Modified Formalin-Ether Concentration Technique for Diagnosis of Human Strongyloidiasis

We compared the efficacy and applicability of a modified formalin-ether concentration technique (M-FECT) to the conventional FECT (C-FECT) and the agar plate culture (APC) method for the detection of Strongyloides stercoralis larvae. For this purpose, we used 600 human fecal specimens collected in an endemic area of southern Thailand. In the M-FECT, we used 2 layers of wire meshes, instead of gauze, to avoid the loss by absorption/adhesion of larvae to the gauze during filtration, and we reduced the exposure time of S. stercoralis larvae in stool samples to formalin. By such simple modifications, the efficacy of M-FECT has become comparable to APC and was much better than that of C-FECT for the diagnosis of strongyloidiasis.

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

Epidemiological Study of Strongyloidiasis in Southern Thailand, 2007

A survey of Strongyloides stercoralis infection was conducted in 11 southern provinces of Thailand by agar-plate culture technique. A total of 1,308 stool samples were collected by 30-cluster sampling technique during July-August 2007. The results revealed that the overall prevalence of S. stercoralis in the study areas was 20.6% and the intensity was mostly low. The highest infection rate was found in Phatthalung Province (29.9%), and the lowest in Phuket Province (7.5%). The highest positive finding was among the group aged 60 years and over (28.5%), and the rate of infection was comparatively high among males (25.4%). At cluster or village level, the highest infection rate was 51.9% in Ban Don Gun Village, Nakhon Si Thammarat Province, and the lowest 2.3% in Ban Yang Mark Village, Trang Province. The results of the surveillance showed that a majority of the population had high trongyloidiasis-related risk behaviors–poor hygiene and inappropriate footwear behaviors, such as wearing open sandals, so that 89.9% had an enhanced risk of infection, and only 22.2% wore casual shoes. Only 24.1% habitually wore boots when they worked in the paddy field, with the remaining 75.9% at higher risk of infection. However, it was also instructive to learn that the proportion of people who routinely washed fresh vegetables thoroughly before eating, to prevent larval contamination, was quite high (94.4%). Almost all (96.0%) of the people habitually defecated in a sanitary latrine when at home; however, when they worked in the field, the rate was far lower, at only 37.7%. It was interesting to find that 11.6% of the people habitually defecated outside a latrine, on the ground, while about 50.1% sometimes defecated on the ground, which would also result in a higher risk of the spread of disease. The information obtained from the behavioral survey also showed that high-level risk behaviors for the transmission of strongyloidiasis in southern Thailand, where potential hosts do exist, higher than the previously reported data about the prevalence of S. stercoralis infection. Proactive health education and empowerment of the community are recommended to control strongyloidiasis, and so prevent health problems among the people in such areas.