Oral drug therapy for multiple neglected tropical diseases: a systematic review

The neglected tropical diseases include 13 conditions that occur in areas of extreme poverty and are poverty promoting. The neglected tropical diseases produce a disease burden almost as great as that associated with human immunodeficiency virus/AIDS, tuberculosis, or malaria, yet are virtually unknown by health care workers in North America, because they occur almost exclusively in the poorest regions of the world. Seven of the most prevalent diseases have existing oral drug treatments. Identifying treatments that are effective against more than 1 disease could facilitate efficient and inexpensive treatment.

To systematically review the evidence for drug treatments and to increase awareness that neglected tropical diseases exist and that treatments are available.

Using a MEDLINE search (1966 through June 2007), randomized controlled trials (RCTs) were reviewed that examined simultaneous treatment of 2 or more of the 7 most prevalent neglected tropical diseases using oral drug therapy.

Twenty-nine RCTs were identified, of which 3 targeted 4 diseases simultaneously, 20 targeted 3 diseases, and 6 targeted 2 diseases. Trials were published between 1972 and 2005 and baseline prevalence of individual diseases varied among RCTs. Albendazole plus diethylcarbamazine significantly reduced prevalence of elephantiasis (16.7% to 5.3%), hookworm (10.3% to 1.9%), roundworm (34.5% to 2.3%), and whipworm (55.5% to 40.3%). Albendazole plus ivermectin significantly reduced prevalence of elephantiasis (12.6% to 4.6%), hookworm (7.8% to 0%), roundworm (33.5% to 6.1%), and whipworm (42.7% to 8.9%). Levamisole plus mebendazole significantly reduced prevalence of hookworm (94.0% to 71.8%), roundworm (62.0% to 1.4%), and whipworm (93.1% to 74.5%). Pyrantel-oxantel significantly reduced hookworm (93.4% to 85.2%), roundworm (22.8% to 1.4%), and whipworm (86.8% to 59.5%), while albendazole alone significantly reduced prevalence of hookworm (8.1% to 1.3%), roundworm (28.4% to 0.9%), and whipworm (51.9% to 31.9%). No RCT examined treatment of river blindness or trachoma as part of an intervention to target 2 or more neglected tropical diseases. Adverse events were generally inadequately reported.

At least 2 of the most prevalent neglected tropical diseases can be treated simultaneously with existing oral drug treatments, facilitating effective and efficient treatment. Increasing awareness about neglected tropical diseases, their global impact, and the availability of oral drug treatments is an essential step in controlling these diseases.