Sex ratio ofWuchereria bancroftiin surgical specimens from an endemic area of Brazil

Abstract

The sex ratio of adult Wuchereria bancrofti from 172 histologically diagnosed cases of lymphatic filariasis, all from an endemic area of Recife, in north-eastern Brazil, was investigated. Of 172 tissue specimens examined, 74 (43%) were lymph nodes and 98 (57%) lymphatic-vessel segments. The morphology of the worms was generally disrupted, in some cases to the point where the worms were almost completely absorbed by the granulomatous inflammatory response. Parasite gender was clearly determined in only 110 (64%) specimens, 61 (55.5 %) of which were lymph nodes and 49 (44.5%) lymphatic vessels. Eighty-seven (79.1%) of these tissue specimens contained only female worms, 17 (14.5%) both males and females, and six only males, giving an overall female:male 'specimen' ratio of 4.5:1. Of the 63 tissue specimens in which dead or degenerating worms were noted, 60 (92.2%) contained only females. All the female worms detected were gravid, regardless of whether male worms were present in the specimen. The implications of these findings for parasite dynamics, the pathogenesis of bancroftian filariasis and the interpretation of ultrasound images of living adult worms are discussed.

Lymphatic Endothelial Cell in Endemic Bancroftian Filariasis: A Focus on the Lymphatics of the Tunica Vaginalis Testis

“…In our surgical [ 12 ] and pathological [ 25 ] experience, AWs in the PL lymphatics, whether living or dead, were found only in two cases, one of which is included in the present study. Therefore, the PL lymphatics appear to be the less preferred intrascrotal location of AWs and their absence does not rule out the filarial etiology of fluid accumulation in the tunica vaginal cavity.…”

Intrascrotal Nodules in Adult Men as a Marker for Filarial Granuloma in a Bancroftian Filariasis-Endemic Area

“…11 These three possible outcomes, based on ultrasound and physical examination findings, have been validated by both surgery and histopathology. 11,12,[14][15][16]18,19,27,29 Interestingly enough, these reactions might occur alone or in combination in patients with more than one nest. Unfortunately, it is still impossible to determine whether the death of a single worm (male or female, gravid or not) always results in a scrotal nodule perceptible by physical examination.…”

“…All subjects who underwent DEC treatment were examined before and after treatment. Male patients were selected from various drug trials [7][8][9][10][11][14][15][16][17][18][19] and from a routine protocol used at NEPAF for patients seeking medical attention. To be included in the study, the patient had to have 1) lived his entire life in Greater Recife, 2) denied previous antifilarial treatment before the first consultation, and 3) provided written informed consent.…”

“…2,3 The largest case series that analyze the pathology of nodules after DEC treatment have been accumulated by Chinese 4,5 and, more recently, by Brazilian workers. [6][7][8][9][10][11][12][13][14][15][16][17][18][19] Most commonly, the nodules were reported in the scrotal contents.…”

“…23 This peculiar anatomic location of W. bancrofti adult worms in the male population has provided a unique opportunity to study host-parasite interplay, both before and after antifilarial treatment. 15,16,18,24 In this regard, access to the AW habitat-the intrascrotal lymphatic vessels-through physical examination, ultrasonography, and biopsy has facilitated studies of the effect of macrofilacidal effect of old and new drugs, alone or in combination, 9,11,12,14,16,[25][26][27] and the performance of antigen tests. 10,19 According to Ottesen, 28 in a classic paper that described five criteria for assessing the efficacy of DEC in killing the AWs of lymphatic filariasis, only one criterion is direct-the histologic examination of nodules.…”