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WormFaxNSW – April edition
The April edition is now online.
The old is new again
Angiostrongylus in rats – a zoonosis
"There have been some cases of Angiostrongylus cantonensis (
infections in children in Sydney who have presented with aseptic meningitis.
Presumably their exposure was through eating infected snails or slugs. The larvae are carried in the pulmonary arteries of rats and migrate to the pharynx and are passed in rat faeces. Rat faeces are ingested by slugs or snails. Humans can acquire the infection by eating raw or undercooked snails or slugs infected with the parasite. They may also acquire the infection by eating raw produce that contains a small snail or slug. In humans, juvenile worms migrate to the brain where the worms ultimately die." (Slightly edited).
I referred the inquiry on this to Dr Gareth Hutchinson, formerly parasitologist at EMAI and before that James Cook University, Townsville, QLD.
Gareth kindly provided the following information for the medical epidemiologist and for me. It may be of interest, at least to some.
I’ve been digging in the archives (spare bedroom).
There is a good detailed description of life cycles, pathobiology etc. for both Angiostrongylus cantonensis
(and A. costaricensis
), including treatment and control in “Veterinary Parasitology” Third edition 2007, by MA Taylor, RL Coop and RL Wall (Blackwell), pp 631-634.
There is also another species A. mackerrasae
described from the Australian native rat, Rattus fuscipes
. This can be distinguished from A cantonensis
, and they can cross breed. Work conducted at University of Queensland in the late 1960s and 1970s by Manoon Bhaibulya a post grad student of the late Prof John Sprent (recently deceased at 100 years of age!) described this species.
It should be relatively easy to detect the L1 stages in rat faeces (eggs hatch in the rat’s tissues and will not be detected using faecal floatation) or in lung tissues, using a Baermann apparatus (Any parasitology diagnostic lab (commercial or at EMAI) can do this), and there are photos and measurements and descriptions in the references cited below. Adult worms should be recoverable by dissection of pulmonary arteries and right side of heart. The terrestrial snails Helicarion
sp can act as lab intermediate hosts; I’m not sure if they are common in NSW.
Bhaibulaya M, 1968. A new species of Angiostrongylus
in an Australian rat, Rattus fuscipes
. Parasitology 58: 789-799
Bhaibulaya M, 1974. Experimental hybridisation of Angiostrongylus mackerrasae
, Bhaibulaya, 1968 and Angiostrongylus cantonensis
(Chen 1935). International Journal for Parasitology, 4: 567-573.
Bhaibulaya M, 1975. Comparative studies on the life history of Angiostrongylus mackerrasae
Bhaibulaya, 1968 and Angiostrongylus cantonensis
(Chen 1935). International Journal for Parasitology 5: 7-20
Gareth Hutchinson 18/5/11 (Published here with permission).
Tapeworm-REDUX – another comment
This from John Moffat (Schering Plough-Intervet; 3 May):
Re Southworth et al trial – Some comments:
* I was interested in the comments by Graham Lean re number of tape worms. Because the tapeworm burden (either by faecal or slaughter of sentinel animals) was not recorded in the growth trial
* The burden of strongyle or efficacy of levamisole was not recorded- if resistance was an issue variable efficacy in the lambs could have been an unlikely complicating issue- would have been nice to see standard deviations for each group to see if variability was similar in each treatment group.
* Growth of the lambs was recorded for only 8 weeks from ~17kg to ~26kg liveweight- compensatory growth may have meant any difference in weight gain was diminished by the time animals were at slaughter weight.
Read no further….
New parasite – Hattus ridiculosis
Discovered at or around the time of the recent royal (U.K.) wedding.
Worms – coeliac disease
Apart from the ‘hygiene hypothesis’, another theory (perhaps a complementary theory?) to explain the apparent rise in autoimmune diseases relates to increased gut permeability (leaky gut syndrome), with key culprits said to be among the so-called neolithic foods. These are foods introduced into the human diet in the last 0.5% of human evolutionary history, i.e. the last 10,000 years (since the Agricultural Revolution and the end of the paleolithic area). It has been estimated that 70% of calories in modern western diets (e.g. the US) come from neolithic foods (grains/cereals, legumes, dairy), with some of these being implicated in leaky gut syndrome, whether by way of lectins or other means.
Exogenous molecules (eg foods, microbes etc) can pass the first line of defence (the gut wall) and evoke an autoimmune response by way of molecule mimicry. eg protein in wheat etc (gluten/gliadin) can (according to one theory), in coeliac disease, mimic structural elements of the gut , evoking an immune response to these structures, with consequent villous atrophy, a mononuclear inflammatory infiltrate, and the clinical signs associated with coeliac disease (malabsorption etc). A broadly similar pathogenesis has been posited for other autoimmune disease eg MS, type 1 diabetes etc. Interesting. 🙂 SL.
Take Two Hookworms and Call Me in the Morning
Habitual coffee consumption and risk of hypertension: a systematic review and meta-analysis of prospective observational studies
One for the fisherpersons
Plagiarism: stealing from one.
Research: stealing from many
Ethics: a county in England
(Source: unknown, but they smack of Ambrose Bierce (Devil’s Dictionary).