College of Pharmacy- Dr. Jarvi
Rat Lungworm Disease in Hawaii: A Public Forum
0:00-This is a recording of a public forum held on rat lungworm disease in Hawaii caused by the parasite Angiostrongylus Cantonensis. It was held at the University of Hawaii at Hilo, College of Pharmacy, November 9th 2011. The Moderator is Dr. Sue Jarvi, associate professor in the College of Pharmacy at University of Hawaii. Dr. Rob Cowie, a snail taxonomist from the Pacific Bioscience Research Center at the University of Hawaii at Manoa; Dr. Rob Hollingsworth, an entomologist with the U.S. Department of Agriculture: Pacific Basin Area Research Center; Jim Hollyer director of Agricultural Development in the American Pacific program in the College of Tropical Agriculture and Human Resources at the University of Hawaii at Manoa; Dr. Jon Martell, associate professor of medicine at the University of Hawaii John A Burns School of Medicine and a position at the Hilo Medical Center; Marlena Dixon with the Hawaii Department of Health; Dr. Ann Kobsa Vice President an Invasive Species coordinator from Malama O Puna, an environmental non-profit organization; and Kay Howe who is a community educator and whose son Graham was a victim of Rat Lungworm disease.
1:23- This forum was sponsored by the University of Hawaii at Hilo College of Pharmacy, by the National Institute of Food and Agriculture of USDA, University of Hawaii at Manoa, and Global H.O.P.E.
1:42-Dr. Sue Jarvi: I would like to start off this forum by reminding everyone that Rat Lungworm disease is not native to Hawaii. It is truly a global disease. The causative organism is a nematode, a worm called Angiostrongylus Cantonensis, which was originally discovered in Canton, China in the 1930’s. This worm reproduces in rats and completes further development in mollusks, like slugs and snails. Since the 1930’s, Rat Lungworm disease has spread to at least thirty of countries, likely by rats on shipping vessels. Since the first case of human rat lungworm disease was reported in 1945, nearly 3,000 cases have been reported worldwide, with the highest numbers being reported from Thailand and China. Here in Hawaii, we have all the basic ingredients for outbreaks to occur: rats, slugs, snails, and the nematode. Rat Lungworm disease has been reported in Hawaii, and other pacific islands, since the 1960’s.
2:42- Dr. Rob Cowie: Ok while she’s doing that, let me just preface what I’m going to talk about by saying that this workshop, this forum, and future forums that are going to take place on the other islands are funded in part by a grant from the United States Department of Agriculture that I, Jim and Rob, and a couple of others that are not here, that were able to get and to bring together a bunch of people from all over the world, all those countries that(some of those countries) that Sue just showed you, to all experts in their fields to discuss what is and what is not known about Rat Lungworm disease on sort of a global scale. And we brought together people who ranged from people like me who I’m a snail person, that’s what I work on is snails. And so I come from that end of the spectrum here. We went through everything from epidemiologists, pathologists, food safety experts, all the way through to people who use diagnostic techniques for the disease all the way to physicians who treat the disease. And so we all have a really good sort of overview of the entire spectrum of what is and what is not known on the disease. And the idea, as Sue said at this meeting, is to distill what we came up with at the meeting in Honolulu, back in August, and provide it to the community to the extent that we can. That’s the purpose of this meeting and partly how is has come about.
4:28- Rob Cowie Continued: So as a snail person, what I’m going to talk to you about is basically the biology of Rat Lungworm so you all understand how it all actually works, because it’s very very important to understand the mechanisms by which the worms get around in order to understand how to deal with getting infected.
4:55- Rob Cowie (first slide): So this first slide is a little bit complicated, and I’m going to take a minute to go through it quite carefully. I don’t think there is a way of, I can put, if everyone can see it I can put this screen, but I can’t put the other one. So what happens is that we start here in this cycle. It’s blocked up here (top left corner) and what it says is definitive host. The definitive host is the host is which the worm matures and reproduces, and is this case its rats. What happens is the rats defecate material that includes the first stage of the worms. Snails come along and eat the rat feces that contain those first stage worms. Sorry wrong button. They are really close together. And then the worms mature to the so called third stage in those snails and slugs. What happens then is a rat comes along, eats the snails or slug, and ingests those third stage worms. Then those worms, obviously they go down the mouth of the rat down into its intestines ultimately. From its intestines they get into the blood system/circulatory system. Then they move from the circulatory system into the central nervous system, and that’s where they end up maturing to the fifth stage. So we’ve gone from the first stage in snail feces, I mean rat feces I’m sorry. Eaten by snails, reached the third stage in the snails, then a rat eats the snails, ingests the third stage worms larvae which the reach the central nervous system and mature to the fifth stage. Fifth stage worms then move back into the blood stream of the rat. There they mature and mate, in fact in the heart and pulmonary artery, and females lay their eggs there and those eggs are just washed through the circulatory system from the pulmonary artery into the alveoli or the lungs. What happens there, is that they hatch theirs eggs there into brand new first stage worms, and those worms work their way up the windpipe and get swallowed back down the gut of the rat defecated out the back end and the cycle starts again with snails eating first stage worms. So you’ve gone all the way through the cycle, and this is the natural cycle in the wild. This is how they evolved to be, it’s complicated and it’s sort of horrible but there it is. Now this whole thing takes about forty-five days. The only sort of real variable on that is this stage here. Because when the snail eats the first stage worms, the worms mature at a natural rate. But if the snail is not eaten by a rat, then the worms just stop there at the first stage. Until they get eaten by a rat, or until the snail dies. So this stage here can be longer or shorter, so you can add on however long you like to this forty-five days, sort of a minimum for the cycle. That’s in a rat.
8:39: Rob Cowie (next slide of worm in rat’s brain). This is what it looks like inside a rat’s brain. These worms, these are adult worms, in a rat’s brain. This one here, that’s about an inch and a quarter long. Just think about that.
9:00 Rob Cowie (next slide on human infection) Okay this is what happens, how we get infected. So the same thing happens. Rats defecate feces with first stage worms, the feces are eaten by the snail or the slugs. The worms mature to the third stage in the snails or slugs. But then instead of a rat eating the snail or slug, someone else eats the snails. I did actually eat it. So I ate the snail or slug and the same thing happens. The worms go down here and penetrate the wall of my intestines and get into my circulatory system. Move from my circulatory system into my nervous system, also into my brain, where they reach the fifth stage. But my brain is different from a rats’, thank god, and they can’t find their way out. So they die there. And that’s, dying there, seems to be what causes the major symptoms of rat lungworm disease. Which as most of you probably heard, is also known as angiostrongyliasis, and the symptoms are described as eosinophilic meningitis or eosinophilic meningoencephalitis. Okay so that’s the cycle, it’s not a cycle because it’s not complete, in humans. Very similar to the rat, but stops at the fifth stage in your brain and that’s what causes the problem.
10:40: Rob Cowie (Next slide with hosts): So unfortunately the thing is covering the first word there, but that word is paratenic, so you don’t have to worry about that. But there are other kinds of hosts other than the definitive hosts, which are the rats, the intermediate hosts, which are the snails or the slugs, and accidental hosts, which are things like us who eat them by mistake and the cycle cannot go through. I keep doing the wrong thing (regarding slide changing). The paratenic hosts are other organisms that can get infected by eating rat feces for instance, or by eating an infected snail or slug with worms that’s either first stage, second stage, or third stage. But the larvae in that case do not mature; don’t move from one stage to the next. They just stay put in these paratenic hosts and that’s that. But what can happen is that if something, you or I for instance, eats one of these so called paratenic hosts, we can get infected through eating these as well. There’s a whole bunch of things that I’ll come back to that towards the end of my presentation, in terms of sort of local context.
11:58: Rob Cowie (Next slide with slug hosts) Okay, so you’ve all heard that perhaps the most, the worrying snail or slug is the so called semi-slug, which is/seems to be the most heavily implicated in the spread of the disease particularly on this island and Ron Hollingsworth is going to talk about more on that I think. But what we’ve done, what my graduate students have done in fact, has been to screen a whole bunch of other snails and slugs that we’ve collected here in Hawaii, from across the state. We’ve sampled from, I did that again (accidental slide change). It turns out that of the sixteen on this slide, all but three of them, these three here, did carry rat lungworm. So it’s not just the semi-slug, it’s all sorts of snails and slugs. And the fact that these did not carry, doesn’t mean that they cannot. It just means that we haven’t managed to pick up a snail or slug that did at that time carry rat lungworm. Because other studies have shown that at least this species (the picture he is pointing at) can indeed carry rat lungworm. This one here (pointing at another picture) you might know is, this is the apple snail, that is the big taro pest in Hawaii. This one, it carries rat lungworm so you have a good idea not to eat that.
13:30: Rob Cowie (Next slide with Hawaii islands): So we have done this survey, we covered all the islands quite extensively. We could probably do more intensive surveying in this area for sure. We haven’t got the money for that. But we show is that the red dots are wear we’ve detected rat lungworm in snails and slugs. The other dots we did not detect. So rat lungworm is on all the islands except Lanai. Kauai you can just see a red dot, Oahu, Molokai, Maui, and Big Island. None found yet on Lanai, but we’re not done yet surveying that. So that’s not showing the existence.
14:15: Rob Cowie (Next slide on contracting and risks): Okay how do you get it? And what are the relative risks of the different pathways virus you can get? Obviously if you eat snails and slugs, especially raw snails and slugs, then you stand a really good chance of getting sick. And just a little bit of information, the first case in Brazil which was in 2007 was two guys who got drunk and they saw a big slug crawling around. One said to the other, “I dare you to eat it”. The other guy said “no, I will only eat it if you eat it”. So they cut it in half and they both ate it, and they both got really sick. And there has also been a recent case in Hawaii, just last year I think. It’s actually a guy in the military, he was up in I think Scofield, up in the mountains somewhere camping overnight with his mates. And they saw this big, giant African snail. And the one guy said to this guy, “I dare you to eat it” “How much?” “Two hundred bucks”. And so he said alright and he eats it. And so a few days later, maybe a week later, he felt this really bad headache and he wasn’t feeling at all chipper. And the doctor there happened to know about this disease, and a lot of doctors don’t. He did happen to know. He thought, he asked the guy, “Have you been hanging around with snails, been messing around with snails?” And the guy says no, no. And then he treated him as if he did have rat lungworm disease. The fellow went away and then came back even worse and the doctor began to build a rapport with the guy. And eventually the guy said, he said are you sure you never played around or touched with snails? He says well we did play around with some snails the other day. Eventually the guy admitted that, yeah I had one. He ate it raw and he got really sick. The doctor says, well did you claim the bet? He says, yeah I got the two hundred bucks. Was it worth it? He says, Hell no. So anyways that’s just a little anecdote. So the point is this an apple snail. I work on apple snails; well I have been in the lab. Under-cooked or raw apple snails are actually a delicacy in Hawaii. I know that some people eat them in Thailand; I know that some people eat apple snails in Hawaii. Although I think mostly they get cooked, but it’s important that even though you cook it, you cook it thoroughly.
17:07: Rob Cowie (Nest slide with group photo): So that’s eating raw snails deliberately. You can eat raw snails accidentally through the sort of debris associated with preparing them for cooking. This is a picture of us in Brazil a few years ago; we’re eating apple snails here. But this lady cooked these snails/prepared them out in the Amazon forest on this wooden board. And you can see there is also some junk here, probably bits of snail. And you can imagine if she got that on her fingers and licked her fingers or whatever. You have to be careful in this kind of situation, if you are preparing snails, make sure that you thoroughly wash your hands on any uncooked debris from the preparation table.