redux: sky high counts at Bre?

TO: WormMail list (recip. undisclosed) + DVs     WormMail 2010.03.17

Redux: sky high counts at Bre’

Further to the ‘WormMail’ on 8 March (see URL and summary of lab results below), I asked the lab to re-look at the larval cultures because the counts were extraordinarily high for Trichostronglyus.

The EMAI parasitology lab is as good as any, and the technical officers (TOs) have decades of experience in parasitology, so I was pretty sure that ‘they had got it right’.

The larval differentiation was re-done on Friday, and the previous result was confirmed: 86% Trichostronglyus.  

 (68800 x .86 =  ~ 59, 000 Trichostronglyus eggs per gram of faeces)

Of course, it would have been a lot easier to understand this case – in some respects – if the majority of worms were Haemonchus, but there is always something new and interesting to ponder….   (WormMail 2010.03.08.1500)

EMAI Parasitology
Nematode Egg Count (Modified McMaster)   M10-01265  

Units epg epg
Sample No. Sample ID Sample Desc
0009 YELLOW TOP FAECES 1 68800 840 Neg Neg
0010 WHITE TOP FAECES 2 54160 400 Neg Neg

epg: worm eggs per gram of faeces    WEC: worm egg count

Larval Differentiation for WormTest

Units % % %
Sample No. Sample ID Sample Desc
0009 YELLOW TOP FAECES 1 1 86 13

On a more general note, Kathleen Cooper from the EMAI lab has commented that, doing larval differentiation over the last few years, there has been more ‘WormTests’ with high Trichostronglyus counts, and wonders if this is related to drought conditions in recent years. Perhaps there is something in this given that Trichostronglyus eggs (and more so, Teladorsagia eggs) are more desiccation and cold tolerant than Haemonchus. (And ‘elderly’ parasitologists will know that nodule worm (Oesophagostomum columbianum) – which was very important in northern NSW until about 40-50 years ago – is even more sensitive in this regard than Haemonchus. But don’t dismiss Oes. columbianum altogether: it still has a niche market, but that is another story.).

Comment from District Vet at Narrabri

Following is a comment – used with permission – from Shaun Slattery. For those who don’t know, his district is to the east of Brewarrina, in  the ‘inside country’ as ‘true’ outback people would say.

 Two comments on the Trich story.  Luckily they are of little help.
1.       Trich burdens are rare in adult sheep west of the slopes in the North West LHPA  – unless they are introduced from western Qld.  I explain this by saying that the usual level of Trich resistance in an adult is enough in most situations in the west to prevent burdens.
What is the WA situation re exposure to Trchs.
2.       I do have a Burren Junction property, which for some reason has the reverse of the usual 90/10 Haem/Trich ratio.  On at least two occasions burdens in hoggets around the 1,000 epg in Jan have been found to be mostly Trichs.  This property is very standard in how they run sheep – so I have no idea why this occurs.
Shaun Slattery
Senior District Veterinarian
North West Livestock Health and Pest Authority
Narrabri NSW 2390




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