Baermann
Aims: The Baermann method is a qualitative analysis for the examination and identification of larvae of bronchopulmonary nematodes and Strongyloides stercoralis, present in the faeces of farm and companion animals.
Materials:
- Faecal sample
- 1 funnel with a stopper (rubber stoppers from test tubes may also be used)
- 1 filter
- 1 piece of gauze 20x20 cm
- 1 transfer pipette
- 1 small funnel
- 1 centrifuge tube
- 1 laboratory centrifuge
- Pasteur pipettes
- Lugol’s solution
- Microscope slides and coverslips
Procedure:
Place the faecal sample in the gauze/cheesecloth and secure it by twisting the free ends of the gauze or bind it with a rubber band. Fill a close-bottomed funnel with lukewarm tap water, and gently place the wrapped specimen in the upper widened portion of the funnel. Fill the funnel with tap water until the faecal sample is entirely submerged. Let the sample sit at room temperature for at least 12 hours to allow the motile larvae to escape from the faecal pellet and settle at the bottom of the funnel. After 12 hours, remove the wrapped faeces from the funnel and aspirate the supernatant using a transfer pipette, being careful to leave only the liquid contained in the narrow bottom portion of the funnel. Transfer the remaining liquid into a centrifuge tube and centrifuge the sample at 2,000 rpm for 10 minutes. Again, carefully remove the supernatant with a transfer/Pasteur pipette leaving only the sediment pellet. Then, add an equal volume of undiluted Lugol’s iodine (about 2 drops) to the pellet and gently mix.
Results:
Place a drop of the sediment (about 50 µl) on a microscope slide, cover it with a coverslip, and examine it under a compound light microscope. Begin at a low at low magnification (10x objective), and if larvae are found, examine at a higher magnification (up to the 40x objective) to identify characteristic features and take accurate measurements of the larvae for further identification.
References:
Giannelli, A., Capelli, G., Joachim, A., Hinney, B., Losson, B., Kirkova, Z., René-Martellet, M., Papadopoulos, E., Farkas, R., Napoli, E., Brianti, E., Tamponi, C., Varcasia, A., Margarida Alho, A., Madeira de Carvalho, L., Cardoso, L., Maia, C., Mircean, V., Mihalca, A.D., Miró, G., Schnyder, M., Cantacessi, C., Colella, V., Cavalera, M.A., Latrofa, M.S., Annoscia, G., Knaus, M., Halos, L., Beugnet, F., Otranto, D. (2017) Lungworms and gastrointestinal parasites of domestic cats: a European perspective. International Journal for Parasitology, 47 (9), pp. 517-528. DOI: 10.1016/j.ijpara.2017.02.003
McGarry, J.W., Morgan, E.R. (2009) Identification of first-stage larvae of metastrongyles from dogs. Veterinary Record, 165 (9), pp. 258-261. DOI: 10.1136/vr.165.9.258
Paradies, P., Iarussi, F., Sasanelli, M., Capogna, A., Lia, R.P., Zucca, D., Greco, B., Cantacessi, C., Otranto, D. (2017) Occurrence of strongyloidiasis in privately owned and sheltered dogs: Clinical presentation and treatment outcome. Parasites and Vectors, 10 (1), art. no. 345. DOI: 10.1186/s13071-017-2275-5
Cardoso, L., Maia, C., Mircean, V., Mihalca, A.D., Miró, G., Schnyder, M., Cantacessi, C., Colella, V., Cavalera, M.A., Latrofa, M.S., Annoscia, G., Knaus, M., Halos, L., Beugnet, F., Otranto, D. (2017) Lungworms and gastrointestinal parasites of domestic cats: a European perspective. International Journal for Parasitology, 47 (9), pp. 517-528. DOI: 10.1016/j.ijpara.2017.02.003
Van Wyk, J.A., Mayhew, E. (2013) Morphological identification of parasitic nematode infective larvae of small ruminants and cattle: A practical lab guide. Onderstepoort Journal of Veterinary Research, 80 (1). DOI: 10.4102/ojvr.v80i1.539