In the May, 2006 issue of PLoS: Medicine, Hotez et al argue for a substantial targeting of neglected "tropical" diseases in their article Incorporating a Rapid-Impact Package for Neglected Tropical Diseases with Programs for HIV/AIDS, Tuberculosis, and Malaria.
In their article, they propose that in addition to targeting the "big three" of AIDS, malaria and tuberculosis, we should also be targeting a suite of neglected "tropical" diseases including leishmaniasis, African trypanosomiasis, Chagas disease, trachoma, leprosy, Buruli ulcer, hookworm, ascariasis, trichuriasis, lymphatic filariasis, onchocerciasis, guinea worm and schistosomiasis.
While the big three kill 5.6 million people per year and the neglected thirteen kill "only" 534,000 per year, the article notes that both cause massive impacts in terms of lifelong disability. The big three lead to 166 million disability-adjusted life years (DALYs) lost annually, and the neglected thirteen contribute another 57 million DALYs each year. Members of the neglected thirteen also negatively impact growth, development and cognition, meaning that even individuals who are not killed or incapacitated by these diseases may suffer from lost opportunities and lifelong limitation.
On top of this, members of the thirteen contribute to the effects of the big three. Thus, infection by a parasite can lead to increased infectivity of HIV, and disease-induced anemia may compound with the effects of other diseases, or limit the immune system's ability to fight disease. Vaccines may also be rendered far less effective by prior parasitic infection. Not only would it be helpful in itself to cure these conditions -- it would directly benefit the fight against the major killers.
The kicker of the article is that, for a cost of $0.40 (that's forty cents) per person, people could be treated for the thirteen, using a four-drug combo pack of albendazole, ivermectin, praziquantel and azithromycin. You could, at that price, cover all of Africa for about $300 million.
That is a good deal and, as the authors argue, would be a pharmaceutically cheap way to promote the construction of the kind of infrastructure that's going to be needed for eventual distribution of more effective drugs and vaccines that directly target the big three.