These Kenyan widows are fighting against sexual 'cleansing'

The health problems of millions of Americans are directly related to patients' failure to follow doctors’ orders. Community health workers are increasingly successful in New York and other American cities – not to substitute for doctors, but to help patients stick to their treatment plans.

Two columns on how Iran averted a major AIDS epidemic through needle exchange programs; a conservative theocracy is successfully treating drug abuse as if it were Amsterdam.

One-pill-a-day generic AIDS drugs for poor countries are hard to make because each ingredient is patented by a different pharmaceutical company. The Patent Pool provides a way for companies to donate their intellectual property safely.

For decades, AIDS has taken the lives of millions of people and infected millions more worldwide. The key to reducing the effect of AIDS, and even potentially curing it, involves treating patients as early as possible after being diagnosed with HIV, before the disease damages organs. San Francisco General Hospital developed the RAPID program for this purpose, with the goal of “Getting to Zero” the number of new infections and deaths.

Two Iranian brothers worked as doctors to reform how Iran tackles HIV, moving the country toward the harm reduction approach. By providing clean needles and methadone, the doctors were able to lower infection rates, even in prisons.

PrePex, a new nonsurgical circumcision tool, could revolutionize the prevention of H.I.V. and AIDS in sub-Saharan Africa. Cheap and easy to assemble, the device has proven successful in several randomized trials.

Soon, AIDS in Africa will be doing more than killing millions every year. It will destroy what there is of Africa's economy and cause further instability and, perhaps, war. But a nondescript hospital in Brazil could serve as a model for treating AIDS in Africa and worldwide.

Two columns on how Iran is treating its massive epidemic of injecting drug use by tackling it as a health problem, effectively lowering H.I.V. rates among drug users using an approach to drugs known as harm reduction.

In a mountainous region of Lesotho, a man named Tsepo Kotelo visits 20 villages every week on his new motorcycle to provide health care to local villagers. The Elton John AIDS Foundation gifted the motorcycles to Kotelo and his colleagues, allowing them to increase the number of patients they visit by 600 percent. An organization called Riders for Health helps maintain the bikes, ensuring that remote villages will continue to receive medical care.

Ecological toilets that use natural composting to break down waste are simple to construct, waterless and are easy to fix. But as philanthropists are finding, getting these to those that need it most is harder than anticipated.