In kala-azar the double temperature rise in 24 hours with the Leishmania bodies in spleen puncture material, instead of M. melitensis, are differentiating.
The short course and more sudden onset of influenza and the more marked pulmonary symptoms of phthisis should prove diagnostic aids.
Liver abscess and empyema with their tendency to anaemia and sweating may prove confusing, but the history, leucocytosis and location of pain should differentiate. Then too the joint and nerve manifestations of Malta fever are absent.
Laboratory Diagnosis.—Eyre obtained cultures from blood from the 2d to 300th day of the disease. He recommended the taking of at least 5 cc. from a vein and that this be done at a time when the fever is at its maximum point—the days when the fever is at its maximum and in the evening of that day. By taking 20 to 30 cc. in an equal amount of citrated salt solution, as described in chapter on blood examination, one should have as great success as had Eyre—158 positives in 235 cases or 65.4 per cent.
It must be remembered that the colonies only appear about the fourth day, becoming quite distinct by the tenth day.
Bassett-Smith takes about 10 cc. of blood in the afternoon during pyrexial waves and distributes this blood in several tubes of broth. He makes plates from these tubes every day. He also recommends the taking of 1 cc. of blood which he allows to clot and subsequently removes the serum and adds bouillon (clot culture).
Agglutination is the chief reliance in diagnosis. As result of two infections in his laboratory Widal uses emulsions killed by ¾% of formalin. He uses the microscopic method in the test with dilutions not exceeding 1 to 200. Such emulsions keep for at least a year.
In connection with agglutination tests Nicolle recommends that the serum be separated at once and removed from the clot and Nègre has shown that by heating the serum to 56°C., for thirty minutes, reactions are not obtained with nonspecific sera.
Some workers prefer the macroscopic agglutination.
Complement fixation methods are of value but the application of such tests is confined to large laboratories.