SIOLIM, India — At the faded one-story medical clinic in this fishing and farming village, people with depression and anxiety typically got little or no attention. Busy doctors and nurses focused on physical ailments — children with diarrhea, laborers with injuries, old people with heart trouble. Patients, fearful of the stigma connected to mental illness, were reluctant to bring up emotional problems.

Last year, two new workers arrived. Their sole task was to identify and treat patients suffering depression and anxiety. The workers found themselves busy. Almost every day, several new patients appeared. Depressed and anxious people now make up “a sizable crowd” at the clinic, said the doctor in charge, Anil Umraskar.

The patients talk about all sorts of troubles. “Financial difficulties are there,” said one of the new counselors, Medha Upadhye, 29. “Interpersonal conflicts are there. Unemployment. Alcoholism is a major problem.”

The clinic is at the forefront of a program that has the potential to transform mental health treatment in the developing world. Instead of doctors, the program trains laypeople to identify and treat depression and anxiety and sends them to six community health clinics in Goa, in western India.

Depression and anxiety have long been seen as Western afflictions, diseases of the affluent. But new studies find that they are just as common in poor countries, with rates up to 20 percent in a given year.

Researchers say that even in places with very poor people, the ailments require urgent attention. Severe depression can be as disabling as physical diseases like malaria, the researchers say, and can have serious economic effects. If a subsistence farmer is so depressed that he cannot get out of bed, neither he nor his children are likely to eat.

In India, as in much of the developing world, depression and anxiety are rarely diagnosed or treated. With a population of more than one billion, India has fewer than 4,000 psychiatrists, one-tenth the United States total. Because most psychiatrists are clustered in a few urban areas, the problem is much worse elsewhere.

As a result, most Indians with mental illness go untreated, especially in poor and rural areas. “There is a huge treatment gap for people with depression,” said Dr. Vikram Patel of the London School of Hygiene and Tropical Medicine, the psychiatrist who began the Siolim project. “In most places in the developing world, 80 percent to 90 percent of people with severe depression don’t receive adequate treatment.”