Dw. Meyrowitsch et Pe. Simonsen, LONG-TERM EFFECT OF MASS DIETHYLCARBAMAZINE CHEMOTHERAPY ON BANCROFTIAN FILARIASIS - RESULTS AT 4 YEARS AFTER START OF TREATMENT, Transactions of the Royal Society of Tropical Medicine and Hygiene, 92(1), 1998, pp. 98-103
Citations number
22
Categorie Soggetti
Public, Environmental & Occupation Heath","Tropical Medicine
The long-term effect of 4 strategies for control of bancroftian filari
asis using mass diethylcarbamazine (DEC) chemotherapy was assessed and
compared in 4 endemic communities in Tanzania over a period of 4 year
s. The strategies were the standard 12 d treatment (strategy I), semi-
annual single dose treatment (strategy II), monthly low dose treatment
(strategy III), and DEC-medicated salt treatment (strategy IV). Treat
ment was given only during the first year. All strategies resulted in
considerable reductions in microfilaraemia, with maximum effects occur
ring 1-2 years after start of treatment. At 2 years, the greatest redu
ctions were seen for strategies III and IV, followed by strategy II an
d finally strategy I. The overall performance of the 4 strategies eval
uated over the 4 years period followed the same sequence. Between the
2 years and 4 years follow-up surveys, a significant increase in micro
filarial (mf) burden occurred in all 4 communities, but the mf geometr
ic mean intensities (GMI) remained low. Thus, in individuals who were
microfilaraemic before treatment, the rates of microfilaraemia were 66
%, 44%, 34% and 43%, and the mf GMIs were 6.8%, 3.3%, 0.5% and 0.7%, o
f pre-treatment level, 4 years after start of treatment with strategie
s I, II, III and IV, respectively. Most individuals who developed micr
ofilaraemia between the 2 years and 4 years follow-up surveys had been
microfilaraemic before the start of treatment. Hence, the rate of dev
elopment of microfilaraemia was much higher (18 times on average in th
e 4 communities) among those who were microfilaraemic before treatment
than among those who were amicrofilaraemic. The long-lasting effect o
f treatment adds a promising potential to the use of mass DEC chemothe
rapy for the control of bancroftian filariasis.