The number of cases of a potentially fatal parasitic disease has increased six-fold in southern Sudan.
Visceral leismaniasis- also known as kala-azar - is the most severe form of the disease.
More than 6,000 people have been infected and over 300 have died in the last year.
The World Health Organization and the Sudanese ministry of health are leading the distribution of treatments and testing equipment to affected areas.
Visceral leishmaniasis is caused by the Leishmania parasite and transmitted via the bite of an infected sand fly.
It is the most dangerous form of the disease because the parasite migrates into the spleen and liver.
It causes high fever, significant weight loss, enlargement of the spleen and liver, and anaemia. If left untreated visceral leishmaniasis is nearly always fatal.
The number of cases from September 2009 until now is more than six times higher than in 2007-08.
The counties of Old Fangak and Ayod in the south of the country are particularly affected.
Dr Abdi Aden, head of the WHO's office for Southern Sudan said "The increased number of cases in Old Fangak, Ayod and surrounding areas is very disturbing and it is becoming difficult to contain the outbreak.
"Before the situation becomes uncontrollable, we must do something about it."
To keep responding to the outbreak over the next six months an additional $700,000 is needed.
This will buy more treatments, diagnostic kits as well as food supplies.
Kala-azar suppresses the immune system making patients vulnerable to other infections like pneumonia and malaria. Those that are malnourished are at particularly high risk of dying.
The disease is difficult to treat - daily injections for a month are needed, so patients need to stay close to health facilities.
But many patients still cannot reach treatment centres due to insecurity, flooding and distance.
Dr Mounir Christo Lado of the Sudanese ministry of health said the kala-azar outbreak could worsen between now and next spring.
"Insecurity, flooding and the lack of health facilities across a vast geographical area are all playing a part in limiting access to treatment for this deadly disease."