What may be deemed proof positive is the practical disappearance of the disease among the naval and military forces of Malta, as the result of boiling the milk, while still continuing among native civilians. Bassett-Smith has noted that in 1905 there were 798 cases among civilians and 245 naval cases. In 1907 there were 457 cases among civilians and only 12 cases in the naval forces.
There are however occasional cases which Shaw has considered as due to carriers. As the organisms are excreted in faeces as well as in urine, and as the course of the disease is so protracted, as well as the convalescence, it would seem that the carrier factor should be of more importance than facts would justify.
Mohler has noted that in Texas, where the disease has existed for twenty-five years, the Mexican goatherds boiled their milk and hence were rarely infected.
Gentry and Ferenbaugh, in Texas, noted that cases of Malta fever were most common in the spring and early summer months when the goats were in full milk and the ranchmen were caring for the kids and teaching them to suckle. The disease in certain areas was called “goat fever” and in others “dust fever,” this latter name coming from the idea that the dust-filled goat pens had to do with the disease.
The souring of milk does not destroy the germs of the disease, hence transmission may be brought about by butter and cheese.
Malta fever was stamped out of Port Said by destroying all infected goats.
Infection may occur: (1) By the stomach atrium (usual); (2) contaminated dust reaching lungs; (3) by subcutaneous injection.
Pathology and Morbid Anatomy
The germs are found early in the blood and spleen; and are also present in lymphatic glands and kidneys.
The blood is most apt to contain them at the height of the fever curve and a striking feature is the appearance in waves of the organisms in blood, urine or milk. While serum immunity reactions are striking features, there is some question as to the conference of immunity by an attack.