Geneva, Switzerland - International health experts believe the wave of illnesses in a remote region of the Democratic Republic of Congo, which had been dubbed "Disease X," is entirely due to known pathogens.

The Geneva-based World Health Organization (WHO) said on Friday that malaria, influenza, rhinoviruses, coronaviruses, and other known viruses had been found in 430 laboratory samples taken from sick people in the region.

Hundreds of people had fallen ill since the end of October in the Panzi district of the southwestern province of Kwango.

The sufferers had flu-like symptoms, including fever, colds, headaches, aching limbs, and breathing difficulties.

The WHO reported 48 deaths, while the local authorities said more than 130 people had died.

A particularly high number of children under 5 years of age were affected.

About 40% of the people in the region are said to be malnourished, and among children, the proportion is estimated to be as high as 60%.

People who do not eat enough and are therefore lacking in nutrients are at a much higher risk of becoming seriously ill from various pathogens.

The Congolese health authorities found it hard to obtain good samples from the remote region because it takes three days to get from the country's capital of Kinshasa to the area.

The WHO team has now been able to thoroughly investigate, and say that their findings "suggest that a combination of common and seasonal viral respiratory infections and falciparum malaria, compounded by acute malnutrition led to an increase in severe infections and deaths, disproportionally affecting children under five years of age."

Multidisciplinary crisis response teams have been deployed to investigate the incident and strengthen measures on the ground.