Sodium azide as a preservative in epidemiological studies of helminth ova in fecal specimens
Srinivasan, V.; Ramakrishnan, R.; Prabhakar, L.
Indian Journal of Medical Research 91: 440-442
1990
ISSN/ISBN: 0019-5340 PMID: 2091990 Document Number: 351744
In 20 fecal specimens stored at ambient temperature (30-40.degree. C) for 3-7 days, substantial reductions in hookworm ova load were observed when a sensitive egg counting method (modified Kato's technique) was employed. Aliquots to which sodium azide (3 mg/g of fecal matter) was added showed considerably less reduction. A larger study on 120 specimens confirmed that there was no reduction up to 3 days. Significant decreases, however, occurred by 5 days, and these could not be prevented even by doubling the sodium azide dose (to 6 mg). It is recommended that in epidemiological studies of hookworm infestation in tropical countries, 3 mg of sodium azide should be added per g of fecal matter within 6 h of collection and the specimen tested within 3 days.