Table 2.

Characteristics of Larval Detection Methods for the Diagnosis of Strongyloidiasis or Hookworm Infection

Method	Procedure	Comments	Reference
Baermann method	A large amount of feces (10 g) are kept with warm water over gauze in a glass funnel. Soil samples can also be used Larvae crawl out of the feces and migrate into the water after 1–2 h Centrifuged water sediment is monitored for larvae of hookworms or Strongyloides by microscopy	- Almost 4 times higher sensitivity than FEC or DS -Requires fresh and non-refrigerated stool samples - Soil samples can also be used to detect larvae - Time-consuming, labor-intensive and a large quantity of stool is required	[44]
Harada-Mori filter paper strip culture	A small amount of stool sample (0.5–1.0 g) is spotted on filter paper strips, inserted into a test tube with water slightly below the fecal spot and incubated upright at 25 to 28 °C for up to 10 days Test tube fluid is monitored for larvae of hookworms or Strongyloides by microscopy daily	- More sensitive compared with FEC or DS but less sensitive than Baermann or agar plate methods -Refrigerated or preserved specimen cannot be used	[45]
Filter paper/slant culture technique (Petri dish)	A slide containing fresh stool (1–2 g) is placed in a glass or plastic Petri dish with water Petri dish fluid is monitored for larvae of hookworms or Strongyloides by microscopy daily up to 10 days	-Low sensitivity -Refrigerated or preserved specimen cannot be used	[45]
Charcoal culture	Stool suspension in water and ground charcoal (both 20–40 g) are mixed and placed in a storage dish and incubated for 5–6 days Sediments of centrifuged water are monitored for egg hatching and/or larvae development	- Suitable in remote regions - Long incubation period -An efficient method to harvest large amounts of larvae for experimental work	[44]
Koga Agar Plate culture	Feces (3 g) are placed on an agar plate with double walls (with an outer surrounding solution of glycerin) and incubated (2–6 days) Larvae form tracks on agar surface and are visualized by microscopy	- More sensitive than filter paper culture, DS or FEC -Strong diagnostic agreement with Baermann’s method - Time-consuming	[46]

Notes: Caution must be exercised and gloves must be worn as larvae may be infective and can penetrate through skin.

Abbreviations: FEC, formol ether concentration; DS, direct smear.