288 The Control of Mosquitoes 



there were as many as 200 Americans living there. 

 All suspects arriving at -the hospital were placed 

 in beds under large screened cages located within 

 the screened wards, and the yellow fever cases 

 were kept in these cages during the first five 

 days of their illness. These precautions made it 

 necessary for a mosquito to pass through a cloud 

 of smoke and four screened doors before it could 

 reach a patient, and then escape through a door 

 into the ward, where it must survive a twelve 

 days' search for mosquitoes before attacking a non- 

 immune. It was almost impossible for such a 

 combination to happen, and it never happened. 



When the yellow fever wards were first fitted 

 up, no metal screening was available. Cotton 

 mosquito bar had to be used for screening the 

 buildings, and with care and the precautions taken, 

 it gave satisfactory results. Its fragile nature 

 renders it unserviceable for extensive use, but in an 

 emergency it can serve, as at Ancon. 



With the installation of water and sewerage- 

 systems in Panama, it became unnecessary to use 

 water containers for storage purposes, and as fast 

 as water was installed in each house, the tanks, 

 barrels, cisterns, etc., were removed or destroyed. 

 This assisted to a very large extent in eliminating 

 mosquitoes. But public water and sewer systems 



