In an examining room at the Mother of Mercy Clinic in Zerqa, Jordan, Dr. Ibrahim Ghabeish puzzles over a patient’s condition. Somehow Salah, a 3-day-old infant, has contracted dysentery. The infection is relatively common among adults in Zerqa; usually it is contracted by consuming food that has been contaminated by dirty water. But how could an infant, whose only nourishment is his mother’s milk, get infected? After questioning the child’s 25-year-old mother, Maha, Dr. Ghabeish put together a likely scenario.

“The child’s mother was cutting up carrots washed in contaminated water,” he explained. “When Salah started to cry, she brought him to be nursed without washing her hands. She must have transferred the disease when she prepared to nurse him.”

Established in 1982, Mother of Mercy Clinic offers a wide range of general heath care services to thousands of patients — over 26,000 in 2008 — regardless of creed or origin. The clinic, however, specializes in prenatal and postnatal care, giving priority to needy mothers and their infants.

As the clinic’s head doctor, Dr. Ghabeish has treated mothers and infants for years. “People like to come here because they know they will get quality service, that they will be treated in a clean environment run by good administrators,” said the 59-year-old doctor, a Palestinian refugee.

Though only 20 miles northeast of Amman — the increasingly cosmopolitan capital of the Hashemite Kingdom of Jordan — Zerqa struggles with a multitude of problems: escalating crime rates, insufficient housing, inadequate infrastructure, pollution and poverty.

A city of 852,700 people, Zerqa boasts the kingdom’s only oil refinery as well as about 50 percent of its factories. Several military bases also are located in the area.

Attracted by the lure of jobs, many of Zerqa’s residents come from distant areas of Jordan, the Middle East or further afield. While Jordanian nationals fill most of the well-paying factory positions, immigrants and refugees find work in an array of low-paying, labor-intensive jobs. Quite a few of these immigrants first arrived on their way back from the hajj, the annual Islamic pilgrimage to Mecca. Despite Zerqa’s woes, many preferred to remain in the city, believing the availability of work, regardless of its pay, promised a better life than what awaited them in their home countries.

But most of Zerqa’s residents are refugees. By far, Palestinians make up the largest group and most live in a refugee camp located in the center of the city. Thousands of Bangladeshi, Chechen, Iraqi and Pakistani refugee families also call Zerqa home.

Zuheir Baghal, a local business leader, described the city as culturally diverse, yet transient. “People come to Zerqa for work, but they have little loyalty to the city,” he said, looking down at the congested streets from his office window in Zerqa’s business district. “The results can be seen all over.”

What unites this diverse population is Sunni Islam, the religious faith of most of the city’s inhabitants. According to Father Ala’a Alamat, pastor of Zerqa’s Roman Catholic church of St. Pius X, the city’s total Christian Arab community includes no more than 20,000 people, a mere 2 percent of the population. Despite the small numbers, he said, “Christians are an integral part of this society. We share with our fellow citizens’ happy days as well as sad ones.”

“Zerqa’s Christians provide essential social services, such as education, health care, job training and social assistance,” added Ra’ed Bahou, CNEWA’s regional director for Jordan and Iraq. “Christians may be a tiny minority, but their reach is significant.”

Born in Bangladesh, Noor Bahar has lived in Zerqa with her family for decades. Clutching her son, Jandal, Mrs. Bahar said in fluent Arabic that she knew Mother of Mercy would heal her 3-year-old boy, who was running a high fever.

Soon after Mrs. Bahar registered her son, Suhad Abu Shamsia, one of the clinic’s lab technicians, asked a routine set of questions, recorded the toddler’s temperature and drew blood samples.

“We have established a reputation for efficiency, cleanliness and accurate lab testing,” said Ms. Abu Shamsia, who has been working in the clinic’s lab for 12 years. “We also have a wonderful relationship with our community,” the 42-year-old technician added. She is proudest of the relationship between Muslims and Christians that the clinic has come to represent: “We work as human beings and pay no attention to people’s backgrounds.”

Ms. Abu Shamsia pointed to the heavily polluted Zerqa River as the primary source of the region’s infectious diseases, especially dysentery. Raw sewage, as well as untreated factory waste, flows directly into the river, one of the tributaries of the Jordan River. Unfit for human consumption, the river water is used to irrigate farms and as drinking water for sheep and goats. She said children who come to the clinic with severe diarrhea or food poisoning have almost invariably consumed raw vegetables contaminated by the sewage-tainted water.

The Franciscan Missionaries of the Divine Motherhood, an English Catholic foundation, administered the clinic until 2001. Citing a decline in the number of active sisters and a growing commitment to the church in Africa, the sisters transferred the administration of the clinic to the Dominican Sisters of St. Catherine of Siena. Founded in the late 19th century in the city of Mosul, the Dominican community now includes more than 150 sisters drawn from all of Iraq’s churches.

The clinic’s director, Sister Habiba Toma, is a charismatic no-nonsense nun who combines administrative toughness with loving kindness. Admired by her staff and adored by the patients, Sister Habiba knows her patients by name, cheerfully chatting with mothers and children as she walks the clinic’s corridors.

She offered a simple explanation for her and her sisters’ attitude. “I see the face of Christ in every person who walks into our clinic,” she said simply. “Whenever anyone steps into our center we treat them as daughters and sons of the Almighty.”

The sisters’ good will, however, is not always reciprocated. Sister Habiba recalled how once she boarded a public bus and sat next to a woman who, seconds later, shouted derogatory remarks about Christianity, calling the nun an infidel. The woman then abruptly stood up and stormed off the bus. Sister Habiba was taken aback, but kept quiet, praying for the strength to forgive.

When Sister Habiba reached her stop, she got off and walked to her destination. However, a man from the bus caught up to her and, having seen what had happened, expressed his sincere apologies.

While the sisters enjoy a warm rapport with the local population, they note that children often mistake them for Westerners and greet them in English. The nuns reply in perfect Arabic that they, too, are Arabs.

Generous friends of CNEWA and a few European social service agencies fund the clinic, the annual budget of which runs around $175,000. While the clinic has managed to operate successfully within its budget, it faces its fair share of challenges.

Both Sister Habiba and Dr. Ghabeish enumerated, albeit reluctantly, some of the clinic’s current needs. In particular, the Iraqi nun stressed the importance of investing more in preventive health care. “We had a social worker who regularly gave lectures to the women about hygiene, but she retired and we have not hired someone to take her place,” she said. She added that some of her female patients, especially those in abusive marriages, would greatly benefit from a social worker.

Sister Habiba also expressed frustration at not having appropriate health awareness films to play while patients wait to see the doctor. “Not everyone can read the public health brochures,” she said. “We need videos speaking in simple language that can help them easily avoid many of the recurring problems.”

For his part, Dr. Ghabeish put new equipment at the top of his wish list. At present, the clinic outsources numerous lab tests, which he would prefer to conduct internally to ensure more reliable results. Specifically, he mentioned the clinic badly needs equipment for virology testing for highly contagious diseases such as hepatitis. By the same token, Dr. Ghabeish acknowledges that equipment alone does not guarantee quality care; he cited a well-funded and well-equipped clinic nearby that closed because of bad management.

Even with these day-to-day challenges, the clinic’s staff members leave the clinic each day feeling fulfilled. The clinic’s pharmacist, Keffayia Muhammad, has worked at Mother of Mercy for the past 20 years. Framed with a traditional headscarf, her face radiated a gentle smile as she explained the policy of charging patients nominal fees for medications. When asked why she thought people traveled long distances to the clinic, she immediately noted the kindness of the sisters. “Their smile and love are contagious.” And, she concluded, “we have started to act like them.”

Based in Amman, Daoud Kuttab is a former professor of journalism at Princeton University. Photojournalist Nader Daoud regularly contributes to The Associated Press.