138. RIPL - Tick borne infections

Jame and Callum are joined by Christina Petridou. In this episode we give you an overview of ticks and the key infections they transmit..., but NOT Lyme disease.

Some of the infections we DO cover include: Rickettsiosis (spotted fever group), relapsing fevers, anaplasmosis, ehrlichiosis, babesiosis, TBE & CCHF. 

Not Lyme. THIS IS NOT A LYME DISEASE EPISODE. 

Show notes (including lots of summary tables and horrible tick pics) for this episode are here.

Register for the BIA Spring Meeting 2026 here! 

Transcript

RIPL - Tick borne infections

Jame 0:18

Hi everyone. Welcome to the Idiots Podcast. That's infectious disease insight of three specialists. I'm Jane. That's Callum. This is Christina. And we are going to tell you everything you need to know about infectious disease.

0:29

Soon, may the editing come to discontinue the Tazo sun one day when the S piece done, we'll take our leave and go.

Jame 0:39

Callum, how you doing?

Callum 0:42

I'm doing? Very well. I was thinking that you should write the pun this week,

Jame 0:46

Why? Why should I write the pun this week?,

Callum 0:49

Because I've done everything else.

Jame 0:51

Oh really? Is that annoying you?

Callum 0:53

Yes. It's really yeah.

Jame 0:56

I knew exactly where you were going. Callum. Okay. It was either gonna be a ripple, pun or so, some, presumably some sort of ice cream thing or a tick based pun, and I beat you to it. So there, what do you gotta say to that?

Callum 1:08

I was out on the farm the other day and there were all these oxen and I was bringing them out of the farm field because I know what farming and I was like, I ox these,

Jame 1:27

it was gonna be some sort of wine-based pun. So you could say that you put the port down to greet our illustrious guest

Callum 1:33

Oh, that's actually really good.

Jame 1:35

No, it's too late. Hello, Christina. Welcome to the show. How are you doing?

Christina 1:38

Hi guys. I'm doing well. I'm trying to understand what the hell just happened, but.

Jame 1:44

I think it's unknowable. So let's just, move on.

Callum 1:47

So we're honored to be joined by, Dr. Christina Petou. Christina is a consultant and infectious diseases and medical microbiology. She works across, the NHS and also at the rare imported pathogens lab at Port and Down. and she is a clinical lead there for Lyme disease.

Jame 2:06

Yes. Which we are specifically not going to talk about today. Is that right? Cal?

Callum 2:12

Yes.

Jame 2:13

Christina, welcome to the show.

Christina 2:14

Thanks guys. Happy to be here.

Callum 2:17

So we're talking about tickborne infections, and this is something that I remember very clearly as a junior registrar, first couple of weeks in the job, and I was assessing someone who'd been abroad, I think South Africa. And they'd had a tick bite. And I knew that this was important because ticks. Spread diseases, but I had no real framework by which to assess, how important that tick bite was. What diseases I should be worried about. And I remember feeling at that time in my career that the weight of just so much, it just felt like there was this unknowable, vast amount of knowledge to acquire. And since then I did the diploma in Tropical Medicine and have seen more things that tick and it now makes sense, so I guess my first question would be, B, what are ticks? And then the second one is, why do they matter,

Christina 3:13

so ticks are heus arthropods. So blood feeding, arthropods, don't have wings. They don't fly or jump. But they are important vectors for lots of different diseases. Diseases caused by bacteria, viruses, and parasites. And different species of ticks are found all over the world, and the diseases that they transmit are influenced by the species of the tick. The animals around the tick which might be the hosts of various diseases. And if they feed on humans, they may or may not pass on an infection depending on various things such as how long they're attached, et cetera.

Jame 3:59

And how many of them are attached to you as well? And they're arachnids, aren't these they're closely, but not exactly related to spiders. So that's the way to remember them as a sort of spider parasite.

Christina 4:12

Very true. Yeah. And the way we classify them anyway, they're grouped into two really big groups, the hard ticks, which are the most important for us really to know about the X sodi ticks and then the soft ticks which are a little bit less important, but can transmit some diseases.

Jame 4:31

Yeah. And we've got some pictures in the prep notes that we'll point. No,

Callum 4:37

No, I just don't like looking at the pictures. I'm sorry.

Jame 4:39

Okay, fine. Other people can look at the pictures. Cam doesn't want to, I think probably because the heart ticks look very spider like in their, appearance. And the soft ticks looked like a big blob that just has eight legs sticking out of it,

Christina 4:53

Basically, yeah.

Jame 4:54

And they don't really have a head. They've just got mouth parts directly attached to the body. Is that right?

Christina 5:00

yeah., Don't have a very distinct head at all. No. They've got those really important mouth parts that can be left inside you sometimes if you don't remove the ticks correctly. But yeah, they've got, they look very much like spiders. Correct.

Callum 5:14

Yeah, so having seen many ticks on hikes in Scotland and not enjoying it, I guess you get to see that there's, there's some ticks that you can quite obviously see, like the adult ticks are pretty obvious when they're on your leg. But they go for this lifecycle, obviously start as an egg. They then hatch into, weirdly a six legged larva, and then they go into nymph, which has eight legs, and then they become an adult. So there's a picture in the prep notes about the different stages. They, to transmit the disease they need to have become infected themselves. So they have to have taken a blood meal. So it's quite easy to miss a tick bite, particularly when it's first bitten you. And it's not engorged with blood.

Christina 5:57

Yeah. So normally most infections that humans get from od sticks are from the hardback. Ticks are from the nimal stage. These are really tiny. They're like little poppy seeds, very easy to miss. The adults are significantly bigger, so you are more likely to notice them, more likely to remove them. Um, So most of the infections are from the nial rather than the adult stage. um, either can, they Do have to become infected. So they become infected by feeding on usually small mammals like rodents or birds that are infected. And then for for most infections, once they're infected at that stage, so at the nimal stage they will just remain infected rest of their li their lives really. So when we think about Lyme disease, that's how it works.

Jame 6:43

And the, just to point out, their host range is quite wide. They're not very fidelus. As to what they mind feeding on. As long as you're a mammal or a warm blooded creature, they're usually good to go

Christina 6:57

it depends on the species of tick. So in the UK we've got about 20 different species of ticks. And actually the majority are what we call specialist parasites of wildlife. So they actually are very picky about what they feed on.

Jame 7:09

Uhhuh.

Christina 7:09

example, they'll feed on specific species of birds. Um, But the exodus ticks, so Sodis rice us, the the main one we worry about in that it's the transmitter of Lyme disease is not very picky at all and will feed on a whole host of things. but actually a lot of the other species that aren't so important for transmission of diseases in the UK will be quite specific in terms of what they feed on.

Jame 7:33

So that infidelity is with the

Christina 7:35

it's

Jame 7:36

that cause Lyme more than,

Christina 7:38

it's more species specific. Um.

Jame 7:41

turning the, trying to turn this into a Lyme disease episode,

Christina 7:43

no, no. i'm not gonna do that.'cause you were very clear with the instructions that it wasn't, that, it's just, it is the most common, uh, vector born disease we see in the uk.

Jame 7:52

know I, and my favorite Tickborne infection as well

Christina 7:54

to hear it. I'm glad to hear it. But X sodis rising is the one that transmits Lyme disease also transmits the other important infections that we're gonna talk about

Jame 8:03

Okay. Okay.

Christina 8:04

as you say, it's one that will feed on lots of different things. But just going back to the thing you said before about the ticks being really difficult to spot. I find ticks on my kids all the time, and they can be really really tricky. So they're often in the hairline behind the ears, the behind the knees in the groin, funny places. So you have to be really careful when you do, tick checks. But the poor thing went on a school trip to the New Forest the other day, and I think I picked off about six ticks from her, including two in her eyebrows.

Jame 8:35

surprised as the UK's foremost ologists that you'll let your kids within a hundred miles of the new forest.

Christina 8:41

uh, we go all the time. Of course you should

Jame 8:44

Right.

Christina 8:44

the great outdoors, but just your tick checks and hope for the best.

Callum 8:50

Yeah. So that's odes. And are there any other ticks that we need to worry about?

Christina 8:56

Uh, significantly less important. The main tick we see in the UK by far and away is absurd, is rice. So it's got lots of names, but the casta be tick, the deer tick, the sheep tick. It's called various things, but another very important tick in that it's, very common as ex's hexagons, which is also called the hedgehog tick. And that tends to spend most of its time in the nests and burrows of, hedgehogs and its other it's One of the most common ticks, for example, that you would find on your domestic cat or on your dog. But of the ticks that are of relatively less importance, but we do sometimes see are things like derma center, Ulis and other names for that are the ornate cow tick or the ornate dog tick. And. It's not really that important in the UK in terms of transmission of diseases, but in other countries it is quite important. So for example, In Siberia it transmits something called OMS hemorrhagic fever, a flavor virus infection. But we don't have that in the uk. So as far as we're concerned really in terms of things that we're more likely to see in our patients, it's really diseases caused by so but in other countries there are other ticks that are more important potentially in returning travelers.

Callum 10:12

and that could be a hour long episode just talking about all the ticks of the world.

Jame 10:16

Let's talk a little bit now about Xdi itself, seen as it's the most important tick vector. How does it get onto humans? What kind of grassland do you find it in? Do you find it in trees, in et cetera, et cetera.

Christina 10:30

Okay. So that's a good question. So people always think of you only really being able to tick-borne infections if you go to very specific places in New Forest, et cetera. But actually we know they're pretty widespread across the uk. The tick density is higher in the southeast and the southwest of England, which is where we see most of our infections. And also higher in some areas of Scotland, like the Highlands for example. But they are pretty widespread. And it's not that you have to go in the forest to get a tick bite. You can easily also get them from urban parks, for example, Richmond Park and other places like that. But we see them really in places where there's ground level vegetation. But they are also found in people's gardens, for example. We always get tick bites in our garden. and the way they actually get to you, if we're talking about ex stick specifically, they do something called questing. So they are basically hanging out on foliage with their back legs, kind of wrapped around them and their front legs waving about. And as you go by, they opportunistically will latch onto you and then they'll crawl around and find a place that they like where they then start feeding. So for kids it's often, closer to their ears, their heads, their necks. That's the type of place they tend to be bitten. Whereas adults, it's often in the legs because of obviously different heights and just walking around, but they won't pursue you to get you, and they won't jump or fly onto you to get you. Whereas there are other species that are a little bit more aggressive will come after you to get you. But theod sticks, which are the most important ones for us to talk are not like that.

Jame 12:08

Okay, and does the, do the exhibit see atonality?

Christina 12:12

Yes. We used to be more concrete when we talked about this and kind of talk about Lyme disease, et cetera, and other tick-borne infections really happening in the spring and summer months. And we definitely do see more in the spring and summer. It's up big time now at port and, but we actually do see cases of tick-borne infections all year round. We do a lot of work with Forestry England and speak to the rangers and people there a lot. They talk about finding their deer full of ticks in December and January still. So, although it it is a seasonal. Disease are seasonal. We still have to be mindful of year round.

Callum 13:11

So How do we know like where the ticks are and what types of ticks there are, and also what sort of in infections the ticks are carrying? Because quite a lot of the time when I'm, talking to patients and they're say worried about Lyme disease or other tick-borne infections and they're looking for information on to to point them to words.

Christina 13:30

So there are two main ways One is something called the tick surveillance scheme. And that's been running for 20 odd years. And essentially this is members of the public. So basically anybody can submit ticks that they find on themselves, on their pets. And really what that does is identify the species of tick. So it's looking at whether we are having any incursions of non-native species, what the rare tick species are, what distribution is, what types of ticks we're seeing. But that doesn't tell you the, Number of ticks are infected, just Which ticks exist. there's something else called the National Tick Survey. And this is something done every year by uk. Just say, we've got a very big and very active entomology team, and they go out to various locations across the uk. Where they will actively collect ticks, Using this sheet that they drag across the forest floors. And they will get those ticks and they will then test them for various diseases so they know what percentage of ticks are carrying various diseases in the uk. when people submit their own via the tick surveillance scheme, really keen to know if that particular tick that bit them, is infected. Usually it's Lyme disease they care about, But we don't really give them that.

Callum 14:47

Think it's really interesting. So I guess is we can briefly mention, removing ticks properly. I think to my understanding is that for Lyme in particular the tick as opposed to some other. Pathogens transmitted by insects, it, it is only transmitted once. It's been feeding for a while. So if you remove the ticked promptly and you dramatically reduce your risk of an infection, so is that true? And also, how should you remove a tick?

Christina 15:13

Yeah, that is true. So for, to transmit BIA that causes Lyme disease, ticks need to be for many hours. And removing them quickly will massively reduce your risk of, developing Lyme disease. And really the way to do it properly is to use either sharp tweezers, so not the ones that are flat, but the kind of pointy tweezers or a tick removal kit. And if anyone is particularly interested, there's loads of information on the UK to say website about the correct way to remove ticks. We are asked all the time about removal of ticks. Yesterday I think I had two calls about, circumstances where ticks weren't removed properly, and mouth parts were left in and what to do. So it is something that is worth people understanding and knowing about.

Jame 16:00

But presumably if the mouth parts are left and you can't do anything about it, they're too small to be removed.

Christina 16:05

is really really difficult to remove them. You might be able to remove them with proper tweezers. One of the calls recently, the mouth pots were left in and the patient developed a little bit of an abscess around them'cause I guess they were causing quite a bit of irritation. So ideally you wanna get them out if you can, but it can be quite tricky. So the best thing is to just remove them properly. At the outset, patients do show up to Ed with their ticks in asking for them to be removed. So I think worth people knowing how to actually remove them properly. If you had a patient rock up with a tick in them.

Jame 16:37

Yeah. And so the next part here is a table summary of tick-borne infections. Me and Callum have a little tradition, which is Call and James alternately read out the names of things in a big boring list as a sort of sending our audience to sleep as SMR sort of tradition. I wonder if you would be so good as to help us out with this and I'll even let you go with the first disease.

Christina 17:01

Okay.

Jame 17:04

Bacteria

Christina 17:06

Lyme disease,

Jame 17:07

hard, tick-borne, relapsing fever,

Callum 17:10

tick-borne, relapsing fever,

Christina 17:13

Ana Plasmosis,

Jame 17:15

Rocky Mountain Spotted Fever.

Callum 17:17

African tick, bite, Fever.

Christina 17:20

Mediterranean Spotted Fever

Jame 17:23

Parasites. Babesiosis. Viruses.

Christina 17:29

CCHF?

Callum 17:30

Tick encephalitis

Jame 17:32

And that's all the tickborne infections known to humanity. Maybe. I assume I

Callum 17:37

are from it, I think

Christina 17:39

No, there are loads more, but probably, to talk about.

Callum 17:44

So I guess we've talked about the ticks and we've talked, we've listed the different infections there, although that probably isn't that helpful if you're the pure FY two presenting to the intimidating infectious disease consultant about the patient that's been bitten by a tick, and you just list off all those diseases, that's not gonna help you. So if in Ripple you get requests for testing for a patient that's traveled. Or hasn't traveled, has been bitten by a tick what's the sort of pathogens that you would test for and what sort of things point us towards it being one pathogen? The other, and maybe we could start with boring, all the Europe.

Christina 18:27

Uh, You're super

Callum 18:29

Oh.

Christina 18:29

Uh, Generally, I think I just, the first part of your question, just to mention, when we get requests coming through to Ripple, most of the Tickborne related things align. And of course we're gonna have another, chat about Lyme in the future. But in terms of us deciding whether we wanna do anything more than Lyme testing, really it's the clinical picture very important. And we don't always get very good clinical information. So really we wanna know the symptoms when they came on and when the tick bite was thinking about things like incubation periods, et cetera. If the patients traveled. We wanna know not only where they've been, but where exactly they've been. So when we get requests that say things like Europe or America, These are obviously very big places and we wanna know proper details. If they happen to know anything more about the Tick, that would be great. But the chances are very very small. People aren't gonna obviously write, I've been bit you know, an amb. gonna just write tick. we wanna know. All that kind of information and really any blood tests that you might have, any results, any CSF especially'cause a lot of these people present with CNS so really as much information as you can is, really really important for us. So Europe that you mentioned by far and away the most important disease is Lyme disease. I'm not gonna delve into it in any detail um, because of what we said

Jame 19:53

Yeah. This hypothetical section would actually tested negative for Lyme yesterday.

Christina 19:57

but When were they tested versus when their serious

Jame 20:00

Oh my god.

Christina 20:02

But I Okay. I'm not gonna delve into it, but just to say

Callum 20:06

You walked right into that, Jim.

Christina 20:08

Yeah, just in terms of Europe. We think we see a lot of Lyme disease in the uk, but actually we see about a hundred times less people in central and eastern Europe where they see way more Lyme than us and they have way more experience than us. So really someone comes with a tick bite, from Poland, from Slovenia, Slovakia, et cetera. You really do have to have lime high up on your differential depending on where they've been. So just to say lime very, very common in certain places of Europe. other thing to mention, which I think is probably the second most important, and not only in Europe, but also in the uk, is tickborne encephalitis.

Jame 20:48

A relatively new development as well.'cause we've only just started detecting TBE virus in the uk.

Christina 20:55

we've, we've had cases of probable and confirmed tickborne and encephalitis for about six years now, but we're very small numbers. tickborne and encephalitis is transmitted by Exodus ticks. So the same ticks that will transmit breia that causes Lyme disease. And again, it's much more common in certain parts of Europe. So Estonia, Latvia, Germany, Austria, and there is a really good vaccine for tickborne encephalitis.

Jame 21:23

Yeah.

Christina 21:24

if you've got patients who are going to those countries where, you know it's highly endemic, and they come back with an illness, it's really worth asking whether they had a vaccination for

Jame 21:33

Yeah,

Christina 21:34

encephalitis.

Jame 21:35

They've got it, the treatment is only supportive, but the vaccine is highly preventative. So if somebody says to you, I'm going to go to Latvia and become a wood cutter, you may want to broach the subject of A TBE virus vaccine.

Christina 21:47

Yeah. And it's really important to know whether they've been vaccinated,'cause that will affect our testing and how we interpret it hugely. So it's a really important question to ask in your returning travelers.

Jame 21:59

Is that because you're testing IgG and if they're IgG positive, you won't be able to tell between vaccinated and infected.

Christina 22:06

We not necessarily be able to tell whether it's because they've had tick-borne encephalitis vaccine or a related vaccine. So for example, yellow fever, Japanese encephalitis, they'll all cause reactivity on our assays. So really, vaccination history is very important.

Jame 22:24

Right? So these are all flay viruses and they're all

Christina 22:27

different, there are different subtypes of tickborne encephalitis and they've got different geographical distribution. So in the uk and in most of Europe, it's the European subtype. as you go further east you get different subtypes and the European one that we get is generally quite mild. again, light Lyme, it's quite a seasonal infection in that motor. Of the cases we see at Ripple of Tickborne encephalitis are in the spring summer months. And in the European subtypes are the one that you are most likely to see. Many people are actually asymptomatic, but if they get a clinical syndrome. And usually they get a very non-specific viremic phase initially, and then they can have an asymptomatic interval and then they can present with neurological symptoms following that. So if you've got someone who presents having come back from, say, Estonia with a neurological picture that looks like either a meningitis or a meningoencephalitis, it's worth trying to figure out the trajectory of the illness. Did they initially have this kind of non-specific. Disease then get better and then come in with neurological symptoms or not. Um, The mortality rate for the tip borne encephalitis we see,'cause it tends to be the European strain, has a very low mortality um, but can have significant neurological seli attached to it. So as,'cause sometimes people, I don't know about you guys, but sometimes people ask us, do you know you've got somebody with a meningitis or encephalitis you've decided is viral? Do we really care what it is in terms of the name? Obviously as infection doctors, we super, super care. But it's important for something like tick point and encephalitis in terms of, giving a prognosis and what you might expect.

Callum 24:10

Do lumbar punctures.

Christina 24:11

Mean, Actually the most important samples for tickborne encephalitis is a blood sample. So if they have negative serology, then we often won't go and test SCSF'cause really we would expect the serology to be positive.

Callum 24:25

Do blood tests,

Christina 24:26

we also like urine as well.

Callum 24:29

is that for PCR? The urine?

Christina 24:31

Yeah. So we do PCR. yeah. Yeah. we do I mean, A lot of stuff will stay positive in urine depending on the infection for quite a while. But it's a really good yeah. But CSF, we know, we'd like to know what the white cell count is, et cetera, if you think someone might have DBE encephalitis. But as you said, there's no real treatment if someone's got it. So tickborne encephalitis the second most important thing, after Lyme disease. And then the other one to mention, I'll mention it now in terms of European stuff, but it's not very common, commonly seen, but important to not forget Crimea and Congo hemorrhagic fever. So we don't see this a huge amount in Europe, but we do know it's endemic in many countries. So this is a viral infection. It's not present in UK ticks. It's transmitted by different ticks are not ex odis ticks. These are hi ticks. These are also hard body ticks. And we don't have these ticks in the uk so we don't have hi ticks. But you can get incursion events. So when I was talking before about the tick surveillance scheme, it's looking for these ticker. Aren't endemic to the UK and whether they are appearing here or not. And these are quite different to ods, ticks, they're quite aggressive and they'll actively seek you out to bite you. And crime and Congo hemorrhagic FIFA, CCHF is important to know about in Europe because we know that there are cases in Spain. I'm sure most ID doctors will know this and there've been cases in Spain for many years now, but it's also endemic and places like Bulgaria, we had a case, um, of a patient in Southampton that had, crime and Congo hemorrhagic fever after traveling to Bulgaria. So it's important to think of these diseases in Europe as well, although they're rare and we diagnose those by PCR and I think there'll hopefully further sessions talking about viral hemorrhagic fevers at some point. And you'll go into more detail. There are lots of other tickborne diseases that we would worry about in Europe, but I wanna just mention, Mediterranean Spotted Fever, because we do occasionally see this and patients can be. Quite unwell with it. So Mediterranean spotted Fever is ettal infection. It belongs to spotted fever group and Mediterranean spotted fever is called Rickettsia Canor. Subspecies canor. So lots of different ricko species. But um, que is Mediterranean spotted fever and it's transmitted by the brown dog, tick, which is ripper. Phylis. And the reason I think it's worth mentioning, like I said, people can be unwell with it. What you tend to see in your patients is a fever, Rash, which usually spares the face and often an escar as well. And although the majority of cases we see with Mediterranean spot fever are quite well and they, it's quite a mild infection, it can be severe enough that patients develop multiorgan failure. And that's usually because people haven't thought of rickettsial infections in returning travelers from Europe. So they'll think about it in patients coming back from Africa, for example, and we'll shove in that doxycycline, but we'll often not think about it in European returning travelers. So, Another reason, there are many reasons to give doxycycline to returning travelers, but that is one of them.

Callum 28:04

Good old Kef trax and doxycycline.

Christina 28:06

And then, I'll mention one other, burial infection which is, BIA, Mya Moto. Which is one of the relapsing fevers. And the reason to mention it is that we know that beryllium, myeloid is actually in ticks in the uk. But we don't really have a way to actually diagnosed Brelia, my Moto specifically. So what we do is we request for people to do a blood smear if they think the patient might have a relapsing fever and to send us blood for PCR testing and we can do a pan Borrelial PCR at Ripple and then we can check to make sure it's not Lyme disease. And occasionally we can sequence it, but bium my. We know is present in the UK and in Europe, and it can cause a febrile illness, which can be relapsing. and again, just like with other Borrelial species, so like with Lyme disease, the way you treat it is with doxycycline. And we get a significant number of queries, I would say about beryllium, miato um, from clinicians. And it's a, it's transmitted by X tick, so the same ones that transmit Lyme disease. And we know that there are cases in several countries in Europe, but also in the US and other countries further afield. In terms of asking people to do blood smears having Blood sent to us, but you should be doing all these things when the patient is febrile, and I think it's really hard to test people when they're febrile. Will be outpatients and getting them tested at the right time is pretty, pretty difficult, but it's something to be aware of.

Jame 29:48

The, let's move to the USA now. Now obviously Lyme is still an issue here and people will probably know about Babesiosis as well. What about the rest of them?

Christina 29:59

Yeah. So in terms of tickborne diseases, the US is actually very exciting. They have lots and lots of tick-borne diseases there. As you said, they see a lot of Lyme and when we say this year, a lot of Lyme, we think we get a couple of thousand cases a year. They have, 300,000, 400,000 cases a year. So they really are um, very,

Jame 30:21

You are talking about lime again?

Christina 30:23

I cannot help it. Apologies. You mentioned, babe This is a really an important disease that we do see in our returning travelers from the us. It's a parasitic infection, so different to the bacteria and viruses we've spoken about so far. and it's an intraerythrocytic parasite.

Jame 30:44

It's not even oid, almost in its presentation.

edited to here 1/5/26

Christina 30:48

There are various Different species of Babesia. So in the UK for example, we know that there's a low level of Babesia species in ods ticks. So the same type of ticks that spread Lyme, of belia that causes Lyme disease. And in Europe it's mainly Babesia divergence. And the reservoir for this is cattle. There's also Babesia Ator, and the reservoir for this is deer. And there have been UK acquired cases, I can't remember the last one, but I think it was many years ago, around 2020. And patient who presented in kind of multiorgan failure was very unwell. In Europe it tends to be Babesia divergences and there are a handful of cases throughout Western and central Europe, but it really isn't a very common disease. Whereas in the US they have Babesia Microti, which is, endemic, especially around the northeast and northern Midwest us. And they get a couple of thousand cases a year. So significantly different to what we see. And the reservoir there is the white-footed mouse. And again, it's the xdi ticks that are the problems. So these hardback ticks that transmit the infection to humans. But interestingly, also and important to mention with Babesia, that's different to what we've spoken about so far, that it can also be transmitted via blood transfusion. And also during, pregnancy as well. And many people who have Babesia will actually asymptomatic. It's specific groups of people where we tend to see worse disease, more serious disease. So these tend to be patients who are older and also patients who are immunosuppressed and who are asplenic and they're more at risk of complications like DIC Multiorgan failure and dying. Other people who get babesiosis, they tend to have a non-specific flu-like illness and they can develop a hemolysis as the erythrocytes are infected. And really for doctors who practice in the us they're so used to seeing, you know, babesiosis and at certain times of the year in certain places of the US they would always think about it, whereas we're probably much less likely to think about it. The way you diagnose it is by doing syn and thick blood

Jame 33:03

Okay.

Christina 33:03

And looking for kind of the intraerythrocytic ring forms.

Jame 33:07

So a, again, very oid and, uh, there's a characteristic appearance on the film.

Christina 33:12

yeah.

Callum 33:12

was Ted Tra. I remember something from DTM.

Jame 33:15

Oh, well done, Callum. That d, t, m and h

Callum 33:18

They're beautiful.

Christina 33:19

So this is the multiuse cross that you're talking about., I'm assuming but you don't always

Callum 33:24

oh.

Christina 33:24

so if you, if you, don't see it, you shouldn't a hundred percent. Put aside the fact that this person could have the busy, if they've got a clinical syndrome that fits, especially if they mention a tick bite and they've come from an endemic area.

Jame 33:37

there any further diagnostics that can help? Um,

Christina 33:39

Yes. So we do not test for Babesia at Ripple. I'm only really mentioning it because the way we get involved with it is just general kind of tick infections and unwell returning travelers. But really we are not the experts. It's the, the clever parasitologists in London that we would refer to and ask for help. but yeah, you can do. PCR, there is serology, but I believe that serology for Babesia divergence is not available in the UK as far as I'm aware.

Jame 34:08

yeah.

Christina 34:08

it's really mainly blood films

Jame 34:10

Okay.

Christina 34:11

and discussing with the experts in the parasitology,

Jame 34:14

Yep.

Christina 34:14

Lab in London. And the important thing I guess to think about in terms of Babesia is that unlike pretty much all the other tickborne diseases we're talking about, the treatment is not doxycycline. So it's a toron, plus azithro or clindamycin plus qui. So it's important to think about if you're treating someone for a tick-borne infection with doxycycline and they're not getting better, could you have missed the fact that they might have or babesiosis,

Callum 34:45

so we've talked about Lyme, Babesia. There's a long list of things things in my head, so REIA and anaplasmosis. I remember finding that very confusing. Is it worth talking about them?

Christina 35:01

Ana plasma's very important I would say in your returning travelers from the us. So these are they are bacterial infections again, so these are obligate small intracellular gram-negative organisms, and they infect neutrophils. And they, and anaplasmosis is called Caused by Anaplasma. Cyto. It used to be called Human granulocytic anaplasmosis because of the fact that it infects granular sites and we know that. A significant number of ods ticks. So again, these are ods ticks, the most important ticks. We know significant number in the UK are actually infected with Ana PLAs, actually about the same numbers that are infected with bIA that cause Lyme disease. So we're talking, significant numbers. And we know that and we know that, PLS cyto is found in ticks and animals throughout Europe, but we don't really see cases in the uk and we don't really see cases in Europe. So the numbers are very small, although we know that it's present in the ticks and animals. So, Most of the cases in Europe have actually been in Slovenia, Poland, and Italy. And there have been two cases I know of that have been acquired in Scotland and none in England and Wales that I know of. And the last case from Scotland was actually in 2013. I think.

Jame 36:29

Okay.. Do you have a an explanation for that? If it is rise at similar amounts to Lyme, but the ticks and the anaplasma don't transmit the same way that the tick the same species of tick and the same pls transmit in the.

Christina 36:44

Yeah, it's really interesting. So in the US, it's a very different picture. So they have thousands of cases per year. Numbers are going up. And again, there it's also the bite of an infected ex tick. There they have different ex species, so they have, scapularis, mainly and, pacificus and there's also per caters in other parts of the world as well. But the reason probably that we see different species, different clinical kind of pictures in Europe and the UK and the US is that there's different, what we call eco types of the strains of anaplasma circulating. And there's a lot of genetic diversity in the strains of anaplasma seen in Europe and in the US they really don't have that same genetic diversity and the anaplasma oph and it just bacteria behaves differently there.

Jame 37:34

what A higher bacterial load within the ticks.

Christina 37:37

no, they probably don't have a higher bacterial load. It is just the specific genetic markers are slightly different in the strains in the US versus the strains in the uk and it's probably something to do with that. And the fact that in the UK we have a huge amount of genetic diversity. And in the US there's really not very much of that. And just the type of ecotype of anaplasma cyto in the US for some reason are more likely to cause an infective syndrome in Europe and in the uk actually, if you do serological tests in Europe, a significant proportion of people will have positive antibodies to anaplasma, whether that's cross reacting with lots of things, not sure, but potentially it's just that it's causing no disease, so completely asymptomatic. Whereas in the US they're getting symptoms and generally what you see is sudden onset febrile illness. Sometimes they can have headaches. And again, the main risk factors there, like with Babesia are age and immunosuppression and it's usually self-limiting, but they can get multiorgan failure. They can get CN CNS abnormalities and they can even die at the more extreme end of it especially if they're elderly, which is probably the most important risk factor. And the way we diagnose it at Ripple is on serology and on PCR. And the treatment for it, thankfully, is doxycycline. you mentioned AIA before. This is a really similar disease.

Jame 39:06

find them very difficult to differentiate. Like I, I can never remember which one does which.

Christina 39:10

Yeah. So it's very similar to Ana Plasmosis. Again, it's an obligate small gram-negative organism. And it's osis is usually, most cases of osis are caused by ichs. And this is transmitted by a different tick. So it's transmitted by the amb um, AMB Mein, which is the Lone star tic and the distribution of the Xdi tics that cause Babesia and the Lone Star tics that cause EIA is slightly different. Although my understanding is that it's merging and it's becoming less distinct. When we think about eia, we think a little bit in terms of where exactly in the US the has been. And that kind of helps decide could this be aia, could this be Anaplasma? the other thing is with they tend to be more unwell often than with anaplasmosis. but you can be unwell with both. The risk factors are the same. So age and immunosuppression. With anaplasmosis, as we said before, it used to be called human granulocytic anaplasmosis. Whereas this is a bit complicated. And this always used to really confuse me, but with Aosis, it's also caused human monocytic osis because it tends to affect monocytes rather than cytes. So you might see that when you're looking at a full blood And then another thing that can be slightly different is for both anaplasmosis and Aosis, one of the tests really you should do is a blood smear and you're looking for something there called ly. And these are clusters bacteria within Cytes or monocytes. So Cytes, if it's anaplasma monocytes if it's oia, and you're more likely to see morely if it's anaplasmosis rather than aosis. So for us, there's just a couple of things that might be a bit of a giveaway, whether this is anaplasma oria, but actually in terms of, treatment, It's the same thing. It's doxycycline. Unfortunately, at Ripple we don't actually have a way to diagnose Aosis, so we don't have an IOUs specific PCR the way we do for Anaplasma, what we rely on is the fact that the serology normally cross reacts with the ana Plasm serology, and then we can kind of say, well, the Anaplasma PCR is negative, the serology is positive. They're quite sick, they've been to these places in the us. So it's probably more likely to be aosis rather than anaplasmosis. But actually the treatment ultimately will be the same thing.

Jame 41:50

Okay.

Callum 41:51

That's really interesting. I actually don't think I understood that until now. And I think what you're saying there about the bidding, the clinical picture together, the diagnostics show that like the beauty of microbiological laboratory work is often that it is so dependent on the clinical story. It's not like potassium, not to like, dump on biochemists, but it's not just a number that comes out at the end of the day. There's a lot of interpretation in that post analytical phase. I know James is anxious, so move on to the next tickborne pathogen.

Jame 42:23

I dunno what it is.

Christina 42:25

the, probably the other important thing to mention with the US is Rocky Mountain Spotted Fever. We do get a couple of cases of those and patients can be very sick. So again Mediterranean Spotted Fever, we mentioned before in the US you might get something called Rocky and Spotted Fever. This is a infection. Soia are obligate intracellular gram negative bacteria and broadly we divide them into two groups. So it's a Spotted fever group. And the, typhus group, the Typhus group isn't transmitted by ticks, so we're not gonna talk about it today. It's mainly mites and fleas and things like that. The Spotted Fever is the one we can talk about today. So we already mentioned Mediterranean Spotted Fever which is transmitted by the brown dog. Tick. And then Rocky Mountain Spotted Fever is really important. And this is Rickettsia Ricketti. And it is transmitted by dermacentor ticks usually, or rip ticks. there's a whole kind of belt in the US where you might see patients with Rocky Mountain Spotted Fever, so east of the Rocky Mountains, all the way from, oklahoma to the Carolinas and highest level Arizona probably, and most patients will present with a rash and it can be quite difficult. You might not necessarily think of it. The rash could look, for example, like a patient presenting with measles. so it'll start off as like a macular rash and then it'll become partal from day five as they become more unwell. So if you've got a patient presenting with a particular you might think about it, but if you've got a patient presenting with a macular rash, it could obviously be one of many things. Often, very early on in the disease, when patients start to seek help, they might not actually have a rash at all because that'll come a couple of days in. So you might have a patient presenting who's sick from that part of the world who may or may not remember a tick bite. And they don't have a rash and they just have flu-like symptoms. So you just have to be mindful of it. And they can quite quickly develop shock and A RDS and multiorgan failure. So you just need to be aware of it. And the treatment for that is, of course, doxycycline. And really you should start it on clinical suspicion because the highest and the most important risk factor for patients developing, shock and A RDS is delayed treatment. So you just get on that and give it. And if you think you've, even if you've got a child who you think's got Rocky Man Fever, you should just give them doxycycline.

Jame 45:05

yes. We've actually had previous episodes on the safety, giving tetracyclines in pregnancy, breastfeeding, and in indeed in children as well. And particularly if you have a severe infection, which you know, the best therapy for would be doxycycline.

Christina 45:20

Yeah.

Jame 45:21

do not worry about some stained teeth down the line. Just save the kid's life and then.

Christina 45:25

no, completely Yeah, definitely. And the things, people always think patients with ettal infections will have scars, but that is not always the case at all. And especially with Rocky Mountain Spotted Fever, it'll just be an all over rash that will be macular and then Pete kill, and then they'll become super, super sick. So just if you think about it worth giving the doxycycline.

Jame 45:51

Yeah. And then let's just finish off a by talking about tick-borne infections in Africa and Asia and we've written here in the prep notes in our table for Africa. We've got CCHF, which we're not going to talk about again. And the same is true of CCHF and tick-borne encephalitis virus in Asia, you've got here African tick-born fever for Africa as well.

Christina 46:21

Yeah, so this is probably the most common infection that we infection that we see in patients coming back from Africa. We see it a lot in patients who have co gone to South Africa, especially those who have been to safaris. And, Afghan tick bite fever is RCIA Africa, and unlike some of the other infections we've spoken about today, it's transmitted by the amb. And these are, often quite aggressive and sometimes people will have multiple bites from infected ambs. And see it, usually, like I said, in patients who have been hiking or on safari. So as with everything, with Id getting all the, exposures is really important if you think someone's got a tick-borne disease and generally they present with a fever and an ES scar. And because of this aggressive nature of these ticks and the fact that they can be bitten, patients can be bitten by multiple ticks. They might have multiple ES scars as well. And they can then develop a headache, a generalized rash, but it tends to be quite a mild infection. So if you compare that, for example, to Rocky Mountain Spotted Fever it's a very different disease and that patients tend to be, well,

Jame 47:34

Hmm.

Christina 47:34

We've had, we we get many, many, every single year. And a lot of them are actually in, the community and they're first seen by their gps. And again, like, other recile infections, the treatment is doxycycline.

Jame 47:48

Do you recommend treatment or can you.

Christina 47:50

we generally, We would generally, yes, give it, we have had instances where patients have been diagnosed way down the line, and they have fully recovered. But, usually they'll present with a rash an escar, which can be missed because it can be funny places. And people, you need to strip down your patients really, and have a really good look to make sure they don't have But normally when they present, they have symptoms at that point. So we would treat them with doxycycline.

Jame 48:16

Alright, fine. Fine. And then lastly for Asia, we've got CH and Congo hemorrhagic fever, Which we've previously discussed, and CAS neuro forest disease and SFTS, which we're not going to discuss.

Callum 48:29

What does SFTS stand for?

Christina 48:31

So it's severe thrombocytopenia and fever syndrome.

Jame 48:35

So let me finish off by asking you lastly to describe the loyal listeners Alpha Gal syndrome which we may encounter in our travels.

Christina 48:44

So Alpha Gal syndrome, I think we need to be aware of as ID doctors because it's become quite popular in social media on the internet. There's quite a lot of misinformation out there. And we get asked about Alpha Gal syndrome a lot at Ripple. We get a lot of queries from GPS especially, but also from ID doctors about it. So I think as people are becoming more aware of it, you're gonna be asked about it more and more. So Alpha Gal Syndrome is very topical, but it's not actually an infection. But we Are the go-tos in the initial phase normally. So Alpha Gal is a sugar molecule and it's found in most mammals, not in humans, not naturally present in humans, but in most other animals. And Alpha Gal is galactose Alpha one three. Galactose is, that is a sugar molecule. And what happens is, the tick is normally a lone star tick, which we don't have in the uk. The ticks will feed on humans. The ticks will transfer Alpha Gal from mammals into humans that don't naturally have Alpha Gal. And then cause, an allergic reaction when humans then eat red meat or exposed to products from mammals that contain Alpha Gal. And the symptoms that people will get will be completely allergic type symptoms. So they could get from mild hives all the way through to anaphylaxis and that will tend to happen within two to four hours after eating products that might contain Alpha G. So meat and dairy products

Jame 50:23

So it's a delayed because the meter dairy product has to be broken down and the Alpha gal has to be released and the body's exposed to it, so it's almost like a delayed foodborne allergy.

Christina 50:34

yeah.

Jame 50:35

Interesting.

Christina 50:36

the reason we get involved is because it's. Is because it's triggered by the tick bite. Most of the cases are in the US by far, which is where they have the lone star tick. we know that there are some cases in Europe and there have been some cases in the UK as well that sound genuine. And probably the numbers are going up as people are becoming more aware of it. And if you get referred a patient who you think might have Alpha Gal syndrome or if someone calls you about them, really there are no tests that we can do as ID doctors. They need to be referred to Allergy Clinic there they need to look for specific IgE to Alpha Gal. And then I think the only treatment is probably just avoidance of things that will cause them to get a reaction. You know, avoidance of the food stuffs. That would be a problem.

Jame 51:27

Okay. Brilliant. Call, why don't you sum up?

Callum 51:30

So, thanks to the lone star in this, show, Christina

Jame 51:34

Mm.

Callum 51:34

Coming on to tell us all that. yeah, I think this episode for me has got a hard tick in the, it was good box. So, to summarize what we've talked about, we went through, what ticks are and why they matter. We briefly looked at the different types of ticks, and specifically in the uk how we know what they are. Then we talked about the importance of getting those ticks out quick. We took you through the different tick-borne infections and in the show notes as a summary table talking about each disease, the pathogen that causes it, and the vector in summary grouped by bacteria, parasites, and viruses. And then for some of the most important ones, although not the most important one, which we alluded to, like the ominous villain, who's going to be introduced in the second part. We did a quick rundown of the important tickborne pathogens that you might come across. There's many more in the show notes. We've listed a couple more and, this is enough to get And who knows, maybe we'll come back and cover some more of the niche. One when we all the way through all the bacteria and viruses and fungi, parasites that we still yet to cover.

Jame 52:46

Yeah, getting to it. All right.

Callum 52:49

Yeah, carry up Jim.

Jame 52:50

Okay, Christina, thanks for coming on the