Following is the start of a conversation regarding Nematodirus
(thin-necked intestinal worm; ‘Nem’) with Graham Lean following on Paul Nilon article on Parasites in Sheep in Tasmania( Turning the Worm newsletter
Issue 26, May 2010; also here
Graham has given permission to put this in a WormMail i.e. essentially public). If you would like to comment – and agree to have you comments added to a final compilation to be published in WormMail i.e. public)- then feel free to reply to this email.
Here is the conversation:
[GL]: Hi Steve,
[GL]: I enjoyed Paul’s article
. I thought it was very good.
[SL]: I agree. Interesting stuff and nice writing style. It was the second in a series…the first (some time go) being one on sheep worms in the Falklands…. (Derek Clelland, TTW Issue 5, July 1999)
[GL]: I also thought that his observation of Nematodirus was similar to mine in SW WA when I was there and also here in western Victoria. Some parasitologists agree with our view, others dismiss it.
[SL}: Here is what Paul Nilon said in his TTW article
(don’t ask which species) predominates in dry summers and autumns. While it is regarded as relatively benign in other parts, in Tasmania it can cause significant parasitism, particularly in weaners. Moreover, because of sporadic egg output FEC Faecal worm egg count. triggers for treatment are low (150 epg).
[SL]: My view…. It is a second order parasite ( in NSW at least) compared to Haemonchus-Ostertagia-Trichostrongylus in sheep – but under certain circumstances can be important…
* young sheep – more vulnerable.
* certain seasonal conditions … eg rain after prolonged dry spell…through which the tough Nem eggs can survive for extended periods
* certain management conditions…e.g paddocks set-stocked with young sheep or regularly used by young sheep…resulting in higher numbers of Nem eggs
* other stressors contributing…. nutrition, weather, other parasites
* drench resistance
[SL]: And… there may be clinical disease before Nem egg counts rise much at all…due to large numbers of immatures
[GL]: Agree with all that. Nicely put.
[SL]: Nem (N filicollis at least?) is a big deal in NZ…but it was not always so. I seem to recall it become a 1st order parasite only since the 1960s? (Love and Hutchinson 2003) …. not sure why….Changes in farming practices??
(Our NZ colleagues may help out here)
[SL] [Postscript] Regarding Nematodirus species in sheep in NZ, Pomroy lists N. filicollis of major importance, and various other species (spathiger, helvetianus, and abnormalis) of minor importance.(Interestingly Pomroy also lists Trichonstronglyus axei – stomach hair worm- as of major importance, which is generally not the case in Australia).
[SL]: Maybe we can run Paul’s comments (in the Tassie article), your comments, and my comments above…. through WormMail…and invite comments… then compile all the comments into a follow-up??
[GL]: More than happy to see that occur.
[GL]: Hate to open up a can of worms (yes, I couldn’t resist the pun), but this might be worth looking in more detail at some stage in turning the worm, or worm mail? What do you think?
[GL]: = Graham R. Lean BVSc, MAAAC, authorised rep AFS License No. 316516 (futures) PO Box 105 Hamilton VIC 3300 Australia Principal Consultant Graham Lean and Associates Farm Business Advisers
[SL]: = Stephen Love
Pomroy WE (1997).Internal helminth parasites of ruminants in New Zealand. In, Sustainable control of internal parasites in ruminants, Animal Industries Workshop, June 1997, Lincoln University, NZ. Ed: GK Barrell
Nematodirus at WormBoss: http://www.wool.com/Grow_WormBoss_Know-your-worms_Thin-necked-intestinal-worm.htm
Love and Hutchinson (2003):
is a very common parasite of young Australian sheep, and usually relatively
non-pathogenic unlike the situation in New Zealand where this parasite inexplicably become more
important from the 1960s. Heavy infections, scouring and ill thrift with mortalities can be seen in
young sheep under or soon after drought conditions in Australia (south western NSW, for example)
presumably become Nematodirus
eggs are relatively desiccation–tolerant. Clinical nematodirosis is
also not uncommon in young lambs in irrigation areas such as the Riverina area of southern New
South Wales." (Love and Hutchinson 2003)
or Love SCJ, Hutchinson GW (2003). Pathology and diagnosis of internal parasites in
ruminants. In Gross Pathology of Ruminants
, Proceedings 350, Post Graduate Foundation in Veterinary Science, University of Sydney,
For more information on service providers
such as Paul Nilon and Graham Lean go to: http://www.wool.com/Grow_WormBoss_Professional-service-providers.htm
Veterinarian / State Worm Control Coordinator
Industry and Investment NSW ~ Primary Industries
Armidale District Office ~ Tel: 61 2 67388519
I&I NSW-Primary Industries
~ LIVESTOCK HEALTH INCL WORMS pages http://www.dpi.nsw.gov.au/agriculture/livestock/health
~ OFFICE DIRECTORY http://www.dpi.nsw.gov.au/aboutus/about/office
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