The UN Office for Humanitarian Affairs, OCHA, says that more than 50 people have died from kala-azar in the Country this year.
Kala-azar, is a disease caused by protozoan parasites and is characterized by irregular fever, substantial weight loss, swelling of the spleen and liver, and anaemia.
In a report, OCHA said that the disease has killed at least 52 people and sickened 2,447 mainly in greater Upper Nile region.
It said the majority of the cases were reported from Lankien, Old Fangak, Kurwai, Walgak, Chuil, Malakal, Pagil and Bunj areas in the former Upper Nile state.
According to the report, Lankien has most infections with 907 cases, followed by Old Fangak and Kurwai with 733 and 201 respectively.
OCHA also said that health partners have warned that many more people are likely to be infected.
It added that authorities in Malakal have reported an upsurge in cases of kala-azar in Baliet County and called on health partners to scale up response in the affected areas.
In an attempt to decrease vector-human contact, OCHA says health partners are employing a multi-sectoral approach to prevent the spread of kala-azar in the affected areas.
It said that the parasitic disease normally peaks between Septembers to December, every year.
However, UN Office for Humanitarian Affairs says there has been significant reduction in cases and deaths compared 3,079 cases and 79 deaths by this time last year.