For the possible good of the order, here are some notes and comments from last night's expert panel presentation, discussion, and Q&A at UHH's College of Pharmacy public meeting on rat lungworm disease.
Those who signed up at the meeting for receiving a link will be emailed the URL whenever a video of the meeting is posted online. I will update this thread with the link whenever video editing is complete and they send the notice indicating the meeting video is up and available. I was told this will probably be several weeks from now. Another way to find it whenever the meeting video becomes available is to watch the UHH College of Pharmacy website for a link.
Sue Jarvie was the moderator of the forum. The event was very well organized; an overflow crowd was accommodated with additional seating and live video feed in another classroom. College of Pharmacy students in neat white smocks worked the front table, distributed questionnaires and question slips, served as runners, and were generally courteous and efficient in facilitating the meeting.
The format of the evening was for each expert to speak with the aid of a slideshow with question slips being collected and collated by the students. After all of the speakers had finished their presentations then Dr. Jarvi moderated a Q&A session. There were several disruptive interruptions by one audience member as well as some appropriate questions and comments by other audience members along the way, but for the most part the format held together and was followed. The speakers were flagged with "5 minutes remaining" and "time is up" cards so everything stayed on track and kept moving along.
Most of that which was presented was an educational overview of rat lungworm. Anyone not familiar with the life cycle of the parasite and how it accidentally finds itself causing disease in humans (and pets) would quickly have a good feel for this from the excellent diagrams and photos which were shared. The speakers managed to work in some funny slides too, for welcome comic relief amidst information on a topic which has caused so much grief and heartache.
I will just list the speakers and some points &/or resources I found interesting or noteworthy from their presentations. When the video is available anyone interested can watch the detailed version online. Apologies in advance for typos and especially if I misheard, misunderstood, or poorly relate any of this information. Please do post corrections if you see I have made any errors. RLD = Rat Lungworm Disease and RLW = Rat Lungworm in the meeting's shorthand.
The speakers all stressed that there are more unanswered questions than solidly known answers.
Part of the reason questionnaire slips were distributed at the door was to get in contact with people who had experienced rat lungworm infection and collect more data.
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Robert Cowie (with the Pacific Bioscience Research Center, UH Honolulu) noted the rat lungworm lifecycle requires a minimum of 45 days to run one complete cycle from rats to invertebrates (usually slugs) and back to rats. Importantly, though, the L3 nematode (rat lungworm) larvae can remain viable in the slug for much longer than 45 days if the slug is uneaten by a rat. The L3 will still be alive when the slug dies of old age.
L3 have now been detected in slugs on all the main islands in Hawaii.
A baby semislug is very tiny, less than a quarter of an inch long, yet can be infested with thousands of infectious L3.
There is no actual evidence of slime paths infecting anyone with L3; this is theoretically possible though for practical purposes seems unlikely.
L1 (the form of rat lungorm larvae present in rat feces) cannot infect humans. Must be in the L3 form (in a host such as a slug) in order to infect humans.
L3 liberated from the decaying tissues of drowned slugs in water catchment tanks can theoretically infect humans drinking the unfiltered water, yet the dilution factor is so large this may not be a serious threat in practical effect. [It was later noted that having a 15 micron filter between the catchment tank and the tap would prevent L3 from being present in the tapwater. A 20 micron filter will theoretically keep them out of the tapwater, but depending on how much pressure is behind the L3 a 20 micron filter might not be 100% effective. A 15 micron filter should screen out all L3 from the water even with pressure behind them.]
Robert Cowie concluded by noting there are 30 pdfs filled with information on rat lungworm disease issues from the August conference in Honolulu which are available online via this link:
http://www.hawaii.edu/cowielab/Angio%20w...20home.htm
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Rob Hollingsworth (entomologist, with USDA-Pacific Basin Agricultural Research Center in Hilo) presented on slugs.
There can be over 2,000 L3 present in one Cuban slug.
Semislug neonates (babies) can be only 1mm to 2mm in length (very difficult to see) yet have massive L3 infestations as well; any slug or snail should be treated as a likely disease vector.
Populations of slugs peak in late winter and early spring when adults lay egg clusters and die.
Flatworms are quite likely also a significant source of L3; they hunt slugs so may concentrate the L3 in their tissues then be present in lettuce or other produce.
Gastropods (slugs and snails) are nocturnal feeders; their munching on veggies looks like insect damage but if you see spirals or spaghetti-like messes of poo then this evidence indicates it was likely slugs and snails, not insects, doing the munching. Caterpillar droppings look like pellets.
To control slugs remove shelter, use shelter as traps, create a drier environment in garden areas.
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Jim Hollyer (work with UHH to educate farmers about sanitary growing and harvest practices; was careful to post disclaimers for legal liability regarding information shared and stressed personal responsibility) noted ducks and chickens for slug control may assist to solve one problem while contributing to another. Ducks and chickens eating slugs may be defecating
Salmonella bacteria and other problems.
A biofilm secreted by the bacteria can cover
Salmonella such that even washing with chlorine rinse will not kill them. Recommendation: do not harvest produce with poop, slime, and slugs present.
Is about to commence a trial of 15 chemicals and additives testing how effective they are as sanitizer dips for produce.
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John Martel (medical pharmacologist, Hilo)
Only 1 in 10 to 20 cases of rat lungworm disease will present with worms in spinal tap fluid. Relatively rare. Diagnosis must usually be one of elimination, indirect. Antigen test possible but only after 2 to 3 weeks for marker to appear in blood; big difficulty in locating labs to reliably test for this, none in Hawaii [Sue Jarvi noted testing may be available from Thailand and China].
Medicating to kill larvae and so reduce duration of viable L3-L5 infection (during which time the larvae are growing and burrowing around in neural tissue) can be accomplished with Albendazole, Mebendazole, Ivermectin. Side effects usually minimal. Mouse studies suggest this does not do much good in terms of overall outcome.
Reducing inflammation with two week treatment of steroids like Prednisone is another approach. Can cause major side effects.
Noted efforts to educate local medical staff regarding recognition of RLD symptoms.
Best to avoid infection because treatment after the fact is potentially ineffective or even harmful negative side effects) as well as expensive. Disease effects may be severe and permanent.
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Marlene Castro-Dixon (field investigator for Hawaii Dept of Health) recounted the most commonly asked questions she receives and provided her answer. Notable among them was this: "What should I do if I find a slug in my salad at a restaurant?" Reply: call me and report where this happened. She will go educate them about the dangers involved and assist them to improve their effectiveness. [Discussion indicated this does happen; one speaker said she will not eat salad at restaurants -or elsewhere, unless she or a small number of people she personally knows take rat lungworm very seriously are the cook].
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Ann Kobsa (Puna biologist and resident) surveyed people in her community and found 15% had experienced rat lungworm disease; some people had experienced it more than once.
Noted difficulties and lack of treatment experienced by a number of people at local emergency rooms; commented some people now keep Prednisone from Thailand in the freezer so as to have some on hand in case of an infection with RLD.
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Kay Howe (nutritionist and mother of RLD victim Graham) presented an overview of holistic medicine and herbal treatments for the care of RLD victims. Of particular note were glutathion, treatments stimulating the Nrf2 pathway, and a Chinese herbal (Bu Nau Wan?) containing the plant
Sch..... chinensis (I did not accurately catch all of this info in my notes).
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An audience member who had experienced rat lungworm disease appropriately requested the microphone and shared with constructive intention the importance of not leaving salads unattended on a lanai table or at a picnic; slugs can crawl in faster than one may realize. He is sure exactly this happened to him.
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An audience member repeatedly interrupted and indulged herself in the use of sarcastic, hostile, and belittling comments directed at three panel members. It was unclear what her anger with Rob Hollingsworth and John Martel was about, though she alluded to wanting to identify "what faction you belong to." Marlene Castro-Dixon was verbally attacked for the failure of government agencies and presumably she, herself, personally to have heeded the upset audience member's calls for them to come up with and post educational posters which are larger, easier to read, and replaced more frequently than the posters which were actually produced and distributed. The panel's speakers remained gracious and courteous even while being subjected to sarcasm and being angrily harassed, to their credit.
Dr. Jarvi and others noted the difficult and emotional nature of this topic for some people it has touched personally; they invited people to participate in the forum as it was structured (to allow everyone to be heard) as well as in upcoming studies.
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One of the speakers (either Rob Hollingsworth or Robert Cowie, if I recall correctly) noted that EPA had changed regulations regarding poison rat baits. If formerly available forms of rat bait are not already gone from store shelves then they soon will be, not to come again. There were problems with kids and pets coming to grief with peanut-butter flavored and other baits in an easily accessible form, so in future rat poisons will only be marketed in sealed one-use containers.
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Sue Jarvi noted Kay Howe and she have applied for grant funds to study rat lungworm disease incidence in Puna. She invites participation in this study (as via the questionnaires available at the meeting).
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A very good question was asked by an audience member which nobody on the panel was able to answer: "How long do the rat lungworm larvae in rat feces remain viable and infective to slugs?" [Note: these are the L1 or L2 stages, which are not infective to humans].
It was noted 72 hours in water will kill L3. Freezing Giant African Snails also killed L3, but two to three days in the freezer were required to solidly freeze Giant African Snails. Cooking thoroughly remains the most sure way to eliminate risk of L3 infection with foods such as leafy veggies, invertebrates like shrimp, and when one wants to eat snails.
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Some comments and observations of my own:
The evening was informative and useful. The local team of experts is clearly dedicated and hardworking. Students of the College of Pharmacy are to be commended on their cheerful efficiency and the pleasant courtesy they showed as hosts to the public last evening.
Oddly missing from an otherwise excellent lineup of experts, imho, were two perspectives: that of an expert on rat control and that of an ecologist.
Advice received from workers in Australia indicates the weakest and most vulnerable link for breaking the rat lungworm lifecycle is to eliminate rats. While invertebrates such as slugs and snails are relatively short-lived and do not travel very far, rats are relatively long-lived and highly mobile. An infected rat can live for years, spreading highly concentrated doses of rat lungworm larvae everywhere it travels. Coating the ground with infectious slug candy (slugs love eating rat feces, just as rats love eating slugs, which is how the parasite's lifecycle evolved in the first place) insures that slug neonates become dangerous quickly after hatching. If the garden environment is not filled with infectious rat feces, however, then even if baby slugs slip by detection on ingested raw veggies & fruits then they are far less likely to be infected at all ...and even if they are infected they are perhaps less likely to be filled with thousands of L3, each.
A speaker noted that it is currently unknown whether 1 in 10,000 L3 ingested reach L5 stage in human neural tissue or if 9,999 L3 of each 10,000 ingested reach L5. True enough, yet since we do know that dose is all-important as regards the ultimate damage resulting from RLD, it stands to reason that reducing the likelihood of a high L3 dose from accidental ingestion of a slug neonate will translate to less ultimate harm in the event this happens. To say this a different way, yes, a single L5 tunneling through a delicate brain structure the size of a grain of sand can produce permanent damage. Whether a L5 will hit such a critical cluster of nerve cells or miss them is a haphazard process. The more L5 which are present, though, then the higher the statistical odds that one of them will randomly burrow through such a critical cell cluster. So, anything and everything which can be done to lower both the chances of a neonate slug harboring any L3 at all
and if L3 are present then to lower the number of L3 being harbored in the slug neonate should be constructive.
As I have gone around Puna trapping rats during the last year or so and then dissecting their hearts (the adult rat lungworms lives in the rats' pulmonary aorta) I have found the nematode present everywhere I have checked. What I do not know but very much wonder about is the relationship between worm burden in rats, rat population demographics, and L3 prevalence in neonate slugs. This deserves study. It may turn out that age of the rats has a significant bearing on how much of a contribution they are to the density and degree of infectious hazards their droppings represent in a given territory. As with the slug species (wide variation appears indicated between the suitability or goodness-of-fit between rat lungworm and various species of slugs as intermediate host) it may be there are significant differences between the suitability of various rat species as definitive hosts. There are several very different rat species present in Puna. Putting the full court press on one rat species (habitat elimination, trapping, poisoning where appropriate and environmentally acceptable, cultivation and promotion of predators) could shift the niche advantage to another rat species less likely to harbor rat lungworm, or even to another critter entirely (such as mongoose).
Which leads me to my second observation: an ecologist's perspective would be very useful in this discussion, particularly that of an ecologist with some training and experience in the branch called human ecology as it overlaps with epidemiology, parasitology, and vertebrate zoology. Several questions were asked last night regarding the seeming abundance of RLD cases in Puna relative to the rest of Hawaii. Speakers on the panel were understandably reluctant to speculate on potential reasons behind why this does indeed appear to be the case. These folks are all specialists in very narrow areas, and seem to be very good at what they do in those areas, yet probably do not feel qualified (and are perhaps reluctant to go out on a limb and risk their hard-earned professional reputation) by opining about complex interactive factors outside their fields. This is where an ecologist would be useful. Not a lab ecologist who does beaker studies, but a field ecologist who has worked in human villages.
What is the seasonal relationship between the relative abundance and seasonality of food (such as fallen fruit) on rat populations for leeward versus windward sides of the Hawaiian islands? What is the relationship between local geography, culture, income level, dietary preference, public policy, and spending by public institutions relative to effective rat lungworm prevention education? How do rat predator-prey population cycles (if present, as would seem likely, for rats both as predator --on slugs-- and as prey --for cats or raptors--) affect rat lungworm densities? How can Hawaii's agricultural and tourism sectors best participate and aid in RLD prevention? How do rat population age demographics by species affect prevalence of highly infective L3-laden rat poop in a given territory? Where are the bottlenecks and key centers of influence for effective RLD policy? Which control strategies work best for which rat species and are both acceptable and affordable in various communities? And so on. This is the sort of work done by human ecologists. It would be useful to have such a presence on Hawaii's team.
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Here is the questionnaire distributed at the door:
RLW Informational Survey
Name:
Have you ever experienced symptoms you believe were caused by rat lungworm? [Yes/No]
If so, what were your main symptoms?
Are you willing to be interviewed about your experience? [yes/No]
Phone number and/or email
Please return to Dr. Sue Jarvi, College of Pharmacy, 34 Rainbow Drive, Hilo, HI, 96720.
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[End of record]
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