The children of Ambohijafy, a rural village among the green valleys and sloping hills of Madagascar’s fertile central highlands, are among the poorest in the world. Yet kids in this village of thatched mud huts dream of rising above their circumstances.

Rakotonirina, a solemn 10-year-old whose father is a fisherman, loves to read books and wants to be a schoolteacher. Twins Rosel and Michel Roland, seven, don’t want to follow their father into farming. One would like to be a soldier, while the other talks of being a doctor.

But half of Madagascar’s children are so chronically malnourished they grow up too small for their age, a condition known as stunting. The odds against these children making it to secondary school, let alone managing an intellectually or physically challenging job, are vertiginous. Research shows that if a child is stunted by the age of two, the damage to their young minds and bodies is virtually irreversible.

Francine Rasoanandransan, 25, the twins’ mother, who is eight months pregnant with her fifth child, frets about her boys, who are not much taller than their four-year-old sister, Leonie.

“They are seven. They should be much bigger,” says Rasoanandransan. According to World Health Organization markers, the children are the same height as a five-year-old.

Rasoanandransan suffered a fever while pregnant and had little breastmilk to sustain the twins after birth. So she weaned them early, at three months, on cassava and water. The diet is poor in nutrients, but cassava is a staple, year-round crop here.

This Indian Ocean island is a biodiversity hotspot, rich in crops and minerals. But it is a poor country, with a mainly rural population of 24 million, projected to double by 2030, and a poverty rate of more than 90% . Villagers here grow small quantities of crops rich in nutrients, like avocado, sweet potato and maize, but the harvest only lasts two months and they are forced to sell the food for cash – much needed for school books, clothes and other necessities.

Malnutrition, in its acute form, still kills here. A third of all child deaths – 18,000 a year – are linked to poor nutrition, not least mothers’ diets and breastfeeding behaviour.

Chronic or long-term malnutrition may not kill, but its effects haunt its victims for ever. A child who is born stunted is prone to disease and will often find it difficult to learn or concentrate properly. The WHO describes stunting as one of the “most significant impediments to human development globally”.

In rural communities, where 70-80% of Malagasay people live, high rates of malnutrition can lead to anaemia, low birth rate and delayed development, perpetuated from generation to generation.

It not only robs children of their future, but countries of their future workforce. A stunted child, will, on average, earn 26% less than her peers. The annual loss of income in Madagascar due to malnutrition is estimated to be $740m (£565m), or 7% of the country’s GDP, according to Unicef.

During the latest political crisis, which followed the 2009 coup, many health centres closed, salaries went unpaid and foreign aid dried up. The little progress made in achieving the millennium development goals was undermined. Today, education, health, nutrition and water access in the nation is among the worst in the world.

In May 2017, the country set a target to reduce malnutrition from 47% to 38% by 2021.

The health minister, Mamy Lalatiana Andriamanarivo, is confident the goal can be achieved by expanding the number of nutrition centres around the country and recruiting more local volunteers to educate their villages on the importance of nutrition. There are currently almost 6,000 centres, covering 29% of the population.

“We are very optimistic that – maybe not in 10 years, but in four to five years – we will reduce the malnutrition rate in Madagascar,” says Andriamanarivo. “We are confident we will win the battle.”

Others are more sceptical. Lovy Rasolofomanana, WaterAid’s country representative, says the plan is vague, and that there is no target to increase sanitation or safe water access – major factors in malnutrition. Less than half of the population has access to safe water, and 88% lacks proper sanitation.

“We need a drastic increase in the number of people with access to safe water and sanitation,” says Rasolofomanana.

If 70% of the population had access to safe water, it would have a “significant impact on malnutrition and stunting”, he says, but adds: “We would need $200m a year. At the moment, the Wash [water, sanitation and hygiene] sector receives $120m.”

In Ambohijafy, water is drawn from a muddy well. In the rainy season, the children often suffer from diarrhoea and intestinal worms. For handwashing, children spit on their hands and rub them together, and they bathe in the river, an hour’s walk away, just once a week.

A long, foot-wide channel in the red earth, being dug in the village, spells progress. A collaboration between WaterAid and the local community, it will bring safe, clean water, from the top of the nearest mountain to 800 people by December.

At the nearest health centre, an hour’s walk from Ambohijafy, Faramalala Ramanandraison, a nurse of 30 years, sees children with respiratory problems in the winter, and fevers and diarrhoea in the rainy season. Most of them have underlying malnutrition, she says. Those suffering from acute malnutrition are sent to another centre, in nearby Ankazobe, for treatment. For those with chronic malnutrition, they advise meat, milk, fish and fruit, a big ask in a poor community.

“Life is getting hard, and food prices are high,” says Ramanandraison, sitting in a small, yellow painted room facing a poster advising handwashing after toilet visits. “People work hard, but they have a lack of food. From October to April, they do not have much food to eat. Six days out of seven, just cassava. They have very few proteins – milk and maybe zebu meat just once a year.”

The local primary school headteacher, Fananirina Rantamalala, paints a stark picture of malnutrition’s crippling effects. “Most of the children here are short for their age. Some find it difficult to concentrate, they get sleepy. They miss school days because of their hunger. Their parents find it very hard to earn money and don’t allow their children to attend school.”

Asked whether they could succeed in their ambitions to be teachers or soldiers, Rantamalala places her hand over her heart. “Life is hard for people with no money. I feel very sad about it. Many children could be good, because some of them are clever. But they are not able to rise above it. In the future, some could succeed to high school. But now, no one.”

Jean-Benoît Manhes, Unicef’s deputy representative in Madagascar, describes the government’s new health target as “both extremely ambitious and not ambitious at all”.

“The main problem in Madagascar is poverty,” he says. “Today, it is 30% poorer than the day of independence in 1960.”

He cites a number of challenges, including the difficulty of communicating basic messages about nutrition and handwashing in a rural country where only 15% of people have electricity. Solutions used by Unicef in other countries, such as flour and oil fortified by nutrients, do not work where the staple is cassava.

“That’s why, for us, community mobilisation is the best solution,” he says.

In Andafiavaratra, a district on the outskirts of the capital, Antananarivo, one such community mobilisation is at play. Four new mothers and their six babies giggle as they listen to Nenette Razanamora, a community worker, who gives advice on breastfeeding, and growing and cooking food. In June, only 49% of babies measured had attained normal growth, while 51% were below average.

But Razanamora hopes that, in time, things will change. “There is one woman whose baby was really vulnerable all year and was not responding well. But I’m proud to see, after coming here, the baby is good now.”