The current burden of cholera and diarrheal diseases in the fast-urbanizing areas of low-income nations shows how the urban health agenda remains unfinished and must continue to evolve.

The earlier studies resulted in the development of an oral rehydration solution, which now costs a few cents per packet. This therapy can be administered at home, without assistance, and has replaced the indiscriminate and unnecessary administration of antibiotics to treat diarrhea. WHO, UNICEF, and the U.S. Centers for Disease Control and Prevention have included oral rehydration solutions in their protocols as an essential medicine to treat diarrhea.

As a result of these collective efforts, oral rehydration solution has saved the lives of an estimated 50 million people globally. Decades-old interventions, such as oral rehydration solutions, the promotion of exclusive breastfeeding, and the more recent recommendation to use zinc for diarrhea treatment, have helped to check diarrhea to the much appreciable extent. Additionally, a new oral cholera vaccine, which requires clean water and two doses given two weeks apart, has also helped to reduce massive outbreaks in some badly affected countries.

Even after more than 50 years after its development, oral rehydration solution (ORS) still remains as an important treatment for other forms of dehydration as well, including dehydration-induced kidney injury and Ebola virus disease. 

A recent study found that cities offer greater access to piped water and sanitation but that reported rates of diarrhea increase with greater urban density in lower-income nations. Municipal water systems in dense urban areas are older, poorly maintained, and suffer from low or intermittent water pressure, reducing chlorinations effectiveness. In addition, urban water systems are only effective at fighting water-borne diseases when combined with street cleaning and functioning sewer systems, which are lacking in many lower-income country cities. 

We may need to think about urban health more in terms of economic geography than cityscapes. Societal and medical responses to cholera have helped shape the history of cities. Still, cities will broadly define the future load of cholera, diarrheal disease, and global health.

Bollyky TJ. Oral Rehydration Salts, Cholera, and the Unfinished Urban Health Agenda. Tropical Medicine and Infectious Disease. 2022; 7(5):67. https://doi.org/10.3390/tropicalmed7050067