Recovery of nematode eggs and larvae in deer: evaluation of fecal preservation methods

Fresh fecal specimens from deer were examined for nematode eggs (primarily Haemonchus and Ostertagia), using a flotation technique (sugar, sp gr = 1.27), and then were reexamined for up to 200 days after storage in 2.5, 5, or 10% formalin, absolute methyl alcohol, or 70% ethyl alcohol at room temperature (20 C) or after storage without preservative at 4, 0, or -20 C. For long-term storage, 10% formalin was the best fixative for recovery of eggs (compared with the rate of recovery of eggs from fresh feces). Approximately 50% of the strongyle eggs were detected in feces stored in formalin for 200 days. However, between days 3 and 10 of storage, the recovery rate was low (less than 50%), presumably due to ion binding. Alcohols were unsuitable for preservation, and storage at 0 or -20 C resulted in an egg recovery rate of less than 50%. Storage at 4 C for 50 days resulted in approximately 90% recovery of nematode eggs. Number of Parelaphostrongylus tenuis larvae recovered from fecal specimens stored in 10% formalin for 24 days was greater than that recovered from fresh fecal specimens.