Militias in the region, known locally as bandits, routinely attack communities, loot villages and carry out mass kidnappings for ransom, driving what the international aid group called a "neglected humanitarian emergency."
MSF said its teams in five northwestern states treated 171,465 malnourished children last year and admitted 32,104 to hospital for life-threatening malnutrition, a 14 percent rise on the previous year.
Many children had died because they arrived "too late to be saved due to the barriers in reaching healthcare," it said.
Nigeria is also experiencing its worst economic crisis in a generation, and people in the north, already suffering the effects of violence and insecurity, have been hit particularly hard.
In December, fighting between armed groups and the army in the northwest forced MSF to evacuate some of its staff in Zamfara state, where clashes broke out around a hospital — a move which highlights the challenges humanitarian groups face in the region.
Last week gunmen kidnapped almost 250 schoolchildren in Kaduna state, where heavily armed criminal gangs on motorbikes target victims in villages and schools, as well as along highways in the hunt for ransom payments.
Many international aid groups operate in northeast Nigeria, where jihadist conflict has displaced more than two million people since 2009.
Violence in northwest and north central Nigeria has also displaced around one million people, according to the UN's IOM migration agency, but aid groups are less present there.
MSF said the crisis — which has also led to recurrent outbreaks of preventable diseases — was "largely being ignored by donors and aid organizations."
"The lack of recognition of the crisis is having a severe impact on the health and humanitarian needs of the population, and delaying the response which is desperately needed," MSF said.
It called on the UN and donors to recognize the crisis and urged the humanitarian community and Nigerian government to take action in the region.
MSF Warns of 'Catastrophic' Malnourishment in Northwest Nigeria
ABUJA — Medical charity Doctors Without Borders (MSF) on Monday warned of "catastrophic levels of malnutrition" and an escalating humanitarian crisis in northwest Nigeria.
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