Abstract
During a recent series of experiments by the Department of Physiology of the University of California there appeared a very high rate of mortality in young rats. These rats, ranging in age from 3 to 8 weeks, were brought to us for protozoological examination. The symptoms were as follows: yellowish watery faeces; haemoglobinuria in some cases; anemia; and decided lack of muscular coordination. Twenty-three such rats were examined by us. They were on a raw milk diet.
At biopsy and autopsy the duodenum was quite inflamed, while the jejunum and ileum were frequently black with congested blood. The lungs were often hyperemia The macroscopic appearance of the liver, spleen, and kidneys was normal.
Microscopic examination revealed the presence of a far greater number of Giardia than ever before observed by us in rats. They were most abundant between the limits of 6 and 20 inches below the stomach in the jejunum and ileum. They were so abundant that the microscopic field contained countless numbers of these protozoa, while tissue scrapings from the wall of the intestine revealed them massed on the surface of the cells, apparently feeding on tissue juices.
Potter 1 distinguishes 2 species of Giardia from the rat: G. lamblia and G. muris. The forms found in these rats were of the G. lamblia type in the majority of cases, occasionally accompanied by G. muris.
Due, however, to the fact that the disease was of such an acute nature, death occurring in from 24 to 48 hours, a concurrent bacterial infection was suspected. Cultures were therefore made asep-tically in lactose-fermentation tubes from heart, liver, and intestine of typically diseased rats with the thought that we might recover one of the paratyphoid group.
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