men of the united nations are landing everywhere soldiers from new york and chicago i'm moving up to fight in the m did that to fight on battlefields of snow in the jungle men from the little towns of montana moving up in the heat of asia africa the caribbean their job is fighting they must be kept safe against disease against the special dangers of the jungle behind all men stand scientists of the western hemisphere these doctors are good neighbors from two american countries the united states and the republic of colombia here with their first battle their weapons the test fuel the sterilized needle between the equator and the panama canal they thought that silence was the enemy was hidden in the green branches of the jungle here the home of jungle yellow fever a man who came here to work or to fight on these dark trails was condemned to grow sick delirious eyes and skin turning yellow death waited for them in the heat of the valley wooden crosses for the young men who dared to walk in the jungle they died from the bite of a mosquito and a few laboratories they put this disease behind glass and started it was a virus it had to be fed on living tissue on unborn chicks and human blood syrup it was dangerous invisible had killed men who worked with it first battle had been won inside the white walls of a laboratory the second battle was here in the heat and wet of the jungle above their heads was the solution to the mystery of jungle yellow fever the guilty mosquitoes lived and bred not impose on the ground but in the tree tops they did not only men but animals especially monkeys and thousands of monkeys grew sick but did not die their blood was a living reservoir of yellow fever mosquitoes which had fed on these monkeys flew down from the tree tops attacked men and inspected them with the vials of yellow fever the ride on these trails became a sentence of  steep for navigation at night they set up their portable refrigerator unit to renew the supply of ice in the morning it is carried on mule back with the needles and syringes a task force against the yellow fever yes it is true that doctors are coming sunday masses just over and in front of the church the news spread it is true it is printed it is signed by the mayor the vaccination will be here in the open air it is a dull cloudy afternoon two hundred miles north of the equator the vaccine is removed from the summit got the answer month to sterilize in boiling water there are people here who read slowly others who have never learned but there's one where they they know one thing more that if we are sick with yellow fever two will surely die and only one will live a few drops of vaccine injected under the skin of the would give them dependable and lasting immunity those whose names are in this book need have no fear of yellow fever that is only one shot and there's no illness afterwards the protection last for years perhaps for life it is a product of the genius of the combined american already five hundred thousand citizens of colombia have been vaccinated now the vaccine is taken to army hospitals where the entire colombian army unit by unit is vaccinated against on the dark islands of the south pacific and the jungles of burma and the solomon in the depths of new guinea and the philippines when we come to take them one by one all men today are safe against yellow fever free to fight the worst disease of all that she has and i'm told that too shall be blasted from the face of the