 The discovery of a sick Red Howler monkey, (who was found to be suffering from yellow fever) in 1953 provided the first indication that yellow fever was still endemic in Trinidad although there had not been a case reliably reported from Trinidad since an outbreak in 1914.It was discovered that a form of the disease "jungle yellow fever" was carried by Red Howler monkeys ("Alouatta macconnelli" Elliot) who provided a continuous reservoir for the disease and spread by the "Haemagogus s. spegazzini" mosquito which normally inhabits rainforest regions, both at ground level and in the treetops.After Government felling of large stands of native forest, yellow fever was isolated from a patient from Cumaca in the northern range in 1954.