Atlas of livestock parasites
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Trichostrongylus axei (cattle)



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Trichostrongylus axei
Stomach hair worm, bankrupt worm

General Description:
The adult worm is tiny (0.5 centimeters) and hair-like.

Life Cycle:
Direct. Infective third-stage larvae are produced about 6 days after the eggs leave the host in feces, if temperature and humidity levels are sufficiently high. Infective larvae are ingested by animals. The prepatent period is approximately 20 to 25 days.

Abomasum and occasionally small intestine.

Geographical Distribution:

Serious weight loss and poor growth Occur when animals are heavily infected especially in mixed infections with Ostertagia. Young cattle are most susceptible but infection also occurs in older animals.

Effect on Host:

Adults may penetrate the lining of the abomasum, causing irritation. Wart-like swellings may occur in these areas and cause diarrhea and reduced appetite.

Diagnostic Information:

Strongyle-type eggs are found in feces. Differential diagnosis of L3 larvae is possible.

"Strongyle egg"

Approximately 80 µm long
Broad ellipse
Barrel-shaped side walls
Blastomeres present, number vary
It is not often possible to identify strongyle eggs to genus level as the eggs of most strongylid and trichostrongylid species are similar in appearance and overlapping in size.
If identification is necessary the faecal sample must be cultured to provide L3 larvae for further examination !!!

The identification of L3 larvae

Can be approached according to individual requirements.
To access the description of a particular species, click on the relevant image in the picture index below.
To identify an unknown L3, proceed directly to the identification key which leads the user systematically through the step-by-step identification process. The flowchart below is a step-by-step identification key.

Trichostrongylus L3

16 gut cells
Head tapered
Sheath forms short cone
Length 560-796 µm


Pasture management and anthelmintic treatment of animals are important in reducing populations of infective larvae on pasture.


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T.axei L3
Source: T.axei L3
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T.axei head
Source: T.axei head
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T.axei tail
Source: T.axei tail
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