Mansonella Perstans - Management and Treatment - Doxycycline

Doxycycline

Doxycycline has been shown to decrease the development, embryogenesis, and fertility of worms in species that harbor the intracellular endosymbiont Wolbachia. Wolbachiae are bacterial endosymbionts of insects and many filarial nematodes, such as Onchocerca volvulus, Wuchereria bancrofti, and Brugia malayi. The dependence of these parasites on their endosymbionts has led to the use of antibiotics directed against the wolbachiae, antibiotics that have been demonstrated to have a profound salutary effect on filarial infections. In 2009, Coulibaly et al. conducted an open-label randomized trial of doxycycline, an antibiotic, for Mansonella perstans infection. This resulted in a dramatic and sustained decrease in microfilarial levels: they decreased to 23% of pretreatment levels at 6 m after treatment and to 0% of pretreatment levels at 12 m after treatment. In addition, doxycycline has been shown to have macrofilaricidal activity, which is unique among the drugs for filariasis.

However, in some areas, such as Gabon and Uganda, wolbachiae have not been detected in the microfilariae of M. perstans. This suggests some geographic isolates of M. perstans may have lost (or gained) the endosymbiont. This has occurred in various geographic isolates of B. malayi, in which the Wolbachia pipens genome is integrated into the chromosome of their hosts (the parasite). When this integration occurs, Wolbachia can no longer be targeted as means for treatment for filariasis. This presents a controversial argument for the use of doxycycline as treatment of filarial infections. On one hand, doxycycline has been shown to be one of the only successful treatments for M. perstans, and could facilitate the eradication of filarial parasites. However, some scientists argue that the treatment of filariasis with doxycycline may select worms that will have already integrated Wolbachia genes into their genome, which could potentially have unforeseen consequences.