Australasian Science: Australia's authority on science since 1938

Fighting Creepy with Crawly

Credit: asbtkb

Credit: asbtkb

By Samantha Nixon

The Australian sheep industry is crippled by drug-resistant parasitic worms, but the unique chemistries in spider venoms are showing promise as a new class of drenching agent.

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It’s a sight all too common for Australian farmers. A ewe collapses while being driven into the yard, her lamb circling anxiously by her side. The farmer carefully checks around her eyes and gums. They’re pale, almost white instead of a healthy, rosy pink. This sheep is anaemic, her blood being drained from the inside by thousands of parasitic worms.

Eaten Alive: The Barber’s Pole Worm

The barber’s pole worm (Haemonchus contortus) is one of the most virulent parasitic worms of sheep. It lives in the abomasum – the fourth stomach – where it feeds on sheep blood. The name comes from the worm’s blood-filled intestines, which twist around white ovaries along the length of its body, giving it a barber’s pole-like appearance with red and white stripes.

These worms are only 3 cm long, but they have numbers on their side. As many as 10,000 of these writhing worms can infest a sheep, draining it of up to 10% of its blood each day. This makes the sheep anaemic, weak and malnourished, reduces its ability to produce wool and meat, and can be rapidly fatal.