[Evaluation of Giardia lamblia detection method in stool specimens fixed with SAF solution]

The present study has been designed as a basic study on laboratory diagnosis of giardiasis and to demonstrate a more effective method for the detection of Giardia lamblia cyst with the inherent advantages of minimizing both the number of stool examinations required and the interval of stool collections for estimating the real state of prevalence in the shortest time possible. There were 3 subject groups of 75 children each currently residing in an orphanage in Gunsan city, Jeonbuk province from which stool specimens were collected every day, every other day, and every 3 days. The procedure is as follows: Resuspend the fixed sample after fixation with SAF solution. Centrifuge the sediment for 1 min. at 2,000 rpm after straining through gauze into a tube. Divide the sediment into 3 parts and use them for direct fecal smear, formalin-ether concentration (MGL) and zinc sulfate (ZnSO(4)) floatation techniques. The results are summarized as follows: Overall infection rate after 10 trials showed a 60 percent positive indication. The positive rate among children under 4 years old was significantly higher than the rate in children over 4 years old. No significant difference in rate by sex was observed. The results of examinations by direct fecal smear and MGL techniques appeared more accurate than that obtained by ZnSO(4) floatation method as indicated by a higher positive rate. Of all three methods concerned, combinations of two demonstrated a higher positive rate than that shown by any one alone. In three consecutive examinations under varying conditions such as different days, the cyst detection rate by MGL technique indicated 83 percent. In 5 examinations under the same varying conditions, the indicated rate was 94 percent. The interval of stool collection proved to be insignificant for the cyst detection rate. In conclusion, both MGL method and modified fecal direct smear can provide a good cyst detection rate of G. lamblia provided that more than 3 consecutive examinations of stool under varying conditions are carried out.