Evaluation of filarial skin test with Brugia malayi larval antigen in the field.

To obtain comparable and reproducible results by filaria skin test with B. malayi larval antigen, standard procedure has been evolved. Antigen protein of 2 micrograms per test, injected intracutaneously, was found optimum for positive skin reaction. The reaction ratio based on increase of wheal area by 2 times or more was found to be statistically significant for interpreting positive results. However, in larger field trials, the simpler measurement of increase of wheal diameter by 1 1/2 times or more was found to be equally reliable. Patients treated with diethylcarbamazine citrate, antihistaminics and anti-inflammatory drugs are likely to be unresponsive to filarial antigen and will yield incorrect information.