A single course of one antibiotic can successfully treat elephantiasis (filariasis) - a parasitic worm disease that is one of the most common causes of global disability, concludes a study published in this week's issue of The Lancet.
Bancroftian filariasis is a disease characterised by severe and debilitating swelling of the limbs. The search for compounds active against the causative organism, Wuchereria bancrofti adult worms, has so far failed to deliver a radical curative treatment. The antifilarial drugs currently used, diethylcarbamazine and ivermectin, are predominantly active against the larval offspring of the parasite. These treatments form the basis of global programmes used to eliminate lymphatic filariasis. However, drugs with adult worm activity could greatly improve the prospects of programme closure.
Mark Taylor and colleagues tested whether treatment against Wolbachia-a bacterium the adult worms are dependent on - could be effective for filariasis. They recruited 72 men infected with W bancrofti from Kimang'a village, Pangani, Tanzania, aged 15-68 years. Half were assigned to placebo and half to an 8-week course of the antibiotic doxycycline.
They found that doxycycline treatment resulted in almost complete elimination of adult worms 14 months after treatment and a sustained loss of larval offspring from at least 8 to 14 months after treatment. Dr Taylor concludes: "In our study, an 8-week course of doxycycline against W bancrofti induced both sustained reductions in the larval offspring and, most notably, the adult worm activity.
This is especially important since the adult worms cause the disease pathology in lymphatic filariasis and no safe, effective treatment against adult worms exists - However, an 8-week course of doxycycline treatment is not applicable to mass treatment strategies because of both the logistical difficulties of delivering long-term treatments and doxycycline being contraindicated in children younger than 8 years and pregnant women."*
In an accompanying Comment Wilma Stolk states: "Research should now focus on identification of regimens, based on doxycycline or other antibiotics, that are practical for use in mass treatment..."