#30 – Dabie Bandavirus: the Tick Virus From Asia

00:00:05: These infections have a case fidelity rate of ten to thirty percent.

00:00:10: So, not as high as with NEPA for example were Ebola but still substantial case fidelity rates.

00:00:46: Yeah hello and welcome to this episode of Virological!

00:00:49: This was recorded on August the first of twenty-twenty six in Sapporo Japan.

00:00:58: I just arrived here from New York, so let's see how well this recording works.

00:01:03: Since i'm in Asia and Japan... ...I thought that I am going to talk about the virus which has been discovered a while ago in China but is now also found in Korea And it was quite exotic But still interesting.

00:01:21: It had a sibling in US.

00:01:23: Today we are going to talk about a virus that's called Severe Fever with Trompocytopenia Syndrome Virus and will unpack it little bit later.

00:01:33: At some point the virus was renamed to Huayangshan Banyang Virus.

00:01:38: probably not much less complicated, very recently it has been called or renamed into Dabbi Banda Virus.

00:01:49: so the name Debbie comes from the Debbie Mountains, which are on a border between Henanhubai and Anhui provinces in China.

00:01:58: Okay so what is this virus?

00:02:00: This virus is a Punevirus.

00:02:02: it's related to a certain degree to cream congo hemorrhagic fever virus rift valley fever virus hunter viruses and so on and so forth.

00:02:12: So they're little bit further away there as closer relatives And we'll get that but basically a Pundevirus.

00:02:18: And so we know that bunior viruses carry a single-stranded RNA genome.

00:02:24: Most of the genome is in negative orientation, The virus has three genomic segments.

00:02:30: So their genome is divided into three segments A little bit like influenza virus but fewer segments and here you have L segment, M segment and S segment.

00:02:42: The L segment is about six thousand five hundred base pairs long about six thousand five hundred letters, so to say.

00:02:50: The M-segment is shorter that's about three thousand three hundred base pairs and the S segment is about one thousand seven hundred base pair.

00:02:59: The L segment codes for the polymerase... ...the m segment code for the glycoprotein which in this case it called GNGC So basically its one glycoproton thats cleaved into two parts And one is the n-terminal part, the other one this c-termininal part and that's why they're called Gn and GC.

00:03:18: Then there s segment encodes for two proteins –the nuclear protein or N–and then in the outer direction so basically bi-directional in terms of reading frames.

00:03:33: we have the NSS protein which is a nonstructural protein that is an interferon antagonist protein contracts than native immune response of cells.

00:03:45: Of course LMS stands for large, medium and small for these segments like with the other bonilla viruses we don't have a matrix protein which a lot of viruses has but in this case that's missing.

00:03:59: The virus particles are eighty to one hundred twenty nanometers in diameter And they're pleomorphic Which means there kind of roundish.

00:04:06: But you can also have other shapes X shape then so on and so forth.

00:04:11: And these viruses are also genetically diverse.

00:04:15: There is genotype A, B C D E and F... ...and there's also reassortance between this genotype so they can mix because you have these genomic segments.

00:04:27: a little bit about the history.

00:04:29: The virus was first isolated from a patient in two thousand nine in China.. ..And then it was found in South Korea in twenty twelve and then Japan in two hundred seventeen.

00:04:42: But then investigations in China identified retrospective cases and clusters.

00:04:48: So basically people looked into stash serum samples to look if the virus was there earlier, disease outbreaks wasn't clear what caused their outbreak... ...and it turned out that already was a cluster in nineteen ninety six another one in two thousand six.

00:05:08: The nineteen ninety-six one is pretty interesting.

00:05:10: that happened in Jiangsu.

00:05:12: There were eleven cases, they started with one person being hospitalized and a second person related to the first person being hospitalised.

00:05:22: then another number of other family members also got sick and hospital personnel got sick and in the end two out of these eleven infected individuals died.

00:05:33: But what that means?

00:05:34: when hospital personnel get sick, if you have a family clustered they could've infected themselves from the same source right?

00:05:42: In this case we'll get to it's tick bites that transmit the virus.

00:05:48: but If hospital personnel gets infected That mean there was likely human-to-human transmission.

00:05:54: And that is the case here can be the case with this severe fever with thrombocytopenia syndrome virus or SFDSV.

00:06:05: All right, after the virus was isolated there was an investigation into the source and it turned out that its transmitted by tick bites... ...by a number of ticks but I think the main vector would be hemophysalis longicornis.. ..or the asian longhorned tick.

00:06:23: And then also an investigation in to the natural reservoir And it turned out that a lot of animals have antibodies against these viruses or they've been found to be positive for the virus in terms of RNA genome detection.

00:06:39: That's on one side.

00:06:40: domesticated animals like sheep, goats cattle, yaks even dogs and cats has been found positive but then also wild animals hedgehogs wild boars Korean water deer Those are these weird deer that where the males have this vampire like canines.

00:07:02: So really long teeth, which is weird for a deer but yeah they can be positive for the virus too.

00:07:08: Weasels has been found positive opossums and I think also mice.

00:07:13: so it's not clear what the main reservoir is.

00:07:16: But the virus seems to infect in number of different animal species.

00:07:20: How do people get infected?

00:07:23: Yeah typically via tick bite from the animal reservoir, but as I mentioned also in some cases there can be human-to-human transmission often in hospitals.

00:07:34: It seems that this requires direct contact or contact with bodily fluid so it's not easily transmissible.

00:07:41: But there is a good number of cases where it happened recorded then.

00:07:45: incubation time is five to fourteen days and Then symptoms start.

00:07:50: these can be fever nausea, vomiting, abdominal pain, diarrhea but also neurological symptoms.

00:07:59: The liver enzymes are typically elevated.

00:08:02: then people have leukopenia which means the count of white blood cells is pretty low and then trompocytopenia.

00:08:09: that's what virus is named after right?

00:08:13: Severe fever with Trompocitopenia syndrome just describes whats happening to these patients.

00:08:20: This basically means that there's very few thrombocytes left in the blood.

00:08:26: Unfortunately, this often leads to multi-organ failure and thats what people die of when they have these virus infections And death often occurs relatively quickly within nine days of symptom onset.

00:08:41: These infections have a case fidelity rate of ten to thirty percent.

00:08:45: So not as high as with NEPA for example or Ebola but still a substantial case fidelity rate.

00:08:55: And interestingly, most infections are found in older individuals.

00:09:00: so the risk goes up with age and typically infections I've seen in individuals older than forty years of age.

00:09:09: it's not clear if that has to do with the immune system which might get weaker or what people have different age groups too out in nature to ticks, right?

00:09:23: Which are the source.

00:09:25: So one hypothesis I think is that younger people tend to work maybe in factories and offices...in cities in general while older people specifically in rural China still working their fields.

00:09:38: And may be that introduces a bios here but there's pretty clear age effect.

00:09:44: When do people get infected?

00:09:46: in China typically between March and November.

00:09:50: Most cases occur between April and June.

00:09:53: Where do people get these virus infections?

00:09:56: As I mentioned, the virus was first identified in China... ...and is now found in Anhui, Henan, Hubei, Jiangsu, Liaoning,... ...and Jiangdong provinces.

00:10:09: So that's basically kind of in the middle of China.

00:10:14: Basically if you look at Shanghai then go a little bit to the west.

00:10:18: that's where most of these provinces are.

00:10:22: In Japan, the area affected is the southern part of Japan so not the northern part.

00:10:28: I am right now but should be safe in Sapporo there.

00:10:32: other things around here can be nasty like bears for example.

00:10:40: and when we look at case numbers China has basically every year more than a thousand cases often up to two thousand that are reported.

00:10:50: In Japan the case count is around approximately a hundred cases per year and in Korea there's about two-hundred cases every year.

00:11:00: so it's rare infection but its not super rare, certainly something people should be aware of for example when they go hiking south of japan.

00:11:11: what can you do if your have this infection?

00:11:13: to prevent?

00:11:14: it basically helps best to prevent tick bites.

00:11:19: you know when your outside in nature were long pants, long sleeves.

00:11:24: use tick repellent but there's not much else that can be done.

00:11:28: There is no vaccine and in terms of treatment there also are some intervals that have activity against the virus.

00:11:36: Riboburion is one of them.

00:11:38: Favibirovir is another one.

00:11:40: so these are compounds that inhibit develop polymerase But I'm not sure they really work very well in cases where people already hospitalized.

00:11:51: So there are some potential treatment options, but it's not key if they're very efficient.

00:11:57: Now here is the interesting thing.

00:11:58: this is clearly an Asian virus But In two thousand nine when This virus as of DSV was first isolated in China.

00:12:09: similar virus Was found in the US and Missouri And that virus was termed heartland virus and turned out it's transmitted by the Lone Star Tech, Amplioma Americanum.

00:12:26: And there have been since the discovery about eighty cases in a handful of deaths.

00:12:34: so doesn't seem as this virus is as prevalent as SFDSV in Asia but they are certainly cases that the virus has not be found at lot US states So their relatively closely related.

00:12:49: That's super interesting in a way that very similar virus shows up on the other side of the planet.

00:12:56: But yeah, this heartland virus has now been found in Arkansas and Georgia and Illinois Indiana and Iowa Kansas Kentucky Missouri even New York State not New York City.

00:13:12: I think North Carolina had detections Oklahoma Pennsylvania Tennessee Virginia and West Virginia.

00:13:20: So again, there have been very few cases although I think it's not a reportable disease that needs to be reported to the CDC.

00:13:27: so they could be more cases but It doesn't seem as prevalent in terms of diseases as the Asian version.

00:13:36: All right!

00:13:37: To summarize this SFDSV or severe fever with Dramposidopenia syndrome virus which also has a bunch of other long names, is prevalent in China and the southern part of Japan.

00:13:55: And also in Korea.

00:13:56: it's a pneumonia virus transmitted by ticks probably from different animal species to humans causes severe disease with case fidelity rates of ten-to-thirty percent.

00:14:07: there not really much that can be done in terms of vaccination or treatment ticks in the US.

00:14:20: That's it for today, thanks And don't forget to follow and leave a review on your favorite podcast app.