Ibrahim Ali al-Jadari's four teenage daughters lie at home on intravenous drips that will soon run out as they, like tens of thousands of other Yemenis, battle a seasonal surge of dengue fever.

Mosquito-borne dengue is the latest challenge facing Yemenis who have endured almost five years of a conflict that has killed thousands, pushed millions to the brink of famine and caused major cholera outbreaks.

"We don't have a penny to pay for (more) treatment. Our children are dying on their beds and we can't do a thing," Jadari said from his makeshift home of rushes and canvas in the hills of Hajjah district, one of Yemen's poorest.