Preventing meningitis caused by parasites

[AlohaSteven]

"... dogs getting infected.
How many? What are the symptoms? Any tests a vet can do?"

Dr. Prociv and Dr. Carlisle wrote:

"Other animals also get Angio, especially mammals. We’ve seen lots of cases in dogs, who eat lots of slugs n snails (probably accidentally, from food bowls left out overnight); fruit bats and horses are well documented, and no doubt probably most mammals which are exposed will take up L3s, meaning the parasite is not fussy about whom to invade (which makes sense evolutionarily), although as far as we know the L3s will develop into fertile worms only in rats (they get pretty close in people, too). Birds are probably extremely rarely infected; a PhD project in my old dept. (University of Qld) from the 1970s says chickens are refractory (altho I can’t vouch for the reliability of that limited study), and our case reports of infection in a few native birds just show how rare the infection is in them; this could reflect on the relative size of the avian CNS and hence its limited blood supply."

In telephone conversations they further said the beginning of a wet spell in the weather is often followed by outbreaks of infection in pets and farm animals, as slugs and snails come out of hiding and so are ingested. Many dogs developing CNS disease in Queensland, Australia, near the beginning of each rainy season are subsequently brought in to vets, this owing to the dogs eating slugs and snails on dogfood and drowning in water dishes.

Wild rats are largely unaffected by the L3 and adult rat lungworm parasites living in them but humans, dogs and other animals eating the third larval stage act sick, in pain, disoriented, and sometimes like they lack control of themselves. Perhaps some instances of erratic behavior in otherwise pleasant dogs may trace back to their being in pain stemming from rat lungworm L3 infections.

I am unsure what tests beyond diagnosis at autopsy a vet might do to establish angio (maybe look for heightened eosinophil counts, as in humans?), but will relay the question on to Dr. Carlisle for her comment.

Rat control measures and keeping pet food and water bowls away from slugs (as at night) will probably be the most effective ways to keep dogs protected from massive episodic infections of angio.


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A pleasant slideshow: http://www.thejoymovie.com

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[Menehune]

What about cats - not in the hat - that ate the rat - hiding under the hat...........................- never mind!

Really - can cats become infected, suffer - can they pass it on?



"Each thing I do I rush through so I can do something else" - Cemetery Nights/Stephen Dobyns

[Shekelpal]

Our dogs were protected already because we have been giving them ivermectin once a month, for heartworm, another roundworm. We were told by our vet that ivermectin will protect dogs from angiostrongylus as well. This is used on horses and other mammals. "Revolution" a spot for cats, protects against heartworm and roundworm so probably has ivermectin in it. Ivermectin can be bought at Del#699;s and is much cheaper than getting heartworm pills for dogs from the vet. As it comes in a large tube, just be careful of the dosing. We soak the dose up in a bread ball.

[StillHope]

Thank you,Alaskasteven and Shekelpal.

I am more worried about my furry son than myself: he doesn't know any angio - or L3[]

[AlohaSteven]

Dr. Prociv & Dr. Carlisle have responded to the question I forwarded on to them last week regarding dogs and rat lungworm disease ("Angio," as it is apparently called in Australia). I asked- Another question today, this time directed at prophylaxis, detection, and treatment in dogs -I think you mentioned something before about heartworm nemacide perhaps being somewhat protective against small incidental L3 infections in dogs, but not against massive doses of L3?

They reply:

This is a contentious area, as little good work has been done (or had been, while we were working on it) on Angio in dogs, so most of what we think about this is purely speculative. It would be a difficult study to do well, especially given present ethical constraints (about experimenting in dogs). What would be feasible is an epidemiological study comparing dogs on heartworm prophylaxis with those not on it, but you’d need to be in a place where there were lots of cases, and seriously cooperative veterinarians (plus irresponsible owners who didn’t bother protecting their dogs).

The window of opportunity for killing the L3 is the time from when it enters the gut circulation, i.e. within minutes of being eaten, until it invades the CNS, which can be from perhaps 24 hours to as long as maybe 2 weeks (but generally within a few days) after ingestion. The best drugs to hit it are in the ivermectin group (albendazole might also work), so you’d need to have high blood levels in this time window, and that’s why dogs on regular heartworm prophylaxis would be protected (but I’m not sure if this has been shown by any studies).

Can’t resist this opportunity to preach: dogs don’t have symptoms (which are subjective, i.e. what the patient complains about, so only people have these – except for babies, who can’t talk), but show signs, which are objective indicators of something not right. The signs of angiostrongyliasis in dogs cannot be distinguished from those of other CNS infections, i.e. those of meningo-myelo-encephalitis, and so range from lassitude thru to partial paralysis which can be very focal (e.g. hind leg weakness, or bladder incontinence, or convulsions) to coma (when they are usually put down). Again, the severity of abnormality depends purely on numbers and location of developing larvae. In our experience most dogs recover, often without obvious residual dysfunction, although it can take quite a while, often many months. However, a severely affected animal becomes a management problem (and expensive), so it’s a lot easier just to euthanize it. Diagnosis is a challenge, just like in humans, and we’re not aware of any specific test offered to the veterinary fraternity – of course, as you say, eosinophils in the CSF (gained by spinal tap) would certainly strongly support the diagnosis, especially if you’re living in an Angio-endemic area. Sadly, though, there’s no specific treatment (except, as mentioned in the past, corticosteroids seem to settle the CNS inflammation much better in dogs than in humans) – at least if you know the diagnosis, you can offer some sort of prognosis.

Well, it’s not much more than we said before, but we hope it’s of some help. Don’t hesitate to fire away should there be other queries.

All the best
PP & Melissa

---

So, as Shelepal suggests, the heartworm treatments are probably a good idea, along with keeping pets' food and water bowls away from where slugs can climb into them.


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A pleasant slideshow: http://www.thejoymovie.com

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[AlohaSteven]

In reply to Menehune's question "Really - can cats become infected, suffer - can they pass it on?"

Looking online, there is an odd absence of scientific papers describing Angiostrongylus cantonensis &/or rat lungworm disease in cats. Maybe I am just using the wrong keywords and search engines?

There are plenty of lungworms which commonly afflict cats (ever see a cat coughing? It is fairly likely this was due to lungworm, if a furball was not subsequently produced), but to me it seems unclear in the record if A. cantonensis is in fact one of them. Theoretically, it seems like Puna's A. cantonensis should equally be a problem for cats as for seemingly every other mammal, but perhaps for some reason A. cantonensis is not in demonstrated fact a big issue for cats?

Lungworms in Cats
http://www.petplace.com/cats/lungworms-i...page1.aspx

As to cats passing A. cantonensis on, that should not be able to happen. The rat lungworm only successfully reaches adulthood in rodents (rats, for sure; I am unclear whether or not sexually mature adult A. cantonensis can set up house in the cardiovascular systems of mice) whereas in other mammals from fruit bats to humans the A. cantonensis larvae die before reaching adulthood.

If anyone finds more info on this topic then please do post and share it.



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A pleasant slideshow: http://www.thejoymovie.com

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[Menehune]

Like other postings this one continues - I am not sure everyone would have access to this news article so I am posting a link.

http://www.honoluluadvertiser.com/articl.../902080359

The good news is that the initial cases posted about are showing some signs of improvement.

Along with that - the local politicians, medical and other personalities are showing and expressing a more serious approach to the outbreak.




"Each thing I do I rush through so I can do something else" - Cemetery Nights/Stephen Dobyns

[Shekelpal]

alaskasteven, Is there any chance of getting the full text of Donald Heyneman and Boo-Liat Lim#699;s journal article entitled "Angiostrongylus cantonensis: Proof of direct transmission with its epidemiological implications" from Dr. Procliv and Dr. Carlisle? If they have it or can get it but cannot share it on Punaweb would they be willing to e-mail me or the aunty of Graham (who is in a coma). She is a scientist as well, and was very interested in the full article.
Mahalo

[AlohaSteven]

Hi Shekelpal- I've been traveling and just saw your question about getting hold of the Donald Heyneman and Boo-Liat Lim journal article. The friendly Aussies do not have a copy but anyone in the local University of Hawaii loop should be able to access the full text through their library privileges. I am in Puna at the moment but once I am back up in Alaska will see about getting a copy via the University of Alaska's library [Punaweb's mail has been unreliable for exchanges of PMs but if you email me at alaskasteven@yahoo.com with an address for yourself then I'll update you on the results of that quest].


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A pleasant slideshow: http://www.thejoymovie.com

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[AlohaSteven]

Dr. Prociv and Dr. Carlisle have responded to Menehune's question about rat lungworm in cats along with a couple of other questions I had for them. They write-


G’day Steven

Sorry I missed it earlier, but I’ve just come across your old e-mail; we’ve been having a few problems with e-mails lately, leading to our need to close down the old account and open a new one, hence the new address. We hope this has not caused you difficulties.

Anyway, to your questions . . .

In reply to Menehune's question "Really - can cats become infected, suffer - can they pass it on?"

Yes, that’s fascinating. It is something we have thought and talked about, but we’re not aware of any reports of Angio cantonensis infections in cats. You need to be careful with the term, “lungworm” as several different species fall into this category. However, as far as Angio goes, you’d think it should invade and migrate in cats, but nobody has ever done the studies (as far as we know), or reported natural infections in them. I’d be surprised to learn that cats are never exposed, i.e. never eat molluscs, either intentionally or accidentally. If people are finding cats to be affected, it’d be worth publishing (we know of lots of interesting cases in other animals that should have been, but never were, published).

Well, would you believe, I just saw website for lungworms in cats you provided in your letter (and checked it out), which reinforces what I said above. They’re ones that use cats as definitive hosts, i.e. complete their development in the cat, whereas Angio officially is not meant to do that outside of rats (although it gets pretty close in humans, judging by the few autopsy reports). I did find sexually mature Angios in a young child who died here, but there was no clear evidence of their copulating – while some of the females might have contained eggs, there was no evidence of eggs or L1s being released. There is no way a cat could transmit it (and if a cat somehow did, it could only be to a snail or other invertebrate!)

[In my letter, I asked: In your experimental work did you ever actually grow out L3 to adulthood in mice, as opposed to rats? I see in the literature where mice are used in nemacide trials against L3, but am not finding any records one way or another stating for documented fact whether or not sexually mature A. cantonesis have been dissected out of the pulmonary arteries of mice, as distinct from rats. Do you know if mice can carry Angio, or only rats?]

No, I never worked with Angio in mice, but I recall reading a paper that categorically stated Angio will not develop in mice. Those literature reports are concerned with drug effects against migrating L3s, which can be tricky to interpret, given the small size of mice, plus the short longevity (brevity?) of these L3 in them. My reading has always confirmed the idea that it’s highly specific for rats, although different rat species vary in their susceptibility (of course, there are several species of Angio, which prefer different host species). As far as I know the child here and a very similar case study from Melbourne about the same time were the first time Angio was found in human pulmonary arteries – although human lung changes (on chest X-ray) have been described many times in the past, in presumably heavy infections.

[Any comments on Angio in cats? Perhaps there is a role for ivermectin dosing prophylaxis in cats as well as dogs.]

Well, until there’s good evidence of feline infection, I wouldn’t advocate that – have there been suspicious cases? Of course, folks might be using ivermectin in cats for other reasons (just like in dogs), when its use could have an extra benefit (assuming them to be susceptible to angio).

[I am a bit worried that folks in Puna are going to flip out and start dosing their infants and children with ivermectin, anxious the tots will eat a heavily infected slug and die. The sense I am picking up is that ivermectin prohylaxis may be useful against low-level incidental infecton, but perhaps not so much against a massive dose of L3? I wonder what long-term exposure to ivermectin does to human physiology, particularly in developing children and in pregnant women (especially since many folks do not even know they are pregnant until week five or six).]

Good point – apart from the expense of such a strategy; it must cost quite a bit? I think if ivermectin is going to knock out a couple of L3s, it’ll do the same to a few thousand, so that’s not a problem. But you’d need to keep taking it periodically, forever. I’m only aware of its use in human strongyloidiasis, when only a few doses are given, apparently with no ill effects. For longer-term use, I have no idea – it would be best to ask the manufacturers, who should have big files of potential toxicity (but also who’ll probably have a fit, and tell you not to touch it! They’re very sensitive about legal liability, of course).

[Glad to hear you are located in Australia's sweet spot between the drought and flood zones!]

Yes, but now we’re expecting a cyclone (a.k.a. hurricane) to bear down on us in the next 1-2 days – winds are building up, and rain is on the way. It’s all fun’n’games as summer winds down.

Please let us know how you’re getting on, and sincere apologies again for having missed your e-mail for so long.


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A pleasant slideshow: http://www.thejoymovie.com

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