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“The silent scourge of development”

More than two decades ago Yale public health experts warned that dams along the Senegal River would bring disease. A Yale medical student’s research finds that their predictions have come true.
A letter from Senegal.
Article and photographs by Kohar Jones, M.D. ’05 
In the Senegalese village of Mbagam, health worker Fatou Kine Manga fines those who enter the waters of the Senegal River. Despite her warnings to others, Manga admits to breaking her own rule. “Even me, I go to the river!”
Snails that carry parasites lurk there, threatening infection with schistosomiasis. This debilitating chronic disease attacks the poorest of the poor—those who, like Manga, lack access to clean water and sanitation and rely on infected water for drinking, cooking, cleaning and bathing. Poverty and schistosomiasis are rampant in Mbagam, both despite and because of the dams along the Senegal River.
I arrived in the West African nation of Senegal in September 1998, on my 21st birthday, to examine the health effects of the dams for my senior essay at Yale. This research would later become the topic of my medical school thesis, as well. For two months I lived in the capital city of Dakar, the westernmost point of Africa. Described by a friend as a miniature version of Paris—after a bombing—downtown Dakar had multistory apartments with ornate wrought-iron railings and crumbling facades. Outside the skyscraper that housed the West African Bank, I dropped change on the blankets of beggars with polio. At the West African Research Center, as part of my study abroad program, I studied the country’s economics, politics and culture.
For my monthlong field project, my instructor in the indigenous language of Wolof encouraged me to follow in a Yale tradition and study schistosomiasis along the Senegal River. Twenty-one years earlier, he proudly told me, he had been the interpreter for a Yale team studying the potential effects of the dams on human disease. Wilbur G. Downs, M.D., M.P.H., led the team, which included Herbert S. Sacks, M.D., HS ’53; George A. Silver, M.D., M.P.H.; Eric W. Mood, M.P.H. ’43; Robert B. Tesh, M.D.; and Curtis L. Patton, Ph.D. My Wolof teacher’s enthusiasm sparked my own. When the director of the nongovernmental organization Environment and Development Action in the Third World asked me to conduct an informal field survey on whether schistosomiasis would limit the socioeconomic development of the Senegal River region, I gladly agreed.
Sugar fields, rice paddies and near-desert
That November, I left the city for the Sahel, the region south of the Sahara, to begin my survey. Two months after the rainy season, the Sahel was already tan and dry. Herders wearing the traditional wraparound headdresses of the Pulaar people drove thin cattle over the land. Barbed wire prevented the herds from encroaching on the irrigated plots that nurtured dreams of agricultural development.
From the sugar cane boomtown of Richard Toll I continued a few kilometers downstream to Mbagam, a rice-farming village. My hosts were a prosperous farming family, wealthy enough to own a latrine and a mosquito net for guests. There was no electricity, but at night we gathered with villagers in a neighboring compound to watch television—powered by wires connected to a car battery—under the stars on a dirt floor next to cows. A relative of these neighbors lived in France, where he washed dishes and sent his wages home to support the family, pay the taxes and buy the car that provided power for the flickering images that allowed the villagers to dream of a different life.
The dams along the Senegal River also fed hopes of a new life. Omar Niang, president of the village farming cooperative, praised the dams for doubling the rice harvest. But standing next to a pump that transported water from the river to the rice paddies, he noted the negative aspects. Workers wore uncomfortable plastic boots for protection from infected water, and they all took the anti-schistosome drug praziquantel. “Everything has a good side and a bad,” he said.
Schistosomiasis, named “the silent scourge of development” by the World Health Organization in 1998, is the bad side of dams. It follows water development projects that create the perfect habitat for the snails that carry the disease (See sidebar).
In 1994, less than 10 years after the dams were completed, Mbagam had a disease prevalence of 91 percent. About 2,500 villagers joined the estimated 200 million people worldwide who are infected with schistosomiasis. The other 9 percent joined 400 million people around the world at risk of infection.
The dams and the disease they brought emerged from Senegal’s colonial legacy. Senegal, the former jewel in the crown of colonial French West Africa, became independent in 1960 but maintained close trading ties with France. In 1968, however, France stopped subsidizing the dominant peanut economy just as a drought hit sub-Saharan Senegal. Both peanut farmers and nomadic herders saw their economies and lives devastated. Villagers flooded the capital cities in search of work, and starving masses threatened to undermine political stability. In 1972, amid widespread famine, Senegal adopted French colonial plans to dam and irrigate land along the Senegal River.
With its neighbors Mali and Mauritania, Senegal formed the Senegal River Development Organization (Organisation pour la Mise en Valeur du fleuve Sénégal—OMVS). Dams provided hope for a desperate population. The massive hydroelectric Manantali Dam in Mali promised both electricity and a link between landlocked Mali and Atlantic trade routes. The small Diama Dam at the mouth of the river, between Senegal and Mauritania, would prevent salt water from creeping up the river bed during the dry season, allowing for two harvests of rice each year. Unfortunately, reality never matched the hopes.
By 1988 the dams were completed, but the promised new civilization never came to be. Following the dictates of Structural Adjustment Programs (SAPs) of the World Bank and International Monetary Fund, which demanded a balanced budget, Senegal dismantled and privatized its national health system and agricultural agencies just as they were needed most. Senegalese economists wryly renamed the SAPs “the Suffering of the African People.”
Disease comes to Richard Toll
During my month surveying schistosomiasis, my base was in Richard Toll, home to the Senegal Sugar Company (Compagnie Sucrière Sénégalaise—CSS). My new home became the gated Cité Cadre, where electricity generated by the burning of sugar cane stalks powered the air conditioners of the expatriate and Senegalese managers of the CSS, who directed development in the region. It was a city on a hill, separated from the center of town by a scattering of neighborhoods and the tall green waving stalks of irrigated sugar cane.
Trucks carrying molasses and sugar cubes to Dakar rumbled along the paved, two-lane National Route, dodging horse-drawn carriages, pedestrians and the occasional cow. The paychecks of the sugar cane workers supported a bustling market, a regional economic magnet. Electric lines strung overhead connected cement block homes. Two water towers were under construction. A latrinisation program promised to sanitize the town. Richard Toll was the model of agroindustrial development for the nation.
But development had already brought disease. In 1986, the completion of the Diama Dam blocked the saltwater tongue of the Atlantic. Freshwater snails migrated from a nearby lake through a sugar company canal and into the fresh water of the Senegal River, where their population exploded. The human population of the sugar boomtown was also exploding. From 10,000 when the CSS was founded in 1972, Richard Toll’s population had more than quintupled by 1988, to an official 50,000 (but closer to 75,000) residents, largely due to immigration. Urban amenities had not kept up. An infected migrant worker is believed to have brought the parasite to Richard Toll. The CSS canals became ground zero in a massive schistosomiasis outbreak.
Although there had been 50 isolated cases of intestinal schistosomiasis among migrant workers between 1970 and 1980, before the dam was built, in January 1988 Diokel Dieng, a government health worker in Richard Toll, diagnosed a new case of intestinal schistosomiasis along the Senegal River. By the end of the year, he had found 29 cases. By the end of 1989, there were nearly 2,000. By August 1990, a full 60 percent of the population of Richard Toll was infected with intestinal schistosomiasis. And it spread. By 1998, schistosomiasis had infected hundreds of thousands of people in the Senegal River region. In many towns and villages, as in Richard Toll, the prevalence rates were just shy of 100 percent—only the youngest children, who had not yet had extensive contact with infected water, remained free of disease. It was the largest public health problem facing the region, greater than the looming threat of AIDS and the constant presence of malaria—and all because of the ecological changes wrought by dams and irrigation.
Still, when I asked Aboubakry Gassama, M.D., the head of the CSS health services, whether schistosomiasis would limit socioeconomic development, he said no. Although most workers were sick with schistosomiasis, there were enough healthy migrant workers desperate for a paycheck to replace them. The limiting factor, he said, was the lack of financial resources to irrigate the land around the river. (Of the 600,000 acres that planners had hoped to irrigate by 2000, only 75,000 were in use—the same number that had been irrigated 10 years earlier). This was not to say that schistosomiasis wasn’t a problem. Of every 100 workers waiting on benches that lined the clinic’s long concrete hallway, nursing machete wounds from the fields or parasitic lesions from the Senegal River, Gassama estimated that all but two had schistosomiasis. “If people don’t do anything, then in 10 years they are indisposed, and in 30 years they are dead,” he said.
Return to the States
From Mbagam, I took a donkey cart to the main road to catch a car rapide to the regional capital of Saint-Louis to take a sept place (a seven-seated old Peugeot) back to Dakar to catch my plane home—a century’s worth of development compressed into 24 hours. Descending through the cloud cover over New York City, I appreciated the rains that watered the gardens that provided food for farmers and industrial workers alike. I returned to New Haven, where libraries serve as cathedrals of knowledge and the sum of human experience could be consulted to shape future planning. medline provided information about schistosomiasis and disease outbreak in Senegal. Patton, a professor of epidemiology (microbiology) and one of the original Yale researchers, provided the team’s reports.
The schistosomiasis epidemic, I learned, could have been prevented. In 1972, when the OMVS decided to develop the Senegal River, the link between dams and disease was well-established. Nevertheless, dam planning progressed with minimal attention to public health concerns.
In 1978, the Yale researchers warned development planners that schistosomiasis was a “serious public health problem” that, without adequate control measures, “might be aggravated by irrigated agriculture. … inhibiting both agricultural and economic development.” They recommended a disease surveillance team to track outbreaks and implement immediate control measures. They “strongly urged” that Senegalese groups with “considerable experience” as well as “the necessary trained personnel and mobile units to carry out such work” conduct the health surveys. The only reason the Senegalese weren’t already doing this work was that they were “rather short of funds and supplies.”
Unfortunately, as budgets contracted under the SAPs, the recommendations were ignored. Nothing was done to avert the preventable outbreak of schistosomiasis. And a generation later, I arrived in Senegal to ask if schistosomiasis would limit the socioeconomic development of the river region. After my first visit in 1998, I made three more trips to Senegal, with support from the Fund for Investigative Journalism and the medical school’s Office of Student Research, to explore this question. There was no easy answer, I found. It depended on how you defined development.
For individuals struggling to become masters of their own destiny, schistosomiasis severely limited their progress to greater personal and economic freedom. Sick, they could not work. Without work, they could not pay for health care, school expenses for their children or even food.
For industries struggling to make a profit, schistosomiasis had little impact. There were always healthy workers to replace the sick. The limiting factor for economic development was simply the lack of local money to invest in irrigation, factories and industry. Foreign investors shied away from supporting further irrigation at the edge of a desert.
Instead of boosting macroeconomic indicators, the dams ushered in an era of epidemic infectious disease. Poverty trapped villagers in an endless cycle of infection and reinfection. In retrospect, Patton described it as an “extraordinary example of poor planning.”
The Yale team’s recommendations—disease surveillance, strengthened health systems, implementation of available measures to control disease—remain apt today. Health planning must be part of all development planning.
In Mbagam, where four spigots provided water for up to 3,000 people, Manga continued to violate the very rules she had set to protect the health of the villagers. “Only four flasks a day,” said Manga, bemoaning the daily ration—about eight gallons for each household of up to 30 people. “That’s not enough water for sure. You have no choice but to enter the river. It’s the financial means that we’re missing. Above all, the means.” YM
Kohar Jones, M.D. ’05, is a resident in family practice at Middlesex Hospital in Middletown, Conn. She plans to publish her medical school thesis under the title Germs of Progress: Schistosomiasis in Senegal and the Ethics, Politics and Economics of International Health Research and Development in the 20th Century.
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A disease of poverty and progress
No disease is as clearly linked with development as schistosomiasis. Nicknamed the “germ of progress” in the 1970s for its close association with water development projects that allowed freshwater snails to thrive, schistosomiasis remains the “silent scourge of development.” Though preventable and treatable, it flourishes throughout the developing world. It has infected 200 million people worldwide, and threatens an additional 400 million, primarily in Africa, Asia and Latin America. Of those infected, 120 million people are symptomatic, 20 million have severe complications and 200,000 die each year, more than the number of deaths from AIDS, diabetes, kidney disease, pneumonia and influenza combined in the United States.
Humans are at risk when they enter freshwater sources infested with snails that release fork-tailed parasites called cercariae. Cercariae burrow through skin and grow into worms that inhabit the capillaries of the intestines or bladder. The worms mate and lay barb-tailed eggs that cut through vessel walls, eventually leaving the body in the feces or urine. When people relieve themselves near snail-infested water, the eggs enter the water and hatch, then grow into parasites called miracidia that lodge in the shells of specific snail hosts. Each miracidium gives rise to thousands of cercariae, and the cycle explodes.
An initial acute infection with schistosomiasis is followed by chronic debilitating disease. After an initial itchy rash at the site of cercaria entrance, accompanied by fever, weeks go by with minimal symptoms. The cercariae grow into worms that use molecular mimicry to evade detection by the immune system. Schistosome eggs, not the worms, bring disease. Anemia—often severe, sometimes deadly—accompanies blood loss in diarrhea or urine. In many regions with endemic urinary schistosomiasis, a boy is considered to be a man after blood appears in his urine, thought to be a form of male menstruation.
Severe complications ensue when excess eggs wash deeper into the body, eliciting an inflammatory immune response. Liver scarring clogs the return of blood to the heart. Initial heavy infection with intestinal schistosomiasis can kill with bloody diarrhea, or cause irreversible paralysis if eggs are washed into the spinal cord.
Communitywide access to clean water, sanitation and snail eradication programs can prevent schistosomiasis outbreaks. Praziquantel, a miracle drug discovered in the 1970s, kills both the worms and their eggs in a single dose with minimal side effects. It does not prevent reinfection, but it does prevent serious complications of heavy infection. Unfortunately, all these measures to prevent and treat schistosomiasis are costly, often beyond the means of developing communities. (Happily, the cost of praziquantel recently dropped considerably, increasing access worldwide.)
Schistosomiasis is a disease of poor sanitation, contaminated water, ineffective health systems and unaffordable medications. It threatens impoverished communities struggling to build better lives.
—Kohar Jones
Senegal at a glance
Population living below poverty line
54 percent (12 in the U.S.)
48 percent (urban youth, 40 percent)
40.2 percent
117,714 square miles (slightly smaller than South Dakota)
Arable land
12.78 percent
HIV/AIDS prevalence
0.8 percent (7.4 in sub-Saharan Africa)
Infant mortality
56.53 deaths per 1,000 live births (6.5 in the U.S.)
Muslim, 94 percent
Christian, 5 percent
indigenous beliefs, 1 percent
fish processing, agriculture, phosphate mining, fertilizer production, petroleum refining, construction materials         
Originally published in Yale Medicine, Summer 2005.
Copyright © 2005 Yale University School of Medicine. All rights reserved.

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