Follow-up observations are given for periods up to 14 months on a group of Guianese patients infected with Wuchereria bancrofti and treated with various doses of Hetrazan. Negative microfilarial counts were maintained in 53 out of 83 patients (63.9 per cent) for 14 months, and with few exceptions the remainder exhibited counts far below the original. The reduction in total microfilariaemia within the entire group was greater than 90 per cent, including all dose ranges of Hetrazan. With the exception of total doses less than 50 mg. per kg. no significant relationship could be determined between the amount of Hetrazan administered and the presence or absence of microfilariae during the follow up period. The greatest number of recurrences occurred at the 6th month follow up examination and declined thereafter. No new recurrences of small numbers of circulating microfilariae occurred during the 12th, 13th or 14th months.
Clinical symptoms after treatment varied considerably. Some patients who showed complete or partial relief from pretreatment during therapy remained free of symptoms throughout the follow-up period and are apparently cured. Others revealed recurrences of pretreatment symptoms with various degrees of frequency after treatment. The number of microfilariae present after treatment seemed to bear no relationship to the presence or absence of symptoms after treatment.
It is believed that the sustained absence of microfilariae in a large proportion of the patients treated, together with the complete absence of symptoms after treatment in many cases, demonstrates indirectly that mature worms are permanently affected by treatment with Hetrazan.
Lederle Laboratories Division, American Cyanamid Company, Pearl River, New York.
Former resident physician, Berbice Company, Ltd., Kwakwani, British Guiana. Present address: 336 West End Avenue, New York, N.Y.
Mosquito Control Service Laboratory, Georgetown, British Guiana.