Dreyer, G., Addiss, D., Roberts, J. & Norões, J.


Transactions of the Royal Society of Tropical Medicine and Hygiene 96: 157-161, 2002.


Bancroftian filariasis, a mosquito-transmitted disease commonly known as elephantiasis, is caused by infection with the parasite Wulchereria bancroti. Infection with this parasite can induce a broad array of chronic debilitating and socially stigmatizing conditions, but the pathogenesis of this morbidity remains obscure. Recent evidence indicates that in filariasis-endemic ares the primary lesion is not lymphatic vessel obstruction but, rather, dilatation. To determine the extent to which lymphatic dilation occurs in the presence of living adult W. Bancroft, we perfomed logitudinal ultrasonographic measurements in 80 men (mean age 24 years) in Brazil who had a total of 107 W. bancrofti nets detecctable by ultrasond. Initial mean lymphatic vessel diameter at the site of the worms was 3.4 mm (reange , 0·7 - 11·3), and was greater in men with 2 or more nests (3·9mm) than in those with only one nest (3·0 mm, P = 0·003). During the study period (2 – 35 months, mean, 13·7), lymphatic vessel diameter increased at the site of 92 (86·0%) adult worm nests. Mean rate of increase of lymphatic vessel diameter was 1·2 mm per person-year (reage, 0-0·93 mm per month). In a general linear model, no factors, including treatment with antifilarial drugs, were significantly associated with rate of vessel diameter inccrease. Thus, lymphatic vessel dilatation progresses in the presence of living adult W. bancrofti; the rate of this progression is heterogeneous. These data suggest that lymphatic dilatation will continue to progress in most infected persons even after mass treatment with currently recommended antifilarial drugs. In addition to interrupting transmission, the global programme for elimination of lymphatic filariasis should address the potential for disease progression in persons who remain infected with adult W. bancrofti.