Factors affecting recovery of Strongyloides stercoralis larvae: an approach to a newly modified formalin-ether concentration technique for diagnosis of strongyloidiasis.
To improve the diagnosis efficiency of human strongyloidiasis by using formalin-ether concentration technique (FECT), the effects of various factors on the recovery rates of Strongyloides stercoralis larvae were comparatively evaluated. Fresh stool and a short time exposure of larvae to formalin yielded significantly higher numbers of larvae than preserved stool and 10-min exposure. Likewise, straining through wire mesh yielded a significantly higher number of larvae recovered than straining through gauze did. In addition, centrifugation for 5 min for separation of larvae from debris yielded a significantly greater number of larvae recovered than centrifugation for 2 min did. The efficacies of the five versions of FECT with different factors--FECT 1, FECT 2, FECT 3, FECT 4, and FECT 5--were then compared. It was found that FECT 5 was 1.8, 2.0, 1.9, and 1.4 times more effective than FECT 1, FECT 2, FECT 3, and FECT 4, respectively. FECT 5 is a modified FECT method, whose modifications included using fresh stool without a preservative substance; a short-time rather than 10-min formalin exposure; and the use of wire mesh instead of gauze.
Anamnart
Witthaya
W
Department of Medical Technology, School of Allied Health Sciences and Public Health, Walailak University, Thasala, Nakhon Si Thammarat 80160, Thailand. awitthay@wu.ac.th
Pattanawongsa
Attarat
A
Intapan
Pewpan Maleewong
PM
Maleewong
Wanchai
W
D000818:Animals; D002498:Centrifugation / Q000379:methods; D004986:Ether / Q000494:pharmacology; D005243:Feces / Q000469:parasitology; D005404:Fixatives / Q000494:pharmacology; D005557:Formaldehyde / Q000494:pharmacology; D006801:Humans; D007814:Larva; D010274:Parasitology / Q000379:methods*; D011309:Preservation, Biological / Q000379:methods; D012680:Sensitivity and Specificity; D017171:Strongyloides stercoralis / Q000302:isolation & purification*; D013322:Strongyloidiasis / Q000175:diagnosis* / Q000469:parasitology*; D013997:Time Factors
D005404:Fixatives; D004986:Ether; D005557:Formaldehyde