Addressing the health needs of the world’s most vulnerable people is often a costly and complicated undertaking. But on rare occasions, if the will is sufficient, it can be simple.

So it is with the No. 2 cause of death among children in low-income countries: diarrhea. Weak health and poor nutrition can make these children especially susceptible to deadly dehydration. Among those less than 5 years old, 1.5 million die from the condition annually, mostly in Africa and South Asia. India, Nigeria and the Democratic Republic of Congo have the highest numbers.

In the past three decades, childhood diarrhea deaths have been greatly reduced, mainly through huge efforts to introduce an elementary treatment. Called oral rehydration salts (ORS), this mix of five basic ingredients that dissolves in water has been called the most important medical advance of the 20th century.

The treatment was improved upon in 2004, when the World Health Organization and Unicef recommended that, in addition to ORS, young children be given zinc supplements. Research showed that zinc, an essential micronutrient found in protein-rich food, lessens the severity and duration of the condition and suppresses future episodes. One study estimated zinc treatment could reduce diarrhea-related deaths by 23 percent.

Yet this intervention has barely been taken up. Since 2000, ORS expansion has stalled, as fights against AIDS, malaria and tuberculosis have taken priority, so that just 39 percent of developing-country children with diarrhea receive it. Worse, less than 1 percent get the zinc supplement.

One problem is that in most of the developing world, zinc is defined as a drug, which means just pharmacies can sell it and only by prescription. Even so, it’s scarcely available. For zinc manufacturers, the developing-world market is unappealing. Given the poverty of the target buyers, profits look to be small, and reaching consumers is difficult.

There are good reasons to regulate zinc. Excessive intake can cause side effects, such as stomach pain and fatigue. As a compromise, the WHO and Unicef should recommend that countries make zinc available over the counter in a variety of locations, including kiosks and grocery stores, as well as pharmacies. That way, caregivers could easily buy it for a sick child.

Making zinc more available has been shown to work. In one district of Cambodia, in a collaboration between the government and the nongovernment organization PATH, village health workers who are neither doctors nor nurses are allowed to dispense ORS and zinc to parents. As a result, cases of moderate and severe dehydration have fallen there.

A partnership between private and public sectors can address the supply issue. Zinc manufacturers are reluctant to enter countries until a market has been reasonably established. But health ministries, foreign-aid donors like the U.S. Agency for International Development, and NGOs such as PATH can help build demand.

One strategy is to give away the treatment, initially, to prime the pump. It’s not very expensive. A full course of ORS and zinc costs about 70 cents.

Parents who try it quickly recognize its value. ORS alone rehydrates the child but doesn’t lessen the diarrhea. With zinc, a kid bounces back faster, appetite and activity return, and a parent’s anxiety diminishes. Plus children who are given zinc are less likely to be given antibiotics, almost always useless against diarrhea and dangerous because they encourage antibiotic-resistant bugs. In one trial of zinc in India, oral antibiotic use fell by 88 percent.

Points of distribution and education could include the community-health centers and other networks that have so successfully delivered childhood vaccinations to the developing world (today 80 percent of all children receive them before age 1). Immunization workers are reluctant to allow others to piggyback on their system; parents whose children have just been pricked can absorb only so much new information. But with developing-world children suffering two to 10 bouts of diarrhea a year, an exception should be made for a short, potentially life-saving discussion about ORS and zinc.

The goal should be for parents to routinely give diarrheal kids zinc as well as ORS, and for the free market to provide it. When the public sector supplies such products free of charge, it doesn’t learn from consumers which flavorings or formulations (syrup or dissolvable tablet) they prefer. Because the market does, it can help ensure zinc is embraced by consumers in a way that will make a life-and-death difference to their children.

(Bloomberg)