With the purposes of studying the recent prevalence of Wuchereria bancrofti infection in Thai-Myanmar border areas, and evaluating the usefulness of a new ELISA, which uses urine as samples (urine ELISA), 519 people in Sangkhla Buri and 84 people in Suan Phung were examined by ICT card test for filarial antigen and by urine ELISA for filaria-specific IgG4. In the former area, positive rates by ICT test and the ELISA were 16.8% and 21.2%, respectively; in the latter area, the respective rates were 10.7% and 7.1%. These figures were unexpected, because the urine ELISA used to give much higher prevalence than antigenemia tests in our previous studies. In addition, only 37 of 96 ICT positives (38.5%) were urine ELISA positive. Our previous studies showed that the sensitivity of urine ELISA among the microfilaria and/or antigen positive individuals was more than 90%. Diethylcarbamazine treatment given to the known ICT positives at 300 mg/day for 12 days reduced antigenemia rate from 100% to 32.8%, which was determined 2 months after treatment by Og4C3 ELISA. The reduction of 67.2% seemed to be unusually high. These conflicting results could be explained by possible false positive reactions produced by ICT test.
The mechanism of thrombocytopenia in dengue virus infection remains unknown. We report herein an imported case of a 21-year-old male Japanese with dengue fever caused by secondary dengue 2 virus infection. The thrombocytopenia detected around the day of defervescence was associated with an increased level of platelet-associated IgG (PAIgG). The eluate from the platelets during the acute phase of this case contained an increased activity of anti-dengue virus 2 IgG, while the eluate from platelets during the convalescent phase contained a low level of anti-dengue 2 IgG. These findings suggest the transient formation of PAIgG involving anti-dengue 2 virus IgG during the acute phase of secondary dengue 2 virus infection.