Diagnostic methods

Parasitological diagnosis
In fresh stool preparations, motile rhabditiform larvae (with a short buccal cavity) can be seen. However, the sensitivity is rather limited even when concentration methods are used, because numbers of larvae vary from day to day. Several faecal samples have therefore to be processed to get a good predictive value for a negative result. It is debated whether duodenal samples (aspirates or Entero-test) may be more effective.
There are special parasitological methods, e.g. Baerman or faecal culture on Petri dishes (on charcoal or on gels), but they face the same limitations as other coprologic methods.
Infected patients often remain without symptoms for many years.

Molecular diagnosis
Molecular tools in evaluation process

Antigen detection
No tests available

Antibody detection
Serology is of great interest as a screening test.
There are a few ELISA and dipstick tests available to detect circulating antibodies. However, there is still room for improvement in sensitivity and even more in specificity.

Diagnostic strategies  

1. To detect infections in endemic areas
   In many areas, strongyloidiasis and filarial infections are co-endemic. Therefore serological tests with low specificities cannot be used. Diagnosis relies on stool examinations.
    
2. To detect an infection in a returning traveller
   The rather low sensitivity of microscopic diagnosis asks for alternative diagnostic tests. So far, serology is an option, since co-infections with filariae are unlikely.
    
3. To monitor success of drug treatment
   Besides blood eosinophilia (if demonstrable before infection), the follow-up of serological titres might indicate the outcome of drug therapy. Serology should be done not before 9–12 months after start of therapy. A declining titre can be interpreted as sign of a cure.