The rains had come at last to this remote corner of northern Zimbabwe. Workers were harvesting grain from fields that had produced only stunted, parched stalks for three years. On the main road just east of town, gleaming new silos built with American aid money were bursting with corn.

But at the hospital nearby, two girls, Caroline, 2, and Chiha, 4, were dying. They lay listlessly on cots, their heads and stomachs bloated and swollen, raw sores on their feet and hands, their thin legs and arms marked by black, charred-looking patches of skin. The diagnosis was kwashiorkor, a disease associated with malnutrition.

I saw them on a sunny day in March last year. Within a few weeks, both were dead. They died just a few miles from the silos, in the shadow of plenty.

Six years after Zimbabwe gained independence, it has made great strides toward improving health and living conditions for its children. The percentage of youngsters receiving immunizations has doubled, and a massive village health worker program designed to promote preventive care has been launched. Although the actual figures are in dispute, it is clear that more children are surviving the critical first five years of life.

This nation boasts Africa's most extensive family planning program, strongly embraced by the government, and, emerging from three years of drought, one of its most vibrant and productive farming sectors. This year, there is enough corn to feed a nation two or even three times Zimbabwe's size.

Yet children in Zimbabwe still are dying of malnutrition and related diseases -- nearly 36,000 of them each year, most of them under age 5, according to health officials. Another 500,000 are being stunted in their physical and mental development because of malnutrition.

In its most recent report here, the United Nations Children's Fund said 30 to 48 percent of the under-5 population suffer from malnutrition, a situation that the Ministry of Health has called "a national disgrace."

"We feel we have made some very significant progress, but the improvements come slowly," said Office Chidede, the country's secretary of health. "There's no question that it is a long, difficult struggle."

The reasons are a mix of poverty and politics. While Zimbabwe has the most productive commercial farming sector in Africa, researchers have found much of the country's malnutrition among the children of farm workers. As in other countries in eastern and southern Africa, including Zambia, Kenya, Tanzania, and Malawi, government pricing policies generally have favored export crops and corn at the expense of traditional crops that peasants once relied on for a balanced diet.

Despite a strong effort to build rural clinics, most of the government's health resources go to urban hospitals and a medical system that emulates those of highly developed western nations.

The highly touted family planning program is mired in political disputes and turf fights, and critics contend it emphasizes statistics over actual performance. Zimbabwe's birth rate remains one of the world's highest.

These children are not dying of exotic tropical diseases. The main killers are similar to those prevalent among children in England and Wales at the turn of the century -- malnutrition, diarrhea, pneumonia, whooping cough, measles, diphtheria and tetanus.

Although death certificates invariably cite one of these diseases as the cause, most children die from a combination of infections and hunger. They die "not because they lost a battle" against one disease, "but because they lost a war," said UNICEF in its report last year on "The State of the World's Children."

It notes that illnesses are more frequent because environmental conditions -- unclean water, poor sanitation, overcrowded housing -- help spread infection. Children's resistance is also lower because they are either inadequately fed or have not recovered from previous bouts of illness.

The lethal combination, said UNICEF, means that an illness such as a cold or diarrhea, which is only a temporary setback for a well-fed child, "is often the first step toward an early death" for a malnourished one.

Child death rates in England and Wales started to fall long before the introduction of medical breakthroughs such as immunization and antibiotics. The real change began with better nutrition, followed by environmental improvements such as cleaner water supplies, sewage disposal and better housing and working conditions. A Focus on Poverty as Cause

UNICEF contends that a low-cost approach emphasizing immunization, prolonged breast-feeding, growth monitoring and oral rehydration therapy for children suffering from diarrhea could reduce child deaths by at least half. But some health experts here argue that while the UNICEF approach is worthwhile, the real cause of malnutrition is poverty, and the cures -- clean water systems, better housing and food -- cost money that the vast majority of rural black Zimbabweans do not have.

"Rural health care has improved greatly here and there are many programs dealing specifically with childhood," said David Sanders, a pediatrician and lecturer at the University of Zimbabwe medical school. "But you can only get so far with medicine. The real burden on children can't change substantially until socio-economic conditions do."

The boom economy of white Rhodesia was built on a foundation of abundant land and cheap labor. About 6,000 white farmers held roughly half of the country's arable land. The other half -- the sandier, more parched, less-productive half -- was divided among a million peasant farmers.

Because the land was scarce and unyielding, most peasants barely could coax a subsistence living from their soil. Instead, many became part of a vast human reservoir willing to work long hours on the white man's farms and in his mines.

The large estates resembled small feudal kingdoms, where the farmer's word was law. He provided food and housing to his workers and the large families that lived with them. Conditions were often primitive and wages minuscule. At the time of independence in 1980, according to a government commission, the average farm worker's wage was about $30 per month.

The white farms continue to produce more than half of Zimbabwe's surplus food. Their tea, coffee, peanuts, soybeans and cotton also constitute the country's largest earner of foreign exchange. As a result, the farmers enjoy a certain immunity from the changes wrought by black-majority rule.

While occupational health and safety laws cover factories and other work places, health inspectors in Chinhoyi say there is no specific law covering living conditions on the commercial farms. Because the farms are private property, they also are excluded from large-scale, aid-assisted programs to build wells and toilets and provide village health workers in rural areas. Survey Finds Income Low, Living Grim

"Conditions are improving but there are many places where things are very, very bad," said Michael Mawere, general secretary of Zimbabwe's largest farmworkers' union. "There are places with no toilets and no fresh water. The government feels the same way as we do, but things move very slowly."

Just how slowly can be seen from a University of Zimbabwe survey last year of Mashonaland West, where Chinhoyi is located. It is the province with the greatest proportion of commercial farm workers. Average income here for a family of six was about $50 a month, most of which was spent on food, according to the survey. Only 20 percent of the workers had access to functioning toilets, and the average number of people using each toilet was 40. Nearly half the children under 5 suffered from diarrhea, an indicator of poor sanitation and an illness that often contributes to malnutrition and dehydration.

A typical example is a corn farm in the Doma area. Its white owners live in a comfortable farm house with running water, electricity and a 20-inch color television, surrounded by an eight-foot-tall chain link fence topped with barbed wire.

Outside the fence, down the hill, live 42 black families -- about 250 people in all -- with access to four toilets. They sleep in dark, poorly ventilated one-room huts where infections spread rapidly. They get their water from one pipe.

The drain is blocked, so the water has overflowed and forms a stagnant swamp through which children must walk to get to the pipe. Mosquitoes breed in it, as do snails, hookworms and other parasites. Four cases of typhoid were reported here last year -- and doctors estimate that for every reported case, 10 more go unrecorded.

At Wildene farm nearby, 115 families get their only water from a well pumped into a small, open cistern about a mile's walk from their huts. The water is green and brackish. "It was meant to grow coffee, not for the people," said a health inspector who accompanied a reporter on a tour of the area.

If the children survive birth, they often enjoy six to nine months of good health and weight gain on a diet of breast milk. But when they are taken off the breast -- often too early because mothers want to get pregnant again, and breast-feeding retards ovulation -- their health begins to fade.

A 1984 survey cited by UNICEF showed malnutrition among children of farmworkers jumped in one rural area from 21 percent in the first year of life to 66 percent in 4-year-olds. "The babies are nice and fat for the first six months," said Sanders. "Then the charts begin to fall off." Some Problems Begin With Water

There are many reasons for the drop-off. Bad sanitation and water make the children more prone to water-borne diseases and diarrhea, which destroys their appetites and their ability to retain nutrients from the food they eat. The standard farm workers' meal is often a hard cake of corn flour, called sadza, and a relish of vegetables. It is often prepared only once a day because of lack of fuel.

It is cold and indigestible for young children, and their stomachs are too small to eat the large quantity necessary to provide the minimum necessary protein. Nutrient-rich traditional foods like peanuts, millet and sorghum have declined in availability either because the government has pegged them for export or because they are simply not as profitable to grow or as easy to prepare as corn.

Social and seasonal factors also come into play. Girls tend to go hungrier than boys, and older children get more food than their younger siblings. In peasant farming areas, the worst months are just before the harvest -- October through January -- when old grain stocks are lowest. But for the children of farm workers, the risk continues until the harvest is over in June because workers have to concentrate on the fields.

"When it is time to pick the crops, workers are paid based on how much they pick," said Grace Changata, a government nutritionist in Chinhoyi. "So they work all the time, and they leave their children at home alone. No one is there to cook for them." Farmers 'Are Very Individualistic'

Not all the farms show the same conditions. At Summer Hill, a farm owned by J.W. Hall, the 80 resident families have ventilated cottages and electricity. Each also has a small vegetable plot with seeds provided by the farmer. Hall, who said he is motivated by a deep belief in Christianity, said he invests more than $12,000 a year in improved conditions.

"Farmers obviously are very individualistic people," said John Laurie, president of the Commercial Farmers' Union. "There have been significant improvements and major strides on many farms, and there have also been others that lag behind. We understand that these must be upgraded but we don't want to see legislation that could affect the viability of the entire farming sector."

Others contend that despite the good-faith efforts of some farmers and of the government, conditions on some farms actually are worsening.

The official minimum wage for farm workers is only $50 a month, well below the government poverty line but still too high for many employers. They are increasingly relying on migrant laborers, many of them refugees from Mozambique, who are willing to work for less. Total employment on the farms is dropping as farmers turn increasingly to mechanization.

Before the minimum wage, farmers generally provided rations, the quality of which varied widely. Now, workers must supply their own food and generally are required to work longer hours, leaving less time to work their own small plots. The result is often malnutrition.

"My impression is that there hasn't been any significant change in living conditions," said Rene Loewenson, a community health researcher at the University of Zimbabwe. "Even worse, you get the impression that the momentum gained at independence is now close to gone."

Health officials say they are doing what they can to increase the amount of money spent on rural programs. But statistics cited by UNICEF indicate that 44 percent of publicly funded services still go to big city hospitals that serve less than 15 percent of Zimbabwe's population. Only 24 percent goes to rural areas, where 85 percent of the people live. Seventeen percent of the country's doctors and 32 percent of its nurses work in those areas.

Foreign donors are chipping in. The World Bank is helping fund a massive national health plan. The Italian government has donated more than $3 million to upgrade Chinhoyi hospital. But that kind of project, emphasizing curative rather than preventive care, is not what Zimbabwe most needs, some experts say.

"Until we can get conditions improved on these farms," said a doctor at Chinhoyi, "that $3 million won't be worth very much at all."

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