Millions of children in countries around the world are bearing the brunt of the past year's strong El Nino weather phenomenon, with hunger, malnutrition and disease rampant in the worst hit areas and likely to get worse, UNICEF said in a report published Thursday.

The UN children's agency said that in eastern and southern Africa alone, 26.5 million children are suffering from the lingering impact of El Nino, with one million needing immediate life-saving treatment for severe malnutrition.

El Nino begins as a huge patch of abnormally warm waters in the Pacific Ocean near the equator. That sets off a chain reaction of climate effects that can lead to warmer conditions and drought, especially in parts of Africa, and central and South America.

That added warmth increases the incidence of mosquito-borne diseases. Outbreaks of malaria, dengue and yellow fever occur every time a strong El Nino sweeps across the world.   

"El Nino may be over but its impact is not," UNICEF Canada president David Morley said. "Its devastating consequences have created a dire humanitarian situation for millions of children. Families are selling off assets, skipping meals and doing whatever they need to survive."

The 2015-16 El Nino was one of the strongest on record, spawning severe droughts in some areas and major floods in others.

"In South America, and particularly Brazil, El Nino has created favourable breeding conditions for the mosquito that can transmit Zika, dengue, yellow fever and chikungunya," the agency said in its report.

La Nina worries

UNICEF said vulnerable children would face even more serious challenges if La Nina develops. That's a cooling phenomenon that sometimes follows right on the heels of El Nino. The aid agency says La Nina could contribute to the spread of the Zika virus to areas that have not yet been affected.

AFRICA-DROUGHT/SOMALILAND

A farmer works in an irrigated field near the village of Botor, Somaliland in April. Across the Horn of Africa, millions have been affected by a severe El Nino-related drought. (Siegfried Modola/Reuters)

Vulnerable children and their communities need help to prepare for the possibility that La Nina will make the existing humanitarian crisis even worse as climate change leads to more frequent extreme weather events, UNICEF said.

"Climate change impact comes in many colours," said Dr. Jay Keystone, a tropical disease expert at Toronto General Hospital. "The assumption is that climate change plays a role because we know that temperature makes a difference.  With increases in temperature, you get increased mosquito breeding … and [higher temperature] increases the viral replication within the mosquito and therefore accelerates transmission."

Keystone said the fallout from El Nino could lead to large numbers of people moving into urban areas — something that can exacerbate the spread of serious insect-borne diseases like dengue and Zika. Malnourished children are especially vulnerable, he said. 

The UN Food and Agriculture Organization estimates that 60 million people are facing food shortages because of droughts linked to El Nino.

"EL Nino has caused primarily a food and agricultural crisis," FAO director general Jose Graziano da Silva said Wednesday at a meeting of UN agencies in Rome, which focused on the impact of El Nino in Africa and the Asia Pacific.

Da Silva said almost $4 billion US is needed to meet the humanitarian demands of countries affected by El Nino.   

With files from Reuters and the CBC's Kas Roussy