Rural northwest Nigeria has been ravaged by gangs of bandit militias who raid villages, loot cattle and kidnap people, holding them for ransom in camps deep in the forests that carpet the region.
Hundreds of thousands of people have been displaced across the northwest and central regions, and thousands killed.
The impact rivals that of a 13-year jihadist conflict in the northeast of Nigeria which has claimed more than 40,000 lives.
MSF, one of the few international agencies to be active in the northwest, said the complex crisis has fuelled a surge in severe acute malnutrition among youngsters.
In Katsina state alone, nearly 44,500 children have been admitted to nutrition programs this year, and aid agency and local health authorities are preparing for this to rise to 100,000 by year's end.
Nafisa Sani, a senior Katsina health official, said the state is seeing "high" numbers of malnutrition even for a region that often struggles with children malnourishment.
The Kofar Sauri in-patient clinic in Katsina city was set up to treat 200 patients, but admits up to 350, with mothers often sharing beds in tented wards. Other health facilities see a daily flow of hundreds of mothers seeking help.
MSF's in-patient sites in Katsina will expand capacity to 500 beds next month to attend to growing need over recent weeks, but complicated cases rose 40 percent just over the last week.
"We have measles ongoing, there is a hunger gap and with banditry we have a lot of displaced. It takes a toll on children," said Dr Yakubu Abubakar, a paediatrician working at one MSF Katsina city clinic.
"And this is just one state."
MSF said in Gummi in neighbouring Zamfara state, its teams screened more than 36,000 children under five years old in June, following a nutrition alert.
More than half the children were malnourished. One in four was severely malnourished and in need of urgent medical care.
UNICEF says Nigeria ranks first in the continent and second in the world for child malnutrition. Around eight million children in the northwest are undernourished, the agency said.
Fear of attacks or violence from bandit militias based in nearby Rugu forests in Katsina's western areas near the Niger border has kept many families away from farming the land.
Just this year, around 20,000 people were displaced by violence or threats in three areas of Jibiya local government area, a local official and community leaders said.
Many crossed the border to stay with families in nearby Niger, others shelter with families in Katsina city or other towns, but some are staying in two camps near the city.
"People are fearful of being kidnapped, killed or displaced," said Nuhu Iliya, a primary health care official in Jibia local government authority.
"Parents are struggling to get what they need to eat, so the babies and children suffer."