A quantitative analysis of the diagnostic value of diethylcarbamazine provocation in endemic Wuchereria bancrofti infection.

The efficiency (delta) of the day-time provocative effect of diethylcarbamazine (DEC) on the circulation of microfilariae (mf) of nocturnally periodic Wuchereria bancrofti compared with the night mf count was evaluated in terms of sensitivity and specificity. In one test, the mean mf count for finger-blood samples from the same person on 3 successive nights was compared with the day-time post-DEC count; another test compared the mf count in one night-time finger-blood sample with the following day-time post-DEC count. Both tests were efficient (delta = 0.74 and 0.77, S.E. = 0.07 and 0.07, respectively). Night and day-time post-DEC mf counts were significantly correlated (r = 0.81, P less than 0.001, and r = 0.79, P less than 0.001 for the 2 tests respectively), but mf densities tended to be relatively lower after DEC provocation than in the corresponding night-blood samples. In both tests the regression coefficients differed significantly from zero (P less than 0.001). The simple 24h test was almost as efficient as the 3-nights test and based on its regression relationship, a table is presented predicting the expected night mf counts from the observed day-time post-DEC counts. The provocative dose of DEC, 2 mg/kg body weight, evoked no side-reaction in either microfilaraemic or uninfected persons.