DIAGNOSIS OF DISEASES CAUSED BY PARASITIC WORMS 41 



Board in the West Indies a combination of the smear and 

 centrifugation methods is used. Two or three smears are 

 made from each sample to eliminate the heaviest cases and 

 the negatives are examined after centrifugation. 



The brine flotation-loop method: This technique was 

 devised by Kofoid and Barber for the examination for hook- 

 worm disease of men in the Army from the Southern States 

 during the war. In this method a fecal sample is thoroughly 

 mixed with concentrated brine. The coarse float is forced 

 below the surface with a disc of .No. steel wool and the 

 container allowed to stand for about an hour for the eggs 

 to ascend. The surface film is then looped off onto a slide 

 and examined without a cover glass. The microscope must 

 be focused on the surface of the drop on the slide. This 

 method gives fine concentration and a very clear preparation 

 for study. It is without doubt the best and quickest method 

 of examination for hookworm eggs and when combined with 

 a preliminary single smear to eliminate the heaviest cases 

 can be highly recommended for use in hookworm campaigns. 

 Unfortunately operculate eggs are not floated by this method 

 so that it cannot be used where it is desirable to detect such 

 forms as the liver fluke, Clonorchis sinensis, and the fish 

 tape worm, Diphyllobothrium latum. Also it is of no value 

 in the detection of Strongyloides stercoralis since the larvae, 

 which in this case are found in the stools, are also not 

 floated. 



Ordinary routine fecal examinations are not sufficient to 

 detect the presence of all types of eggs. Since the eggs of 

 Schistosoma japonicum and especially S. mansoni are not 

 evenly distributed throughout the stool it is necessary to 

 take special precautions in taking the sample when examin- 

 ing for these forms. The eggs of Enter obius vermicularis are 

 rarely found in routine fecal examinations, but this species 

 offers little difficulty in diagnosis on account of the anal 



