that that species was detected in California and in northeast, as well as in Europe. Another one: Borrelia valaisiana, European species, kind of European species, was detected by commercial laboratory in patient from northeastern New York, and the person didn't travel for the past, maybe, 30 years. Borrelia garinii, Borrelia bavariensis, was detected in ticks in Canada. Borrelia garinii, Borrelia afzelii, were detected in samples from rodent and ticks in southeastern United States that were collected 20 years ago. It means that the population of those two European (inaudible) species was well established in that area.

Borrelia americana and Borrelia canadiensis, this is our key, so we describe these species. They were detected in Aix, in France, and we found them in patient child from a hospital of children, neuroborreliosis. Recently, these spirochetes, both of them, were detected in China, in eight out of ten locations that were analyzed. So, and updates, novelty is Borrelia finlandensis, year 2011, Borrelia chilensis, the first spirochete from southern America, and Borrelia mayonii, that was detected in Wisconsin. We're going a little bit too fast.

So, yeah, we can move. If you check your neighbour-actually, all those ticks, if you overlap the map, there is not a single spot that is tick-free, and…

[Discussing technical difficulties]


Actually, what is the main engine of this distribution? And believe me, this is definitely not the final version. It was updated till the beginning of 2016. I am sure that in June 2016, there will be more species and more hot spots where unusual spirochete can be defined.

Migration, migrative animals; so, how far can mice go? Maybe 300 metres in their lifestyle, but birds? We have quite a lot of flyways, and the worst thing is that those flyways are overlapping. So there is no problem for spirochete to go from Japan, let's say garinii, through Russia, to Canada, or all the way down to United States. And this is a map (inaudible) was publishing in 2010. The idea about the presence of sensu stricto only in United States is too far, to be truth, because as you can see in the red, there are an update. Southeastern United States, that's considered by CDC as non-endemic region, actually represents or contains the longest list of spirochetes, and using migrative animals, believe me, they can move anywhere.

The spirochetes, if you are talking about sensu stricto, because this is a species that you all believe cause Lyme disease in U.S. and in Canada, the spirochetes are completely different. Just try to imagine a huge family with multiple members; they all are under the same name, but they're all different. And some species from some strains, or types that were based on OspC sequences are believed to be assigned exclusively to North America or exclusively to Europe, and three of them, only, were detected in both continents. This is a very simple presentation of Borrelia burgdorferi sensu stricto. That flower actually includes the analysis of 202 isolates that were collected all over the world, and believe me, there is no more complex thing than this one, because each and every branch, it can produce another flower. If you check the presence of OspC types in southeastern United States, there are only four of them. And right now, there are 32 OspC types known. There are only four of them in southeastern United States, and there are much more in Canada. Those are three OspC types that cause the most severe Lyme disease in humans. Nick, your map, thank you so much (inaudible). And what is interesting, the map from Nick's publication shows this hot spot, let's say, for OspC type L. Auspicid type L, a few slides back, was considered to be exclusively European, but we found the species of OspC type L in southeastern United States, and the sequences that we compared were almost identical.

Talking about the competent and non-competent tick. Competent are those that transmit Lyme disease, and we accepted this. But there are some ticks, let's say, from Amblyomma americanum; Amblyomma americanum bites humans in the United States like crazy, seriously. But it's considered to be a non-competent vector for Lyme disease spirochete. It transmits some other pathogens, but not Lyme disease. We did detect it, these spirochetes, from Borrelia burgdorferi sensu lato complex, in these species, with one interesting finding: those vectors transmitted a little bit different strains of Borrelia burgdorferi sensu stricto comparing to those that are traditionally distributed. So, the distribution of Borrelia burgdorferi is an extremely dynamic process, and actually, we make quite a lot to support this. You wouldn't believe, but humans transmit some ticks during vacation, or field trips, whatever. But the majority of all impact for this distribution of Lyme disease spirochete definitely belonged to migrating birds. And where Lyme disease is absent is as a tick, the vector, or this is just a matter of time.

And the last sentence, that I truly love: The absence of proof is not the proof of absence. And I think that everyone should consider this talking about Lyme disease, and I greatly appreciate your attention, and will be happy to respond to any questions if you all have some. Thank you.

Alain: The good news is that there is no test, today, on this matter, okay? I'm going to suggest we take a quick stretch break. I think there's coffee out there. We can take a 15-minute break. We'll come back, we've got two more presentations and then we'll engage in Q's and A's, and discussion. So let's take a quick break, stretch out and we'll be back in 15, please.

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