Wireworm in antelope. Part 1: The signs


Game species are being farmed more and more intensively in South Africa. It was therefore only a matter of time before parasites and diseases – which were usually a problem of domestic livestock – started to become a problem in wildlife as well.

Wireworm (Haemonchus sp) has become a huge issue especially where high value antelope such as Sable and Roan are kept intensively. This parasite is about 2 to 3 cm in length and resembles a piece of hair (Afrikaans: Haarwurm). On closer inspection one might see the worm’s ovaries twisted around its blood filled gut in females, which is where the term ‘Barber’s pole worm’ originates.

haarwurm in melkpens geannotteer

The arrow points to a single wireworm adult female within the abomasum (fourth stomach, Afrikaans: melkpens). The worm’s typical ‘barber’s pole’ appearance can be seen.

The crux of this parasite is that it causes severe blood loss and eventually death. Each worm removes about 0.05 mL of blood a day. This might not seem like much, but once an animal is infected with around 2000 worms the loss becomes 100 mL, with an infection of 20 000 worms the loss becomes 1 L and with 35 000 worms 1.75 L  of blood is lost every day!!

Wireworms sieved from a sample of abomasal fluid after it caused a sable's death.

Wireworms sieved from a sample of abomasal fluid after it caused a sable’s death.

Animals that die from this parasite are typically extremely pale (mucous membranes are basically white). In many cases animals are also emaciated and there is accumulation of fluid in the abdomen, chest and between the muscles.

bloedarmoede in 'n swartwitpens

An example of pale-white mucous membranes caused by severe blood loss (anaemia), in turn due to wireworm in a Sable antelope

Poor body condition in a sable. This specific animal was too weak to run away when approached.

Poor body condition in a sable. This specific animal was too weak to run away when approached.

Fluid build up in the abdomen (ascites)

Fluid build up in the abdomen (ascites)

In the next post I’ll be looking at the wireworm lifecycle….

 

 

Pictures are the property of Brand van Sittert and may not be used for commercial purposes without his permission.