Baermann Technique Information

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Baermann Technique Information

Test Code: BAERF
Test Name: Baermann Fecal Technique

Contact Name: Dr. Mani Lejeune
Contact Telephone: 607-253-3581

Test Method: Nematode larval identification
Sample Required: 10 grams of feces
Collection container: plastic leak proof container
Transport: Ship on cold packs
Test Day: M-F
Lag Time: 2-3 days
Species: All species
Results Format: Positive with identification of nematode larvae detected, or Negative for parasites


This technique is a modification of the Berlese Apparatus used by entomologists to collect insects from plant material and soil. It is used to retrieve nematode larvae from feces, soil, plant matter or other organic material. The Baermann Technique operates on the principle that the nematode larvae wiggle out of the biological material, cannot swim against gravity and will fall through the water to the area of clamped off tubing. The clamp is released to collect the larvae for identification. Any fecal sample submitted for this procedure must be freshly voided so that the sample is not contaminated by free-living nematodes.

The Baermann Technique is not recommended as a primary diagnostic technique for evaluation of parasites in feces. It is not useful for those nematode larvae that do not leave the feces or other biological material, or for detection of parasite eggs or cysts that may be in the fecal sample. Some lungworm larvae are retrieved using this technique, but some larvae such as those of Filaroides hirthi, Filaroides osleri, Strongyloides sp. and Dictyocaulus sp. are better recovered using flotation techniques. Lungworms, such as Eucoleus (Capillaria) aerophilus, that do not produce larvae are detected only by using flotation methods as well.