Survey of Infective Stage of Strongyloides stercoralis in Fresh Vegetables at Thasala Food Market, Nakon Si Thammarat

Abstract

Survey of Infective Stage of Strongyloides stercoralis in Fresh Vegetables at Thasala Food Market, Nakon Si Thammarat

Witthaya Anamnart BS (MT), MSc (Trop Med)

School of Allied Health Science and Public Health, Walailak University

Objective: To survey the contamination rate of infective stage of Strongyloides stercoralis in fresh vegetables at Thasala food market, Nakon Si Thammarat.

Study design: Descriptive study.

Samples: Seven kinds of vegetables including cirantro, celery, lettuce, white cabbage, green onion, sweet basil and asiatic pennywort were sampling for 24 times during April 2004 to March 2005.

Methods: Each vegetable was soaked in a beaker containing 300 ml of distilled water and was rotated at 180 rpm for 2 hours. Then, the soaked water was centrifuged at 2,500 rpm for 5 minutes and the rough sediments were gathered together. Formalin-ether Concentration technique was then performed and the consequent sediments were examined by microscope.

Main outcome measures: Number of third stage larvae (infective stage), first stage larvae and free living male and female adults.

Results: From 168 samples, third stage larva (infective stage) of S. stercoralis was found in 1.2% (95% CI, 0.1-4.2). First stage larva, free living male adult and free living female adult of S. stercoralis were also found with 1.2%, 1.2% and 3.6% respectively. Both larvae and adults of S. stercoralis were found in asiatic pennywort, sweet basil, white cabbage and cirantro for 5, 3, 2 and 2 samples respectively. Furthermore, Ascaris lumbricoides egg, Hookworm egg and larvae as well as adults of free living nematode were found in 2.4%, 6%, and 81.5% respectively.

Conclusion: Contamination rate of infective stage of S. stercoralis in fresh vegetables at Thasala food market, Nakon Si Thammarat was 1.2% (95% CI, 0.1-4.2).

Vajira Med J 2007 ; 51 : 129 - 133