The World Health Organization (WHO) is warning of an increased risk of disease epidemics in Syria as summer approaches.
The WHO says outbreaks of diseases carried in water - such as hepatitis, typhoid and cholera are likely to spread.
A third of Syrian hospitals are out of action due to fighting in the country and in some areas, up to 70% of the health workforce has fled.
Cases of measles have also reappeared in Syria.
Syrians who have had to leave their homes are now living in overcrowded, unsanitary conditions, and there are real concerns about the provision of safe drinking water.