Short-term effects of treatment with 300 mg oral-dose diethylcarbamazine on nocturnally periodic Wuchereria bancrofti microfilaremia and antigenemia.

Seven microfilaremic Myanmar patients were treated with a single 300 mg dose of diethylcarbamazine (DEC) orally, as part of a case-finding survey in Ranong Province, Southern Thailand. This was conducted in order to evaluate the short-term effects of single-dose DEC on Wuchereria bancrofti microfilaremia and antigenemia during a 12-week course of treatment. Analysis of microfilarial periodicity on initial treatment revealed the microfilarial peak density (k) was at 52 minutes after midnight (0052). The periodicity index was then 103.26%. Single-dose DEC treatment did not affect the k values. A linear model of W. bancrofti microfilarial density reduction predicts a sharp decrease in the mean microfilarial density 2 weeks after DEC intake (Z = -2.197, p = 0.028). Over a longer period, a non-linear model predicts an increase in the mean microfilarial density to pre-treatment levels, having little or no macrofilaricidal effects. We reconfirmed the existence of nocturnally periodic W. bancrofti infection in Myanmar migrants in Ranong Province, and the short-term microfilaricidal activity of 300 mg single-dose DEC treatment used for biannual mass treatment and the DEC provocative test. Without an adequate DEC treatment dose, recrudescence can occur. A rational approach to the management of introduced nocturnally periodic W. bancrofti in Myanmar migrants, who came for short periods of stay in transmission-prone areas, is needed.

Evaluation of a single oral dose of diethylcarbamazine 300 mg as provocative test and simultaneous treatment in Myanmar migrant workers with Wuchereria bancrofti infection in Thailand.

We assessed the efficiency of oral diethylcarbamazine (DEC) 300 mg as a provocative test on blood examination 30 minutes after administration, while gauging the overall infection rate in Myanmar migrant workers with Wuchereria bancrofti infection who enrolled for work permits in Thailand in 2002, using circulating filarial antigens (CFA) assays, the NOW ICT Filariasis card test and the Og4C3 ELISA as reference. Overall infection rates of 0.3% (95% CI=0-0.7%), 4.2% (95% CI=1.8-6.5%) and 5.9% (95% CI=3.2-8.7%) by three diagnostic tests, respectively, were observed. Among three different location groups of Myanmar population sample tested, there were no statistically significant differences in the overall infection detection rates. When either the ICT card test or the Og4C3 ELISA was used as a reference, the specificity and positive predictive value of the DEC-provocative day test was the same, 100%. The sensitivities were 25.0% (95% CI = 0.5-49.5%) and 17.6% (95% CI = 0-35.8%) on the ICT and ELISA tests, respectively. The negative predictive values were 96.8% (95% CI = 94.8-98.9%) and 95.1% (95% CI = 92.6-97.6%), respectively. In three microfilaremic persons followed-up monitored at 8-weeks DEC post-provocation, there were 6 x 10(-1) and 7 x 10(-1) decreases in microfilaremia and antigenemia. These findings suggested that, unlike the CFA assays, the DEC-provocative day test is unsuitable for the diagnosis of active W. bancrofti infection in the population tested, and for gauging current infection prevalence. The treatment would likely be beneficial to reduce microfilaremia and antigenemia.