Some morphological aspects of Wuchereria bancrofti uterus after treatment with diethylcarbamazine

Ultrastructure of reproductive system of female Litomosoides chagasfilhoi Moraes-Neto, Lanfredi and De Souza, 1997 (Nematoda: Filarioidea)

The ultrastructure of the female reproductive system of the filariid Litomosoides chagasfilhoi by transmission electron microscopy (TEM) is described for the first time. The ovary is composed of primary oocytes surrounded by a single layer of epithelial cells apposed on the basal laminae. The ovarian wall is completely filled with primary oocytes, which are arranged radially and are centrally connected around the rachis. The uterine wall consists of muscular fibers surrounded by a basal lamina and the epithelium underlying the lamina. Ameboid and aflagellate spermatozoa are present inside the distal portion of the uterus, some of them near oocytes, which present bacteria in its cytoplasm. An eletrondense well-defined eggshell covers the zygotes, which presents in its cytoplasm bacteria arranged in groups. These bacteria are also observed in embryos and in the hypodermal cord. These ultrastructural aspects of L. chagasfilhoi female worms presented herein contribute to the knowledge of the morphology and embryonary development of this filariid, providing means for further comparative analyses of the action of anti-filarial drugs. Besides this, the presence of bacteria Wolbachia-like is being reported for the first time in this species, showing the great importance of this experimental model of study.

Comparative analysis of a chemotherapy effect on the cuticular surface of Wuchereria bancrofti adult worms in vivo

Wuchereria bancrofti is the main species responsible for human lymphatic filariasis and remains a major public health problem in tropical countries around the world. Diethylcarbamazine (DEC) has been used for decades in control programs as an effective microfilaricide, although its efficacy in killing adult worms is only around 50% and its direct mode of action is unclear. Recently, in an attempt to control and eliminate lymphatic filariasis, WHO has recommended albendazole (ALB), a broad-spectrum anthelminthic combined with DEC or ivermectin for mass treatment. Some studies have shown that DEC alone blocks oogenesis, fertilization in adult worms, and loss of the microfilarial sheath of several filarial species, whereas ALB is thought to target nematode tubulin. So far, the direct effect of ALB in combination with DEC has not been described in W. bancrofti adult worms. Therefore, the purpose of this study is to investigate by scanning electron microscopy if DEC coadministered with ALB can induce in vivo morphological alterations of the W. bancrofti adult worm surface obtained from a patient in whom the adult worm remained alive, checked serially by ultrasonography for 2 months after antifilarial treatment. Our analysis demonstrates that worms presented morphologic alterations in some regions suggesting cuticular surface damage. On the other hand, adult worms that were recovered from a patient treated with DEC alone after a single dose did not show such any abnormalities.

Efficacy of co-administered diethylcarbamazine and albendazole against adult Wuchereria bancrofti

Although diethylcarbamazine (DEC) and albendazole are recommended to interrupt transmission of Wuchereria bancrofti, little is known about the macrofilaricidal effect of this drug combination. Forty-seven men with W. bancrofti infection were randomly assigned to receive a single dose of either DEC alone (6 mg/kg) (n=25) or a combination of DEC (6 mg/kg) and albendazole (400 mg) (n=22). Physical examinations for scrotal nodules (resulting from worm death) and ultrasound examinations (to detect living adult worms) were performed before treatment and 7, 14, 30, 45, 60, 90, 180, 270 and 360 days after treatment. Blood was examined for microfilariae before and 30 days and 360 days after treatment. Seven days post treatment, intrascrotal nodules were detected at the site of 21 (46.7%) adult worm nests in men who received DEC alone compared with 2 (6.1%) sites in men who received DEC and albendazole (P=0.002). One year after treatment, 10 (22.2%) original adult worm nests remained detectable by ultrasound among men who received DEC alone compared with 18/32 (56.3%) nests among men who received both drugs (P=0.016). Microfilaraemia prevalence and density decreased to a similar extent in both groups. Addition of albendazole appeared to decrease the macrofilaricidal effect of DEC against W. bancrofti, with no detectable enhancement in microfilarial suppression.