Inspired To Heal
Stories of clinicians, educators, innovators, and researchers who built or led programs of excellence in government health institutions. Each guest has excelled in clinical medicine, program building, or public health. They persevered and succeeded through a clear vision, collaboration, and a passion for the mission of government-run health systems. Their stories will inspire those seeking change in their own organizations.
Inspired To Heal
Koch Institute Disease Detective: Poisons, Choirs & Sprouts
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In this episode, veteran disease detective Dr. Udo Buchholz from Germany's Robert Koch Institute (RKI) unpacks five outbreak investigations spanning Los Angeles to Germany.
Dr. Buchholz reveals the twists of tracking intentional poisoning cases in the workplace—including toxic dynamics of both boss and employee malfeasance. Discover how intentional food poisoning in a restaurant led to a unique methodology for tracking foodborne illnesses. An approach that helped health officials solve a massive international E. coli outbreak linked to contaminated fenugreek sprouts.
Finally, we go inside the science of airborne transmission. Dr. Buchholz breaks down his detailed epidemiological study on how SARS-CoV-2 (COVID-19) spread rapidly among members of the famous Berlin Cathedral Choir (Berliner Domkantorei).
Listen in to hear how solving complex health crises requires a massive network of experts—ranging from Berlin engineers, CDC scientists, to a health official in Thailand.
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Introduction
SPEAKER_02Public health epidemiologists or disease detectives receive outbreak alerts from diverse settings with many different clinical manifestations. Most of the time, these outbreaks are unintentional. Maybe good practices could have prevented the outbreak, but rarely was it caused willfully.
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SPEAKER_02Udo Buchholz investigated outbreaks for the Los Angeles Department of Health and then the Robert Koch Institute in Germany. He investigated outbreaks in both settings, some of which you'll hear about were unintentional, but there are also intentional poisonings. The outbreaks he investigated spanned diverse settings from ethnic restaurants to construction sites to cathedrals. His curiosity and attention to detail identified the causes of these interesting outbreaks. Udo, welcome to Inspired to Heal. Thank you for having me, Bill. So you've been, I would say, fortunate or unfortunate enough to be involved in some very interesting outbreaks.
SPEAKER_01Yeah, definitely. They were very interesting, and yeah, I have experienced some of them and I happy to share them with you. Could you describe the institute that you now work in? Yes, I'm working at the Robert Koch Institute. He detected and described mycobacterium tuberculosis for the first time, and then in his name the institute was founded about 120 years ago. Today the institute is similar to CDC. It is government institute, and we are under the auspices of the Ministry of Health.
SPEAKER_02So you are the national program to investigate communicable diseases. Yeah, that's right. We're kind of the National Public Health Institute, if you will. In some of these, or at least one of these outbreaks, we'll find that you worked with a European health agency. How do you connect with the European Union? What is the health body that you coordinate outbreak response with?
SPEAKER_01Yes. On top of the national levels in Europe, we have another level, which we don't have in the US obviously, and that is called the European Center for Disease Control and Prevention, the ECDC. To varying degrees, we connect with them when we have outbreaks. That might depend on the size, and also, of course, if they are if they have international connections. So one of the outbreaks where ECDC was involved with was a large outbreak of Shiga toxin producing E. coli, and it was a very, very large outbreak. So a couple of colleagues came over from ECDC, which is based in Stockholm, and also reviewed what we were doing, which was helpful because we had an additional four eyes and uh two intelligent heads to see if what we were doing were okay and if they had additional advice.
SPEAKER_02And that's um one of the outbreaks that I wanted to talk about. That is one of your more complicated investigations, a multinational, international investigation that was quite interesting.
Thai restaurant poisoning
SPEAKER_02Let's start with one of the outbreaks that you did in California. There was food poisoning in a Thai restaurant. Could you describe how you were alerted to that?
SPEAKER_01Sure. My boss at the time, she received a telephone call by the California Health Department. They said that they had outbreak that was associated with a restaurant in Fresno, a Thai restaurant, and with a very short incubation period.
SPEAKER_02Incubation period is referring to the time difference between when people were exposed or ate the meal and when they became ill.
SPEAKER_01The colleague in California said, Can can your EIS officer uh work on that? It should be very fast. He will he will find it out very quickly.
SPEAKER_02A little bit of ominous foreshadowing with that comment.
SPEAKER_01So I talked with my boss and she said, Yeah, why don't you do that? Go up. And I took a student worker with me, and we we drove up to Fresno, which is about in between Los Angeles and California, halfway.
SPEAKER_02So this was to be some simple outbreak for someone in training to go in and handle their first foodborne outbreak. Aaron Ross Powell Exactly.
SPEAKER_01Little did I know how complicated it it became. First we we talked with the local health department and they told us that in fact they had uh cases already since two weeks in in the restaurant. Very few cases per day, but very similar in in the symptoms. They had dizziness, vomiting, and some even while they were still in the restaurant. So it was a very short incubation uh period, which uh always points towards something that is quite likely not infectious. They were uh thinking relatively early on on some uh some toxin that is leading to the disease. They were quite good actually because they had devised a very nice uh questionnaire and had talked with a lot of the customers already. And what I found so excellent is that they didn't ask them only like what kind of dish did you eat, but also how much? And also did you share food with anyone you were dining with?
SPEAKER_02So you're going up there with an outbreak in a restaurant with vomiting and dizziness, and you said they thought it was toxin because it was so quick. But were you thinking a lot of toxins are foodborne, right? So you're are you thinking still this is likely a foodborne toxin?
SPEAKER_01Yeah, by all means we had to consider different options, and there are a couple of maybe three bacteria that also produce toxins that may lead to such symptoms. But we had to take into account also, for example, chemicals, and then perhaps glutamate, you know, you may have heard of Chinese restaurant syndrome, if that is kind of highly concentrated. And it could also be like, for example, a pesticide that could be in in the food for some reasons. For example, maybe pest control in the restaurant has left something on the premises. So what we did early on, we had samples, of course, from the restaurant, from what they used, salt, sugar, and all the ingredients, but we had just one stool sample, if I remember, and we had interesting even uh one sample of vomit, and we sent all of these to different laboratories to look for all of these kind of toxins. But uh none of that really uh came back positive. So from that point of view, we were left in still in the dark, unfortunately.
SPEAKER_02And from the questionnaire that they gave, you know, oftentimes if it's a source that it's a single source outbreak, your epidemiology or your survey of questions can identify the people who got sick compared to the people who didn't and the food that they ate. And so I'm guessing that survey did that not come up with anything.
SPEAKER_01Yeah, we had interviews both from persons that became ill, and since because they came often as a family, for example, there were other persons that did not become ill. So we had a comparison crew, which we usually use in epidemiology. Since we had the the data there already, we analyzed them rapidly and we saw that there were definitely several dishes that were quite highly significant. For example, one soup that you may know is a chicken soup in the Thai restaurant is called Tonkakai, and it was highly significant, but the problem was it didn't explain enough of the cases. So not all of the cases, by far not all of the cases, had eaten it. So it could not alone be responsible for the outbreak.
SPEAKER_02So at this point you're not finding the smoking gun or the obvious culprit to the outbreak. So what were your your next steps? You were concerned about a toxin? Your typical case control study didn't identify what was the cause. What did you do next?
SPEAKER_01Yes, I mean we obviously we did also an inspection of the restaurant, of the kitchen, with and extensive interviews with the owners, also with the employees, just try to gather as much evidence as we could, and also to explore as many hypotheses as we could. So my inclination of the hypothesis was that it is likely some ingredient in the dishes that is not just in one dish, but in several. So what I did then when I was back in in LA, then almost like every evening I had another hypothesis. So I thought, no, I was thinking about the tomkakai soup. Okay, what's in that? So I thought lime leaves, for example. So I called up the chef cook of the restaurant and asked her literally, I went through the entire menu and asked her how many lime leaves are in each of the dishes. Then that took like two hours each time. I went back, plotted it in in the computer, did my analyses, and lo and behold, didn't find it again. So I had to go on and on. But that went like that, you know, several times. Uh she was so patient, I really have to have to say, and was very thankful for her. She was also interested, obviously, to find the cause.
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SPEAKER_02Udo, how were you concerned that lime leaves that it was an herbicide or a pesticide that had been sprayed on the leaves? Or it was just that you asked about the recipe and thought this is a unique ingredient?
SPEAKER_01Yeah, I just thought about the recipe, and of course, you don't know. We had to consider also intentional poisoning because it was just so peculiar the whole circumstances. We had initially set uh screens for toxins, including pesticides. In my desperation, I also wrote an email to the Thai Ministry of Health and explained to them the situation. They said we have this restaurant, this is the Thai restaurant, and the guests have symptoms with dizziness and vomiting, and many also with diarrhea, very quick incubation period. Do you have any idea what that could be? And uh he answered immediately. Almost he said, it's quite clear to me because in Thailand it's very frequent that when we have food on restaurants with uh with a pesticide which is called methamil, which is used a lot in agriculture. And even sometimes, apparently, couples do that when they have a partner that they don't like so much anymore, that they give give them that in the in the food. And a particular characteristic is that it's really a crystal and it's very similar to salt and sugar, and it's almost tasteless, so you cannot recognize it until you have ingested it. So what we did is then I said, okay, let's bet on that. And I went back to the to the laboratories and said, I know you have done the screenings, but can you particularly test for methanol? And so when they did that, they found it also in significant amounts in the food, also in the vomit. And so now we had kind of the smoking gun. We still needed the epidemiological evidence. And what I haven't done until then, I said, okay, I'm going to the last one. I I called up the chef cook again and I said, Can you tell me exactly how much salt you put in every dish? And so we went through the whole menu again. And then what I had, because I had, I told you previously, we had how much everyone adds, and if they add even from uh like from a neighbor or from a partner. So I could calculate fairly exactly the amount of salt that every person ingested. And doing that, I could find what we call a dose-response relationship. So the more salt you add, the higher was your chance to become ill.
SPEAKER_02So you had something that's used in Thailand to intentionally poison other people. And you have a restaurant owner who I'm sure is saying, I don't put methanol in my salt. So did you ever identify what had happened?
SPEAKER_01Not exactly. I think we came pretty close because obviously we didn't know which which cook prepared which meal. But what we did have is which employee was in which shift. And so then we did an analysis also on the likelihood of certain employees being associated when there was a higher degree of illness. There was particular one that came out and this this person also lived in an apartment complex with another person that had access to methanol. That has to know methanol is a registered pesticide. It's used a lot in refreshing because it's an agricultural area, but if you want to use it, you have to register first. It was was conceivable that that this cook would have access to this poison, actually. And we so we all, of course, we also then handed all over everything we knew to the to the police department and FBI, and they did quite a bit of investigation, but to my knowledge, no one ever was accused or came to a trial or something like that. Had the cases stopped by the time you you made it to Fresno or were they continuing? One of the first things that we did is that we closed the restaurant. But of course you cannot do that because the people have to and the restaurant owners, that's their source of living. But since we had collected all the ingredients, all what's what was used in the kitchen, we said, okay, I think we did what we could and let's open it again. So after I think a 10 days or so it was opened again. And and I said, Well, I'm willing to to come up there and uh be among the first guests. But really what prevented me is uh that when I was trying to go up, there was in Bakersfield that there was a snowfall, which happens like once in 20 years. So so I w I I was a little bit grateful, I must say, but anyway, so uh that prevented me from uh being among the guests in the when after the restaurant had reopened. But nothing happened. It was all good, and I think they re regained all their customers.
SPEAKER_02That's a happy outcome, and hopefully you make it back to Fresno for Tomka guy someday.
SPEAKER_01Actually, I did already, yes.
SPEAKER_02You know, one of the things with uh restaurant work is uh I had worked in a restaurant. You typically eat the meals, your meals, while you're working from the restaurant, and I wonder, you know, there's probably one person who was not eating the meal with everyone else.
SPEAKER_01It's uh it's quite good thinking, Bill. But the thing was that the employees they replaced one ingredient, which is salt, by fish sauce. So they were not exposed. So that's why they they never had the disease. Of course, the person who did that, he knew that. One must also know that uh the owners were Thai, but the employees are from Laos. And uh there is a certain relationship between Thailand and Laos. Many persons from Laos go to Thailand and are migrant work, so it may happen that that they feel kind of second-class people in that country. So maybe from that history there was perhaps some disgruntlement or they were not happy, which may have led to that uh quite extreme reaction.
SPEAKER_02Yeah. Udo, this is at the beginning of your public health career, and things didn't really get much easier for you.
Buffalo fish toxin-Haff disease
SPEAKER_02We have some other interesting ones to dive into. So we'll we'll stay in LA. I think this one is particularly interesting to me because it was a German import. The condition that you investigated is called Haf disease. It comes from a cluster that occurred in northeast Germany along the Baltic Sea and caused muscle rigidity, and there was a description of coffee-colored urine, and there were about a thousand cases over nine years, and so the name Hoff disease came from this region. And do you want to talk about the outbreak in Germany and then what happened in the United States?
SPEAKER_01Yes, sure. These outbreaks in Germany, they occurred, as you say, over a period of about nine years between 1924 and 1933, along the coast of a city which was called Königsberg. There is a like a lagoon which is kind of brackish water, so it's half sweet water, half salt water. And there were many cases among persons that did eat fish, even among seamen. For example, they tended to be fishing for a long time, sometimes even overnight. And so what they ate then was sometimes also the fish that they got. And there was one story which I remembered that one fisherman he became so rigid and so stiff that he couldn't move and was lying literally in his boat for a couple of days until it became better and could go home again. So that is really an earth-mark symptom, the rigidity, and that comes from from a breakdown of them of the muscles. So it's the toxin that causes it. There were other small incidents, for example, in Sweden, also in the Soviet Union over the next decades, and then these clusters in Los Angeles and Missouri that that I happened then also to investigate.
SPEAKER_02You're in the Los Angeles Department of Health, and you get alerted to some cases of what I call rhabdomyolysis where the skeletal muscle breakdown occurs. Correct. How did you end up suspecting fish? And then how did that lead to Missouri?
SPEAKER_01What happened in one of the hospitals, a married couple came into that emergency room, and then on the same day in the same hospital, a third case also. And what they had in common was the ingestion of a particular type of fish, which was called buffalo fish. And there was a very astute physician, and he went up into the library and searched and found this half disease, actually. So he he basically resolved these diagnoses on his own very quickly. And we heard about another single case from neighboring health department. And so we put all of the evidence together, and all of them, in fact, had eaten this type of buffalo fish. It came from Missouri, in fact, which was then transported to Los Angeles. What is known is that it's heat resistant. Even after two hours of cooking, which they had done, they made a dish which is called gefilterfish, which is uh kind of used in Jewish communities. Luckily, among the six cases, nobody died.
SPEAKER_02Aaron Ross Powell This is Los Angeles, where you have access to the some of the best seafood in the United States, and people are are importing a bottom-feeding fish from Missouri, Louisiana, probably the Mississippi River, to California.
SPEAKER_01Yes, I think one one reason is, as I said, it is part of the like Eastern European culture to eat this type of fish with the special preparation. And there was also one gentleman in a bakersfield who had had become ill. And the reason why he became ill, I think that because the fish was affordable for him. He was he was not certainly not someone who would eat like very expensive fish that would be available in Los Angeles. What I've read about is it's similar to carp, so it's a bottom feeding fish. Yes. And that turns into a toxin in the fish or is already a toxin at the time. It's still a mystery.
SPEAKER_02But had heard about the saltwater toxins, cigatera and scamoid. And how do those fish toxins present that are different than half disease?
SPEAKER_01Yes, it is quite different. And and as you say, this is quite peculiar that this is a sweetwater toxin. Usually we know, for example, uh cigwatera toxin, which presents in a quite an interesting way because it turns around the sensation of temperature. So if anything is warm, you feel cold. And if anything that's cold, you feel it warm. So that's that's quite interesting.
Amphetamine spiked "herbal" energy drink
SPEAKER_02I wanted to also touch base on one outbreak that was really surprising to me. A group of construction workers became ill soon after starting their work shift. Someone alerted the health department that all these construction workers have come to the emergency room with a constellation of symptoms. What happened in this one?
SPEAKER_01Yes, we were caught up early in the morning in an emergency department in West LA, said, Well, we have here 13 construction workers that are ill with DNS and also nausea and vomiting. Can you come and see what was the cause? I went out there and interviewed other persons there and also talked with the physicians. And they had already received some blood results. And what was interesting is they had elevation of the called creatin kinase, and that is can be an indication that there's something wrong with the muscles. Similar to the heart disease, right? The rhythmyolysis. Yeah. Exactly. In that respect, similar to half disease, exactly. And uh what they also did is they had uh tested the urine for different kinds of drugs, and they found amphetamine in the urine. So you wonder why why do 13 people coming from the construction site have amphetamine in their urine and uh obviously so much that they that they become ill and have to stop on their way home in the emergency room. So it turned out their boss had in fact given them a few thermoses that were filled with uh fluid, and he said it's a herbal drink. So it it should help you to work better and to keep you strong, but don't drink too much, he said. So he had a fantastic idea to spike these drinks with amphetamine so to to Make them work a little better. And so that was the reason how they got intoxicated. And it it was interesting. It was even for epidemiologically significant because the the three only ones who haven't had that drink, they remained healthy. They didn't have any symptoms.
SPEAKER_02If I understand correctly, this was a nighttime work site. Exactly. Yeah. So they wanted to keep them up all night working.
SPEAKER_01Exactly.
SPEAKER_02And probably the most sleepy ones are like, uh, you know what? I'm kind of tired. I better drink a little more of this stuff. Exactly. I read what you wrote about this, and and interestingly, I think two of the workers said they had increased strength because of the uh of the track. Exactly. So that turned the tables on the Thai restaurant. You have a boss intentionally chemically motivating his employees. Leaving
Fenugreek sprout contamination
SPEAKER_02Los Angeles. You go back to Germany, and there there was a very large outbreak that you investigated and ended up solving that was uh published in the New England Journal of Medicine. And it's about contaminated food causing hemolytic uremic syndrome. This is a very complicated outbreak with a lot of steps. Where would you like to start?
SPEAKER_01Actually, it started slow and accelerated very fast. We had in the beginning, we had just three cases in children, which already led us to to sort of a wrong path. But you see cases of HES in children, if they happen at the same time, that that means something. Because it's a very severe disease, it can even be fatal. So a team of us went up there to Hamburg, and it already became clear that there were many more cases, and the majority actually was among adults. There was a preponderance among women, and they were not only in Hamburg, they were also from other areas, particularly in the north of Germany. Of course, these E. coli outbreaks, they're often associated with some raw food, for example. E. coli they occur naturally in ruminants. So for example, in cow, in sheep, in goat, when food becomes fecally contaminated, then that can lead to outbreaks. So tomatoes or spinach, for example, were culprits that happened in the in the past. So they did a case control study in in the hospital and came back and thought actually that it's that it is due to tomato, perhaps, or cucumber. And that would fit very well also with preponderance among women, as they like to eat salads perhaps a little bit more than men.
SPEAKER_02Just uh interject the cohort study is when you can capture the entire population. So for example, you know everybody that's eaten at a certain restaurant and you try to get in touch with and interview everybody versus a case control study where you just take individuals who had the condition and sample a proportion of those who did not have the condition. And that's a more efficient study design.
SPEAKER_01It turned out we were on the wrong track. So what we did is though the number of cases were rising fast, almost exponentially. At the end we had, I think, more than 4,000 cases, which is really an enormous number. I'm certainly one of the largest outbreaks ever known. And so we did several studies, cohort study, case control studies. It was very difficult. We didn't find the culprit.
SPEAKER_02It sounds like with so many cases and so much pressure, you said we have to really try our best and and expand this to a cohort study.
SPEAKER_01Yes, it depended a little bit on the setting. But as you say, a lot of the incidents happened in restaurants. So, or if let's say like wedding parties or something like that. So then you have a limited and circumscribed group of people, which we call a cohort, and then we can interview at best all of them or almost all of them, and can can calculate what is the risk of those who have eaten a certain food item and compared to those who have not eaten it. That was helpful actually, that a lot of these cases occurred in those restaurant settings. But it was like three weeks into the outbreak where we really tried our best. It was like all hands-on board maneuver, and we couldn't find it out. And I at that time I remembered actually my Thai outbreak in back in Los Angeles, which was 10, 11 years ago, and I said, Well, why don't we do it the same? There was one restaurant where which had also quite a few number of cases. So I had I told my boss about my idea and he said, Yeah, okay, take two colleagues, go up there and do exactly what you say.
SPEAKER_02I want to revisit your innovation. In a classic foodborne outbreak investigation, you can find the dish. So the famous chicken salad at a church picnic. If everyone who ate the chicken salad got sick and no one else got sick, it's clear that it was the chicken salad. But when an ingredient goes across several dishes, it becomes difficult to figure out the cause of the outbreak. So in the Thai restaurant, it was salt, which was in maybe all of the dishes. This idea of interviewing a chef to look at all the ingredients that are in each dish was your innovation. And I believe in this case, it turned out to be very valuable and is a template for how people who get stuck with foodborne outbreaks can use your approach.
SPEAKER_01Exactly. So we called the restaurant up beforehand and said, no, we would like to look at this closer, but we really need like an entire afternoon with your chef and ask him about the ingredients of all the menu. And we split up and a colleague of mine and myself, we we interviewed the chef, went through the entire menu and asked him what's inside, which ingredient, how much. And another part of our team, they contacted the different groups that had dined at the restaurant, which they could because they had the booking notes. So they contacted them and said, Can we make a quick interview with you? In fact, that was very efficient. And the reason is because when you ask the chef about the ingredients, you don't have to ask your interview is about every single uh food item. Because all you have to do is that when you were there, what did you eat from the menu? Three more questions and you're done. So that was that was quite helpful. And within two days, so we brought back the data, analyzed it, and it was very clear that that the cause was so-called fendogreek sprouts. And the reason why we hadn't found it before is something that also was pointed out to us by Rob Tox. He was director of foodborne diseases at CDC, and he was so helpful to help us and give us advice. He said these sprouts they behave like stealth foods. Because when you ask people what they add, they they remember the tomato and the cucumber, but no one remembers the sprouts for some reason. And other studies that we did, just 25% of the ill people remember the sprouts. But of course, with that approach, we could explain 100% of the cases, which was very satisfying, and we really uh could solve it from the epidemiological side.
SPEAKER_02First you're thinking about a restaurant, but it's many restaurants. So then you're thinking about the food, and the food then has a distributor, so that's upstream from the restaurant, and then upstream from that is a producer of the sprouts. You went even farther upstream in this one. You then trace back the source. Do you want to describe that? Because in in my mind, this actually became one of the unique and interesting parts of the story, how you ended up working with the eCDC or European CDC and tracing this all the way back.
SPEAKER_01Yes, this first part was in fact German thing, the institution that was responsible for that, similar to FDA in the US. They went to different restaurants and said, Where so where did you get your sprouts from to find the knot where everything is sort of starting from? And then the other direction is the trace forward. So if you have a distributor, for example, where you know this distributor sold the sprouts to this restaurant where we investigated it, he also distributed to another restaurant or to another canteen or wherever. And we could go there and say, now look, have you also had cases? And there was also, for example, from that distributor, another outbreak in a canteen in Frankfurt that that we didn't know about. So that that is the trace forward. So and that also came also together very nicely, so we could finally bring it down to one single sprouter where where they all were coming from. Now it comes the European perspective, as you say. The sprouter he didn't do much wrong, actually. He just produced the sprouts as they as they're done. I mean, the that whole process is not very hygienic, I must say, because they are done. I don't know if you have seen it ever. They are put in big barrels and uh with which are very humid. And actually, if there's any bacterial contamination, that's perfect. It's perfect to grow. Petri dish. Ex Petri dish, exactly. But what the European perspective was that they went further and they looked at where the seeds were coming from, and and they found out that in fact it must have come from contaminated seeds from Egypt. So that was an outbreak that we excl exclusively could uh solve on epidemiological and trace backgrounds.
SPEAKER_02What were the public health implications of this work? You obviously uh halted the outbreak. Uh any changes in testing of potentially contaminated seeds that that occurred because of this?
SPEAKER_01Yeah, definitely. It had quite large implications. Previously, this particular producer, he was registered as such, but just as a horticulture, something that's a gardening basically, business. So and after that, in the whole European legislation, it had the same level as any food. So it had also the same regulations. So seeds after that needed to be tested for pathogens, also sprouts need to be tested for pathogens. They have a much stricter hygiene control in those businesses. They test also the water quality and so on. So it had a lot of ramifications and I think improvements also for hygiene for that type of food, also.
COVID and the Berlin Cathedral choir
SPEAKER_02The final outbreak that I wanted to talk about, Udo, and this was cathedral. During COVID, very early on, so it was March of 2020, soon after the cases became distributed across the world. Right. There was an outbreak in a cathedral. That was described in the United States. There were outbreaks associated with churches, and it became quite controversial, the closing of churches. There was a concern that choirs and singing could actually cause an outbreak. But what is remarkable about the outbreak that you went to investigate was the intensity of involvement from engineers and modelers to come up with generalizable conclusions in a very unique time and a very unique circumstance. I think it's worth talking about how you decided to use this as a laboratory and see if with engineering you could help solve concerns or issues with transmission of COVID.
SPEAKER_01Yes. As you said, it happened early on in March that particular first outbreak affected a choir of the cathedral in Berlin, which is a fantastic choir. What happened is conductor, he had just a normal rehearsal, and in fact he was also a conductor of a second choir. And they had a rehearsal three days after that. And two days after that, on Saturday, he received notice from one of the members of the first choir that she had become ill with COVID and quickly became more and more of the choir members that also had become ill. Actually, our institute received notice about two months afterwards, where the conductor himself thought, well, I I think this is this is interesting. There might there might be something in it. And they will inform the Robert Koch Institute. So the sequence was actually there was one one singer that came from a party in in Mainz, where it was a super spreading outbreak, but she brought it back, still having no symptoms, so she was what we call pre-symptomatic. Being pre-symptomatic, they did the rehearsal, she sang, and infected a lot of the members, including the conductor. The conductor, again being pre-symptomatic, conducting the second choir, also then infected quite a few persons. So that was the outbreak in the second choir. The interesting thing was that they had a very different attack rate. The first outbreak was about 90%. So nine out of ten of the choir members became ill. The second one, it was just 24%. So wondering why what was the reason for that? We did an interview with them and asked them who connected with whom, who had how much distance with whom, because one of the issues with COVID, if you remember, was is it spread only within a distance of one and a half or two yards or meters in Germany, or it does have a long range also transmission? So when you are in a room and you have someone that is ill and you don't even talk with that person, you're far away, can you become infected? So that was one of the issues. So we connected with the technical university in Berlin, and they devised experiment very quickly in order to measure how much small particles persons emit. The idea was to finally come up with a model where you tie all the information together. And there was actually much work done previously on that kind of questions, but usually that kind of information is not complete. So in this case we had the choir members, we took a sample of 15 of them, including the primary case, and measured how much small particles they emit when they talk or when they sing, to also put that into an equation.
SPEAKER_02When you graphed that, pretty striking differences. So even graft it on a log scale, the differences were so extreme between talking and singing. And I thought it was interesting you chose the two songs that they were rehearsing for them to sing and looked at differences in particle emission. And then you had people with different range of voices, and also had them sing softly and then a louder intensity and looked at particle emission, finding quite a big difference. So if you're singing and you're singing loudly, you're emitting a lot more particles, almost 30 fold more than what you did when you were talking.
SPEAKER_01Exactly. It's enormous the difference. And that was also the reason why you had these outbreaks, one famous one in Washington state that are associated with choirs. But what was interesting is also that we could show and model very nicely what was the reason why there were these two attack rates in the two choir outbreaks. And the reason was that in the first outbreak, there was, of course, the primary case was a singer. She was singing almost the entire time, while the primary case in the second outbreak was the conductor. So he may have sung a couple of times, but nearly not as much, of course, as a singer. So that was a big difference already. She also, as a person individually, she emitted more of these small particles that can carry the virus than the conductor. That was another difference. The rehearsal was longer, and the room was smaller. So all of these combined led to this tremendous uh attack rate of about 90%. So what we did is we, with some number crunching, and we were lucky because one of the members of the second choir was in fact a physicist, and he helped us a lot with uh with those calculations. Then finally we we could, in fact, come up with a dose, so-called infectious dose, that is able to infect 50% of those exposed. And that was only just 15 amplifiable viruses that are sufficient so that 50% of those that have that exposure become infected.
SPEAKER_02Aaron Powell This is uh it was very controversial in the United States and touched on religious freedom and constitutional rights. If you were making recommendations to protect people, what would you say about church? If you have a respiratory transmission of an aerosolized, we will say virus.
SPEAKER_01So there were a number of recommendations that were a consequence of those outbreaks. Quiar rehearsals were not forbidden, were not prohibited, but but there were recommendations given to them. So for example, if you have persons that are vulnerable, that have certain preconditions, or that have reached a certain age, they should not be part of the rehearsals. After testing was available, it was recommended to to test immediately before the rehearsals. In summer you can rehearse outside. So a lot of it common sense, but still trying to not completely prevent the choirs from from rehearsing, because also in Germany there would be very much against any prohibition of providing the rehearsals. But I think that finally we found a good middle way. I think the other thing that we got from this investigation is that we quite clearly found that presymptomatic transmission does occur and in vast amounts. And some models have also estimated that perhaps 50% of all infections have occurred through presymptomatic sources. And what does it mean? It it means that wearing masks has a foundation because when you are in a room with people you cannot tell if you are ill because you may be pre-symptomatic and already transmit. So this is a very good reason to wear masks in closed rooms.
SPEAKER_02Very fascinating and very appropriate last outbreak for someone at the Kotch Institute to talk about airborne transmission since he discovered tuberculosis, another airborne transmission. Exactly organism.
Conclusion
SPEAKER_02He'd be proud. Yeah. I have a final question. If you could choose one item to put into your public health backpack, literal or figurative, what would it be?
SPEAKER_01I think it came out already, perhaps while talking with you. I would put it very simply. The one thing I would love to take with me is at least one or two persons, colleagues that I trust that that they can work with me on an outbreak.
SPEAKER_02Collaboration. Collaboration. The medical students that you brought with you. Exactly. They can be very helpful. They can be very helpful. Thank you very much, Udo. It's been a pleasure and um nice to talk to the I use an American colloquialism, the gumshoe of Germany.
SPEAKER_01What does it mean?
SPEAKER_02The gumshoe? So a gumshoe is like a detective for sleuth. Ah, okay. They wore soft shoes, rubber shoes, so people couldn't hear them. They could sneak up on some sneak up on the diseases and uh thank you very much. Many thanks to our guests for sharing their words, but more importantly, their acts of service. Please email us your inspiring governmental healthcare or public health stories at info at inspired to heal.net. Thank you for listening.
SPEAKER_00Inspired to Heal podcasts are for informational purposes only and should not be considered as health or professional advice. We are not responsible for any losses, damages, or liabilities that may arise from the use of this podcast. The views expressed do not necessarily represent those of the host or the guest's current or past employers.
