Medical experts have flown in by helicopter because of heavy flooding in the area.
On Thursday, Fangak County Commissioner Biel Boutros Biel said an elderly woman’s death came as a result of an unidentified illness.
South Sudan’s Ministry of Health has said that the disease has mainly affected the elderly and children under 14.
It is also said that the symptoms of the mysterious illness include cough, diarrhea, fever, headaches, joint pain, loss of appetite, body weakness, and chest pain.
WHO officials were deployed to the region to investigate the illness, but they reportedly left the area without revealing their findings to local officials.
South Sudan’s Ministry of Health also said that the Fangak region has recently been heavily impacted by extreme flooding.
This has ramped up the pressure on local health bodies placed by endemic diseases like Malaria and cholera.
Back in November, French humanitarian aid group Médecins Sans Frontières (MSF), or Doctors Without Borders, warned that flooding in South Sudan was a “perfect storm for disease outbreaks”.
Over 200,000 people have reportedly fled their homes as a result of what has been called the worst flooding in the region in more than 60 years.
The UN has blamed the flooding on climate change.
MSF said people affected by the flooding were are at “higher risk of outbreaks and waterborne diseases such as acute watery diarrhea, cholera, and malaria.”
The WHO originally thought the mystery illness could be an outbreak of cholera, which is transmitted in contaminated water.
Like the mystery illness affecting South Sudan, the Centers for Disease Control and Prevention (CDC) says cholera causes diarrhea.
People with severe cholera can develop severe dehydration, which can lead to kidney failure.
And if the disease is left untreated it can lead to death within hours. The WHO sent scientists to Fangak to investigate, and they had to arrive by helicopter due to the flooding.
BBC News reported that the WHO tested samples from patients for cholera. But the samples reportedly came back negative for the infectious bacterial disease.
MSF released a statement earlier this year claiming that the global aid response to the flooding has not been good enough.