ParaBoss News - July 2019 - Feature Articles

Taenia solium, the pork tapeworm of man

Observant stockmen quarantine sheep when they see rubbing.

Drench resistance will influence the type of drench you choose.

The dearth of registered anthelmintics for goats is worrying given their vulnerability to worms

Fast Fact: pig tapeworm in a Jewish population

A few issues back, we talked about the confusing world of tapeworms. So, our title is slightly mischievous because the “pig tapeworm” is in fact a human tapeworm (Taenia solium) i.e. the adult tapeworm lives in the small intestine of the human host (referred to by scientists as the definitive host because it carries the adult stage). Larval T. solium form muscle cysts in the intermediate host, the pig, just like sheep measles do. However, the catch is that if humans consume eggs excreted in the faeces from other infected humans the resultant larvae can form nodules in their tissues. Now they have become the intermediate host. A baffling case occurred when cerebral infections due to tapeworm larvae were found in Orthodox Jewish patients in New York in the early 1990s. Turns out that all patients employed T. solium-infected housemaids from Central America, and that these maids were almost certainly the source of their cerebral infections. You can read all about it here.

Should have washed their hands before preparing the food!

Feature articles

What do you do when the lice siren goes off: a case study.

Introduction by Paul Nilon, Nilon Farm Health, Tasmania

A client rang me with an unusual situation: in over 20 years he had never had lice in his flock of more than 20,000 sheep in spite of bush runs with multiple neighbours (hard to maintain fences) and sharing a town boundary with backyard sheep owners. Here is what he did: it serves as a good model on how to react and contacting me was only to get a second opinion:

• His observant stockman noticed rubbed wethers while moving them and immediately quarantined them in a secure paddock. Lice were confirmed a few days later.
• The owner prioritised inspection of other high-risk mobs. This is an ongoing process because of the scale of the property. Moreover, ewe mobs will be shorn in the next month, while infected wethers will not be shorn until the spring.
• The owner examined (budgeted) prem shearing the wethers, but it posed a high risk of overlength wool the following year and it also intruded on a busy work schedule.
• Because this is a fine wool flock, and lice were easy to find, doing nothing was not an option (you can check the value of treating with the LiceBoss Long Wool Tool). And then the Lice Products Tool was used to select an appropriate long-wool treatment. By the time you read this all risky mobs will have been treated.
• Being risk averse, and with knowledge of his stock movements, the owner has elected to treat all sheep off-shears regardless of whether lice are found at shearing. He understands that the long-wool treatment is control, not eradication. Moreover, he knows that visual inspection, even at shearing, is notoriously insensitive, and so it is possible that the ewes shorn earlier than the infected wethers may be carrying a covert infection.
• The owner has elected to inform his neighbours and me, both as a courtesy and in the hope of improving biosecurity.

This thoughtful response ticks all the boxes: isolation, inspection, risk assessment (including budgeting) and selecting appropriate treatments for knockdown and off-shears. The decisions you take may be different, for instance, you may not treat all mobs off shears. >> Read more.

Exotic drench combinations

Introduction by Paul Nilon, Nilon Farm Health, Tasmania

Contributors to WormBoss hammer the importance of using combination drenches, preferably when all of the actives have high efficacy. The rationale is explained here. This is not an excuse for not having a drench test: just the best way to use test results.

In my part of the world (northern Tasmania) thinking on combination drenches is limited to white and clear (these drenches are likely to be unsatisfactory), or triple mectins (more likely to work, but heavily reliant on the mectin component). So, it is timely to reconnect with some of the less used combinations that are highly likely to work. All drench information can be garnered at the drenches page. Just follow the drop-down menus on the left.

• Monepantel and abamectin: A new combination; resistance to monepantel is highly unlikely. While resistance to abamectin is common, it has proven robust against the scour worms such as Trichostrongylus.
• Derquantel and abamectin: Derquantel is another relatively new combination and resistance is unreported. Same comments as above for abamectin.
• Organophosphate (OP) combinations: OP combinations are "old exotic". The only product currently available is an OP/abamectin/albendazole combination. OPs (specifically naphthalophos) have proven remarkably robust, particularly against barber’s pole worm. A good one to consider when all else looks dismal. Be careful handling and administering OPs due to their toxicity to both you and the sheep (you don’t have to mix this one), and drench slowly, carefully and to the body weight range (check label).
• Closantel and abamectin: A barber’s pole special (with residual activity), and also has fluke activity. Resistance is common to both actives in barber’s pole (BP), but it is highly likely to work in the newer BP areas (e.g. irrigation areas in South Australia, Victoria and Tasmania).
• Levamisole and oxyclozanide: another BP special, particularly in the newer BP areas.

There are other 'combos' available, but these are the neglected ones for a variety of reasons. Remember, the best use of any drench relies on current drench resistance data. >> Read more.

Alternatives to drenches in goats

Introduction by Paul Nilon, Nilon Farm Health, Tasmania

The dearth of registered anthelmintics for goats is worrying given their vulnerability to worms. Although copper oxide was covered in the last missive, in this 3-minute section (8:10-11:30) the inimitable Sandra Baxendell gives 2 alternatives to drenching (copper oxide and Barbervax^®) and also explains FAMACHA^© and differences between sheep and goats in body condition scoring. >> Read more.

Finding flystrike resistant sires

Introduction by Paul Nilon, Nilon Farm Health, Tasmania

The May edition linked to Geoff Lindon’s Paraboss presentation on how to select for increased resistance to flystrike. In the same lecture (8:55–12:44)Geoff gives a 3.5-minute exposé on how to use the MERINOSELECT search engine. Now there is no excuse to not find rams that tick the boxes for flystrike resistance and your other performance priorities. Make your sheep Nike sheep and "just do it!"  >> Read more.