Egg Counts: Techniques and Timing
Rolling Nematodes
Used to examine the morphology of small nematodes
in order to classify to species.
Place a worm on a slide with a few drops of water and a coverslip.
Place the slide on
your microscope under low power and roll the worm by moving the coverslip around.
If the
worm is a male try to get it in such a position that the bursa is spread out so the dorsal
ray is visible. If the specimen is a female, roll it until the vulva is visible.
Egg Count Significance
These are only approximate and should be considered in association with the clinical signs.
| condition |
egg count (EPG, eggs per gram) |
| Parasitic gastritis in lambs |
2000 - 6000 |
| Parasitic gastritis in cattle |
300 - 600 |
| Strongylosis in equines |
1500 - 2500 |
| Fascioliasis in sheep |
300 - 600 |
| Fascioliasis in cattle |
100 - 200 |
Egg laying Capacity of Some Nematodes
| species |
egg-laying capacity |
| Haemonchus contortus |
5000 - 10000 eggs per day |
| Ostertagia and Trichostrongylus spp. |
500 - 2000 eggs per day |
| Nematodirus filicollis |
50 - 250 eggs per day |
Severity of Infection
Fatal effects seldom seen with less than:
| species |
body load |
| Haemonchus contortus |
1,000 worms |
| O. circumcincta |
8,000 worms |
| Trichostrongylus spp. |
10,000 worms |
| Chabertia ovina |
100 worms |
Fecal Egg Count Reduction Test (FECRT)
time needed before 2nd count is run:
| drug |
days post-treatment |
| Levamisole, Pyrantel |
7 |
| Benzimidoles |
10 |
| Avermectins |
14 |
|
