Minimizing acarians and house dust in the tropics

Dust collection and mite isolation by Furumizo's method occurred in 33 homes on days 0 and 14. The first application of Paragerm AK (23 homes) or placebo aerosol (ten homes) was done after vacuuming on day 14. The second (final) spraying occurred on day 28, immediately after vacuuming. Vacuum collections without spraying were done on days 56 and 84 in this randomized double-blind trial. With Paragerm, dust volume fell to 80.3% of initial levels by day 28, remained low at 87.9% (P < .05) on day 56, and then rose to 115.9% by day 84. In control homes, comparative dust values were 89.0%, 103.7%, and 109.9%. With Paragerm, mite concentration decreased to 70.8% by day 28 (P < .01), to 65% at day 56 (P < .025), and continued to fall to 47.7% by day 84 (P < .05). With control aerosol, mite numbers rose compared with initial values: 119.1% at day 28, 227.2% at day 56, and 125.1% at day 84. No adverse effects were observed in Paragerm homes besides odor (70% complained). The two asthmatic occupants improved symptomatically and took less medication following the Paragerm. In conclusion, Paragerm, used over 40 years in Europe, is an effective, nontoxic acaricide in Hawaii, acting promptly and for at least 2 months. It was also associated with diminished dust volume, important in nondust allergy.